A Cars forum. AutoBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AutoBanter forum » Auto newsgroups » Technology
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Might be a blown head gasket, might not... How to tell?



 
 
Thread Tools Display Modes
  #1  
Old February 1st 05, 10:44 PM
Don Bruder
external usenet poster
 
Posts: n/a
Default Might be a blown head gasket, might not... How to tell?


My '82 Mazda 626 - 2.0 liter inline four with no computer, in front of a
5 speed stick - has been giving me some weirdness lately that I simply
haven't been able to track down. It's intermittent, so that's not
helping the troubleshooting process. I *THINK* I've got it narrowed down
to two "mostly likely suspect" culprits: Fuel/carb issues, or blown head
gasket. Trouble is, the symptoms could be accounted for by either, or
might even have nothing to do with either one.

Basically, anytime I "get on it" a bit (Climbing a slope and put the
hammer down a little extra to maintain speed, "stomping" on it -
figuratively speaking - while pulling out for a pass, or substantial
speed alteration while cruising) I might get one or more "hiccups"
before the engine really "kicks in" - as if perhaps the extra pedal is
riching out one or two cylinders for a moment. This misbehavior is
SOMETIMES accompanied by a few quiet "pop-pop-pop" type backfires out
the tailpipe, other times, it's not. On a might-be-related note,
occasionally, I get a single, noticable (but not particularly
impressive) "pop" out the tailpipe at shutdown, usually about 3-8
seconds after the engine has stopped spinning - The timing of this
"shutdown pop" is invariably such that if I turn off the key and
immediately start to get out of the car, the "pop" will happen just
about the time I'm flipping the door shut. This "popping", whether it
happens while asking the engine to work harder, or at shutdown, seems to
say to me that there's too much fuel getting dumped into the beast for a
complete burn inside the cylinder(s), so the leftover is burning in the
exhaust.

Generally, dropping RPMS below about 3K will "clear" the problem when it
happens, but there have been a few times when I've darn near come to a
stop before getting the engine to "even out" and pick up the load.

Redline on the tach for this car is 6K, with the "sweet spot" running
around 2800-3200 RPM depending on gear. book specs max output of this
engine to be at 2750 - my usual driving and shifting habits tend to keep
the revs between 2500 and 3000 unless I'm doing sustained high-speed
work like freeway travel, climbing a slope, or substantial speed
alteration. Freeway driving on a 70 speed-limit stretch, ferinstance,
usually puts the revs in the 3300-3600 range in 5th. Hill-climbing might
have me winding it up to the same range in third to keep to the
double-nickel - Can't use 4th/2500-ish for that, as doing so will lug
the engine bigtime when trying to climb. Likewise, dropping down to
second isn't a practical option, since doing that would have me trying
to wind it out to about 4K to keep up with traffic on the slope.

All in all, when this happens, it feels a LOT like back when I had
timing trouble due to the distributor "lockdown" bolt being loose,
allowing the distributor to flop around and throwing timing all over the
place at random. That isn't the issue this time... That was the VERY
first thing I checked when I started seeing the problem. Timing is as
close to dead on as I know how to get at 5 BTDC at idle with vac.
advance disonnected/plugged, exactly as specced, and the distributor is
solidly bolted down.

I've considered plugs/wires/rotor/cap as the culprit. Replaced 'em all.
The car was due for a new set anyway, although not desperately. No
change.

I've wondered about a plugged exhaust - That doesn't seem likely,
though, unless perhaps there's a chunk of something that shifts around
to plug it up, then falls away to free the exhaust path. This problem
doesn't happen either predictably, or consistently. There's a much
better chance of me seeing it happen in certain situations, but
reproducing those situations *DOES NOT* always reproduce the problem - I
may have it hit while climbing what's known around here as Lakeside Hill
6 nights in a row, then not see it happen at all for several nights,
then have it happen once, and not happen again for a week. The
intermittent part is what's driving me nuts.

At this point, I'm wavering between suspecting fuel issues and a blown
head gasket. (And if that turns out to be the case, I'd bet a dollar to
a donut that it's blown between the #3 and #4 cylinders)

As far as fuel, I was suspecting the float may be acting up - I
sometimes get a similar power drop-out while under acceleration on the
flat and the road is curving to the right - Nowhere NEAR as severe as
when I see/hear/feel it when asking the engine to "work harder", but
enough to be noticable as a distinct "miss" or "drop-out". Thing is, I
rebuilt this carb *FOUR COMPLETE TIMES* just a bit over a year and a
half ago, each time even more carefully than the last, while trying to
track down why the beast was failing California smog. (Mondo-high HC,
low CO2) That problem turned out to be a cracked vacuum hose controlling
the air-injection valve. As I said, four complete carb rebuilds, and
each one done more carefully than the previous - I wouldn't be surprised
to find out the carb was/is in "better than brand new" shape when I
finished that little fiasco, so I've got some serious doubts as to carb
problems. I can't rule them out completely, but it just doesn't quite
fit with what I know.

The head gasket is likewise a suspect. But not seeing the problem
consistently makes me wonder if it's even a reasonable suspicion.

I've got no idea how many actual miles on this engine - Speedo cable was
broke when I bought the car it was originally in, had been for an
unknown amount of time, and stayed broke for the better part of a year
as I drove it around a high-milage paper route and worked on other more
important issues with the car. Now that I've swapped the engine into
this vehicle due to the wreck that wiped out the original one, I'm even
more clueless as to the actual miles the engine has gone. Supposedly,
this engine was rebuilt (for the original vehicle it was in) back in
'92, but I have no way to confirm or refute that claim.

It uses a little oil - 1/2-3/4 quart or so between oil changes, with, I
suspect, most of that being burned after bypassing the valve-stem seals
- Some mornings, I get a puff of blue smoke at startup and for a short
time after, and occasionally get some smoke on *REALLY* heavy
acceleration, but otherwise, nothing noticable in that department.

All four plugs were scaled heavily, #1, #2, and #3 with a gray-ish tan
"compressed powder" that flaked right off easily with a toothpick when I
did the plugs/wires/cap/rotor change. Once I get rid of that build-up,
the electrodes on the plugs looked close enough to brand new. The #4
cylinder's plug was *VERY SLIGHTLY* moist - just barely enough to detect
- and a good bit darker in color than the other three, suggesting to me
that it's probably the place where the oil is going. The rest were dry.
Like the others, the #4 plug cleaned up loking practically new.

Coolant in the radiator has a very slight rust/brownish tinge to the
usual green color, and when I let it cool and pop the cap, sometimes
shows a "froth", like the head on a glass of beer. No bubbling that I
can see when looking in the radiator with the engine running. No sign of
oil that I can find. Drawing a coolant sample while the engine is
running, putting it someplace to "settle", and checking on it later
shows only the slight brownish tinge I mentioned, with no oily layer
floating, or anything settling out - basically, looks like healthy
enough coolant that's been in contact with a little rust.

No water in the crankcase that I can tell. Oil filler cap usually (and
always has, since the day I bought the car) shows a TINY bit of
"mayonaisse" in the deepest crevices, but nothing more than I'd expect
from condensation. Definitely nothing even remotely like what I'd expect
to find if there was any significant amount of coolant leaking into the
oil.

Usual head-gasket failure on these engines is the "skinny spot" betwwen
the #3 and #4 cylinders, sometimes between #1 and #2. Never heard of one
that broke between #2 and #3 without filling the crankcase with
water/radiator with oil.

So, WITHOUT lifting the head, is there any practical way to confirm/rule
out a blown head gasket? I'm stumped on this one.

I guess I *COULD* "shotgun" the problem by swapping in the freshly
rebuilt spare engine I've got sitting here, but that seems like an awful
lot of effort when the current engine is running QUITE well - MOST OF
THE TIME...

Anybody got any thoughts for me?

--
Don Bruder - - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.
Ads
  #2  
Old February 1st 05, 11:42 PM
Anthony
external usenet poster
 
Posts: n/a
Default

Don Bruder > wrote in news:3LSLd.4869$m31.64637
@typhoon.sonic.net:

<snip>
>
> Anybody got any thoughts for me?
>


A compression test will rule out the head gasket. The problem seems too
intermittent for a head gasket. Sounds like a carb problem, or vacuum, or
even a weak coil/corroded connection.




--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

Remove sp to reply via email
  #3  
Old February 2nd 05, 11:38 AM
Anthony
external usenet poster
 
Posts: n/a
Default

"TeGGer®" > wrote in news:Xns95F0CEBBF13Eteggeratistop@
207.14.113.17:


>
> A PRESSURE TEST, not a compression test. Different.
>


Depends on how bad the head gasket is...hehe...but you are correct.





--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

Remove sp to reply via email
  #4  
Old February 2nd 05, 02:57 PM
William R. Watt
external usenet poster
 
Posts: n/a
Default


A hand held vaccum guage can tell if there is possible a gasket leak. I'd
plug mine in and rev the engine at idle. I suppose a dash-mounted vacuum
guage might show something when the problem actually occurs. There's a
guide to diagnosing engine problems with a vacuum guage on my website (see
below) under "Cars".

I have a Chilton import car manual for 1983-90 but it doesn't show if the
626 has transistorized points in the distributor. When that starts to go
you can get intermittent timing problems but I can't imagine how it can
cause such delayed ignition after the ignition is turned off. Some auto
parts stores will test the ignition module for free. I've had one off an
'89 Fesitva (Ford/Mazda) tested. The printout test for low and high speed
conditions so they differ somehow.

As for possible emisson control problems, I don't know what the 82 Mazda
has on it but a Haynes emission control book says the following in the
troubleshooting section:

Hesitation or stumble on acceleration:
- defective acclerator pump in carburettor
- defective throttle position sensor or circuit
- defective air temperature sensor or circuit
- defective MAP (mass air pressure?) sensor or circuit
- ignition timing
- trottle bore or plate

Backfiring:
- vacuum leak in PCV or canister purge line
- defective air injection valve
- ignition timing

Engine diesels (runs on) when shut off or dies too fast:
(preignition?)
- vacuum leak
- EGR valuve stuck closed causing overheating
- heat control valve stuck closed
- idle speed too high
- excessive engine operating temperature

Hope that helps.


--
------------------------------------------------------------------------------
William R Watt National Capital FreeNet Ottawa's free community network
homepage: www.ncf.ca/~ag384/top.htm
warning: non-FreeNet email must have "notspam" in subject or it's returned
  #5  
Old February 2nd 05, 04:01 PM
Don Bruder
external usenet poster
 
Posts: n/a
Default

In article >,
Anthony > wrote:

> Don Bruder > wrote in news:3LSLd.4869$m31.64637
> @typhoon.sonic.net:
>
> <snip>
> >
> > Anybody got any thoughts for me?
> >

>
> A compression test will rule out the head gasket.


Indeed it should - I keep meaning to do a compression check, but never
when both I and the sun are up so I can read the gauge! I'll see about
getting one done this afternoon. (My schedule's equivalent of "morning"
- As I type this message, it's roughly my equivalent of "going on
midnight", and I'm just about ready to roll into the sack.)

> The problem seems too
> intermittent for a head gasket.


I sure can't argue with that... That's part of why it's taking so long
to pin this down - It just won't repeat predictably. As mentioned in the
original post, a situation that does it one time might not do it the
next time, or it might do it half a dozen times in a row, only to vanish
on the 7th time when I'm actually TRYING to get it to happen. I'd expect
a bad gasket to make the problem happen every time.

> Sounds like a carb problem,


This SEEMS like it would be the most likely scenario - Perhaps a
sticking/sunk float, which would basically let the fuel pump blast an
overdose of gas into the bores of the carb, rather than letting the
venturis pick up what they're actually supposed to.

> or vacuum,


Yesterday afternoon, did the "unlit propane torch" test on all the vac
lines I can get to with the torch head (which was all of them but one,
and that one line was replaced with brand new after one of the carb
rebuilds, so I don't expect it to be bad) and couldn't find anyplace to
put it that caused any observable change in engine sound/speed. I
*THINK* it's probably safe to rule out a vacuum leak.

> or even a weak coil


Being more than a little electronics-savvy, I've never understood the
whole "weak coil" concept - Either a transformer (which is all the coil
is) works, or it doesn't - To my electronics knowledge, It's a pure
binary "go/no-go" thing, with no "middle ground" available. Ignoring
that, assuming that the trouble is indeed the coil, I'd once again
expect the problem to be reproducible at will - Just put the vehicle in
the same situation as the last time, and watch it start acting sick.
That doesn't happen, though.

> corroded connection.


If this is the case, it's something I haven't been able to find. Which
doesn't bode well for me if it actually is the source of the trouble...

--
Don Bruder - - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.
  #6  
Old February 2nd 05, 04:12 PM
Don Bruder
external usenet poster
 
Posts: n/a
Default

In article >,
(William R. Watt) wrote:

> A hand held vaccum guage can tell if there is possible a gasket leak. I'd
> plug mine in and rev the engine at idle. I suppose a dash-mounted vacuum
> guage might show something when the problem actually occurs. There's a
> guide to diagnosing engine problems with a vacuum guage on my website (see
> below) under "Cars".


I'll take a look at that and see if it'll help at all.

> I have a Chilton import car manual for 1983-90 but it doesn't show if the
> 626 has transistorized points in the distributor.


I'm using the factory service manual for this beast. It's an '82.

'83 model year was the first substantial change to the 626 since 1978.
Quite similar to an '82 engine, but "similar" isn't "same". Dunno exact
details on the differences besides "It's crosswise".

Yes, mine uses the "breakerless points" - Mazda calls the module the
"ignitor" - A hall sensor, or similar type of "Hey, stupid! It's time to
fire the coil!" rig. That unit lives under the rotor in the distributor,
and is the only thing electronic on this engine. And boy, do I hope it
isn't going bad, since trying to replace it looks to be a project that
ranks right up there with finding hens' teeth. The actual replacement
ain't so bad, but first you have to find a replacement module, and good
luck doing that...

> When that starts to go
> you can get intermittent timing problems but I can't imagine how it can
> cause such delayed ignition after the ignition is turned off. Some auto
> parts stores will test the ignition module for free. I've had one off an
> '89 Fesitva (Ford/Mazda) tested. The printout test for low and high speed
> conditions so they differ somehow.
>
> As for possible emisson control problems, I don't know what the 82 Mazda
> has on it but a Haynes emission control book says the following in the
> troubleshooting section:
>
> Hesitation or stumble on acceleration:
> - defective acclerator pump in carburettor


No evidence for this one. Acc. pump dumps what looks to be real close to
the specified amount of gas down the bore when the pedal is mashed. I'd
have to try (and it'll be an interesting task...) to catch the fuel
charge to see how close the amount actually is, but it appears to be
about right.

> - defective throttle position sensor or circuit


As mentioned above, only eletronics on this engine is the "breakerless
points" module in the distributor. Not counting my MP3-capable CD
player, the digital clock in the dash contains more
electronics/computing power than all the rest of the car combined.

> - defective air temperature sensor or circuit


Nonexistent on this engine.

> - defective MAP (mass air pressure?) sensor or circuit


Same as above.

> - ignition timing


Doesn't APPEAR to be a problem, at least when checked as per book specs.
May "go bad" as revs/load increases, but I haven't got a way to test
that, since I've never managed to get the problem to happen without the
speedo reading 35+, and I can't run that fast and hold a timing light at
the same time

> - trottle bore or plate


Pray elucidate? I'm assuming that means "throttle bore or plate
dirty/damaged"? If so, I think that idea can be written off. Both are
"squeaky-clean", and neither shows any visible damage.

> Backfiring:
> - vacuum leak in PCV or canister purge line


Couldn't find any vacuum leaks when I did the unlit propane torch test
yesterday.

> - defective air injection valve

Possible - I'll test that come daylight. But backfire isn't the main
problem - The little bit of backfire I get get seems to be more of a
secondary symptom. If that valve is defective, I'd expect MAJOR
(Gunshot-style) backfiring anytime I get off the gas - Which was exactly
what I had when the vac. line controlling the injection valve was
cracked, leaving the valve effectively non-functional. I have no such
trouble currently - The little bit of backfire I get is a barely-audible
"pop-pop-poppety-pop" type thing - When it happens at all, that is...

> - ignition timing

Again, doesn't appear to be a problem.

>
> Engine diesels (runs on) when shut off or dies too fast:


This isn't an issue - or at least, I don't think it is... Except for the
occasional delayed "pop" out the tailpipe a few seconds after the engine
stops spinning, shutdown is 100% normal.

--
Don Bruder -
- New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.
  #7  
Old February 2nd 05, 04:44 PM
Mike Romain
external usenet poster
 
Posts: n/a
Default

I don't think I saw a new gas filter in there anywhere.... One getting
plugged up can cause your symptoms. You need to give it too much gas
pedal to flow fast, then the filter clears with a flood.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Don Bruder wrote:
>
> My '82 Mazda 626 - 2.0 liter inline four with no computer, in front of a
> 5 speed stick - has been giving me some weirdness lately that I simply
> haven't been able to track down. It's intermittent, so that's not
> helping the troubleshooting process. I *THINK* I've got it narrowed down
> to two "mostly likely suspect" culprits: Fuel/carb issues, or blown head
> gasket. Trouble is, the symptoms could be accounted for by either, or
> might even have nothing to do with either one.
>
> Basically, anytime I "get on it" a bit (Climbing a slope and put the
> hammer down a little extra to maintain speed, "stomping" on it -
> figuratively speaking - while pulling out for a pass, or substantial
> speed alteration while cruising) I might get one or more "hiccups"
> before the engine really "kicks in" - as if perhaps the extra pedal is
> riching out one or two cylinders for a moment. This misbehavior is
> SOMETIMES accompanied by a few quiet "pop-pop-pop" type backfires out
> the tailpipe, other times, it's not. On a might-be-related note,
> occasionally, I get a single, noticable (but not particularly
> impressive) "pop" out the tailpipe at shutdown, usually about 3-8
> seconds after the engine has stopped spinning - The timing of this
> "shutdown pop" is invariably such that if I turn off the key and
> immediately start to get out of the car, the "pop" will happen just
> about the time I'm flipping the door shut. This "popping", whether it
> happens while asking the engine to work harder, or at shutdown, seems to
> say to me that there's too much fuel getting dumped into the beast for a
> complete burn inside the cylinder(s), so the leftover is burning in the
> exhaust.
>
> Generally, dropping RPMS below about 3K will "clear" the problem when it
> happens, but there have been a few times when I've darn near come to a
> stop before getting the engine to "even out" and pick up the load.
>
> Redline on the tach for this car is 6K, with the "sweet spot" running
> around 2800-3200 RPM depending on gear. book specs max output of this
> engine to be at 2750 - my usual driving and shifting habits tend to keep
> the revs between 2500 and 3000 unless I'm doing sustained high-speed
> work like freeway travel, climbing a slope, or substantial speed
> alteration. Freeway driving on a 70 speed-limit stretch, ferinstance,
> usually puts the revs in the 3300-3600 range in 5th. Hill-climbing might
> have me winding it up to the same range in third to keep to the
> double-nickel - Can't use 4th/2500-ish for that, as doing so will lug
> the engine bigtime when trying to climb. Likewise, dropping down to
> second isn't a practical option, since doing that would have me trying
> to wind it out to about 4K to keep up with traffic on the slope.
>
> All in all, when this happens, it feels a LOT like back when I had
> timing trouble due to the distributor "lockdown" bolt being loose,
> allowing the distributor to flop around and throwing timing all over the
> place at random. That isn't the issue this time... That was the VERY
> first thing I checked when I started seeing the problem. Timing is as
> close to dead on as I know how to get at 5 BTDC at idle with vac.
> advance disonnected/plugged, exactly as specced, and the distributor is
> solidly bolted down.
>
> I've considered plugs/wires/rotor/cap as the culprit. Replaced 'em all.
> The car was due for a new set anyway, although not desperately. No
> change.
>
> I've wondered about a plugged exhaust - That doesn't seem likely,
> though, unless perhaps there's a chunk of something that shifts around
> to plug it up, then falls away to free the exhaust path. This problem
> doesn't happen either predictably, or consistently. There's a much
> better chance of me seeing it happen in certain situations, but
> reproducing those situations *DOES NOT* always reproduce the problem - I
> may have it hit while climbing what's known around here as Lakeside Hill
> 6 nights in a row, then not see it happen at all for several nights,
> then have it happen once, and not happen again for a week. The
> intermittent part is what's driving me nuts.
>
> At this point, I'm wavering between suspecting fuel issues and a blown
> head gasket. (And if that turns out to be the case, I'd bet a dollar to
> a donut that it's blown between the #3 and #4 cylinders)
>
> As far as fuel, I was suspecting the float may be acting up - I
> sometimes get a similar power drop-out while under acceleration on the
> flat and the road is curving to the right - Nowhere NEAR as severe as
> when I see/hear/feel it when asking the engine to "work harder", but
> enough to be noticable as a distinct "miss" or "drop-out". Thing is, I
> rebuilt this carb *FOUR COMPLETE TIMES* just a bit over a year and a
> half ago, each time even more carefully than the last, while trying to
> track down why the beast was failing California smog. (Mondo-high HC,
> low CO2) That problem turned out to be a cracked vacuum hose controlling
> the air-injection valve. As I said, four complete carb rebuilds, and
> each one done more carefully than the previous - I wouldn't be surprised
> to find out the carb was/is in "better than brand new" shape when I
> finished that little fiasco, so I've got some serious doubts as to carb
> problems. I can't rule them out completely, but it just doesn't quite
> fit with what I know.
>
> The head gasket is likewise a suspect. But not seeing the problem
> consistently makes me wonder if it's even a reasonable suspicion.
>
> I've got no idea how many actual miles on this engine - Speedo cable was
> broke when I bought the car it was originally in, had been for an
> unknown amount of time, and stayed broke for the better part of a year
> as I drove it around a high-milage paper route and worked on other more
> important issues with the car. Now that I've swapped the engine into
> this vehicle due to the wreck that wiped out the original one, I'm even
> more clueless as to the actual miles the engine has gone. Supposedly,
> this engine was rebuilt (for the original vehicle it was in) back in
> '92, but I have no way to confirm or refute that claim.
>
> It uses a little oil - 1/2-3/4 quart or so between oil changes, with, I
> suspect, most of that being burned after bypassing the valve-stem seals
> - Some mornings, I get a puff of blue smoke at startup and for a short
> time after, and occasionally get some smoke on *REALLY* heavy
> acceleration, but otherwise, nothing noticable in that department.
>
> All four plugs were scaled heavily, #1, #2, and #3 with a gray-ish tan
> "compressed powder" that flaked right off easily with a toothpick when I
> did the plugs/wires/cap/rotor change. Once I get rid of that build-up,
> the electrodes on the plugs looked close enough to brand new. The #4
> cylinder's plug was *VERY SLIGHTLY* moist - just barely enough to detect
> - and a good bit darker in color than the other three, suggesting to me
> that it's probably the place where the oil is going. The rest were dry.
> Like the others, the #4 plug cleaned up loking practically new.
>
> Coolant in the radiator has a very slight rust/brownish tinge to the
> usual green color, and when I let it cool and pop the cap, sometimes
> shows a "froth", like the head on a glass of beer. No bubbling that I
> can see when looking in the radiator with the engine running. No sign of
> oil that I can find. Drawing a coolant sample while the engine is
> running, putting it someplace to "settle", and checking on it later
> shows only the slight brownish tinge I mentioned, with no oily layer
> floating, or anything settling out - basically, looks like healthy
> enough coolant that's been in contact with a little rust.
>
> No water in the crankcase that I can tell. Oil filler cap usually (and
> always has, since the day I bought the car) shows a TINY bit of
> "mayonaisse" in the deepest crevices, but nothing more than I'd expect
> from condensation. Definitely nothing even remotely like what I'd expect
> to find if there was any significant amount of coolant leaking into the
> oil.
>
> Usual head-gasket failure on these engines is the "skinny spot" betwwen
> the #3 and #4 cylinders, sometimes between #1 and #2. Never heard of one
> that broke between #2 and #3 without filling the crankcase with
> water/radiator with oil.
>
> So, WITHOUT lifting the head, is there any practical way to confirm/rule
> out a blown head gasket? I'm stumped on this one.
>
> I guess I *COULD* "shotgun" the problem by swapping in the freshly
> rebuilt spare engine I've got sitting here, but that seems like an awful
> lot of effort when the current engine is running QUITE well - MOST OF
> THE TIME...
>
> Anybody got any thoughts for me?
>
> --
> Don Bruder - - New Email policy in effect as of Feb. 21, 2004.
> Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
> subject unless it comes from a "whitelisted" (pre-approved by me) address.
> See <http://www.sonic.net/~dakidd/main/contact.html> for full details.

  #8  
Old February 2nd 05, 11:19 PM
William R. Watt
external usenet poster
 
Posts: n/a
Default


Don Bruder ) writes:

> Yes, mine uses the "breakerless points" - Mazda calls the module the
> "ignitor" - A hall sensor, or similar type of "Hey, stupid! It's time to
> fire the coil!" rig. That unit lives under the rotor in the distributor,
> and is the only thing electronic on this engine. And boy, do I hope it
> isn't going bad, since trying to replace it looks to be a project that
> ranks right up there with finding hens' teeth. The actual replacement
> ain't so bad, but first you have to find a replacement module, and good
> luck doing that...


I'm pretty sure there should be two parts - the hall sensor pickup down on
the rotor and the transistor module at the top. It's usually the
transistors that start acting up - could be when the unit heats up or the
pickup starts sending signals too fast for it to keep up with. Should be a
black plastic part that screws into the upper part of the distributor with
wires leading out.

--
------------------------------------------------------------------------------
William R Watt National Capital FreeNet Ottawa's free community network
homepage: www.ncf.ca/~ag384/top.htm
warning: non-FreeNet email must have "notspam" in subject or it's returned
  #9  
Old February 4th 05, 03:01 AM
Don Bruder
external usenet poster
 
Posts: n/a
Default

In article >,
Mike Romain > wrote:

> I don't think I saw a new gas filter in there anywhere.... One getting
> plugged up can cause your symptoms. You need to give it too much gas
> pedal to flow fast, then the filter clears with a flood.


Current filter was put in new at about the same time the multiple carb
rebuilds happened. Not likely to be a problem.

On the "good news" front...

Problems came to a head last night - Car ended up sidelined, totally
dead. Couldn't get it to crank. Managed to push-start it and get it back
to base, although it was a battle keeping it running. Once back in the
parking lot at work, it proceeded to unceremoniously die. Didn't have my
meter with me, so couldn't chase wire/voltage issues, but came to the
pretty obvious (Lack of headlights, radio, turn signals, etc is a bit of
a giveaway, no?) conclusion that the battery was dead. Had it dragged
home by the big yellow truck (Thank you, AAA... Last night was a prime
example of why I pay 80 bucks a year for the privilege of toting around
a chunk of plastic - The hookup would have run me $62, and the actual
"get it from here to there" would have weighed in around $170, for a
total of close to triple what I pay for having the card. Am I gonna
renew come July? You damn well better believe I am!) and slapped the
battery charger on it overnight. Come daylight, got up, jumped in it,
and turned the key. The usual "vrooom", and it ran like a champ. Ran it
up and down the hill a few times, and saw no sign of the problems that
led to the original posting. Parked it, shut it down, and went back
inside to tell work I'd be able to make it tonight if they need me. Went
back out to feed the horses, and when I tried to start it again, it was
seriously "draggy" about starting, but once it caught, it ran well.
Meter on the battery showed me 12.13 volts - Uh-oh... Can we say
"alternator pukage"?

Wire the meter into the circuit between alternator output and battery -
It's giving me a grand and glorious 2.61 volts worth of output.

Looks to me like it's time to collect on that Autozone lifetime
warranty... Charge the battery back up, head down the hill, pull the
alternator in the parking lot, and drag it in to be tested. Sure enough,
machine says that the diode-trio is fried. Gonna honor my warranty? Sure
thing! Swap pulleys (new one came with a serpentine pulley installed,
mine runs off a V-belt) and strap the new one in. Check the battery
voltage. 11.96. Drag the battery inside to be topped up so I don't cook
off the nice shiney new alternator before travelling a mile. Meter on
battery - 12.71. Good enough. Fire it up wth meter connected. Voltage
sags to 12.3 while cranking then jumps to 13.73 within a second or two
after the engine catches. Excellent - alternator working properly.

Drive it home. Hit the usual "most likely spot" for the misfiring to
happen. No sign of it. Do everything I can to replicate it. No luck.
Multiple trips up and down Lakeside Hill - Can't make the problem I've
been seeing happen, no matter how hard I try. Looks like the missing was
a symptom of low (and steadily getting lower...) voltage.

This problem has been getting slowly worse over the course of the past
couple of weeks. Interestingly enough, now that I'm actually thinking
about it, the alternator belt shredded itself about 3 weeks ago. I
managed to get the car home to where I had the stuff to deal with
changing the belt, swapped the new one on, and didn't think anything of
it. It was a couple of days later that the missing/hesitation started.
And gradually got worse until last night, when I dragged it into the
parking lot running like it had one cylinder, and that one was blown.

I'm guessing that driving it home with the blown alternator belt drained
the battery far enough that when I put the fresh belt on, the alternator
either died, or got severely crippled, then spent the last couple of
weeks dying, until finally it gave up completely, and left me running on
battery only - Until THAT died, too...


Putting a fresh charge on the battery made it run like the proverbial
raped ape until shutdown. Fresh alternator and topped up battery seems
to have cleared the trouble completely.

Boy, I'm really glad that I didn't pull the head now... Would have been
a serious waste of effort, I'm thinking...

Yes, I know that a drained battery is generally a
not-long-for-this-world battery - Sholdn't be an issue here, since I'm
running a marine starting/deep-cycle battery in this car. For a while, I
was using the car as a mobile "lights and camera" platform for some
nocturnal filming, and wasn't able to run the engine to power the
"toys". The deep-cycle battery has held up quite well to repeated
drain/charge cycles from powering the gear I've been using. I expect
it'll treat this incident as not all that much different than the times
I've fallen asleep while waiting for my "actors" to arrive on scene, and
woke up to a near-dead battery.

Next concept: Heavy-duty alternator...

I'm wondering if paralleling two, three, or even more fairly
high-current diodes in each position inside the alternator wouldn't
"beef it up" enough to cope with the idea of bringing the battery back
from all-but-dead without frying the trio...

--
Don Bruder - - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.
  #10  
Old February 4th 05, 04:13 AM
Bror Jace
external usenet poster
 
Posts: n/a
Default

Might be a good idea to try a UOA ... Used Oil Analysis. Lots of
places offer this service but I usually use these guys:

http://www.blackstone-labs.com/

Signs of excessive sodium and/or potassium in the oil, along with
accelerated wear (usually copper, lead and/or iron, is a surefire sign
of a coolant leak and will be apparent through a UOA long before you
will get other, telltale signs of one.

They can also spot other problems such as high insolubles and/or high
fuel contamination levels which may suggest faulty fuel injectors, PCV
problems, etc ...

Costs about $20-35, depending on the service. Want the best package?
Pay $35 and ask for the Terry Dyson analysis. He's a 3rd party gyuy
who interprets Blackstone's results in much greater detail.

--- Bror Jace

 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Head Gasket Help Dave Skirrow Technology 17 January 17th 05 06:46 PM
'92 explorer blown head gasket? g the b Ford Explorer 6 December 24th 04 06:56 PM
4.0 Head Gasket Oil Leak DougW Jeep 8 December 23rd 04 02:42 AM
Head Gasket Leak? maxpower Chrysler 4 October 11th 04 03:00 PM
Head Gasket Leak? Mandrake Chrysler 0 October 10th 04 10:16 PM


All times are GMT +1. The time now is 07:44 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AutoBanter.
The comments are property of their posters.