Temp

"nachche" > wrote in message
oups.com...

> I was told by a mechanic that in the seventies, it came as a
> manufacture order to take those flaps out...
> is it?

Absolutely. It was on the same bulletin that told the mechanics to neuter
themselves with a ball-peen hammer.

Now what 'mechanic' told you that. Name!

nachche wrote:
> Hi,
> I was told by a mechanic that in the seventies, it came as a
> manufacture order to take those flaps out...
> is it?
> I'm overhuling my engine this week and I've been "arguing" with him -
> he said it can make troubles... "maybe the thermostat will stop working
> etc". I thought maybe i'll put a cable to it - and do it manually...
> (helped by a temp gauge).
> what do you think ?
>
> nachche

Now that the stock type thermostats can't be had new any more, I've been
toying with the idea of a cable operated system connected to a solenoid
triggered by a thermocouple on the cylinder head. The flaps would be
pulled open by springs and only close when there is power to the
solenoid so it would have the same failsafe as the stock unit. There's
a lot of little details to work out and right now it's only an idea...

Fortunately I don't need to do this right now. My Baja has a good
thermostat but who know how long it will last.

Tony

For the guy that said that missing flaps couldn't cause overheating. I
have done some reading on this, and I would be tempted to agree with
you but here are some ways it could cause overheating:

1) the holes that are left in the fan shroud allow air to flow
improperly. If you know anything about the bernouili (sp) principle,
you know that air can do weird things when you are traveling at road
velocity. That's why you need to have your decklid closed. It seems
logical that an open decklid would provide better cooling, but the
argument is that at road speed the air actually ends up sucking OUT of
the engine compartment, which causes more hot air from the engine to
get sucked into the intake for both the fan and the carb.

2) Your cylinders never get cooled properly. They run hotter. Your
engine now has more of a temperature differential between the case and
the heads. This can cause problems due to the thermal expansion
properties of metals (of which there are several kinds along the line
from the case to the heads).

3) In my case I think I am also missing a vital piece of tin at the top
of the cylinders, intended to deflect air over the fins instead of
straight down through the middle. I don't know for sure yet if this is
part of the flaps assembly that was removed but if it is it fits in the
"keep your flaps" category.

I have noticed, although I'm not yet positive, that my temp rises
mostly only at highway speeds. If I'm cruising around town in 3rd gear
(35mph-1500rpms) it doesn't seem to heat. But on the highway in 4th
(70mph-1500rpms) it does. This would point to an air leak problem: IE
my engine compartment is not properly sealed (maybe those flaps holes
in the fan shroud) leading to hot air from below coming up and being
recycled over the cylinders.

I tend to agree with the folks that say that VW spent a lot of money
with the best engineers and equipment they had (albeit early equipment)
measuring temperatures all over the engine in a variety of conditions.
I'm pretty sure they didn't put the flaps on because they seemed cute.
I'm pretty sure that they did it because they were having a problem and
they were trying to solve it. Although they could have made a mistake,
if I were to put money against me and the top VW engineers of the 60's
I think I'd have to put my money on them!!! That's my take at this
point. I don't claim to know everything but some of what I have read
does make sense and even if it is not causing my extra heating it still
sounds like a good idea to get those flaps back.

If nothing else, the flaps should heat the cylinders more quickly
during warm up which would decrease wear, since without them the air is
spread out over both the cylinders and the heads.

That's my contibutory two cents after reading up on the matter for
several days.

By the way, I think you can still get a Mexican thermostat and from
what I've heard they work fine. They aren't OEM for true classic show
cars but other than that they should be a good option.

Chronologic