Small engine rebuild help/question

I have an old cast iron techumseh engine I am trying to rebuild. (The
rod broke). I am putting it back together. At the bottom of the
stroke I can hear a sound and there seems to be some slight "play"
where the rod does not move the poston any. I think the same at the
top of the stroke.

Is this a problem or am I being overly cautious? This is my first
rebuild and have learned alot but wanted to get your opinion. I have
a
video posted he


http://www.youtube.com/watch?v=WG_kcd9VV3Q

"stryped" > wrote in message
...
>I have an old cast iron techumseh engine I am trying to rebuild. (The
> rod broke). I am putting it back together. At the bottom of the
> stroke I can hear a sound and there seems to be some slight "play"
> where the rod does not move the poston any. I think the same at the
> top of the stroke.
>
> Is this a problem or am I being overly cautious? This is my first
> rebuild and have learned alot but wanted to get your opinion. I have
> a
> video posted he
>
>
> http://www.youtube.com/watch?v=WG_kcd9VV3Q

Hello:

It seems that:

1- Your videographer moved the camera, away from the bottom of the
connecting rod, where it passes the lower part (Sump) of the block.

2- It may very well be that, you have the side cover removed, and therefore
allowing crankshaft end play.

I would recommend that, you set the cam timing, and reinstall the side
cover. Then rotate the engine. This is notwithstanding the fact, that I am
assuming the engine is a 4 cycle?.

RK

"stryped" wrote:

I am rebuilding an old cast iron techumseh engine (The rod broke).
I am reassembling it, and at the bottom of the stroke I hear a sound.
Also at the top and bottom of the stroke there seems to be a slight
"play" where the rod does not move the piston any. Here is a video:
http://www.youtube.com/watch?v=WG_kcd9VV3Q
Is this a problem or am I being overly cautious? This is my first
rebuild and I wanted to get your opinion.
__________________________________________________ __________________________

A worn or undersized wristpin would cause the noise and the sticking.

Rodan.

On Dec 31, 8:27*pm, "Rodan" > wrote:
> "stryped" wrote:
>
> I am rebuilding an old cast iron techumseh engine (The rod broke).
> I am reassembling it, and at the bottom of the stroke I hear a sound.
> Also at the top and bottom of the stroke there seems to be a slight
> "play" where the rod does not move the piston any. * Here is a video:
> * * * *http://www.youtube.com/watch?v=WG_kcd9VV3Q
> *Is this a problem or am I being overly cautious? *This is my first
> rebuild and I wanted to get your opinion.
> __________________________________________________ _________________________*_
>
> A *worn or undersized wristpin would cause the noise and the sticking.
>
> Rodan.

It is a 4 cycle. The cover is removed. I installed the cam and the
noise is less pronounced.

The noise is only at the bottom and top of the stroke. Would an
undersized wrist pin cause this? WHat sticking? Will an undersized
wrist pin be detremental to the engine? This is on a tiller that is
only used in the summers.

I appreciate your help!

I am rebuilding an old cast iron Techumseh engine (The rod broke).
I am reassembling it, and at the bottom of the stroke I hear a sound.
Also at the top and bottom of the stroke there seems to be a slight
"play" where the rod does not move the piston any. Here is a video:
http://www.youtube.com/watch?v=WG_kcd9VV3Q
Is this a problem or am I being overly cautious? This is my first
rebuild and I wanted to get your opinion.
stryped.
__________________________________________________ _________________________*_

A worn or undersized wristpin would cause the noise and the sticking.
Rodan.
__________________________________________________ __________________________

It is a 4 cycle. The cover is removed. I installed the cam and the noise
is less pronounced. The noise is only at the bottom and top of
the stroke. Would an undersized wrist pin cause this? What sticking?
Will an undersized wrist pin be detrimental to the engine? This is
on a tiller that is only used in the summers.
stryped.
__________________________________________________ ________________________

A loose wrist pin will push the piston to the top of its stroke,
then leave the piston there until the moving wrist pin contacts
the bottom of its journal and begins to pull the piston down.
This makes the piston stay at the top of its stroke a short time
even though the wrist pin is moving down. The same thing
happens at the bottom of the stroke.

The thumping may be the loose wrist pin banging against
the top and bottom if its journal as it is pushed up and down.

I have no guess regarding how long the engine will last if the
wrist pin is worn or undersized and not replaced.

Good luck.

Rodan.

On Jan 1, 12:31*am, "Rodan" > wrote:
> I am rebuilding an old cast iron Techumseh engine (The rod broke).
> I am reassembling it, and at the bottom of the stroke I hear a sound.
> Also at the top and bottom of the stroke there seems to be a slight
> "play" where the rod does not move the piston any. Here is a video:
> * * *http://www.youtube.com/watch?v=WG_kcd9VV3Q
> Is this a problem or am I being overly cautious? This is my first
> rebuild and I wanted to get your opinion.
> * * * stryped.
> __________________________________________________ _________________________*_
>
> A worn or undersized wristpin would cause the noise and the sticking.
> * * *Rodan.
> __________________________________________________ __________________________
>
> It is a 4 cycle. The cover is removed. I installed the cam and the noise
> is less pronounced. * * * * The noise is only at the bottom and top of
> the stroke. Would an undersized wrist pin cause this? What sticking?
> Will an undersized wrist pin be detrimental to the engine? * This is
> on a tiller that is only used in the summers.
> * * stryped.
> __________________________________________________ ________________________
>
> A loose wrist pin will push the piston to the top of its stroke,
> then leave the piston there until the moving wrist pin contacts
> the bottom of its journal and begins to pull the piston down.
> This makes the piston stay at the top of its stroke a short time
> even though the wrist pin is moving down. * *The same thing
> happens at the bottom of the stroke.
>
> The thumping may be the loose wrist pin banging against
> the top and bottom if its journal as it is pushed up and down.
>
> I have no guess regarding how long the engine will last if the
> wrist pin is worn or undersized and not replaced.
>
> Good luck.
>
> Rodan.

If the wrist pin to piston clearance is enough to make a noise when
you are turning it over by hand I" would think it would be very easy
to see and feel when you have the pin in the piston in your hand. I
think that it won't last long while running before the thing self
destructs. It may be what you are hearing is the piston as it changes
direction.

chris

On Dec 31 2008, 6:37*pm, stryped > wrote:
> I have an old cast iron techumseh engine I am trying to rebuild. (The
> rod broke). I am putting it back together. *At the bottom of the
> stroke I can hear a sound and there seems to be some slight "play"
> where the rod does not move the poston any. I think the same at the
> top of the stroke.
>
> Is this a problem or am I being overly cautious? This is my first
> rebuild and have learned alot but wanted to get your opinion. I have
> a
> video posted he
>
> http://www.youtube.com/watch?v=WG_kcd9VV3Q

if the free play you are talking about was that in the last few
seconds of the video, that is WAY too much...

I have a piston and rod frmo a Techumseh engine sitting on my desk
here. For real, it came out of my lawn mower a few years ago and i
keep it here as a conversation piece.

The rod can slide __back and forth___ on the wrist pin and the wrist
pin can slide __back and forth__ in the piston BUT there is NO free
play at all that I can feel in my hand between the rod and piston in
the ___UP / DOWN___ direction. If i understood what i saw in the
video that you were turining the shaft several degrees back and forth
without the piston moving, i would say something is very wrong.

Mark

"stryped" > wrote in message
news:482878b2-5df1-4192-85aa-
>
> Is this a problem or am I being overly cautious? This is my first
> rebuild and have learned alot but wanted to get your opinion. I have
> a
> video posted he


I couldnt tell anything from the video.

If there is excess slack in the wrist pin assembly, or in the main bearing,
you will have to do something about it.. Otherwise, you are spending
time and money on something that wont last.

It is easy enough to measure the crankshaft journal and the bearing
ID and see how much play there is.

Same on wrist pin diameter and wrist pin bore, AND piston pin bore.

Measure first, then do what you have to do. You can use undersized
crankshaft bearings if you have to. You can also buy a new
piston or connecting rod, or you can usually remanufacture the ones
you have.

Lots of ways around the problems, but putting it together too loose
is a waste of time and money.