# 8hp Tecumseh missing MCR upon disassembly



## fknbzn (Jan 27, 2012)

I purchased a Coleman Powermate Contractor Generator 4200w with a 8hp Tecumseh HM80-155489m. I was told that all it needed was a carb. He told me he put another carb off a chipper and it ran fine. Also told me he rebuilt the motor, which is questionable. After going through the carb, I got a few pops. Check compression and very low, 20-25psi. Did the reverse spin bounce back test to bypass the compression release and it failed miserably. Time to pull the motor apart. Checked valves after puling head. The didn't seem seated and would spin at top dead center with a little force. I thought that that was normal with the exhaust and compression release. Keep tearing down block. Inspect and everything looks good. Nothing tore up. Got to looking at the cam and there is no mechanical compression release. Someone had removed it. The only thing left was the pin in the lobe. I am confused on what I came upon. Why was it taken out? I was told this motor would kick back and not pass the compression stroke without it, if it was a good motor. It looks like the original problem was the valves sticking and not seating and the carb.

Anyone have any thoughts on why someone would go through the effort of disassembling the motor to remove the MCR? I'm stumped??

Thanks.


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## SABL (Jul 4, 2008)

Could be due to availability of the part......Tecumseh closed their engine plant in Dec 2008. According to Tecumseh Products - Wikipedia, the free encyclopedia another company may have picked up where Tecumseh Power left off.

Certified Parts I only checked the FAQ for the "Lausen" link but it seems to have some decent info.


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## fknbzn (Jan 27, 2012)

SABL said:


> Could be due to availability of the part......Tecumseh closed their engine plant in Dec 2008. According to Tecumseh Products - Wikipedia, the free encyclopedia another company may have picked up where Tecumseh Power left off.
> 
> Certified Parts I only checked the FAQ for the "Lausen" link but it seems to have some decent info.




I doubt it was because of availability. There are 1/2 dozen of them on ebay. The cam is still available just not from Tecumseh as of now. Plus I was told that this motor would be close to impossible to start without it.

Still scratching my head????


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## SABL (Jul 4, 2008)

Well.........many people can take something apart but not all of them know how to put it back together (or make the needed repairs). Have you questioned the person you purchased this unit from?? Doesn't make sense to rebuild an engine and overlook a carb issue. I think the engine was taken apart and put back together......minus the CR. Could be due to lack of attention......

Also, just because the part may be available does not mean a person will make the effort to acquire it.


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## k2skier (Sep 30, 2008)

If it broke a rod then that could have caused the MCR to break, and the person who put it back together didn't know any better.

You can start this engine without it, but you MUST have it up against the compression stroke and pull (with 2 hands) like you're trying to kill a bear or you make break a finger. Hard, yes, impossible, no.


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## jrrdw (Jun 26, 2010)

> You can start this engine without it, but you MUST have it up against the compression stroke and pull (with 2 hands) like you're trying to kill a bear or you make break a finger. Hard, yes, impossible, no.


If you don't keep the engine turning through all the strokes (at least 2 full revolutions of the flywheel) the kick back will be strong enough to break parts.


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## Basementgeek (Feb 7, 2005)

I kind have to go with K2 on this, it can start. but be very hard. Remember 
there is a minimum RPMs pull starting it. I think 300-350 RPMs.

BG


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## jrrdw (Jun 26, 2010)

Basementgeek said:


> I kind have to go with K2 on this, it can start. but be very hard. Remember
> there is a minimum RPMs pull starting it. I think 300-350 RPMs.
> 
> BG


Exactly, that's why I stressed 2 full revolutions of the flywheel. I myself have pulled the skin off my fingers, broke starter ropes, flywheel keys, recoil springs etc... Anything in the starter line up is subject to breakage when you run across a hard starting Tecumseh, (most of them).


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## fknbzn (Jan 27, 2012)

This is the only thing weird I found inside the motor, other than the missing MCR.
There is a small piece broken off the end of the camshaft.


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## k2skier (Sep 30, 2008)

jrrdw said:


> Exactly, that's why I stressed 2 full revolutions of the flywheel. I myself have pulled the skin off my fingers, broke starter ropes, flywheel keys, recoil springs etc... Anything in the starter line up is subject to breakage when you run across a hard starting Tecumseh, (most of them).


If you had a flywheel break on you on a kick-back; either the flywheel was already cracked or the flywheel was improperly installed. Break a rope, finger or starter handle, YES, but nothing else should, or I just have been lucky for the last 38 years.


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## k2skier (Sep 30, 2008)

fknbzn said:


> This is the only thing weird I found inside the motor, other than the missing MCR.
> There is a small piece broken off the end of the camshaft.


This is the kind of damage that may occur when a con rod breaks.


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## jrrdw (Jun 26, 2010)

k2skier said:


> If you had a flywheel break on you on a kick-back; either the flywheel was already cracked or the flywheel was improperly installed. Break a rope, finger or starter handle, YES, but nothing else should, or I just have been lucky for the last 38 years.


"flywheel key" all though some where in small engine history I'm sure it has happened....Murphy's law???


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