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Tecumseh Compression Release

#1

D

digr

Having trouble with a 16 HP Compression Release, with the exhaust valve adjusted to .010" or .007" at TDC the de compressor won't work but if I adjust the exhaust valve just after it closes it will work but with no clearance at TDC. Sometimes it seems to work fine with the valves adjusted properly it will work fine. Any ideas?


#2

R

Rivets

Please post all the engine numbers so we don’t have to guess what you have.


#3

D

digr

Rivets said:
Please post all the engine numbers so we don’t have to guess what you have.
Click to expand...
0H160 1700B4F
SER 21742


#4

R

Rivets

First, I think you misread the model number. Probably should be 170084F. Second, the exhaust valve clearance is .010”. Third, I would set the valve clearance when the piston is approximately 1/4” passed TDC. After adjusting the clearance, rotate the engine through 4 complete cycles and recheck the clearance. If you don’t see the exhaust valve move just before TDC, recheck the valve clearance. If the clearance has not changed it’s time to open the engine and see if the compression release mechanism is broken. Here is the service manual for this engine. https://www.mymowerparts.com/pdf/Te...0-8HP-THRU-18HP-CAST-IRON-ENGINES-691462A.pdf


#5

R

Rivets

I forgot to add the following. If you removed the head double check and see if you torqued down the head properly and on these old engines I always replace the head gasket.


#6

D

digr

Rivets said:
First, I think you misread the model number. Probably should be 170084F. Second, the exhaust valve clearance is .010”. Third, I would set the valve clearance when the piston is approximately 1/4” passed TDC. After adjusting the clearance, rotate the engine through 4 complete cycles and recheck the clearance. If you don’t see the exhaust valve move just before TDC, recheck the valve clearance. If the clearance has not changed it’s time to open the engine and see if the compression release mechanism is broken. Here is the service manual for this engine. https://www.mymowerparts.com/pdf/Te...0-8HP-THRU-18HP-CAST-IRON-ENGINES-691462A.pdf
Click to expand...
Thank you, I will give it a try


#7

D

digr

Not good, I can see the rocker dip but not enough to move the valve. I set the lash at .007" about .25" past TDC and using a dial indicator the valve opens .005" so maybe I should check the starter.


#8

Fish

Fish

Are you sure that you at TDC? Or are you doing the TDC when one valve is just closing, and the other one opening?


#9

D

digr

Yes I am sure, the engine had other problems. I opened it up to find a broken tooth on the crank shaft gear that runs the camshaft and that tooth spent some time rattling around. Everything is OK other than battle scars except the decompression assembly. I have a another used cam shaft, new gear and rings to install. The bore is .003" over.


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