[chambo]

I recently got another 400. It registers about 1400 hours on the meter. Don't know any history on the tractor. It runs well until I engage he deck and it loses power. I have tried a new fuel pump, different governor, plugs, took off the carb and did a quick take apart and clean. I have also changed the governor spring hole. The compression checks over 85 lbs, in each cylinder just turning it over without it running. What should my next move be?
Thanks,
Joe

 

[jdalchemist]

Hi Joe,
You have no doubt determined that the mower deck shaft and PTO pulley will rotate freely. An approx. 85 psi compression would be very low for this engine (should see 110-120 psi) and would account for what you are seeing with the mower deck engagement. A proper compression check involves first warming the engine by running for a few minutes, removing both plugs, setting the throttle wide open, attaching the gauge to one cylinder (and then the other) with a few seconds of cranking on each side. If the compression is really 85 psi on both sides, I probably would not even bother with a leak-down test, but would pull the heads to see what is worn or mis-set.
Harold

 

[sreynolds]

Mine did that for quite a long time. It was real real real real real tough to locate the problem. I had to cut lawn like that for two maybe three(?) years time.

It was the governor and the linkage.

But mine is running at 149 psi compression.

 

[denniscary]

Mine did this exact same thing when I bought it. Ran great sounded good drove wonderful, kick in the blades it would fall flat on its face. I ran compression check and found I had on cylinder dead. Pulled the head off hoping it was a head gasket, just to find I had a broken rod. I hope you have better luck than me.

 

[cmitcham]

check your plug wires too.

i had little power from a 532, and finally went to check the timing, and got no timing light trigger from 1 wire. replaced it, and now have a 2 cylinder powerful engine

 

[chambo]

Thanks for the ideas. I will do a better compression check.

Joe