Losing Power - Valve Seat?

[nplsdvr]

I'm mowing last week and have these little dips in my lawn. The mower is having a hard time crawling up the slope, when it used to have no problems at all. Then it starts spewing white smoke out of the muffler.

I pull it into the shop and check the valve adjustment (which has been a chronic problem) - I make a small adjustment, starts right up, but more smoke.

One thing I did notice while adjusting the valves - when the valves were both closed (on the compression stroke), while I hand turn the motor to TDC, I can hear air escaping - I think from the exhaust valve.

Any suggestions how to troubleshoot this further? Then repair?

Thanks,

Nic

 

[Hilllawnmower]

May check the head gaskets...leak down test will show it quickly
Darren

 

[davbell22602]

Might be worn piston rings. How compression do you have when using a compression tester?

 

[nplsdvr]

I can do a compression test tomorrow - not sure what the compression should be, but I can at least report back.

Don't have what I need for a leak-down test.

Thanks for the ideas.

 

[nplsdvr]

Finally had a chance to do the compression test. It was exactly at 50.

Not sure what it's supposed to be - just checked all the manuals I have, nothing mentioned.

Thanks!

 

[davbell22602]

Not enough compression. Its supposed to be 100-120.

 

[nplsdvr]

Not enough compression. Its supposed to be 100-120.

Wow...I had no idea compression in a small engine was so high.

I removed the cylinder head: there seems to be a little wear/thinning right between the cylinder head and push rod chamber, but it's not broken.

Once I took the cylinder head off, the piston was down, and there was a little oil in the cylinder - I'm hoping it's because the mower is at a slight backward angle and not bad rings. My wife is going to get the gasket tomorrow, I'll button it up and we'll see what we get.

<fingers crossed>

Thank you,

Nic

 

[nplsdvr]

Well, it's not the head gasket.

I replaced the head gasket, did another compression test - still at 50.

I don't have the resources for a leak-down test.

If the #1 diagnosis is a head gasket, what's the #2 diagnosis?

Thanks,

Nic

 

[Fish]

Compression readings are useless on these mowers, they have a compression release. Run it and see if the smoking has cleared up. If it has, keep mowing.

 

[nplsdvr]

Compression readings are useless on these mowers, they have a compression release. Run it and see if the smoking has cleared up. If it has, keep mowing.

Running out there now!!

<glimmer of hope>