Jump to content
Rxracer

520xi crank case pressure

Recommended Posts

Rxracer

So has the mower running the other day and pulled the oil fill while running and it literally blew off at idle. 

I checked the crank case reed and it looked good, did a compression test and left was 165, right was 170. Compression check was done on an almost cold motor. 

Spark plugs both looked good a little black no white showing oil burn sign. Since I did the service I've put about 25 hours on it and it's about half way down the safe mark.

I'm think possible head gasket issues? Any advice to diagnose?

Thanks 

Rob

Share this post


Link to post
Share on other sites
 
oliver2-44

Crankcase pressure would sure seem to indicate leakage past the rings or valve stems, but those are good compression readings.  A leak down tester might be a good tool to help look at it from a different aspect.  

Share this post


Link to post
Share on other sites
 
gwest_ca

May be normal. The crankcase should be under a vacuum if the crankcase breather is functioning. When you pull the dipstick with the engine running the negative pressure is relieved. Now there is as much air moving below the pistons in the crankcase as there is above the pistons in the combustion chamber. I can see that blowing oil out.

 

Garry

Share this post


Link to post
Share on other sites
 
Rxracer

We have a 20.5hp Kohler at work I checked, and when you undo the oil fill cap it kinda sucks it back onto the valve cover. Mine def doesn't do that. That's why I was thinking maybe head gaskets. I will try to do a warm compression check tonight to see if numbers change much but with my experience usually numbers come up when hot. I ordered a leak down tester and it will be here Thursday. 

Share this post


Link to post
Share on other sites
 
Rxracer

Just spun a hot compression test after about 5 mins of running, and got 165 on both. Here is a pic of the plugs. 

IMG_20190910_172935.jpg

Share this post


Link to post
Share on other sites
 
Howie

I think about any of these small engines will push oil out if you remove the stick.Think I did 

that when I was a whole lot youngeer and got an oil bath. Did learn from it though and have 

never done it again. not saying there might not be to much crankcase pressure because it 

could have but these will kick a lot of oil up in there when running.

Share this post


Link to post
Share on other sites
 
Howie

After a second look at those plugs they don"t look that bad. With 165 on both cylinders I don't

think you have a head gasket issue.

Share this post


Link to post
Share on other sites
 
Rxracer

Yeah these plugs were changed when I did the full service after getting the mower. So have about 25 hours or so on them. 

Share this post


Link to post
Share on other sites
 
Rxracer

Just did a leak down test. Left cylinder was 10% right was 7%. Seemed on the left cylinder inwas getting quite a bit out of the carb. So guessing a leaky intake valve. No sure sign of a problem for the crank case pressure though. 

Share this post


Link to post
Share on other sites
 
WVHillbilly520H
8 hours ago, Rxracer said:

Just did a leak down test. Left cylinder was 10% right was 7%. Seemed on the left cylinder inwas getting quite a bit out of the carb. So guessing a leaky intake valve. No sure sign of a problem for the crank case pressure though. 

It's easy enough to adjust the valves on those OHV Kohler Commands

Share this post


Link to post
Share on other sites
 

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...