Push mower oil leak Briggs

rwomack said:

Ok so clearance is way too large. Exhaust .031 and intake .045! Will refacing the valves get me close enough to workable numbers?

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Are you sure of those numbers ?????? I have never seen numbers that big before for valves.....

You aren't getting thousandths and MM mixed up are you?
most feeler gauges have both marked on them.

Scrubcadet10 said:

You aren't getting thousandths and MM mixed up are you?
most feeler gauges have both marked on them.

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Yeah I think so toooo. If i'm right 45 MM is 18 tho..............

Yep, .45 comes out to 17 thou, and .31mm comes too 12.thou.

Scrubcadet10 said:

Yep, .45 comes out to 17 thou, and .31mm comes too 12.thou.

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Ok. I was going by top numbers on my gauges in inches. So you guys are talking mm then.

Take a close look at your gauges.
Each leaf will either have 1 or two numbers on them
The smaller number will be the inch size & the larger one will be the mm size.
If the smallest one does not say 0005 or 001 then your feelers are metric.

I went back to the beginning of this thread and looked at the pics of the valves and valve seats. I am curious as to why you would have a wide valve clearance. Normally as an engine gets older the clearances get small, not larger. I would be double checking those measurements as I don’t see a reason that those measurements should be so large. Second, to get the clearance back into specs you are going have to cut the valve seats and then grind the valve faces. If the valve margin becomes less that 3/32”, the valve will not have enough thickness to deal with the heat and fail very quickly. If you do get the clearance in specs, you then have to lap the valves. Here you must make sure that the lapped surface is in the middle of the valve face or the valve will not seat properly, causing a loss of compression. Have you checked valve guide clearance? If the clearance is too large, all your work on the valves and seat will be for naught. Finally, are you sure you really want to stick the time and money into that engine? You have a scored cylinder, bad rings, probably a worn piston due to piston slap, could be replacing valves and will need a gasket set. Plus if you do just the bare minimum it may not last a season. Personally, from the pictures you posted and the measurements you gave us, I would tell you to stop now and cut your loses. Read my signature.

Thanks for taking the time to reply. The cylinder checked out within specs and cleaned up well with a soft hone. The rings were worn. I’m willing to keep going based on all feedback so far. I don’t have that much into it.

Here are pics of the feeler gauges I used to come up with the valve clearances.

In regards to checking the valve guides, do you mean the hole you drop the valves through before installing the valve springs and keepers?

rwomack said:

In regards to checking the valve guides, do you mean the hole you drop the valves through before installing the valve springs and keepers?

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Yes, valve slop back and forth in the block.


**IMO, You knew what you had when you started, your freshening up the engine, not a high performance re-build.
Keep going and she'll run much better than before, even with the imperfections you found. As noted, it's your labor,
parts are cheap and "it's a lawn mower, not the Space Shuttle"..

A great "backyardian: project!