Kohler Valve Leaking

[lefty]

Kohler: PS-SV530-3222 Serial: 4508402463

I did a leak down on this and found a pretty substantial intake valve leak. I disassembled it and gave it a good valve lapping. Everything looked ok. Nothing bent, no real damage to the face.

I tested with some gas to see if it leaked while the head was off and there was no leakage. I reassembled and there's been no improvement. With 50lbs PSI in it's only holding 30 and all of it is coming out of the intake.

I'm puzzled. Something doesn't seem right. I have all the tension off of the rocker. Nothing looks cracked. The faces look good. No excessive play in the guide. Nothing seams bent.

Weak spring maybe? It seems ok but who knows?

I've seen valves that leaked slightly during a fluid test have less leak down than this.

Thank you.

[lefty]

Could assembly lube on the valve face cause this problem? I just took it apart again and found that the lube I used on the valve found its way to the valve face and seat.

[RoyM]

Is the seat face worn (rounded)? It is a common problem if the air filter is not properly maintained.

[lefty]

I think that may be the case. I just gave it another lapping and took it into a dark room. I'm seeing light from under the valve. It's in the same place no matter how I spin the valve. I think that means it's the seat face worn in that one area.

My guess is my options are to either replace the head or find someone to cut it for me and replace the valve?

[lefty]

What's weird is that I'm getting a very clean lapping profile when I'm done. No holidays or dark spots. Just a clean gray surface.

[bgsengine]

not weird to me when you think about it - your valve is rotating, the seat is not, so you can lap only one high spot on the seat and have a nice ring on the valve face... You may have a slightly warped head or valve seat. Also the valve face could be mating up with the seat in one spot only but rotate it a bit and it no longer mates up correctly - that usually means you need to recut the valve seats (square to the guides) , sometimes if the seat is just a little loose also it can be bopped back in place by using the valve and a hammer (gently) on the valve to shift the seat back , and then stake the seat, THEN re-lap everything and re-check. But if the valve seat is loose or out of square, generally means new head time (unless you wanna spend the $500+ on a valve seat cutter kit)

[lefty]

I think it may be warped. The seat is seated all the way down into its home but I noticed that it overhangs the bore a bit on one side. It faces flush on the other. I can feel it with my finger as well. Unless that's normal, something seems to be off.

You may not be able to tell in this photo but if you look at the bottom edge of the seat where it meets the shiny machined surface below, I can catch that edge with my finger. At the 12 o'clock position. At the 6 o'clock position, I cannot feel that delineation.

https://photos.app.goo.gl/7hqh72yGkKMJjakc6

[bgsengine]

Nah I would not judge it based on how it mates to the head, your head does look pretty clean to me. One trick I have used was some colored grease (blue or red) and smear a very thin layer (just enough to see color - maybe half a thou thick) on the valve face and then slap it in to the seat and carefully pop it straight back out and check the seat for spots where there's no grease , that'd be your low spots, which might be more indicative of which way to go from there.

[lefty]

I will do that in the morning and report back. Thank you.

[lefty]

I used some red grease. It looks like the area between the lines stayed dry. At the 1 o'clock position. I actually saw light bleeding at the 8 o'clock position but that probably just means the valve was getting pulled down to the 1 o'clock side causing it to rise up at the 8 o'clock position?

https://photos.app.goo.gl/Qux2uGjMN6BMsUPg6