Poudrette wrote: I did a test on the valve seats before valve disassembly, (again from youtube video haha) filling the space above with gasoline and seeing if it woul leak through in the combustion chamber between valve and valve seat. After a good while, I did not see a single drop on any of 4 exhaust or 4 inlet valves. Wondering if this is considered a good approach by all here to decide if the seat is good, at least before disassembly. I did check for compression before disassembly with the sponnful of oil in the cylinder and tht why «i decided to change the rings and assume the valves are at least mostly ok. If I understand your feedback properly, you are suggesting to change valve guides to avoi oil going into the combustion chmber when valve open up ? .......
Sylvain
No not the valve guides.... the valve guide seals. The little bonnets on top of the guides in the valve spring's bores.
If you have a valve spring compressor, it is a very simple matter to lap in or clean up the valve seats and valve head mating surfaces without having to have a shop regrind the seats and all that.
Just went through this myself.
The valves will be out and you can lap those valves in and maybe get a bunch more time on the head before a valve job is needed.
If there is no leakage now, I would still change the bonnets anyhow. It's really cheap insurance.
WEAR SAFETY GLASSES WHEN DOING ANY OF THIS!!
Another way to test the valve to valve seat seal is to partially fill the ports with a very very thin liquid, like carb cleaner... etc.
Then take your vacuum cleaner with the hose hooked up backwards so it blows air and put the hose into the intake or exhaust port. That will put a little pressure in the port and force the liquid out if there is a leak.
The pressure in the intake runner/port is never more then atmospheric air pressure of under 15psi in a normally aspirated engine.
Exhaust is higher of course but you can still test it.
It has been my experience that leaky valves are usually the exhaust ones but mostly it's caused by improper adjustment of valve lash, rocker, cam or shim clearances.... etc.
