This week I'm working on another 99 cirrus with the Mitsubishi V6. It has 100 k on it and all looks pretty good. I pulled the heads cause the PO left the intake off and leaves and seeds got down the intake ports and into the valves. The car wasnt run with the debris in it. But I pulled the heads to be safe. Anyways. I've been cleaning the carbon on the seat area with scotch-brite pads. Figured they couldnt hurt a hardened seat. Just wondering though, should I try to lap the valves with a fine compound anyways. Or just check for leaks with a thin fluid in the combustion chamber and leave well-enough alone. BTW, its a 4 valve per cylinder head. Had to make a special tool to adapt the "C" clamp spring compressor to the recessed springs and lawnmower sized spring retainers.

 

I would do both. Lap them and then check them,carbon quickly burns the valves because they run soft spring pressure.

 

If you have easy access to the valves (heads off already), I would spend the time now to lap them instead of putting it all back together and having to pull it apart again for a leaking or burnt valve. just my .02

 

I'd check to see if the valves are leaking first...

If not then I wouldn't lap them. If you've already pulled the valves out though, you might as well.

 

The heads are stripped. At 90k, valve seals are included in the top-end gasket kit. I've read about lapping valves from the old folks when they actually needed to do them every so often. I also heard there are 2 different grades of compound you want to use. One is a cutting, and one is a polishing. Nobody talks about this anymore. Guess its a lost art?

 

Yes, you are right. There is a fine compound and a coarse compound.

While working in a shop for almost 2 years, there was only a hand full of cars I remember that got valve lapping when the motors were pulled for head gaskets.

3, maybe 4?

Guess it's just not as needed anymore..

 

my dad use to lap his valves older heads. it might not work so well on harden seats?? idk?

 

Scotty there's three or four different grits for lapping compound, I use three when doing bike heads. If they are really bad you may have to cut the seats. Most of them run a three angle cut. With the relatively low K on the heads I would say a lap would be the way to go. I lap then clean the area real well and here's my little secret...spray the area with Arid Extra dry, you know the under arm deodorant for chicks.. let it dry and then put a little rubbing alcohol into the runner and watch.
Check the CLOVER brand of lapping compounds, they are the best.
Cheers Von Doom
G

 

Thanks for the help everyone! I know its a Japanese motor in a Chrysler, but knowledge is useful for every thing. Results tomorrow night!

 

Ok! Lapped all the valves in one head{stupid 24 valve motor}. And now they are installed. Oh, wait a second.....what is that bag there? Hmmm.... valve stem seals?!! F#%k, F#%k, F#%k!!!!!!

 

hahaha sorry been there not with valves tho

 

A lapping plate shaped to match the valve seat is used with lapping film or compound. On a large valve, it would be turned with a drill. On a small valve, by hand.




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