Hey guys, quick question. If I am getting my heads pulled to replace a few valves, does the head need to be machined before its re-installed. I am hearing different things from different people. Let me know. Thanks,

 

I hope not, I just had 4 valves replaced and we just replaced all the gaskets before re-installation.

 

How long ago was that?

 

I would have them cleaned and checked before put back on. Could save you a headache later.

 

Yes it's a good idea but not 100% necessary. You should at least get them checked at before you put it back on especially if your motor has high mileage. Personally, I just cleaned off my head and block pretty good and slapped everything back together. There wasn't anything wrong with my motor and I only have like 20k miles on my car.

So far no problems Also, I used an aftermarket gasket that has some kind of coating on it to help it adhere to a very slightly imperfect head. If it's really whacked out then you will have to get it machined.

 

IMO, it depends. If you're pulling for valves, why? What's wrong with the valves, could something be wrong with the heads too? They should be looked at by a shop. The shop should be able to tell you if machining is needed.

 

They were bent in a botched timing belt replacement.

 

last week. Not much time on the road.

 

then you couldnt have damaged the head. a piston bent a couple valves...the head wasnt touched. if you would have messed up valves due to detonation, overheating, something broken in the combustion chamber, or something extreme like that, then i would check them, but in this case the damage is very precise to the edge of the valves.

 

Your heads will be fine if it's just a bent valve from the timing belt being replaced.

 

Sorry for the late reply. An aluminun head... If it where mine I would have it shaved to make sure it is flat.

 

Just curious, is it a bad idea to machine the head? In other words, is there ever a situation where would you be better off just putting the new valves in without machining the head?

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It's best to machine your heads if there is damage to the face. Each time you mahcine it you remove a bit and change the compression and clearance.

Some people machine their heads to increase compression. I guess they think they'll get more power.

Hope that helps.

-Bill

 

It would be best to have the head checked out. How do you know that when you bent a valve, you didnt also crack a valve guide? There are a lot of nightmares you could potentially face if you dont have that head checked out. If you have the head off, why would you even risk not having the head checked out? Get it checked out, repair if necessary, and replace those valve seals. That will eliminate problems you may face... no use in doing the job over again cause you decided to skip checking the head.