Hey guys. I got the heads off of my L98 while the shortblock is gettting rebuilt. The combustion chambers and valves have some carbon buildup on em from my previous oil burning problem. Intake was sucking a lot of oil trough the PCV valve so it kinda gunked up my whole intake and exhaust. Anyway... is it stupid to go over the valve faces and combustion chambers with a cup wire brush mounted on a drill ? I did it to one of em and it came out pretty shiney. Does this causing any problems, like stress areas or anything like that ? I would think it's better for the chamber to be "squeeky" clean then have all that build up on em.

 

I would completely disassemble, clean and reasemble the valve assemblies while you have them off. Just make sure you put the parts in EXACTLY THE PLACE YOU REMOVED THEM. you can clean the valves in mild solvent without abrasives like your idea. Plus, sometimes you find problems doing this... Also, change valve seals while in there!!!!

[This message has been edited by FastBroker (edited September 15, 2000).]

 

Yeah I guess I was hoping I didnt have to go get a spring compressor and all that. The heads were rebuilt about 2000 miles ago. I probably need a new exhaust valve on the #6 cylinder where a lot of was being dumped in. I looked at the stem and it looks nothing like a nice shiney valve stem. It's covered in black gunky stuff that wont come off just with carb cleaner. Anybody suggest a strong solvent that will "solve" that stuff off the exhaust port and the valve ? Heh

 

Castrol makes a strong water-based cleaner, but the name escapes me now. Something like "Super Clean", or some such. Works pretty good, I've used it on pistons before.

It would be better to get the heads tanked and reassembled, as FastBroker suggests.

By the way, you can get an oily intake from bad intake seals. So, disassembly isn't a bad idea while the heads are off. But, to answer your last question, you won't cause any stress areas by wire brushing. Grinding is a different story.

 

Blade,

Removing all the carbon with a cup brush is a good idea, and a little polish on the chambers never hurt either.

As suggested, removing the valves, or at least the suspect #6, would be a good idea to insure that there has been no damage. Coked valves will impede flow drastically, so it's worth the effort.

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Also, clean up the valves and inspect the edges for pits....a burned valve will be pretty obviuos...also on that chanber (if you find a burned valve) take areal close look inbetween the intake and exhaust seat for cracking.

Keep in mind that you cannot just buy a valve and put it in (well, ya can, but shouldn't) you should have the seat cut, and the new valve lapped in. Most likely though, the setup cost at a shop to do one valve, will roughly be 90% of a complete valve job.

An oil coked valve doesn't necessarily mean it's burnt, or mean it needs to be replaced.