swmic

While doing some spring maintenance, I decided to pull the exhaust manifolds and discovered a somewhat gummed up exhaust valve on #5. Would this be caused by a worn valve guide?

I would not be too surprised since the car has 136 K on it with no known history of a top end rebuild. The car seems to run well and only burns a quart about every 2.5 K with some leaky valve cover gaskets. The other photo is #6.

Shawn

Mike J

Given you oil consumption (which is a prime indicator), I do not think you have a problem at all. Yes, you have a bit of build-up, and likely its a bit of oil from worn guides, but not much to worry about. The only concern might be that the SAI port is just behind the valve base, and that might be getting a bit clogged.

Now, if you would have said 1 quart/600 miles, then I would worry.

Cheers

Mike

Slow Guy

When I did my previous 993 (clean SAI ports) 2 or 3 of the cyls had that glossy deposit on them, I posted a photo and everyone said not to worry about it. My oil consumption on that car was about what yours is.

cdmdriver

No Worries!

swmic

Thanks guys. I wasn't too worried about it, but it was noticeably different than the other valves. I have been getting an intermittent SAI code which seems to go away after a long drive. I don't remember what bank the code indicated, but like you noticed Mike, I bet this is what is throwing it. It makes a lot of sense now.

I'm going to ream out the SAI passages using the cable method and replace the SAI check valve. It will be interesting to see how clogged #5 is, or if I find any any others. I'd like to go through the motor in a couple of years adding maybe another 15 K. It will also be interesting to see if the condition of #5 gets worse over that time.

Shawn

berni29

Hi

If I were you I would run a can of BG44K through the fuel system. In fact I looked at my exhaust ports having taken the headers off (185k miles) and although I did not have any as gummed up it will clean off combustion deposits inside the chamber.

Berni

matt777

You can check the movement in the valve stem to determine approx. guide wear but if your engine runs well and oil consumption is acceptable I wouldn't bother.

NP993

It's worth considering the possibility that this particular valve guide is in bad shape, and the others aren't. Valve guides do not necessarily wear in perfect harmony with each other.