Been reading through a few threads here, I'm surprised to read about how many valve guides wear out before 100K. A lot of the posts seem to indicate that is pretty routine.

Is that really the case? Also, can valve guide health be checked in a PPI? I was looking at one with 85K miles, seems to drive fine, no smoke, but there has been no engine work done on it.

If there's a 50+% chance that it has worn valve guides and I'm looking at a $5K engine repair in the near future, I think I'll look for one with the work already done.

 

no....so a search on 'wiggle test'...$5K is on the low end...

 

Also, what are the most common areas for oil leaks? Are there any leaking spots which are particularly deadly to fix (like on a 964, oil leaking from the base of the cylinders pretty much means an entire $10K engine rebuild).

 

Common areas for 993 oil leaks are:

Lower valve covers
Timing chain covers
Base of cylinder heads (mostly just small seeping, not causing enough to drip on the floor)

 

You should ask Steve Weiner at Rennsport. he is a true expert in this area.

He has a "sticky" for questions at the top of the page.

My understanding is that oil use is the only way to know for sure, unless of course the PPI reveals fouled plugs.

Also, some shops can get your top end done for $5K, but most top shops will charge more.

 

I sure would love to know a shop that does a competent top end rebuild for $5K. Double that price and then you're getting closer to the numbers I've seen...ugh!

 

I am in the middle of doing one, total out the door is about $5K.
If you need exh valves, the price can go up as much as another $1K

That said, there is a ton of "while you are in there" stuff that can add to the price tag.
Clutch, plug wires, lifters, may as well replace rings, ok maybe rod bearings too, yada yada yada

 

There is one in NH that some on this board have used which charged somewhere around $5k, and people seem to have good things to say.

When I had mine done I used European Performance Engineering (a really well known and respected shop outside of Boston) and it cost almost twice that, but there were a few other things they did while they were in there.

Here is the write up: https://rennlist.com/forums/showpost...6&postcount=42

 

Thanks. How did you/your shop determine your car needed new valve guides? Did it have a CEL problem, running problem, etc?

 

Oil consumption is the way most owners are able to gauge valve guide wear on a 993. I've heard many fellow owners describe their 993s developing a sudden appetite for oil. At what mileage this happens varies tremendously. Some get that way at 20k miles, others can go for hundreds of thousands of miles without a problem. There is a lot of luck involved, as it appears some engines were just bolted together better than others at the factory.
FWIW mine is coming up on 140k miles and I'm not using much oil at all, though I'm starting to notice a little valve noise at idle.

 

I would also add that other than an SAI triggered CEL and/or heavy oil consumption (1k miles to quart or less) there doesn't appear to be any noticeable worn valve-guide symptoms on a 993. I had an '89 3.2 many years ago that cooked its guides. The valve noise and blue smoke were hard to miss. Apparently that is not the case with the 3.6.

 

Oil consumption.

There is a thread which outlined the whole situation and my decision to do it here:

https://rennlist.com/forums/showthre...ferrerid=34752

 

This isn't a topic at all unique to 993's. It's just that these cars are in this typical mileage range where it crops up. And add in the smog check issues requiring some sort of repair.

In any case, on earlier cars you didn't have the problem so much because of worn guides, but rather because of chain tensioner failure. So if you had 10-20-50K on an engine and had to fix a bank from a failed tensioner, sure you'd do them all. And what we saw at those low mileages wasn't very pretty.

 

No, not all will need guides before 100K.

I have 110K on mine now and drive it daily with mixed freeway/street miles. I do light to moderate stop and go (maybe 20 minutes per day). My oil consumption is usually 1750+ miles per quart. So, I think I have many more miles before I have a need to pull things apart. However, I have noticed what might be increased valve noise but this may also be a lifter going soft or my mind messing with me.

At this point, some on this board would consider a valve job a necessity as they are fanatical about their maintenance and have the financial means to maintain their cars this way which is great. I feel my car does not need guides. But, if I were to pull it apart, I am sure wear could be measured and it would benefit from a valve job. When the time comes, I will do the tear down myself and figure I can do the job for under $1500 not including any major "while you are in there" things I choose to do.

Remember also that message boards such as this can reveal a skewed perspective on things like this. We represent an enthusiastic group of owners that maintain and upgrade their vehicles beyond the average requirements IMO. So, the percentage of cars needing a valve job on this board may seem high, but is probably quite low relative to the total population of 993 on the road still running well and passing state smog inspections.

So, it is a concern when purchasing a car, especially if history and oil consumption is unknown, but not something that would kill an otherwise good deal.

 

On my '88 3.2 oil usage got out of hand but I drove it a LONG time before deciding to bite the bullet. Called a highly respected indy Porsche shop here in the Dallas area and was quoted $8-10K for the valve job alone. The guy mentioned, almost casually, that 80% of that it taking stuff apart and cleaning.... That's when I decided to do what I could myself. Of course once you've got the heads off there's little reason not to go all the way and take it down to the crank, which I did...just couldn't help myself. I sent the heads of to Walt at Competition Engineering and they came back looking perfect, although I ended up replacing all the intake(?) valves as well. Everything else was sent to Zim's (not the who gave me the 8-10k quote)for measuring and inspection, like pistons, cylinders, con rods, etc.
Bottom line, $5,000 at a good shop is a really good price. In fact I'd ask them what would it cost to just finish the job since there is little work involved in taking the case apart and putting it back together.