fiftyfive

I've tested a couple of 993 Carrera manuals. Very impressive. After scouring this forum and reading the excellent 10/03 thread on Valve Guides/Oil Consumption(SAI/CEL), is there any idea of the percentage of 993's that develop this issue?

Put another way, right now it seems prudent for me to future-budget a valve guide job to insure the root cause is fixed.

Thanks and apologies for a new thread on a well-trodden subject.

vjd3

It's hard to say ... it's a given that the valve guides wear, but this is an issue on other 911's as well, back to the 3.2 Carreras. There are 993s on this board with very high mileage that have not required valve jobs. The SAI/CEL issue is real, but the 95 cars are not affected by it because they are OBD1 cars and will still pass. The SAI/CEL is not a running issue, it's only emissions on the first 30 seconds on cold start.

Look at it this way ... the car, if it's a nice example, will not depreciate nearly as much as most other performance cars, so the $4k more that, say, a BMW M3 might depreciate over a couple of years would pay for the valve job if it became necessary.

Vic
95 C4

97Targa

IIRC, there are no hard figures on this issue.
Plenty of theories for the cause. Mostly relating to low speed stop and go driving and a lack of preventative maintenance. Seems like a hit-and-mis situation.
Good luck in your search. Let us know what you purchase.

Terry Adams

Good luck in your search, fiftyfive. You would think there is a conspiracy among would-be purchasers to air this and drive the general 993 price down. It is just the first issue that people doing their DD on a 993 come across. The results of a meaningful poll would go something like this:
_% Have had it and post on RL to help others.
_% Have had it and don't post about it.
_% Don't read RL, so you would never hear from them here, had it or not.
_% had it at <50K miles, _% at 50K-100K, _% over 100K
_% over 100K never had it (myself included)
It depends on type of driving, maintenance, engine cover on/off, concurrent with worn valve guides or not ...
The search function at the top of the page, and PPI is your friend.

Chris M.

Just because the 95 doesnt' have OBD II doesn't mean that the guides aren't wearing. It just means the CEL isn't coming on because it's OBD I. All 993 guides are made of the same material, regardless of year. Excessive oil consumption is your best indicator.

c

vjd3

True, but in the 95 car, you don't have to address it because of the CEL. And I don't think clogged SAI passages are an indication that your valve guides are worn to the point where replacement is necessary; some people are getting CEL's at low mileage.

Vic
95 C4

Leland Pate

Terry is right on...
There are soooo many variables to take into consideration it'd be almost impossible to come up with a percentage of cars affected.

For what it's worth, I know 6 guys with 993's, not including myself, who haven't had valve guide problems. As with any automotive forum. People don't typically post threads titled "My car is perfect -Everything's OK" or "No valve guide issues here."

I subscribe to the theory that valve guide wear is linked directly to maintenance, driving style, and the environment in which the car was used. For instance, I'd be more concerned if looking at a later, hotter running 911 (3.2-3.6), with little to no maintenance documentation in some of the southwestern states. And I'd be especially concerned if that engine undertray had never been removed.

As for the CEL issue... who knows, it does seem to be a more chronic problem associated with the OBD II cars. I feel that this is just one more good reason to shop for an early '95 model.
Of course I'm biased, but everytime I read a "CEL nightmare" or an "Immobilizer malfunctioning" thread, I thank god I bought an early build '95.

Chris M.

Vic- please explain. Do you mean that you don't have to address it because the CEL coming on keeps you from passing emissions? Inevitably, won't no CEL just mean that you'll realize there's a problem much later? If the 95s really are immune to the wear then that's great because they can be had for less.
OT but are there some 95s that came without the basket handle?

c

vjd3

No, Chris, what I mean is the CEL light and SAI passages aren't necessarily related to valve guide wear ... the passages get clogged with carbon but that doesn't mean your guides are worn to the point where the car is using oil excessively and needs attention. The only advantage to the 95 cars is not having to deal with the CEL and failing emissions and having to have the passages cleared. And, as I said, lots of people (Ray Calvo, for example, I believe) have a lot of miles on their 993s and have not had the valve guide issue present a problem.

Valve guides have been spotty for years on 911s ... there are 3.2 Carreras that needed valve guides at 8k miles (Charlie Kindel's car was a notable example) and 3.2 Carreras that are well over 100k miles and have never been apart.

Replacing the factory guides with harder ones will cure the guide problem once and for all, but it won't guarantee that the SAI passages won't get clogged again and require attention.

Vic
95 C4

Chris M.

So with the 95 you can just keep driving with clogged passages? What is the actual source of the carbon?

c

mborkow

"Excessive oil consumption is your best indicator"
i did not have excessive oil consumption, but i did have plugged SAI/CEL problems.

vjd3

The passages are only "in play" for the first 30 seconds or so on cold start, as I understand it, it's just to reduce emissions on the cold start. So, if they're clogged, it doesn't really matter; the car runs the same. The carbon is just a byproduct of combustion ... with worn guides I'd guess you'd get more carbon but even a perfectly healthy engine produces it, that's what Techron is for.

Vic
95 C4

Leland Pate

The passages may become clogged on all 993's. The '95's used OBD I and it doesn't trip the CEL fualt code like the OBD II cars.

I bet mine are clogged up, but I'll never know (unless I tear the cam towers off) because the OBD I doesn't care.

trojanman

I believe what was meant is that excessive oil consumption is the best indicator of worn valve guides, not clogged SAI ports.

As for preventative measures related to SAI issues, I know several reputable shops believe strongly that the main culprit is the SAI check valve. As has been posted on this forum numerous times, when the check valve gets crudded up and stops functioning properly hot exhaust gasses are allowed to flow backward into the ports and cause excessive carbon build-up. I know Hergies recommends changing the valve every 15k miles or so.

As for guides, my car grew up in the upper mid-west and appears to have began having clogged SAI ports as early as 25k miles (based on very detailed and complete maintenance records). I didn't have any records of oil consumption but realized quickly after I purchased the car (at 39k) that I was burning way too much oil (a quart in the first 500 miles).

My guides were shot and my ports were plugged, so a new top end was my only real option. I don't know the driving habits of the PO, but I do know from the records that the car was well cared for and had oil changes frequently.

I believe my car is in the minority as far as these issues go, and that more than anything else I was just unlucky. However, I'm not certain that reliance on good records, strong PPI results from a reputable shop, and otherwise proper due diligence will necessarily keep you trouble-free... ask me how I know.

Chris M.

Vic- I got it. thanks.

c