AndyK

I'm starting the process of trying to learn as much as I can about the 993 so that when I'm ready to buy (Spring or Summer0, I'll have the knowledge to buy a good car (like I did with my 944).

Anyway, I understand that the 993 engines need valve guide / top end work when they hit 80k - 100k(?) miles, to the tune of $10,000. I also have read that the '95's computer doesn't produce the CEL like the later ones.

Question is, if I buy a 96-97 with let's say - 30k miles on it, and eventually put another 30k miles on it - will the CEL problem not be an issue due to the low miles? In other words, if any 993 I buy winds up having less than 80k miles if/when I sell it, does it matter what year car I buy?

Avoiding a top end rebuild would be a nice thing, especially since my wife and two young kids need to eat

Thanks for you patience!!

RallyJon

I think you're trying to apply precise logic to a highly variable problem. You could buy that pristine 30k mile 993 for top dollar, drive it home and have the CEL come on the next day. Of you could drive it for years and never have the problem.

If I were you, and I was looking for a OBDII 993, I would want a previous owner who was completely aware of the problem and up front about it and had cleaned the ports and replaced the {edit: SAI} valve in the past. Dealers tend to say, "Que? No comprendo" and look at the floor shuffling their feet when you mention the issue.

But the one thing that all 993 buyers must have as a prerequisite for ownership is $5-7k in the bank beyond what you pay for the car. Go into it with your eyes open and a good attitude or you'll worry yourself to death with all the expensive things that can go wrong with these cars.

98993c2s

First: it is correct to state that 95 models aren't subject to the SAI issue which causes the CEL, due to the fact 95's are OBDI cars.

Second: I do not necessarily agree that 993 engines have a premature valve guide wear problem, any more than any air cooled 911 engine has that problem. It is not a correct statement that 993s generally will need valve guide work/top end when they hit 80k-100k.

Lastly, when you say 'CEL' you are really referring to the CEL caused by SAI. SAI in my view is a separate issue from valve guide wear.

There are those that disagree with this viewpoint, of course.

AndyK

Yeah, sorry. I lumped two issues into one question. Trying to get a grasp on the major issues with these cars, so I know what to look out for, or expect.

I agree about having the extra just-in-case $$ for unforseen problems. I just would hate to buy a clean car and have to put another $10k into it a month later!

98993c2s

The SAI fix doesn't require a top end, so you shouldn't concern yourself with $10k expense a month later.

fast_freddy

If you pay $10k for a tpo end rebuild you are getting "jacked". I just had mine done a few months back and paid $8k. However, I put in an RS Clutch/FS, cat bypass, wires, plugs, distrib rebuild, and a whole host of other things too. For just the top end it figured out to be about $4250.

AndyK

The worst thing I've read about these SAI / CEL issues is it's an expensive repair that really isn't necessary and doesn't improve performance. Is that true?

Do the OBD1 cars have clogged SAIs, but because the computer doesn't care, the issue never comes up? Is it worth passing on a 96-98 car to avoid the OBDII hassle?

Randy M '96 Silver 993

Keep searching the past threads on this issue.

I got my first CEL due to SAI at about 48K miles. I had the ports flushed for about $1,000.

As I understand the Valve guide issue, it is not an issue unless you are burning excess oil. More than a quart in 1K miles.

Keep searching and asking questions. You will find the right vehicle.

epj993

Actually, '95s do have SAI but OBDI doesn't monitor it and therefore doesn't trigger a CEL. However, the ports will still clog.

I think it can be. If your oil consumption is well within spec, you probably don't have a valve guide issue. SAI CEL due to clogged ports doesn't necessary mean you have bad valve guides. Conversely, if you do have bad guides they will contribute to clogging your SAI ports and triggering a CEL.

RallyJon

How will you know that before you have the car? Dealer won't know, and seller might lie. No seller in his right mind would ever allow oil consumption as a sale contingency.

AndyK

I guess if a seller has already had the ports cleaned, or, rebuilt the top end, you can guess the issue has been fixed?

InTheAir

ISV?? I don't think that is what you meant.

The ISV (idle stabilizer valve) is used to maintain a smooth and properly adjusted idle.

I believe you meant the SAI check valve, which can be stuck open, thus permitting exhaust contaminants to travel up the SAI ports and deposit their by-products therein.

RallyJon

If a top end's been done properly you're in the clear. Also, given the irrationality of the used 993 market, you can probably beat the price down more since the car is no longer "pristine" "untouched" "no stories".

Yes, Jeff, that's what I meant.

InTheAir

Depends. Did the top end include cleaning the ports? Did the flush actually successfully clear all ports?

Even if the above is properly completed, the fix is more of a "restart the clock" type fix. The system itself remains unchanged in most cases and thus after X amount of miles or other variables, the clogged ports can come back. But with reasonable attention (i.e. periodically changing the SAI check valve), you can skew the odds in your favor.

vjd3

Some rebuilders will enlarge the passages to further prevent clogging ... just an FYI.

However, do not assume it's been done correctly, the previous owner of my car spent $3800 with a shop to get the car past emissions. From the paperwork and what I have found, they basically changed out every hose, nut and bolt on the intake, plus the MAF sensor, added a ton of labor, got the car to pass and busted the check engine light so it would stay off. They didn't touch the passages or the check valve. He got hosed, literally.

I'm doing the top-end, but I did get the car to pass emissions. I also negotiated a hefty $7500 discount in the selling price because I knew the ports were still clogged. Frankly, I'd rather buy the car with the ports clogged then start fresh with a fix on it, you get to break it in, you get a warranty with your shop, and you can rest easy know it was done correctly.