I am currently looking at two 993's. The first is a Red/Tan 97 Carrera Cab with approx 66,000 miles. The second is a Black/Tan 95 Carrera 4 Cab with approx 33,000 miles. Conventional wisdom would say buy the newest car you can afford, that would be the 97. But on the other side of that wisdom coin would be, buy the car with the lowest milage, the 95.
I am aware that the 95 has the older engine with 270ish hp and is rather reliable. The 97 has the newer engine with the VarioRam induction (raising hp to 280ish) and the OBDII system making diagnosis of engine problems much easier. Now, having said all that, I am aware of the problems caused by the OBDII (or should I say not caused by the OBDII itself, but by premature valve guide wear which subsequently affects the sensors associated with the OBDII) but then the added benefits of the system itself, not the mention the VarioRam...

I guess what I am trying to get at is, is the valve guide wear problem unique to the VarioRam engine or are both engines affected. How expensive is the fix (I spent 7,000 on a top end rebuild on an 82 Targa back in 97)? Is this something that would/should have been fixed in most cars by this date or is it a milage manifested problem.

How about the all wheel drive system in the Carrera 4? I know the 964's system was apparently very complicated and expensive to repair, but that the 993's reliability was improved through simplifying the system...

Any guidance that can be provided would be great.
Thanks.

Mike

 

The valve guide wear is not what triggers the CEL light in the OBDII cars, it is the secondary air injection system (SAI). The heads have small ports in them for the SAI system which aids in emissions on start up. Over time, those ports will clog, and trigger the check engine light. The 95's still suffer from this issue, but since it is an OBDI car, no CEL will trigger. The SAI system is strictly an emissions thing, and have clogged ports will not affect the car in any way. If you don't want to deal with a CEL, then go with the 95. There are some easy ways to clean out the ports in the 96+ cars, but they are time consuming, so if you can't do the work yourself, then you will be paying a shop to try the cheap way, and then if it doesn't work, you go in and rebuild the top end and clear the ports while in there. I have seen the plugs in the distribution ports blow out causing symptoms of SAI with the CEL, as well as just a clogged SAI distribution valve. I've only had to clean out a half dozen ports or so, and I was able to do it without going into the top end. Solvent, some wire, an air compressor, and 8 hours of your time can usually unplug the ports.

Really the OBDII system in the 96 helps diagnose an SAI issue, and bad o2 sensors.....that's about it. So no real advantage there.

Both cars are still going to be subjected to the valve wear issue, so a leakdown test prior to purchase is an absolute must. 5-7k is a good estimate on a top end rebuild.

The AWD system can be tricky. When working, they are a great system, but if the viscous coupling system starts to wear out, then it is nothing more than a giant paper weight up front.

With all that being said, the clogged SAI issue is pretty rare, and usually affects cars that are driven once around the block and put away.

 

Thanks Doc,

Good food for thought...
On another note, not that I am actually considering this at this time, but maybe as a future option. Does either engine lend itself to tuning/modification better then the other? How about adding a turbo (obviously there is other plumbing and such needed there)? I'm in my mid 30's and past the "boy racer" stage, but one never knows what the future might bring...

Thanks again,
Mike

 

I would drop the thought of any forced induction on either motor. Cost and reliability just don't make sense. A friend of mine is rebuilding a 993 motor for a customer who built his home made turbo kit.....the motor internals were pretty ugly as a result.

Not a lot to do for hp performance, you can swap out the exhaust, maybe some intake and chip tuning, but it really isn't worth the money IMHO for what little gains you get.

What i can tell you about 993's, is that if the shocks and struts have not been replaced, they are shot, so plan on that expense. I have never seen a good set of shocks come out of a 993, no matter the mileage if they were original. They used a cheap Monroe shock on the 993's and they are junk. Most guys will upgrade to the bilstein HD's and lowering springs, or go to the pss9/10 kit. Then it will feel like a porsche should!