Peter Zimmermann

The thread that caught my attention was one where the poster was advised, by a shop, AGAINST the purchase of an SC, and encouraged to buy a 3.2 Carrera instead. I almost dismissed that post, but then I began to think about it because to me that advice just didn’t make sense. The newest SC is a 1983, the oldest 3.2 is an ’84, and a nice ’81 is not that much older than a good ’85. Age couldn’t factor into the advice offered, we’re not talking Model As and Mustangs here. Then what could it be?

1. We must throw out comparable issues of the two models. SCs and 3.2s (through ’86) all use the same clutch, and engine removal labor/difficulty is similar. The 1987-89 3.2s use a different, more expensive, clutch. It is no more reliable, requires additional labor, and its flywheel cannot be re-surfaced, only replaced. Although the nod might go to the SC I think that we can call the clutch a wash. Starters, shocks, tires, steering and suspension components, etc., are pretty much the same on SCs and 3.2s. SCs and 3.2s (through ’86) use a clutch cable, ’87-89 3.2s use a slave cylinder and a fluid hose that will leak. We’ll call those items a wash because cost and replacement frequency are similar. Minor and major services on both models are about the same in both frequency and cost. Oxygen sensors, motor mounts, brake hoses and rebuilt alternators aren’t different enough to even think about steering a buyer away from one model or the other. Hmmmm, this is getting interesting.
2. Let’s study some of the “replace-once-in-a-blue-moon” items. They are reference sensors (3.2s only), oxygen sensor/frequency valve relay (SCs only), auxiliary air valve (SC only), injectors (both), decal valve (SCs), idle control valve (3.2s), and throttle switch (3.2s). There are mechanics out there who will spend a career without replacing most of those parts.
3. A couple of “biggie” repairs should be looked at. Each model has a glitch in this category; SCs (some) suffer from broken head studs, 3.2s (some) suffer from high oil consumption. Costwise the jobs are comparable, with maybe a slight edge going to the SC. Neither repair is sufficient to warn off a buyer from one model and steer him/her to the other.
4. Transmissions. All SCs and ’84-86 3.2s use the 915 transmission. That’s a wash. Enter the G50 (’87-89 3.2s) – one bulletproof trans that should last, with care, more than 250,000 miles. So, the ’87-89 cars edge ahead in the advice to buyer race. But wait a minute! The typical SC synchro repair will cost about $1500. The typical G50 car will cost at least $6,000 – 8,000 more than a comparable SC to obtain. Of course, you get power seats and better A/C, but this gets us to a different buyer philosophy – buy the latest model you can afford. This does not necessarily pit one model against the other.
5. Let’s explore some typical repairs that SCs and 3.2s require over time. I’ll mention here that this info is pretty much consistent through 200K miles, beyond that “repairs” have a tendency to become “restorations.” OK, we’ll start with the famous SC airbox (not applicable to 3.2s). When the box blows the car will leave you stranded and the repair will set you back between $1100 and $1300. On the flip side the air flow meter (3.2s only) fail in a way that prevents the car from passing its emission test. Replacement is necessary, which will set you back between $800 and $900. CIS fuel injection (SCs only) use a component called a Control Pressure Regulator (aka Warm Up Regulator). The part is rarely replaced, most often when moisture has entered the system. With moisture present all bets are off for both models, but I’ll include it as a part of this discussion anyway. The part is currently available for about $660, sometimes less. With labor you’re looking at about $800. On the other side 3.2s have a pair of engine compartment fuel lines that require replacement, which, including an intake manifold reseal, will reduce your worth by about $1,000. SCs have a part called a Fuel Accumulator, which will cost about $350 plus minimal labor to replace. 3.2s have two relatively minor issues, one of which can leave you stranded (DME relay), and one that will make the car exhibit unusual symptoms (Cylinder Head Temperature Sensor). The relay will cost you about $50 + minimal labor, the sensor about $300 installed. So, at this point, repair costs are $2350 (SCs) and $2150 (3.2s). Have we supported the adviser’s advice yet? I don’t think so.
6. Upgrades. Carrera Tensioners. That’s about it. 3.2s have ‘em, SCs didn’t. However, by now most good SCs have already been updated, so is it even an issue? Hmmmm...

I report, you decide. Keep the shiny side up!
Pete

JBO

Pete - that's a great list, but was'nt the shops recommendation almost solely based on what he thought were advantages of the motronic over the CIS, and availability/cost of CIS parts? Are you saying that the motronic, from a drivability, etc standpoint really is not much better than the CIS? (I hope so, since I own an SC!!)

J. Brinkley

well said Pete, but no Kjet will ever sit in my driveway

Peter Zimmermann

JBO: I began to write # 5 in the above post, then decided to do a bumper to bumper instead. My reasoning was that you wouldn't buy a '69 T over a '70 T simply because it had Webers instead of Zenith 40 TINs. There is a lot more to a car than the injection system, especially when you realize that both systems, CIS & Motronic, are superb. It would be more fair to compare a '73.5 T with CIS to a very early '73 T with MFI. Those two systems, and their engines, are radical in both approach and performance, and could be reason enough to purchase one or the other. With 3.0 and 3.2 cars, both wonderful models, there has to be more than just the "repair cost" of CIS. To me that was not logical, so I decided to look past that to see if there was some factor that may have played into the advice given. Overall, I feel that the CIS car is actually the superior car in town and commuter use, while the 3.2 holds a slight edge at the high speeds used for Interstate touring. Many CIS problems can be traced directly back to the use of lousy gasoline or incorrect setup by the car's technician. An experienced mechanic will have no more difficulty diagnosing a CIS problem than they will have diagnosing a Motronic problem. To hear some people talk you have to wear ear plugs every time that you start your SC, just to avoid damage to your hearing when the airbox blows. That just isn't the case, I replaced the original airbox on my '82 SC three years ago - at 192,000 miles! Yes, CIS cars require fuel mixture adjustment at every major service/tuneup, but that's why every good shop has at least one good CO% machine, and every technician in the shop should know how to use it. It takes ten minutes to set the mixture, at the same time HC is noted, which can let the tech know of a problem. The same procedure should be followed with Motronic cars. I feel that using my own car as an example is appropriate, because over many years I serviced SCs that just did not break. My car is entirely original except for the airbox, related seals and gaskets, injector sleeves and accumulator - at 203K miles. I did a part search yesterday, and am able to have every single component in the CIS system shipped to my house by this Friday at the latest. There is no difficulty obtaining parts, and as the above comparison shows there is little difference in repair costs. And yes, Jerry is a lucky man to have a beautiful '87. The '87-89 3.2 cars are as good as it gets, but as I said, is it fair to compare a $23K car to a $16K car, and base that comparison solely on the fuel system in each car? No, the late 3.2 cars are in a class by themselves, with refined systems and equipment. As far as the six years of SCs, and the first three years of 3.2s, I see no reason not to buy the best, cleanest car that can be found in that group - without wasting a minute worrying about CIS or Motronic.
Pete

dsher

I think the issue in question was the cost of repair of the mech fuel injection on the sc because of the difficulty in finding parts and cost of replacement favored the 84 to 89 with less expansive to fix and more reliable fuel injestion of the later 911, also it seems a well cared for and documented sc is approaching 19k. my lacal porsche shop quoted mt 5k to make major repairs to fuel injection on a sc to 20 k versus 24k to 25k for 87 to 89. the local porsche shop quoted my a potential cost of 5k for sc fuel inject repair erasing the cost diffenteral between both cars your thoughts

JBO

Not sure where they came up with $5,000 to repair a CIS problem, unless they were talking about water/rust in the fuel sytem requiring the replacement of the gas tank and the entire system, but that is not a normal repair, and should only be necessary on a car that has sat unused forever or is a real dog. Pete clarified that CIS parts are available and no more expensive than motronic parts.

J. Brinkley

it's probably not fair to compare 23 and 16, but, people swear up and down that 20K SC's exist. You have to take an '83 and an 84' same condition, and a guy that would actually pay $400 for two fuel lines and at the same time turn around and ask for a NIB WUR for the other car. For the take it to the wrench everytime owner, it's probably very close to a wash. But for the guy that does all the work himself, $50 fuel lines and just maybe a WUR from a jetta or rabbit, other things have more appeal. Tools necessary, diagnostic ability, ease of maintenance, and other aesthetic aspects.
I feel guilty having not read your book. As soon as Adrian slows down I'll get to it.
thanks for taking the time here to put your thoughts down.

Jay H

Peter,

First, thank you again for the informative posts on the SC and 3.2 comparision of fuel delivery.

Would you wish to comment on each system's reaction to reformulated (or boutique) fuels that are in place in certain areas of the US? I've read in the past on this board that the CIS system is not particularily fond of reformulated fuels over time due to (and I might be wrong on this) reaction of more 'ingredients' in this fuel on the fuel system (metal?) parts. I've read that the Motronic components have fewer parts touching the fuel, so therefore the Motronic might be a better choice for people who are forced to buy reformulated fuel.

Again, this could be all false information, but your expert opinion would be valuable.

Thanks in advance,

Jay
90 964

Peter Zimmermann

Jay: Unfortunately my experience is from California, where Chevron Premium is KING, and anything from Union 76 to Mobil is crap. I had a customer tell me once, a few years ago, that he couldn't get his lawn mower started, remembered what I had told him about Union 76, drained the tank and refilled the mower with Chevron. You guessed it, the mower not only started, but by the time he was half done with his lawn it was running better than it had in a long while. I truly wish that I had people that I trusted in various parts of the country, but outside the midwest, where Phillips 66 Premium seems to be king, I'm kind of lost. One thing that I can surely recommend is the use of Chevron ProGard with Techron additive - I think that they used to call it Techraline. That stuff is magic, and prevents varnish build up inside the fuel distributor, injectors and other components of the CIS. My shop actually cured starting difficulties, a large number of them, simply by insisting that the car owner switch to Chevron from the gasoline they regularly used. Shops replaced fuel distributors, we switched gasoline, and we ended up with a huge clientele of happy customers as a result. That's why the post that I responded to left me thinking, because the SCs that I've cared for since the early-80s, many have gone past 200K miles, have been as reliable as any car on the planet. They might need more love than a Carrera, but they are no harder, or more expensive, to maintain/repair than the 3.2 car. I know this does not fully answer your questions, but I just don't have enough info for you.
Pete