1980 928 Rescue Mission

[dr bob]

I got a call from a local friend about some problems he's experiencing with his low-miles 1980 car. There's a dearth of 928 knowledge here in the high desert of central Oregon, apparently. I've worked on one of his previous 928's. He's what I like to describe as "gentleman enthusiast", an owner who likes to own and drive them, but doesn't really want to actually do the maintenance or repair work needed to keep these antique muscle cars reliable and happy.

Symptom descriptions began with a no-start, but it turned out that it really began with an overheating event. That spiraled into a no-start after a couple of those and a flatbed ride home. Members in another forum had dished out a bunch of advice, but most of that was targeted towards a more tech-savvy owner doing the work. And as happens quite often, the advice steps caused incidental collateral damage with more things to check and fix. At least he knew to stop digging before he was more than a few feet in, head and arms still above ground level. I spent the morning visiting a lot and working on the car a relatively small part of the visit time.

I readily admit that virtually all my hands-on is with later cars. Early CIS cars yes, later LH+ cars yes, but for some reason the AFM cars have been reliable enough so stay clear of my tools. Anyway, a summary of things diagnosed and solved begins with a failing AFC relay. A long-time friend and 928 sage regularly chanted "relay-relay-relay", so I started with the AFM relay and the fuel pump relay, since the symptoms related mostly towards a fuel problem. It would fire briefly on cranking, but immediately sputter and die. The AFC relay has two '87' output terminal in parallel from the same internal relay contact, a 'feature' not detailed in the current flow diagrams in the workshop manual. Moved on to find that the owner had removed the air cleaner, and in the process had lifted the AFM from the throttle section underneath. Hence the sorta-start them dies when it saw no air flow. New AFC relay on the way from 928 International today.

The multi overheating events that initiated the other stuff appears to be a stuck thermostat. It -could- be a loose pump impellor though. The pump was new genuine Porsche 16 years ago but just a few thousand miles. Won't know definitively until a new thermostat is installed, system refilled and burped some. Is the thermostat a chicken or an egg? We'll confirm the diagnosis and prescription mid next week.

----

The reminder and lessons-learned center on the idea of asking for help early in the diagnostic process. Unless you are really sure of the issues. We have run through almost everybody who might ever have passed through the dealer training programs for these cars, and find ourselves at the mercy of newer folks who might be able to learn on your car, at your expense. The user base for the 928 is tiny when compared with those of it's contemporaries so precious few competent folks are left to keep these cars alive and happy. There are some knowledgeable and experienced owners still supporting others in user forums like ours. Some better, some worse, but at least there are 'some'. We are still carrying the flag!

[Tom]

I got a call from a local friend about some problems he's experiencing with his low-miles 1980 car. There's a dearth of 928 knowledge here in the high desert of central Oregon, apparently. I've worked on one of his previous 928's. He's what I like to describe as "gentleman enthusiast", an owner who likes to own and drive them, but doesn't really want to actually do the maintenance or repair work needed to keep these antique muscle cars reliable and happy.

Symptom descriptions began with a no-start, but it turned out that it really began with an overheating event. That spiraled into a no-start after a couple of those and a flatbed ride home. Members in another forum had dished out a bunch of advice, but most of that was targeted towards a more tech-savvy owner doing the work. And as happens quite often, the advice steps caused incidental collateral damage with more things to check and fix. At least he knew to stop digging before he was more than a few feet in, head and arms still above ground level. I spent the morning visiting a lot and working on the car a relatively small part of the visit time.

I readily admit that virtually all my hands-on is with later cars. Early CIS cars yes, later LH+ cars yes, but for some reason the AFM cars have been reliable enough so stay clear of my tools. Anyway, a summary of things diagnosed and solved begins with a failing AFC relay. A long-time friend and 928 sage regularly chanted "relay-relay-relay", so I started with the AFM relay and the fuel pump relay, since the symptoms related mostly towards a fuel problem. It would fire briefly on cranking, but immediately sputter and die. The AFC relay has two '87' output terminal in parallel from the same internal relay contact, a 'feature' not detailed in the current flow diagrams in the workshop manual. Moved on to find that the owner had removed the air cleaner, and in the process had lifted the AFM from the throttle section underneath. Hence the sorta-start them dies when it saw no air flow. New AFC relay on the way from 928 International today.

The multi overheating events that initiated the other stuff appears to be a stuck thermostat. It -could- be a loose pump impellor though. The pump was new genuine Porsche 16 years ago but just a few thousand miles. Won't know definitively until a new thermostat is installed, system refilled and burped some. Is the thermostat a chicken or an egg? We'll confirm the diagnosis and prescription mid next week.

----

The reminder and lessons-learned center on the idea of asking for help early in the diagnostic process. Unless you are really sure of the issues. We have run through almost everybody who might ever have passed through the dealer training programs for these cars, and find ourselves at the mercy of newer folks who might be able to learn on your car, at your expense. The user base for the 928 is tiny when compared with those of it's contemporaries so precious few competent folks are left to keep these cars alive and happy. There are some knowledgeable and experienced owners still supporting others in user forums like ours. Some better, some worse, but at least there are 'some'. We are still carrying the flag!

Good work dr bob! Get your friend over here to Carpokes -- you need company in 928-land. The thermostat is a bear to replace on the 944, due to a circlip that's wildly over-strong and equally hard to get a grip on. Same on the 928? I've gotten to the point where I find it easier just to pull the whole water pump with the thermostat in it, rather than trying to change out those infernal things...

To your last point, funny how things come full circle. The PCA grew out of an informal group of 356 owners called the "Gripe Group" -- the purpose of which was to vent about 356 repair issues and share info on how to fix common problems in the absence of professional help. And here we are 70 years later doing pretty much the same thing -- relying on each other to fix Porsches.

[dr bob]

Fortunately, the 928 thermostat is pretty easy to swap. A couple bolts release the housing and lower hose nozzle. Old one comes out with the seal, new one pushes in with new seal. For later cars, there's a replaceable steel-backed rubber seal for the recirc nozzle in the center behind the thermostat, but that doesn't apply to the subject 1980 car.

There's more discussion going on with the owner about the real sequence of symptom events. As I dig deeper, the root cause of all these symptoms seems to be the thermostat failure. Everything after that is caused by diagnostic mistakes and actions. When I have a more complete picture I'll share the whole thing with the group here. Hopefully it will share some knowledge forward for other owners, and help them avoid some of the pitfalls and collateral damage this owner caused and experienced.

If all this stuff was easy, the cars would be more common and have a higher market. As it is, I think the common opinions lean towards money pits, unsupported, and are backed by too many marginal or worse offerings. Meanwhile, good examples are a joy, an exercise in engineering excellence that very few production Porsche models can match. Want a comfy and relatively effortless 2-fingers drive at 150? Hint: it's not in similar-vintage US 911's. Is there much appreciation for that these days? Hint: more for similar-vintage 911's. It takes a bit more love and knowledge, and more drive than the average independent air-cooled 'specialist' can afford to commit. I consider cars like this as expressions of engineering as an art form. To be appreciated, loved, displayed, and enjoyed. Buy in is low, maintenance can be high, but with the right examples and a community support network, they are fabulous cars.

A question came up today with that owner, and I was reminded of my own purchase decision process. I committed a cardinal sin, buying a used Porsche sight unseen, no PPI, based solely on the sellers too-good-to-be-true description. The car did match the seller's description though, but of course we didn't know that until I bought the car, had a full timing belt and WP service done on it at the dealer in Denver all over the phone, then flying in and driving it back to SoCal. What an introduction!

Part of the due diligence was finding local support, and that identified 928 International less than 30 mins from my home in the worst SoCal traffic, and a real certified 928 technician at the dealer in Pasadena, minutes from my office. The dealer tech was a bust, not discovered until I had the car and brought it to them for a simple timing belt re-tension. More damage than benefit there, so I dusted off the tools and studied the car from end to end. The local parts support was awesome, and the growing online support made it all possible. So here we are. After years of hosting owner clinics in my home workshop, and learning from every owner problem and solution presented, my 928 experience has been among the best of many 'interesting' car ownerships I've enjoyed.

I highly recommend it.

[dr bob]

Following with more on this spellbinding saga --

The overheating issue was just too much coincidence, so I recommended that the owner reassemble the air filter assembly and tighten everything up, following the discovery of the AFM sitting loose in the valley. Then the old AFM relay back in, and... Starts and runs perfectly. Owner shares now that he'd removed the air filter housing looking for a coolant leak after the car boiled over and reservoir vented into the top of the valley. Then left it off for a test drive, not knowing that the air filter housing is what holds the AFM in place.

He'll have the new thermostat in the next few days, and the coolant is waiting to go in when the system is closed up again. We'll have a final report when it's back to running/driving perfectly again.

[Tom]

Following with more on this spellbinding saga --

The overheating issue was just too much coincidence, so I recommended that the owner reassemble the air filter assembly and tighten everything up, following the discovery of the AFM sitting loose in the valley. Then the old AFM relay back in, and... Starts and runs perfectly. Owner shares now that he'd removed the air filter housing looking for a coolant leak after the car boiled over and reservoir vented into the top of the valley. Then left it off for a test drive, not knowing that the air filter housing is what holds the AFM in place.

He'll have the new thermostat in the next few days, and the coolant is waiting to go in when the system is closed up again. We'll have a final report when it's back to running/driving perfectly again.

Am I right to understand the O2 started with CIS, then DME with AFM, and finally DME with MAF sensor? When did they ditch the CIS?

[dr bob]

From memory that could easily be verified, 1979 was the last year of CIS in the U.S., mostly thanks to emissions issues. The engines were, um, calmed down some for the U.S. market after that, and especially for Cali cars. We could only go 55 anyway, so... ROW cars continued a bit longer with CIS, depending on model. Certain market S/S2 cars well into the 1980's IIRC. The hot-wire MAF started with MY1985 US 928's, and continued through end of production in 1995.

I've shared previously that I paid almost no attention to the early cars. I was in the 911 camp, and had a bad Lotus habit at the same time. My weekend race car habit had a Yamaha engine, a situation that brought me to some work with the prancing-horse guys (across the street from Yamaha...) as they were working to pass Cali emissions and still be able to run faster than riding lawn mowers. A 928 with AFM came in as a compliant example of how performance and emissions could happen at the same time. I did a lot of testing on it, but never actually drove it. It certainly worried the redcoats though. Not enough to adopt AFM though. They very much had their own ideas about combustion and fuel management, as you can imagine. My own 928 came to me out of the blue more than 15 years later. I never went through the posters in the bedroom lust for them as many others report, and looked at it as an interesting diversion from the other projects. But I had too many irons in too many fires, so started thinning things. The 928 was the most civilized of what was there, and I'd purposefully kept it completely unmolested, so it earned the right to stay while others found deserving new homes. Coming up on 30 years with it now, it still has the right to stay I think. Good times!