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New (to me) '78 928 troubleshooting

Old 09-14-2018, 09:08 PM
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Hey_Allen
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Default New (to me) '78 928 troubleshooting

Okay gentlemen, I ended up being given a 928 after squawking when a friend told me he was going to be scrapping it.
The car was initially purchased from a towing auction, he did various maintenance (receipts now missing) for around $2500, including a new water pump, timing belt, rebuilt starter and alternator at the local electric shop, radiator was removed and flushed by a local radiator shop, among other work done.
Then it was delivered to the friend that he was building it for, as the friend's early 80's 928 had been t-boned.

I lost track of it at that point, as I had helped with some basic CIS maintenance when it first came to my friend, but had no further involvement with the car.
It turns out that it had serious overheating issues, rapidly heading for the top of the gauge shortly after firing up the engine, every time.
The car ended up parked, and only occasionally moved, for the next ~10 years, until the friend wanted it out of his yard.

Now the questions I have are relatively obvious, but I am hoping for confirmation on the conclusions I was coming to.
If you have no fan shroud, and the stock mechanical fan, I would assume that the car is going to aimlessly flail the air in the engine bay around, not drawing any through the radiator?

The second thing that I noticed, while inspecting the engine bay for low hanging fruit problems, was that there is a radiator drain plug on the top left corner of the radiator, where I see a small hose in the various drawings and posts here on the forum.
Was this a first year quirk, or is there indeed a missing hose, making it harder to get any potential bubbles out of the system?

Since we are often told how useless a thread is without pictures, here are a couple as the car was being picked up from the neglectful prior owner's place.
It's definitely a rough car, but for a non-purist, it's an interesting challenge and something to keep my hands busy with for a good while to come...


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Old 09-14-2018, 09:42 PM
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medipedicman
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Addressing the overheating issues. Pull the thermostat and test it in a pan of boiling water. Does it open? If it opens I would buy a digital thermometer and read the actual temps. You could spend a lot of time chasing issues that aren't there if your cluster is not functioning properly.

Keep posting.
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Old 09-15-2018, 02:47 AM
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The boiling test is next on the list, but seeing things like the missing radiator fan shroud, and the absent bleeder hose from the top left corner of the radiator make me wonder if the overheating was induced by someone who didn't know they were supposed to be there.

I'll be pulling the thermostat housing this weekend to test the thermostat, as well as to see if the o-ring was even in the correct position. I'll definitely post when I know more about what is going on with the car.
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Old 09-15-2018, 04:00 AM
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giddyupp
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Looks to me like that radiator is upside down.
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Old 09-15-2018, 10:30 AM
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gomez123
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That radiator is absolutely upside down. No A/C condenser either.
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Old 09-15-2018, 11:13 AM
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I'll be damn. Concur - upside down. Also, yes that shroud is necessary to focus and direct air flow. It also has the duct connection points for the air tubes that run to the airbox tat the rear of the engine. You can get those parts very reasonably used from 928 International.
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Old 09-15-2018, 11:25 AM
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drooman
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Originally Posted by giddyupp View Post
Looks to me like that radiator is upside down.
Yes! My bet is they got a radiator from a later car and the oil cooler was on the wrong side. If the water pump/ timing belt / thermostat tech is the one who put the radiator in then you should re-check all of that work... there's a number of ways to screw up that job. If you decide to get this one going again buy a capillary (not electric) water temp gauge from discount auto, remove factory temp gauge sender from top of water bridge, install capillary gauge with a thick layer of thread tape (pipe threads into metric fine thread in the water bridge) don't over tighten and you can seal it without damaging original water bridge threads. this is the only 100% reliable way to see water temps when trouble shooting / evaluating cooling systems...you can hook up the "limited usefulness" factory gauge when its all sorted out.

Before doing much I would turn a pressure washer on that thing, you might be surprised at whats under there and it'll help your mojo when working on it. The price was right, so have at it!



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Old 09-15-2018, 11:52 AM
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Okay, the different years having the plumbing on opposite sides explains a lot.
I believe that a good bit of the parts likely came from an 80-81 car that the guy this was being built for had, but that was hit in a side impact accident.
I was given the engine from that car as well.

The car has been pressure washed, but due to the rails on the trailer I couldn't open the door and pop the hood, so the engine bay didn't get any attention.
The washing did reveal a little bit of rust that was under some moss in the top of the left rear window, so one more project, once I get that far.

​​​​​​
Here is the one pic of the car after washing it, and getting ready to drop it off at my garage.
It didn't get as clean as it initially appeared to be, once it dried, but still miles better than it started the day!


Last edited by Hey_Allen; 09-15-2018 at 08:28 PM.
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Old 09-15-2018, 08:01 PM
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Radiator upside down = melt and re-pour =I would tear down and re-do every thing those guys did. Pull the timing belt and water pump and inspect every aspect of the parts and installation. I ran my '79 for a while without the fan shroud. It is better with it on, but if the car is instantly overheating that is not your only issue. My guess is a crap rebuilt water pump and the impeller is just spinning on the shaft, but just a guess. Could be plugged radiator or something else. Getting the air out of the radiator can be an issue. I like to pull the vent hose (that is not there on your car) and let it vent free until air stops coming out. That is rarely the whole solution, though. Tear down and assemble should be only about a days work, and if you get lucky and have a good enough quality water pump in there (I kinda doubt it) you will only be looking at a fresh belt and a gasket. If you are going to pressure wash the engine you might want to pull the plug wires off first as water can get into them and they are expensive. Although it looks to me like the motor is actually pretty clean if you can just shopvac the leaves out of there. If you go the shop vac route make sure there are no gas vapors as gas vapor + shopvac=boom.
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Old 09-16-2018, 10:32 PM
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I have confirmed that the radiator is installed upside down, I found the hose barb on the bottom right with a cap on it.
Having having said that, I also found out that the hose barb and the cap are the same thread and I was able to lift the radiator out and unscrew that hose barb using a 17 mm open end wrench.

The biggest contributor to overheating is likely the missing thermostat, can't be doing any good for the system!

I also found the hose barb off the back of the thermostat housing plugged with a cap on it, but I do not know where both of these lines are supposed to connect to back by the reservoir.

Numerous other lines were also found, either open or plugged. It has what appears to be an L jetronic distributor installed on it, to vacuum lines but only one is connected.

The engine does crank over, I did not hook up an external fuel supply yet, so I don't know if it will fire.

I may resort to installing the L jet intake manifold and injectors, and batch fire them with megasquirt and a test can of gas and the fuel pump next to the car, just to remove the vagaries of a neglected k-jetronic system.


​​​​​​On an unrelated note, the headlights pop up when turned on, though none of the lights actually turn on, other than the battery warning on the cluster, and something else about lights, on the center console.

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Old 09-23-2018, 10:00 PM
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New thermostat acquired and installed, new breather hoses from the radiator and thermostat to the reservoir installed.
Coolant added to the reservoir, slowly filling down into the rest of the system, but pending getting the engine running to burp it fully.

I still need to repair damage to the insulation on the green wire connection on the fender side of the harness, as well as the heater wire on the top of the warm up regulator.
Draining old fuel and flushing the lines with new fuel will be the last thing before testing and seeing if there are any leaks, or if the engine will fire up.

Assuming that it does run, I'll be pursuing hoses and further fine tuning.
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Old 09-24-2018, 05:22 AM
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Load the fuel with Berryman's or similar, and bridge the pump relay so it circulates fuel and let it run as long as you can to flush crud out of the lines. You will need a gauge set to check the K-jet pressures (Roger T) and help diagnose problems. Check the state of the in tank filter by removing the gauge sensor unit in the top. Take care removing the in-tank filter (or pump) - if threads are seized you can ruin the tank by applying too much torque - BTDT.
jp 83 Euro S AT 57k
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Old 09-24-2018, 07:09 AM
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At this point, I am mostly trying to see if I can get the engine running, and if it has any obvious deal breaker issues. Hopefully it will run well enough to start warming up and show whether or not installing the thermostat and hoses fixed the overheating issues that caused it to be parked.

I was given most of another engine with the car, but it's from an l-jet year, probably an '80 or '81.
I can swap it for the k-jet equipped one currently in the car if needed, or pull the intake off of it and swap just that, if I decide that if had enough of playing with CIS when it was on my MB 500SEC.

​​​​​
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Old 09-25-2018, 03:05 AM
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So, I pulled the fuel level sender out of the tank, and luckily it sounds like it's still moving relatively freely in the tube.
Looking into the tank, I could see about 1" of what appears to have started as fuel, still in the tank.

Would I be correct in assuming that I should be able to see the pickup screen in the slosh bowl that the pickup slides down into?
If that is how it should be, something is wrong in my tank, as I can only see some debris scattered around, mostly outside the bowl.

If a '78 is indeed supposed to have the filter sock, and mine is missing, it looks like I'll have to drop the tank and attempt to pull the outlet bung without stripping the plastic.
That, or put a coarse filter in line with the pickup tube, before it hits the pump?


One good thing I observed is that it doesn't appear to have all turned to shellac, so hopefully I will be able to just drain it via siphoning, suction, or disconnecting the pump hose, and get 90+% of it out.
I might have even gotten lucky and not fouled the fuel distributor, but we'll see about that in the future.
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Old 09-25-2018, 03:45 AM
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Usually there is a pick up filter ~6" long, 1.5" dia in the bottom, pointed at the outlet nipple. If not there should be an in-tank pump with a sock on it. Mine had a filter, but it was all broken up, lots of fine silt everywhere. Drain the fuel out and you may see some more detail. I have looked into an external filter between the tank and the pump, but it would be a very tight fit, and filters that might fit in there would usually have their inlet/outlet nipples too small for the normal hoses. If there are wires going to the fuel outlet fitting you will have an in-tank pump - these are almost always more trouble than they are worth - replace it with a filter, tape up the unused wires back along the loom, as the factory did.
jp 83 Euro S AT 57k
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