Just bought an 85 524td

Finally, a home for all you 524td oil burners out there.
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turbodan
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Joined: Jan 09, 2007 10:19 PM

Just bought an 85 524td

Post by turbodan »

First time I ever got an e28 with a turbo already in it. Body is excellent, mileage is indicated at 85000 although the odo stopped some time ago. I believe it is very close to that figure.

It does run but not properly. I hope to get it going well enough to assess the condition of the engine and then probably pull the driveline out and sell it. I know about as much about diesels as I do about nuclear reactors, I understand the fundamentals but I'll be damned if I can figure out what's wrong with one of them. It will be a challenge. With such low mileage I believe the engine should be in great condition but I know the previous owner screwed around with the injection pump and injectors.

I presume these things will run without the glow plugs? Seems like the diesel electronics aren't powering up, none of the indicators are illuminating and it is hard to start. I'm going to mess with it some more tomorrow, jump the main relay and go from there.
Galahad
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Re: Just bought an 85 524td

Post by Galahad »

Sweet! Happy to help with the electronics, I have one that tries its best to run we can check against if need be.
They will run and start without glow plugs if it's warm enough. If the electronics aren't starting you may be having an issue with the electronic fuel cutoff, pretty sure it's controlled by the DME.

If you do end up selling the drivetrain lmk, I may be interested.
turbodan
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Re: Just bought an 85 524td

Post by turbodan »

The plan was to dunk and M20 and a 5 speed in and find a new home for what I believe is a fresh, low mileage M21 and 4HP22. At the moment it has a miss at low RPM in conjunction with hard starting. I suspect fuel supply issues and/or air in the high pressure lines. Checking by hand, only one of the six fuel lines has a strong pulse when it fires, the pipes for cylinders 2-6 don't feel like there's a whole lot of pressure going through them.

I've been reading that they will run quite well without any of the electronics, that simplifies troubleshooting.
turbodan
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Re: Just bought an 85 524td

Post by turbodan »

Found a drip off of the back of the injection pump, I think at least one of the fuel pipes was leaking there. I removed cleaned and reinstalled cylinders 2, 5 and 6. No more leak, runs better but still has a miss at low revs. Would be super cool to do a compression test just to verify engine integrity but it ain't got no spark plug holes and I don't have a proper tester.

The tinkering continues.
Mike W.
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Re: Just bought an 85 524td

Post by Mike W. »

And with your turbo reputation I figured 30PSI or something keeping it diesel!
turbodan
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Re: Just bought an 85 524td

Post by turbodan »

If this thing was running right I would be likely to develop affectionate feelings for the M21. No ignition system, great fuel economy, potential for butt loads of torque. I would be starting over completely on R&D though, and the process would almost certainly involve destruction of some very rare parts.

Not a whole lot of progress today. The glow plug indicators are working, the ecu is working. I think it's running better than it was but there is still a significant issue somewhere. If I pull the main relay it runs smoother. Not as smooth as it should but it's much better. With the relay plugged in and the computer controlling the pump timing it is much quieter but has a fairly regular miss. Not constant but more often than not it's not hitting on one cylinder.

Guy I bought it from said he had pop tested the injectors and had the pump serviced. If that work was done properly this would have to be a compression issue. I would be surprised to see that with such low mileage though.
Galahad
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Re: Just bought an 85 524td

Post by Galahad »

turbodan wrote: Jan 08, 2023 9:29 PM If I pull the main relay it runs smoother.
Well that's horrifying
Mike W.
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Re: Just bought an 85 524td

Post by Mike W. »

Galahad wrote: Jan 08, 2023 11:27 PM
turbodan wrote: Jan 08, 2023 9:29 PM If I pull the main relay it runs smoother.
Well that's horrifying
Yeah, but...

On E39s, yeah, I know, just a little bit different, if the MAF is bad and you pull the connector to it, it runs better. The more things change the more they stay the same?
Galahad
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Re: Just bought an 85 524td

Post by Galahad »

Mike W. wrote: Jan 09, 2023 12:00 AM Yeah, but...

On E39s, yeah, I know, just a little bit different, if the MAF is bad and you pull the connector to it, it runs better. The more things change the more they stay the same?
I plugged the wrong AFM into my e28 one time and it ran better when I unplugged it, sometimes it happens. Usually not main relays but apparently...
gadget73
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Re: Just bought an 85 524td

Post by gadget73 »

When the controller is not powered on these, there is no timing control. Not sure if it goes to full advance or no advance though. If it rattles louder, that sounds like more advance. Possible the pump base timing is retarded and when it ends up at full advance its closer to right. The base timing is set with a dial indicator to get the pump where it belongs. Possible that wasn't done when the pump was re-installed. This does have actual feedback from when the injector fires vs crank rotation so its probably slightly less critical than the old mechanical pump but I don't know how many degrees of control there actually are in these. Too far off and the ECM won't be able to control it though.

also if the lift sensor or the crank sensor aren't working right, all this goes out the window.
turbodan
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Re: Just bought an 85 524td

Post by turbodan »

Alright gents, no tight valves, no super loose valves. They're all in the .3mm range. It was just a quick check, I'll go over them with more care before I button it back up again. I was hoping to find something that would explain the rough running under the valve cover but no such luck so far.

I can say that when the engine is running there is a normal amount of blowby. Not much, I would expect more from a diesel with 22:1 compression. Bottom end should be good. I am concerned about a burned valve, though the possibility remains that the injectors are faulty. If I crack the fuel line loose on each injector, it does affect the idle, so all six are hitting. It just runs rough with a sporadic misfire, don't know if it's the same cylinder or if it's random.

I'm going to ask around to see if I can borrow a diesel compression tester. If I can verify that the compression is good I'll happily spring for some injectors or whatever. I'm not averse to pulling the head and fixing some valves either but it looks like head gaskets and valves are pretty rare. Seems to be a place in the UK that I can order a head gasket from if need be.

Is the electrical connection to the #4 injector critical? I have a torn off wire end on the harness and a perfectly good connector coming off of the injector. Seems like this is just for feedback to the computer, I believe it's still running off of the pump like the other five.
Galahad
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Re: Just bought an 85 524td

Post by Galahad »

I believe the computer does timing adjustment based on that injector.
You'll probably want to read through this service document for the Lincoln diesels. All the US 524tds have the electronic controls system, the Lincolns only had the electronic system on California cars.
(gadget73 feel free to correct me if I'm way off)
gadget73
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Re: Just bought an 85 524td

Post by gadget73 »

thats the case so far as I know. I think it looks at both the crank signal and the injector signal to work out the relative timing.

might be worth an ohm check on the injector to see if its dead. Apparently thats a problem. Mine was missing when I got it, but Lincolns only use it for the fuel economy display.
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