Military prototype with M21D24 engine control issues

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JJPow
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Military prototype with M21D24 engine control issues

Post by JJPow »

Hello everyone- I have a unique military prototype vehicle in my shop with an early 80s M21D24 BMW engine. The vehicle is currently being restored for a client. I have zero information on where the motor came from but I suspect it is out of an early 1980's BMW E series. The problem is the vehicle came to me missing 90% of its wiring harness- I have fabricated a new harness for it but I cannot get the vehicle to run properly. The vehicle has a 24V system and a 12V system, engine is all 12V. The motor itself was pulled from the vehicle, taken apart and meticulously rebuilt, so I am 100% confident that mechanically the motor is good to go. What seems to be missing is the EGR system- I believe this is normally located next to the turbo unit. As far as I can tell the EGR unit is missing. I have researched on this forum and from what I can find it seems that the motor should run without the EGR. There are two electrical spade connectors on the injection pump that are circled in the photos. My first question is what are these for? I imagine one is for an electrical cut off switch, but I am unsure of the other and which one is which. Also from my research I am aware that there are some other engine management sensors that are not connected or missing there is some type of speed sensor screwed into the block next to the fly wheel. I also understand that there should be a coolant temperature sensor, and one or two fuel injector sensors. These go to an engine management control unit which seems to be missing- when I fire the engine it starts right up and then dies after one second- what is missing that I absolutely need to get the motor to run? Is there a way to simplify the engine management control system so that it will run without the sensors? If the sensors are absolutely necessary how do they connect to and control the motor? Thank you in advance for any and all advice and support
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Last edited by JJPow on Dec 30, 2019 11:08 AM, edited 3 times in total.
Mike W.
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Re: Military prototype with M21D24 engine control issues

Post by Mike W. »

Welcome to the group. FWIW, we've got a fairly active guy here who has a Lincoln with a BMW engine and ZF trans in, they came that way for a year or two. So you're not alone in it not being in a BMW. I'm not a diesel guy so I can't help much on nuts and bolts, but I do have a couple of things. First is your pictures don't work. I get this message
Error (403)
It seems you don't belong here! You should probably sign in. Check out our Help Center and forums for help, or head back to home.
Next, something that might be of help is the wiring diagrams, including for the diesel is here, http://wedophones.com/BMWManualsLead.htm

That might help you sorting out the engine management.
gadget73
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Re: Military prototype with M21D24 engine control issues

Post by gadget73 »

Which injection pump does it have? The US-spec BMW and the California Lincoln had a VP-20 pump which uses a computer of sorts to control timing. Euro BMW and 49 state Lincoln had a VE pump which is just straight mechanical. That one is dirt simple, one 12v solenoid to turn the fuel on, and one 12v solenoid for cold start timing advance. I honestly don't know that much about the computer controlled pump since I don't have that one. Don't know if or how well it will run without the computer, but the computer doesn't have a ton of inputs. I *think* all the computer does is control injection timing, so it will probably idle OK without it but as engine speed increases you'd have a lack of power since there wouldn't be any timing advance.

a related question would be is the pump timing set correctly? Most of the manuals cover the VP-20 in fairly good detail but there is only a passing mention of the VE pump. Officially Ford at least wants you to use their expensive special timing light, but it can be done with a simple dial indicator. Its the same type of tool used on old VW diesels and early Cummins 12v engines if you don't already have it.

http://www.mye28.com/viewtopic.php?f=12&t=91517

last post is Ford's spec for both types of pump.

it will run perfectly fine without the EGR. Mine is all there but I have a vac line capped so it doesn't actually do anything. The crank speed sensor wiring is also bad so I don't think it would function even if I hooked it up.

this thread has additional docs. I find the Ford manuals to be a little easier to deal with, but that might just be me.
http://www.mye28.com/viewtopic.php?f=12&t=88207

If these manuals don't have what you need, I've got the Lincoln electrical troubleshooting manual that should have just the engine controls wiring.



pics didn't come through for me at least but I'm curious what you're working on here.
JJPow
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Re: Military prototype with M21D24 engine control issues

Post by JJPow »

Ok, I resent the pics- should be good now. I can see most of the serial number on the side of the pump- looks like it says VE which tells me its the straight up mechanical style- where on the pump do you make the timing adjustment? I'll look over the docs you linked again. Thanks for the help!
gadget73
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Re: Military prototype with M21D24 engine control issues

Post by gadget73 »

the connection closer to the engine should be the fuel cut-off solenoid, the one sticking away from the engine is cold start advance. The advance solenoid runs key-on power through a coolant temperature sensor and gets +12v when the engine is cold to allow for easier starts. The coolant temp switch lives just below the #5 intake runner. The fuel solenoid gets +12v when the key is on, cut power to shut the engine down. Looks like neither one is connected. I'm surprised it makes any effort to start. Clip a +12v wire to the shut-off solenoid and see if the engine will run normally when that is powered.

looks like there is a small electric lift pump near the injection pump too. That also wants power when the key is on. Ford used the electric pump in that location. I think BMW may have had it in the tank. I'm guessing you've got a proper fuel filter somewhere in there too?

if the glow plug stuff is missing or not hooked up, you'll want that working. Mine wouldn't start with 3/6 glow plugs bad when it got below about 50F. Starts fine in the teens with 6 good plugs though. Temperature sensor for the glow plug control is near the #1 injector in the piece where the upper rad hose connects.

injection timing you have to do with a dial indicator, the crank locking pin (a drill bit works, but not ideal) and a breaker bar to turn it by hand. If someone who knows what they are doing rebuilt the engine, this should already be set correctly.
JJPow
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Re: Military prototype with M21D24 engine control issues

Post by JJPow »

Thanks for the reply-so the fuel solenoid needs constant power while the motor is running. The other is a coldstart solenoid that gets power below a certain temperature-got it. I installed all new glow plugs which are connected to a simple timer that is activated when the key is turned to the on position. I added the fuel pump because the motor seem to not be receiving enough fuel by gravity alone. As far as injection timing goes where can I find the correct tool and step-by-step process to do it correctly? Thanks I really appreciate the reply.
gadget73
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Re: Military prototype with M21D24 engine control issues

Post by gadget73 »

One of those links I posted above has the Ford manual for the diesel, and it has nice clear directions. Its in the BMW manual too, but the online copies of that aren't as good of a scan.

one of these will serve for setting the timing

https://www.amazon.com/EWK-Diesel-Injec ... B00H97J1MU

I made my own, so no experience with that specific one. There may be a better or cheaper one, thats just what came up with a quick search. Anything that works on a Bosch VE pump will do it. Some Cummins and VW diesels used that pump so its a fairly available thing. Basically you need the piece that screws into the head of the pump and a dial indicator. If you lose the washer that goes under the head plug, its 8mm or 5/16". I found them at my local hardware store, all the auto parts stores looked at me like I had 4 heads. Prob not a bad idea to replace the washer if you pull the plug anyway, they can leak if disturbed too many times. Besides, if you have spares you won't drop it.

https://www.amazon.com/KTC-BMW1070-P-Cr ... B00U553UUC

is the lock pin. I made my own one of those too, so again no experience with that specific item. You can use a drill bit, but it won't position as accurately. The hole for the lock pin is down near the starter, just above the oil pan rail.

basically you put the dial indicator in the head of the pump with the mounting adapter and rotate the engine until the indicator is at it's lowest point. Zero the indicator. Roll the engine until the pin drops in at TDC. Adjust the injection pump if needed. Its got 2 nuts on the back side of the timing cover. They're kind of difficult to get to, especially the inboard one. Mine had 13mm nuts originally, I changed them to 12mm head nuts when I had to pull the pump for a rebuild. The half mm per side is enough difference to make fitting a tool in there a lot easier. I used a 1/4 drive socket and a long extension.
JJPow
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Re: Military prototype with M21D24 engine control issues

Post by JJPow »

Thanks for the detailed response- I will order those tools and get it done. Happy New Year!
gadget73
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Re: Military prototype with M21D24 engine control issues

Post by gadget73 »

I'd try powering the fuel cutoff solenoid first and see if that makes it run normally before getting too deep into all this.
JJPow
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Re: Military prototype with M21D24 engine control issues

Post by JJPow »

I believe at least 2 of the injectors need to be replaced- what are the correct replacements?
gadget73
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Re: Military prototype with M21D24 engine control issues

Post by gadget73 »

If they aren't physically damaged, they can usually be rebuilt with new nozzles and shims to get the correct pop pressure.

http://www.mye28.com/viewtopic.php?f=12&t=90556

has info on the proper nozzles. I don't know that original Bosch ones are available anymore, but Monark (I think its spelled that way) makes them. Never had mine apart so thats about as much as I can tell you about it. I had the shop that rebuilt my pump test mine and dude told me they were all fine for pattern and pop pressure. The guy from Mercedessource has several videos on his youtube channel about testing and rebuilding injectors. The 80s Mercedes diesels used the same type injectors as BMW did.
mike_e30
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Re: Military prototype with M21D24 engine control issues

Post by mike_e30 »

I am currently rebuilding my injectors. All the new old stock Bosch units I purchased were junk. I found another source of Bosch nozzles but due to a delay in shipping I purchased a set of Monarks. My diesel guy has had good experience using them but I'll know firsthand by the end of the week. Monark# 39305148 or #39305117
gadget73
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Re: Military prototype with M21D24 engine control issues

Post by gadget73 »

Did you buy Bosch nozzles, or complete injectors? What was the issue with them?
JJPow
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Re: Military prototype with M21D24 engine control issues

Post by JJPow »

I have sent the injection pump and injectors to a shop to be rebuilt- should have them back in a few days. I will update when I get them back. Thanks for all the help and info. Much appreciated.
mike_e30
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Re: Military prototype with M21D24 engine control issues

Post by mike_e30 »

gadget73 wrote:Did you buy Bosch nozzles, or complete injectors? What was the issue with them?
Just the nozzles, 8 Bosch units made in Turkey. All leaked like crazy. I sourced them from various ebay sellers in Spain and Germany. I'm still waiting on my made in Germany Bosch nozzles as well as the Monarks. This is a real PITA
JJPow
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Re: Military prototype with M21D24 engine control issues

Post by JJPow »

Ok, so I got a freshly rebuilt injection pump and injectors back and installed- injector nozzles had to come from Germany, took forever, but it's all done. Motor runs sweet! Question- is there a source for the injector return hoses? I replaced mine with plastic, but they are not up to spec, and are leaking. Again, thanks for all the help. I highly recommend Diesel's Fuel Injection in NH- top notch work. https://www.dieselsfuelinjection.com/contact/
gadget73
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Re: Military prototype with M21D24 engine control issues

Post by gadget73 »

I got a roll from some random place on ebay. Same stuff used on Mercedes, VW, and a bunch of other things.

https://mercedessource.com/store/diesel ... -60-length

has it too. No affiliation. Not sure if the end cap is included. The kit I got on ebay had it. The car came to me with a random piece of vacuum line that had a screw jammed in it. The vac line was like bubblegum and it was leaking fuel. The proper end cap is about a 1" piece of that hose with a steel piece in it. You could just make your own easy enough.


good deal on it running proper though. Was it the pump or the injectors at fault?
JJPow
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Re: Military prototype with M21D24 engine control issues

Post by JJPow »

Thanks for the link- the pump solenoids were frozen from sitting, needed a complete rebuild, nozzles were toast. I'll post a video when it's all complete. Thanks again.
gadget73
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Re: Military prototype with M21D24 engine control issues

Post by gadget73 »

wow, all the bad things.

Looking forward to pics of this thing. Sounds interesting. Good to hear that you got it sorted out though. Its not a bad engine and fairly simple to make run, just so long as you don't expect too much "go".
LuckyHenriksen
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Re: Military prototype with M21D24 engine control issues

Post by LuckyHenriksen »

Nice job getting the pump sorted out, are you running without the computer controller and without the injector with the sensor wire in it? This seems like a pretty neat project, I would love to see some more photos and videos if you have a chance to share more!
JJPow
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Re: Military prototype with M21D24 engine control issues

Post by JJPow »

Yes, It is straight mechanical with no computer control or wired injector. Pics and video will follow.
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