just above the turbo, in front of the bypass pipe/trap ox... there is a brass plug in the exhaust manifold front section. remove it and try again. report back with results.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Thats good info, I hope to be able to get to the car for some investigation tomorrow and thats a good test for the exhaust without disconnecting/cutting stuff. Do those generally come out easy or does it normally take a blow torch and a stick of dynamite to get it out of there?

First off thanks for your thoughts! Guys who have been there done that are a great help!

Yes, the glow plug light on the dash comes on for a good deal of time before I crank the engine. It seems to increase in time during the colder weather. I hadn't thought of letting it go for a bit after the light went out though. I will do that. I did check the plugs at one time to make sure 12Volts was getting to all of them. I do have a clamp on ammeter that I just haven't picked up batteries for yet. I want to see an amp draw on the plugs just as a check and also to make sure they are heating for more than just a few seconds.

When I put the new main filter on I did fill it with fuel, I have no doubt that I had an injection pump that was full of air at the time since I believe the car had fuel cut off while it was running. I also did replace the seals on the filter bolt and have been through all the clamps. I have tried cracking the injector hard line nuts in every way I can think of while cranking. One at a time, 3 at a time, all 6 at a time. I generally do that until I quit seeing bubbles around the hard line after cranking. Some of the injectors seem to get fuel much later than the others. If I open all 6, some will stay dry until I bleed the others and tighten the nuts on those. Would that be normal?

I do believe I had algae in the tank with the old fuel (it has been diluted with newer fuel now), when I pulled the tank strainer it was plugged with black crud. I am hoping putting biocide (I have power service biocide in the mail to me now) in the fuel tank and letting it sit this winter will kill the crud off. I figure the 7 or so gallons left in the tank might be better abandoned after that. The last inspection sticker on this car expired in June of 2010 I believe so that gives you the possibility that the original fuel was close to 4 years old last summer when the car chugged out.

Yes, I believe my compression is fine. I have been around gas engines that lost compression due to a timing belt break and this engine cranks fine. I guess I mean that it doesn't sound like it is cranking without compression. I did buy a compression test set last fall in case I have to go there though. I probably should have had that when I changed the injectors a while back but I really don't feel that is the issue. I bought a new battery that spins the engine quite nicely now so cranking speed shouldn't be an issue.

Thanks!
Bryan

Got to do a little troubleshooting and thinking this evening. Mainly looked at the glow plugs and glow plug circuit. This time I took my clamp on ammeter to measure the current going to the plugs. Since I didn't really want to break the wiring apart I just measured the entire bundle at one time. I have a glow plug troubleshooting manual that says these plugs should not draw more than 15A. Of course with 6 of them I expected to measure less than 90A. And with a 80A fuse currently in the relay I didn't really expect to see 90A. Well, I read 110A at first and above 90 for probably the first 5-10 seconds. The circuit timed out at just short of 30 seconds which I expected. When the circuit timed out the plugs were pulling around 60A still.

That gave me above 15A average per plug for the first 5-10 seconds. I can see as the plugs warm up they probably won't draw as much current but have I just proved that I have a bad(shorted) glow plug or two in this circuit? I also assumed that I would have blown the 80A fuse by now.

Any thoughts?

Check the resistance across each glow plug at the glow relay connector to find a grossly open or shorted glow plug. For the sake of discussion, you can remove pins from the glow relay connector (after popping off the lid) to test current through individual glow plugs. Touch the glow plug pin to the glow relay power cable.

Sixto
87 300D

Fuses have the ability to pass more than rated current for a short time without blowing.

Glow plugs normally don't fail totally shorted, but they can fail such that part of the heating element shorts out near the tip. When this happens, they appear to have normal resistance, but only get hot up near the threads, instead of at the tip.

Since only the tip is in the prechamber, this means the glowplug is ineffective even though it appears to be working.

Best thing to do at this point, since it appears you have ruled out just about everything else, is to pull the intake manifold and change the glow plugs to get that out of the equation. It will start with difficulty with one plug down, but with two down, it will be about impossible.

You will need the following, all available at your friendly forum sponsor's web store:
-intake manifold gasket 603-141-08-80 (Victor Reinz brand is fine)
-cross over pipe gasket 602-096-00-80 (Elring brand is fine)
- 6 glow plugs - only get Bosch or Beru 000-159-83-01

While you have the manifold off, check the condition of your hard line clamps, if they are broken get a new set. Cheap compared to the price of a hard line, and if you don't have the hard lines supported correctly, they will fail.
Steel injector lines W124.133 OM603.960 I6 300D Turbo 1986-87
look at the second half of the first post in this thread under vibration dampener clips and shims

If you are curious, after you have pulled the glow plugs, take the glow plug and your jumper cables and try them on your battery. Clip the - clamp to the body of the GP and the + to the terminal on top. The very end of the GP should glow cherry red within seconds. Be careful, they can reach 1500-2000 deg F!

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

You shouldn't have to bleed the system again if you don't open the system upstream of the delivery valves. If you're not getting immediate and consistent squirts of fuel with all injector lines loose, something's not right. There's likely insufficient fuel supply pressure and I'd guess it's because of a worn component or the system is sucking air.

Sixto
87 300D

Thank you for your help! I was hoping that I might have found my smoking gun when I saw the current draw. Dad said he replaced the glow plugs, but I know he didn't remove the intake and I just don't see a good way to do it without pulling the manifold and crossover. Also the support for the hard lines is good info, I do have several that cracked when I was changing the injectors. I will get them replaced. I am not in a huge rush to get the thing running so I guess this will be my project through the cold months. At least I have a heated shop to work in.

If the car is in a heated garage, it should try to catch if the only problem is the glow system. If the starter just spins the engine, my money's on a fuel or airflow problem (exhaust restriction).

Sixto
87 300D

I haven't had the heat on in the garage, it was 40 degrees in there while I was troubleshooting today. Of course I had this same issue last summer while the temp wasn't 40 degrees. The engine does fire but won't stay running. I still believe I could also have a fuel or airflow problem. This was just the first indication I got that there was a problem in the glow plug circuit. Dad told me he thought the glow plugs were weak when he first had the car running (it was picked up from a customer in his shop after an accident). He sometimes tells me he he changes things on a car like this when it is very obvious to me that he didn't. He told me he changed the glow plugs and I have always doubted it. I doubt it more now. Either he didn't change them or he may have damaged them installing them.

My next move will be to remove the brass plug mentioned earlier in the thread. Hopefully that would rule out an exhaust that is plugged. Not sure what to do about the fuel flow, but that is still suspect also. I hope I got alot of those issues when I bypassed the tank and fuel thermostat. Would it be possible for me to plug the new filters without ever having the car started?

I very much appreciate the thoughts and opinions that I am getting. It is a great help in thinking this through. Hopefully I can have this car up and running by the time the weather breaks!

Finally got some time to work on the car today, removed the plug mentioned above and it started! Idles fine, ran two cans of diesel purge through it with the plug out. Shut the engine off during and put the plug back in just to test, the problem was back. I am 100% sure I have a plugged exhaust now. I may have a weak glow plug or two but that isn't my root problem. I would think this may have been caused by all the idle time over the last few years since the car hasn't been driven in almost 4 years.

Now, what is most likely to be the problem in the exhaust? And what is the best way to approach fixing it? I assume there is still a trap oxidizer down the pipe, can that be removed without causing a problem?

BTW, thanks vstech, you hit the nail on the head!

You can poke the guts out of the oxidation catalyst or replace it with a straight pipe. Wear protective gear if you poke the guts because you don't want to breathe that stuff. Either way there might be legal consequences for messing with an emissions device. You obey the speed limit whenever you're on public roads, right?

Sixto
87 300D

With all the people running around in West Virginia (my part anyway) with big trucks pouring black smoke out twin stacks cut into the beds I couldn't imagine drawing much attention with an old Mercedes. These things should be exempt anyway shouldn't they?

Being exempt from inspection and being legal are separate matters. If your car is exempt from inspection, it's up to your conscience how you proceed.

Sixto
87 300D