Hi my step son drove my 87 300d out to Illinois last weekend and the GP relay or the wire that is at the end of it is smoking as long as the key is on. I ASSUME the relay has failed and the previous owner has replace the fuse with something other than a fuse (smaller wire) and it is trying to act as a fuse so is getting really hot and smoking. I have never heard of a GP shorting I understand they normally go open. Any idea what has caused this and or has the relay just failed. I am considering using a ford solenoid and push button to eliminate it altogether but not sure of the cause to begin with. I am heading out this evening to get the car so any help would be greatly appreciated. Thanks Dave

Shorted glow plugs + replacing the glow plug relay fuse with copper wire = smoke/damage to the relay.

Please use the OEM glow plug relay, the W124 chassis glow plug harness is likely to fail with a manual circuit load.

Glow plugs link thread
http://www.peachparts.com/shopforum/showthread.php?p=1019018

Glow plug relay MB# 005 545 45 32


Glow plug harness MB# 124 540 55 09
http://www.peachparts.com/shopforum/showthread.php?t=188856



Have a great day.

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If it's electric, it can short. That's why there is a fuse for the system. Checking the associated wiring would be a good place to start.

I would check (I would remove them and take a look) that the wires from the GP Relay to the Glow Plugs is not worn through somewhere. But I would also check the Glow Plugs too; better to be safe than ruin another relay.
You could go to the Diesel Giant site and follow his trouble shooting procedures with the Ohm meter (Multimeter) and that could narrow it down to a particular Glow Plug circuit.

The normal culprit for a short circuit is a wire breaking off or coming loose at the Glow Plug connection and grounding itself somewhere.
On my 617 the 2nd choice would be the sheet metal clamp that holds the wiring and the wiring runs through down below the fuel filter.
But I guess it is possible for the GP relay to have an internal short also.

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84 300D, 82 Volvo 244Gl Diesel

When I first bought the car a few months ago I did a complete test of the system just to know what I had and everything checked out fine. Obviously everything is not fine now, but it seems as if it is smoking that "fuse" constant as if it is energized all the time not just on start up or GP circuit timer on. As long as the key is on it is smoking or at least as long as he is brave enough to leave it on. I am fairly certian it was on longer than 60 seconds just to see if the car would burst into flames. Actually the condition happened while driving not on start up so could have been smoking for a while. The drivers side fender head light and hood are all smoke residue covered my guess is it was happening for several miles but that is just a guess. I am most greatful the car did not catch fire and he is OK the car can be fixed. I did a search before posting and read a lot of those posts but I didn't find any where my situation was duplicated. Thanks Dave

The thread with a similar issue is 500 pages.

wont start for anything!
http://www.peachparts.com/shopforum/showthread.php?t=104222

The glow plug relay was junk, the first good used was corroded junk also..

Nice talking to you on the phone.

Since you only want to get the car back home.

As we discussed, glow it, start the engine, then cut the relay strip fuse for the drive home.

Diagnosis/repair can wait for a better time/location.

If the relay is not opening after 45 seconds or so, the problem cannot reasonably be anything but the preglow timer/relay.

Sounds about right to me. What Roy and I came up with is I am going to try and glow it, start it, then cut the wire to get it home I will let you know if my hair brained idea works or not. Thanks again for all the help.

I had a similar problem with a 79 300D.

the strip fuse kept burning and melting the plastic housing. Even after replacing the glo plugs with Bosch India plugs. Replaced fuse and housing a couple times after and finally car just would not start.

Some comments on the thread stated the relay could not be culprit.
I replaced the plugs with German made brand from Fast Lane and replaced the relay also from fastlane.

Solved problem.

Evidently the relay got messed up or had been on its way out besids the india made plugs being out of spec.

replace the relay. check the plugs.
get good quality ones.

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1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD

Well here is what I found when I got there. I was able to glow the car then start it with smoke pouring off the relay or wire fuse. I cut the wire and as I suspected it stopped smoking and ran.

What caused the problem to begin with is the #6 injector line broke at the IP again, soaking the relay in diesel. This is what obviously caused the problem to start with. Unfortunately I just replaced this line a couple weeks ago when I was visiting my daughter in Ohio cost me $100 for a used line with shipping. Before you ask yes I installed the clamps on the line (missing on first line) but this one broke in the exact same spot.. I guess I need to find a picture of these lines new and see if a clamp is still missing or what.

Anyone in Illinois have a good running rusty 603. car for sale????? I might just build another motor and get busy with this project right away. Thanks again Dave