Now that I think about it, I think it would be impossible that my GreaseCar system could be wired into the GP circuit. Here's my reasoning - as dumb as it may sound, the installer wired the gauge and toggle switch to constant power. I guess he didn't understand that it should be wired so that it is on with the ignition... Anyhow, the gauge and switch STILL have power - the switch still lights and the gauge still registers the fuel in the tank, so that means it is still getting power. If it were on the circuit with the GP relay (which is currently down) it would not have power. I think this eliminates my concern that the GreaseCar system is in with the GP's... makes sense, right?

I'll have to get that straightened out later - my main concern right now is to simply get the darn thing running!

Now that I think about it, perhaps I already had one bad GP - recently I noticed it seemed to be missing at start-up... PERHAPS. I am not sure and might be projecting... but I do seem to remember noticing it last week in the mornings. One thing for sure, I am certainly learning more about paying attention to the motor on this car, so I am sure I will learn to be much more perceptive as I drive this car more and more! Again, I just have to get it up and running again so I can enjoy it!

you won't know at the very least until you do a resistance test as per multiple posts on this thread. Simple as pulling off the plug on the relay, finding a good ground and then checking each of the six ports on the plug for how many ohms your getting. A good plug will be darn near close to 0, bad plug will head into the 100's, but surely your mechanic knows that.

__________________
1982 300TD 210K miles ("The Replacement" aka "The Anvil") - SOLD
1979 300SD 245K miles (never ending project)
2007 Pinarello F3:13
1995 Ducati 916 (SOLD, sniff)
1999 Ducati 900SSie (SOLD)

Have your mechanic unplug all the glow plugs at the PLUGS then check for the dead short circuit that IS there in one or more of the wires from the 6 terminal output cable of the relayto the plugs. With glow plugs diconnected from the plugs, test on ohms scale lowest range from all 6 terminals to engine block ground any reading much less than infinity means that is the wire with the short. The plug MUST be removed from the relay to test.
A bad glow plug that has burned out will rarely if ever dead short. They pretty much always rise in resistance and the higher resistance WILL NOT blow the fuse.

Blevin,

Easier way to test GP circuit is to remove the GP cable connector from the GP relay and measure the resistance of each GP and connection wire by putting one test lead (banana plug works best) of the ohmeter into the connector hole of the GP cable connector and clip the other lead to a good ground like the fuel injector to injector lines. This saves disconnecting all the GP connections that is not an easy job on a 603 engine.

All readings should be between 0.6 and 1.0 ohms. Any reading that varys from the norm can then be further investigated. The variant wire can then be removed from the GP, isolated from the block, and again test from the cable connector hole for a short in the wire. No short means in the wire means it is likely the GP is shorted. Replace with a new GP, connect GP wire and check the resistance again. If resistance checks out OK, do the normal GP engine starting routine and observed if the problem is solved.

P E H

My mechanic is testing the GP's either today or Monday (he is usually closed on Saturday, but I got the impression he was coming in to work on my problem today anyway.) I mentioned checking each GP from the relay plugs with an ohm meter and he seemed to know exactly what I was talking about, so hopefully he will be able to get to the bottom of it either today or Monday.

I was wondering about the likelihood of a GP shorting out such that it would short the whole circuit - how often does that happen? Practically never according to the RnsWScissors quote above. Anyone else seen it happen before?

I think any direct short is going to pop the breaker instantly,whether it be a a shorted glow plug or the harness assy itself.I think you are on the right track and just start illiminating the possibilities until you narrow it down,this will lead you to the problem,you have narrowed it down to just a few items.

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85 300sd SOLD ,85 745i,95 740i,1972 Suburban,1938 International

Gotta be in the wiring prior to the GPs ... even with only three of the six GPs not working, I would expect something to fire ....

What would happen if you heated the engine up with halogen lighting to see if you can get it up to around 90 degrees or so - while being careful not to get lights too close and melt stuff ... then tried to start it?

__________________
George Stephenson
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg

Blevin,

In almost 40 years and 500,000+ miles in Diesel cars, I had only one GP short. It was a loop type series GP in a 220D MB. I did have all the manifold heaters in my Case tractor go open, though

There were no fuses in those circuits and the shorted GP drew so much current the starter wouldn't crank the engine fast enough to start. The wires in the GP circuit started to melt.

I had to disconnect the GP and wire around it to start the engine because I didn't have a spare GP with me.

The normal failure mode for a GP is to go open like a burned out light bulb.

P E H

You find me a Selmer MK-VI Bari and I'll fly out and fix the car.

Which would you prefer - low A or low Bb? My Mark VI Bari is a low Bb - I chose the low Bb horn instead of the low A because it sounds more like a tenor. Here you can take a look...

Also - check out this link: at the bottom of the page there is a recording of me performing Bach's first cello suite - on my Mark VI Bari and vintage Selmer Soloist mouthpiece, by the way! I performed the whole thing - over 20 minutes of solo baritone saxophone! (Of course this is just 2 short clips - not the full 20 minutes!)

http://www.rustyblevins.com/main.asp?Show=Listen

Just scroll to the bottom for the classical stuff - there's other jazz and R&B stuff there, too!

And now back to the Benz....... hopefully I'll get some good news today, so I'll post what I find out! Wish me luck!

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I prefer the oomph of the low A.
Are you related to Randy Blevins from Nashville?

350SD BACK UP & RUNNING!

Work done:
6 new glow plugs
new GP Relay (w/ strip fuse)
new serpentine belt tensioner spring and shock absorber

Since my mechanic had difficulty diagnosing the problems and it took so long, he gave me a rather large discount on the labor (about 80%) and also a discount on the parts, too. I'm glad he was able to get to the bottom of things since he is a friend.

So - onward and upward! Thanks for all the help/advice/tips/etc. to all the folks here!

NICE!!! Now you're set for the winter (do you have winter?). Did your mechanic have to remove the intake manifold or was he able to sneak the glow plugs out and in with it in place?

__________________
2001 E320
1991 350SD 265,000 - SOLD
2000 VW Beetle 1.8Turbo - restored
1997 E320 - SOLD
1988 190E - SOLD
1969 Mustang - SOLD

I dig the open tenor-y sound of the Bb horn with the big open bell - great for straight ahead jazz. I like the low A horns for funk and big band, but I don't play too many of those gigs much anymore. I just try to stay focused on the 'real jazz' gigs and to stay away from the commercial stuff.

About Randy Blevins - I am often mistakenly called 'Randy' so it is nice to know there is someone out there actually named 'Randy Blevins.' We might be related - a lot of the Blevins family came from the Blue Ridge Mountains of NC (I grew up in SE Virginia) so there is a possibility we could be related, but I don't know him and I don't believe we've ever met.


Not much of a winter here in Las Vegas - it did snow a little once in 1998; the photographers went nuts trying to get shots of the Las Vegas strip under a dusting of snow... anyhow, it never gets really cold here, even over night. It seldom even gets down below 35F, but every so often it will dip below freezing on a REALLY frigid night.

My mechanic did end up removing the intake manifold to replace the glow plugs, but that was alright because he confirmed that the other mechanic who work on the car DID clean out the intake manifold very nicely. He said everything in there was extra clean, so that gave me a bit more faith in the other mechanic's honesty, too.



All in all, it seems to have worked out well - and since I had to pay a mechanic anyway, THIS GUY is the one I would rather pay because he is a great guy and runs a great business. He sure worked his butt off to help me gets this fixed! He was working on the car for nearly a WEEK and only charged me TWO HOURS of labor!

Again, thanks to all who helped. I apologize for my ignorance, but please have patience with me - I absorb stuff like a sponge, so thanks for helping me learn even more about these great autos!

i think there is some unfinished business here. Someone here said he could start his OM603 without the glowplugs. What ever happened with that?

__________________
TXBill



Former owner of a few diesel MB cars
1998 Lexus ES 300 In Chicago We Trust