Brain,
I plan to change the GPs in my 603 within the next week or so. Like you mentioned, I am also concerned with the possibility of breakage. I plan to feed them a daily diet of PB Blaster for a couple days prior to the undertaking. I am also taking the injectors to a shop in Lebanon, NH. Guess we will be able to share our stories of fortune or misery as they unfold.

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Steve
'87 300TD - 132K - Soon 4-Sale
'84 300D Turbo - 122K - Driving
'77 VW Type II - 77K - Restored
'08 250EX Ninja
English Bulldog (Brier) - My best friend. Passed away 12/02/04 while in my arms.

Steve,

Excellent. I'm really keen to hear your observations on the start of the 603 after you change glow plugs. Alan changed the set to brand new ones with little benefit.

I probably will not pull the manifold before the winter unless you see a significant benefit.

How's the 123 doing?

I recently replaced the glow plugs in my 617. The difference was like night and day. The car now starts quickly and runs smoothly. Before the swap, it was hard to start, idled rough for about a minute, and sometimes choked down when first put into gear. Now it starts almost like a gas engine.

That's primarily an OM606 problem - the plugs are much longer because of the 4 valve design. There are a couple guys here who have had plugs snap on 606s, but I've never heard of it on a 603. Peter?

As for glow time, I looked at a 1987 300D in a showroom in Ft. Lauderdale last January. Ambient temp was probably 72 and glow time was about 20 seconds. Compared to my E300 and TDI, it seemed like it took forever.

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Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References

Man I have to tell you, everytime I drive, the car just gets better. I think the old girl is achieving a new level of equilibrium.

Faster
More responsive
Quieter

On the subject of glow plugs. On my 617, which are the old loop style, new or old they all work the same. If the work, they work OK, if the don't they don't. I had the original ones in until about a year ago. Never had a problem. I couldn't stand it, so I just had to change them out and I bet I have at 4-5 of the new Bosch GP's go bad. Even when the new ones work, the don't work any better than the old ones. PEH was right, if it ain't broke, don't fix it.

JCD

Strange, the old loop style plugs are wired in series, if one goes out they all fail to heat. jcd, how did you have 4 or 5 plugs fail? One at a time presumably.

I never had an old loop style GP fail to work - they were the most reliable thing Bosch made. Now if Bosch is having Glow Plugs made in India, then all bets are off as to reliability.
Someone recently compared Beru to Bosch and said the Beru looked to be made better, something about a plastic insulator on Bosch GP's or something I haven't verified what they were saying.
I disagree with what PEH said (if it ain't broke, don't fix it) as it relates to glow plugs of the pencil variety. Those do have a finite lifetime because tungsten wire will eventually fail, the same as in incandescent lamps.
I look for one bad one, when one fails I change em all at the same time, especially on a 603 engine its such a PITA to get to them buggers.

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

dieseldiehard

You are exactly right on a couple of points.

1. They are in series
2. If one fails, none work, they can be bypassed temporarily by removing the insulating ring and "shorting" the circuit, but if one goes, the circuit is broken.
3. They failed one at a time, which was a real hassle
4. The original ones should have never been taken out of the car by the stupid owner. I bet if I left them in they would still be there.