If your engine starts easily, you are wasting your time and money replacing yout GP. GP are not like spark plugs, after the engine starts they are shut off and have no effect on the operating of the engine. Since you might have to take the head off later, I would not bother replacing the gasket now. You might end up doing it again if you have to replace the head.

P E H

PEH,

I'm not sure I understand what part of my post you don't agree with. I said that if the GP's were recently replaced, leave them alone. If they are old, they should be replaced while the head is off, because otherwise they WILL FAIL eventually and the labor will be 5x as much after the head gasket job is done. An extra $75 in parts on a $3k job as preventive maintenance. Are you saying someone should leave old (or unknown age) GP's in just because?

msyoder's case is different, he just replaced the GP's and doesn't need to while the head is off. My one 300D had them done just before I bought it. My other one will get 6 new ones (IF I pull the head or intake manifold) because I have no records of them being done in the last 8 years and 100kmi.


BTW- do you currently, or have you ever, owned an MB with an OM603 engine? Or worked on one? I can't imagine you saying this would be a waste of time or money if you have...


Regards,

__________________
Dave
Boise, ID
Check out my website photos, documents, and movies!

Dave:

The ALDA just sit on top of the actuator in the IP. Held on by a captive nut. Best to use a pair of small adjustable wrenches to get it off if you don't have some "shorty" wrenches -- space is tight (duh, I don't need to tell YOU this!). You will need to remove the windshield washer reservior for access.

My mechanic says he has never had to adjust the ALDA on a 603 -- if you don't get a little smoke at full throttle, check the overboost protection switch and boost lines before digging into the ALDA -- a clog or open overboost switch will reduce power quite a bit. Old tired hoses will give the same result, as will a plugged trap oxidizer, if you still have one, or a tired turbo. To adjust it, you will have to take it off.

The glowplugs can be removed using a deep swivel socket -- the kind where the socket is one side of the swivel. You will need one for the wire nuts and one for the plugs. Use a bit of paper to hold the nut in the socket when you put them back on.

I plan to do the head gasket on mine when the weather warms up, after I check to make sure I don't have a coolant leak. I replaced the thermostat this fall due to low engine temp, and will need to check for leaks there before yanking the head. The only symptom I have of a bad gasket is a slow coolant loss.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

GSXR,

I'm not sure what a OM603 engine is. Is that the engine in a '87300SDL? I got one about a year ago but haven't worked on it yet because I haven't used it much.

However I would not change any of the GP just because they were old or I no records on them. When and if they go bad I will replace them. I always carry a spare GP like I used to carry a spare spark plug when I drove gasoline powered cars.

Even if a GP goes bad, it isn't a show stopper. One cylinder will just miss-fire for a short time after starting and then the engine will run normal until it is started cold again. The bad GP can then be changed at my leisure.

P E H

PEH,

Yes, the OM603.96x is the 3.0L turbo engine used in 86-87 300SDL's and 87 300D's. You are correct about the GP operation not causing anything really bad when one fails, other than a very rough running engine for the first minute of a cold start and a cloud of smoke too.

The whole reason I mentioned it is simply because of the difficulty of replacing them one at a time, only when they fail. On this engine, they are simply awful to replace. It's not like the older (through '85) diesels, where you have pretty decent access to them.

Regardless of engine, though, I believe they should be replaced as complete sets (except perhaps for freak short-term failures) - and more so on the 603 due to the increased labor time. If the plugs are original, or very old, and one fails - it's a bear of a job, and you'll probably end up doing the other 5 one at a time over the next few months or year or whatever. Why do an unpleasant job 6 times? My philosophy is that if one old one of a set fails, change them all - that way you do one unpleasant job one time. And, then you shouldn't have to worry about them for a LONG time, possibly the rest of the time you own the car!


Regards,

__________________
Dave
Boise, ID
Check out my website photos, documents, and movies!

I must agree with Dave.

I have the OM603 engine and I've been there. Two and a half failed (on the same trip) last winter and nearly disabled the car. Luckily the ones that had to be changed coincided with the ones I COULD change. It was cold and I had places to go. It was a huge pain.

Consequently when the shut-off valve failed a month later I had them change out the remaining GPs while the (intake) manifold was off.

Please carry spare (80amp) GP relay fuses with you. If you let the GP nut and wire twist to the side (easy when changing the GP under the manifold) and touch the engine -- poof there goes the fuse. It was a 45deg day when it happened and my car would NOT start without glow plugs.

__________________
-Mike
'87 300TD 304kmi (RIP)
'95 Toyota Camry Wagon 125kmi

on the 300D. After reading/thinking about this thread for awhile I got out there and started nosing around under the hood. What I found was that if I opened the reservoir cap and squeezed the top radiator hose it actually felt and gave indications that it had air in it. In addition, I did not have the reservoir up to the "full" line and looking closely it seemed the top radiator hose was higher than the coolent level that I was running in the reservoir. I topped the reservoir up to the full line, squeezed the top hose alot to insure that it was full of coolant and now when it cools off there is absolutely no pressure in the reservoir just like some of you suggested on a properly working system. Oh yea, my aux water pump does not leak anymore either.

__________________
Jim

GSXR,

I looked at my 603 engine and I agree that GP #3 and #4 look extremly hard to replace and I would agree to put new GP in those two ` if the intake manifold was off. However, I still would not replace any of the other 4 untill they failed. I would keep the 2 from #3 and #4 for spares.


Good idea about the GP relay fuse. They are so inexpensive from Fastlane that it doesn't cost much to carry a spare. I have never needed a GP relay fuse in 11 years and 170,000 miles but I still do carry a spare. I also carry a spare GP or 2.

P E H