Strategy for Intake Crossover Pipe Removal
 

The engine compartment picture below is typical of several I've seen on the web. Note the obvious replacement crossover pipe. My assumption is that the original was broken somehow during removal. Is that a reasonable assumption? Where is it most likely to break?

If such breakage is a possibility, I'd be interested in any experence or suggestions on how to successfully remove the crossover so that it can be reused. :) The plan is to change out all the glow plugs in my '87 300D before winter.

Ken300D

More likely that is some color from having the crossover pipe cleaned to remove the coked oil in it.

Easy to take off -- remove the two bolts at the top and pull off the 0-ring at the turbo end. Get new gasket and o-ring for re-installation.

Watch out for hunks of coked oil falling into the turbo!

Peter

It is possible to chnage the glow plugs without removing the intake. You just have to be creative, but it can be done. I have done it. Additionally I have alos removed my intake & crosover pipe to clean the intake and at the same time I made a block off plate for the EGR so I would not get nasty stuff blown back into the intake. If the glow plugs are working fine, my advice is to leave them, just replace them when they go bad. Really, why give yourself the extra work.

Well preventative maintenance is better than fighting a hard starting engine in the cold! Glow plugs are relatively inexpensive and are not that bad to replace. Why not just to be safe?

The only reason I said to wait is that they are not going to fail all at once, when they fail simply replace them. On the motor that is being pictured here (603), they can be tricky to replace. You and I have versions of the 602 motor which is a bit easier.

I agree that generally you should replace glow plugs individually as they go bad, particularly when you have easy access to any of them that might go bad - like on a W123.

When I got this car last December it had a rather rough startup running characteristic, and the glow plug indicator in the dash did not operate. This turned out to be GP #1 which is probably the easiest one to replace. It was an interesting failure in that the GP was not electrically an open (or short) circuit, but it only drew about 3 amps rather than the 8-10 amps one should normally draw. When I got it out it was not heating on the tip, but only in the lower half next to the threaded end.

The startup characteristic improved on replacing that one glow plug considerably, but I can still tell there are one or two cylinders that don't run well immediately on startup. Everything is fine within one minute, so I think I have more weak glow plugs.

Considering the pain in removing stuff to change one or two, I'm going to undertake changing out the remaining five while cleaning the intakes. Then I should be done with the glow plug issue for several years on the car.

My worry on the crossover pipe removal has to do with thinking there might be dissimilar metal corrosion - and that I might shear off one or more bolts. Steel bolts in aluminum = trouble. It's worse around coolant, like on a thermostat housing.

Ken300D

Ken I've recently removed the crossover pipe and intake manifold to cure an intake manifold gasket leak. Removing the crossover pipe will help the access to the GPlugs but if you really want the access you'll probably also want to remove the intake manifold as well. It's an easy job. You'll likely find the crossover and manifold both are full of oily gunk so this is the time to clean them out. I replaced all the GPlugs because it seemed foolhardy not to when everything was off. The whole project shouldn't take more than 3-4 hours if you work carefully, probably less if you're good at that sort of thing. The bolts should come off without too much trouble, just be careful not to over torque them when you put them back on. I also used a little antiseize compound on the glow plugs. It's a "fun" project. Go for it.