So, at the 100Kmile point I've decided to replace the motor mounts. The right one wasn't too hard to get to. The left is a complete bear. First you have to take off the intake manifold and half a dosen brackets. Even removing the support arm from the engine doesn't free it. The OM606 engine is so tall that it has to sit at a slant in the engine compartment. The bottom of the engine is so far to the left that it traps the mount. I may have to remove the right mount again and shove the entire motor to the right.
Looks like I did this none too soon. The mount rubber was breaking off of the steel frame. The motor now sits 2cm higher, and that is just with one mount changed. Seemed so high up that I had to measure twice to be sure it cleared the hood. It will probably level a bit when the rear mount is replaced.
Question: The mounts have a shoulder on them. See the pic below. As found, the mounts have the shoulder on the left side. Is this a movement limiter for high torque situations? Should they both be on the left? It seems like heavy engine braking could produce a lot of torque the other way. The engine had been taken out before so there was the opportunity for a mistake by an earlier mechanic.
So, at the 100Kmile point I've decided to replace the motor mounts. The right one wasn't too hard to get to. The left is a complete bear. First you have to take off the intake manifold and half a dosen brackets. Even removing the support arm from the engine doesn't free it. The OM606 engine is so tall that it has to sit at a slant in the engine compartment. The bottom of the engine is so far to the left that it traps the mount. I may have to remove the right mount again and shove the entire motor to the right.
Looks like I did this none too soon. The mount rubber was breaking off of the steel frame. The motor now sits 2cm higher, and that is just with one mount changed. Seemed so high up that I had to measure twice to be sure it cleared the hood. It will probably level a bit when the rear mount is replaced.
Question: The mounts have a shoulder on them. See the pic below. As found, the mounts have the shoulder on the left side. Is this a movement limiter for high torque situations? Should they both be on the left? It seems like heavy engine braking could produce a lot of torque the other way. The engine had been taken out before so there was the opportunity for a mistake by an earlier mechanic.
Alan, Did you have any vibrations you suspect were caused by the worn mounts? I still have a vibe in my truck and after your post and some driving, I think it definately could be motor mounts. Fortunately I think the 320 will be easier to get at. The engine sits upright at least.
On engine braking, it will never match the torque applied by engine power. Just imagine the forces at work on the mounts in low range under a full load of turbo diesel torque[:D] I can't say where the shoulder should go, I haven't looked closely at mine yet and I suspect they are a little different anyway. You have an extremely rare engine in the US G's, you will probably just have to use your best judgement.
Alan, in my G those tabs are mounted outside away from the motor. The transmission rear mount is of similar design and it's tab locates to the rear and against the transmission. I replaced that one. This is for a 617 motor and manual 5 speed box. Sounds like your set-up is much more difficult to change out. Hope this helps, best of luck,
Thanks for the help guys. I think that the motors
mounts are common to most of the G's.
A 460 240 70 18 Engine Mount, White, either side
A 460 240 67 18 Engine Mount, Yellow, Left ONLY
The rear mount is from the stock MB parts bin:
A 220 240 02 18 Engine Mount, Rear
After a lot of jacking, prying and cursing I put the new mounts back in the way the old ones came out. I may chose to switch the right side shoulder to the outside too. It is the easy (comparatively) one to get at.
Then I went to fix the original problem that got me to get into the engine to begin with. #2 glow plug had burned out. It was stuck. 24hours of oiling, tapping torquing got me nowhere. It twisted off in the head[:0]. ARGGGGGGH! That sickening feeling of a bolt twisting off.
The 4 valve diesels have one maintenance drawback: The glow plugs and injection pump are hidden by the enormous intake manifold. Now I've got to put the intake manifold back on to drive it to a machine shop. Hopefully I don't have to take the head off to get the plug out. I'll find out soon enough.
Heart ache! Alan that is definately a major PITA. I think I'd rather suffer a 1000 smacks...
Heart ache! Alan that is definately a major PITA. I think I'd rather suffer a 1000 smacks in the thumb with a hammer rather than endure that awfull sinking feeling of a bolt or something similar shearing off!!!
You might want to pop out the rest of the plugs while at the machine shop, if you haven't already.
Best of luck!
__________________
Greg S.
'85 300GD
'73 Unimog 416 Doka
Sorry to hear about the glow plug issue. I agree with Greg, pull the rest if you can and anti-seize them on the way back in. There is a copper based anti-seize that may work better for that then the aluminium based stuff. I found some at a local NAPA house. Best of luck with your repair.
....may work better for that then the aluminium based stuff.....
Dad told me the silver stuff was nickel based. Doesn't seem to be anything "anti-sieze" about aluminum powder, no matter what it's dissolved in.
Is the silver stuff really aluminum?
Just curious, it's a slow morning. [:)]
I've been using the silver colored stuff on exhaust manifold studs (steel nuts on steel studs into aluminum heads) for ever and it always seems to keep things free, even after the carrier oil is all driven off and there's just the silver powdery goop left. I think either type would be fine. One brand of the copper stuff is called "Coppaslip", I'm sure there are others.
I have always used the silver stuff myself except on electrical conducting parts where the copper might be a better choice. I don't know if the silver stuff is aluminum. (aluminium for the brits out there) Does anybody know what it's made of? The Permatex version works great as does "Never seize". I slathered the bolts that go through the control arm bushings on my G. One of the bolts had to be cut out because the bolt had seized to the bushing's inner metal spacer making it impossible to remove. A difficult problem and a delay of game as a new bushing had to come from far away. I use it on the reassembly of most things.
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