Broken harmonic balancer

[Casey]

I'm in a dilemma.

The new alternator belt on the 300D started squealing today, thought it just was a little loose.  Tightened it up.  Started the engine, and it sounded rather rattley.  Looked at the source of the noise, and saw sparks from the two pulleys hitting each other.  "Hmm, odd...".  Turned off the engine, removed the belts, fan and fan shroud, found the main pulley completely loose from the engine, with the big 27mm bolt in the center gone to who-knows-where.  Little bits of metal that were parts of the center of the pulley fell out as well.

Since the 300CD still hasn't had the radiator replaced, I thought I might be able to use it's pulley for now, even though it's designed for a 2-belt alternator.  Hoped it would line up alright to make do until I could fetch a better replacement from the junk yard.  Pulled all it's belts, fan, fan shroud, and even the radiator out to get better access.  Now how do I get it loose?  If I turn the big bolt, the engine turns over.  If I turn the little hex bolts surround it, the engine also turns over (don't think that would accomplish what I want anyways).

There's got to be some way to lock it in place to remove the big bolt, eh?

Many thanks in advance.  I don't have another working car here at the moment (the 450SE's sitting at work) and am hoping to get to work in the morning...

[jbrasile]

Casey,

I was just reading my Haynes manual and to remove the pulley you should only have to undo the small bolts not the large crankshaft l one, that holds the harmonic balancer in place.

Tks,

Joe

[TJ 450]

I think this explains the performance issues in the other thread...

So, the big bolt is missing from the 300D, and you want to use the one from the 300CD to replace it?

The easiest way to remove that bolt is to jam rope into the first cylinder when it is just before TDC... Then rotate the engine slightly and it will lock. This works both ways, but you don't want to have the crank turning backwards where possible.

Tim

[Casey]

I was just reading my Haynes manual and to remove the pulley you should only have to undo the small bolts not the large crankshaft l one, that holds the harmonic balancer in place.

I can't get enough bite to loosen them, even while holding the center bolt with another ratchet to counter the turning which happens if I just try to turn a hex bolt.

The large center bolt is what disappeared from the 300D.  All the hex nuts are still intact holding the two pieces together.

I'm giving up on my attempts to further destroy the 300CD.  I'll try to source a proper part from the junk yard.  Hopefully the one on the 240D is the same as the non-turbo 300D.  Though it looks like the spacing is exactly the same on the two-alternator-belt model, there's just a gap between the belt spaces on the one belt model.  So I might just grab one off one of the many W126 300SD's in my local yard.  For now I'm in the process of installing the new radiator I pulled from one of those 300SD's into the 300CD and getting it reassembled.  Once that's done I guess I'll top off the fluids, fill the radiator with water, and take it in for a coolant flush tomorrow as I've got no idea how to do that myself (or, advice on this welcome).  I think I should be able to get the 300CD drivable tonight as I've got some spare oil and transmission fluid.

So my main question is, if I somehow manage to pull a pulley from the yard, how do I get the big bolt put back in with the proper amount of torque?  I think it needs more than my torque wrench will measure, and I'm still not sure how to keep it from moving (maybe it will stay stationary enough with all the belts put back on?)...  I hate to take it in to the shop just for this but that's all I can think of.

[Casey]

I think this explains the performance issues in the other thread...

Actually, that was the fuel filters.  The primary was REALLY dirty.  I replaced both before fiddling with the alternator belt and it seemed to run brilliantly after that.  Didn't really take it far though.

So, the big bolt is missing from the 300D, and you want to use the one from the 300CD to replace it?

Well, that and the pulley as well, since bits of metal came off the inside of the pulley.  But I think I'll just wait and try to get one from a junk yard.

The easiest way to remove that bolt is to jam rope into the first cylinder when it is just before TDC... Then rotate the engine slightly and it will lock. This works both ways, but you don't want to have the crank turning backwards where possible.

Sounds promising.  How do I access the first cylinder to do this?  Up under the valve cover, or...?  Also maybe obvious question, but does that big bolt tighten the usual direction or backwards?

[TJ 450]

Well, you just need to gain access to the top of the cylinder through the injector hole or some other way. I'm not sure how easy it would be to remove glow plugs on these.

Good to hear that the filters appear to have solved the performance issue... It's nice when it's an easy fix.

Tim

[Papalangi]

I usually jam a brass drift or a screwdriver in the ring gear to hold things still but if you wanted fancy, there is a tool meant to hold the flywheel still without damage.  Never seen one so I don't know how it works or if it works on a Mercedes but it's 12 bucks.



http://www.amazon.com/Powerbuilt-648455-Flywheel-Turning-Tool/dp/B001CZJ4J0/ref=sr_1_1?ie=UTF8&qid=1319085220&sr=8-1

Sometimes, the fan belts are in good enough shape that I can sort of squeeze them and bind the pulley but if things are rusty enough, that won't work.

Michael

[Casey]

Well, you just need to gain access to the top of the cylinder through the injector hole or some other way. I'm not sure how easy it would be to remove glow plugs on these.

The glow plugs are quite small, and underneath the injector lines.  I need some more injector housings anyways, so might as well just pull the injectors.  Now I just need to find a good chunk of rope...

...and my breaker bar.  I don't know where it went.  The torque wrench might not be enough.  I'll bet it's buried at the bottom of my storage facility 300SD boot...

[WGB]

Here is my Porsche Flywheel lock



It has the same bolt pattern as the genuine M-B one but only holds three flywheel teeth(genuine M-B one holds five teeth)

It is designed to torque a Porsche crankshaft bolt to 270Nm and has been used to torque TJ450's 6.9 crankshaft bolt to 400Nm without any catastrophe but I think he was careful not to jerk the torque wrench while tightening.

Bill

[s class]

Well, you just need to gain access to the top of the cylinder through the injector hole or some other way. I'm not sure how easy it would be to remove glow plugs on these.

The glow plugs are quite small, and underneath the injector lines.  I need some more injector housings anyways, so might as well just pull the injectors.  Now I just need to find a good chunk of rope...

...and my breaker bar.  I don't know where it went.  The torque wrench might not be enough.  I'll bet it's buried at the bottom of my storage facility 300SD boot...

Be careful.  I assume the "injector housing" you are referring to is the pre-chamber.  You need some very special tools for this. 

Here is the Klann tool needed to release the pre-chamber locking ring :

http://www.ebay.com/itm/300605189300?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

Then there is another special puller tool needed to take out the prechamber itself.  Behind that is a shim/seal that needs to be replaced, and the thickness of it must be chosen according to if your engine is original or if the head has been skimmed. 

In the case of a diesel, I would suggest that going this route is opening a can of worms.  Rather get the proper flywheel lock. 

Also, bear in mind that if the engine rotates when you try to loosen those crank crown bolts, it is rotating the engine in the backwards direction.  This is 'verboten' as it places massive strain on the chain guides/tensioner etc. 

The torque of those crown bolts is very high - spec for OM617 is 270 to 330Nm.  That should give you some idea of how difficult it is going to be to remove. 

[koan]

To prevent the engine from rotating when dealing with the hub nut I made up a metal plate with about a meter of angle iron attached. The plate has a large central hole to clear the hub washers and bolt head (m100), and six (or eight?) holes round the large hole that match the pulley holes.

Bolt it up where the pulley mounts, may need spacers, the end of the angle iron sits on the ground. With 4 feet of water pipe on a 3/4' drive socket the nut is easily removed or tightened. The required 400 nm torque is 75 lbs pull at 4 feet, just guess.

koan

[s class]

That's very resourceful, as usual, koan.  A bit of fabrication time involved no doubt, but worth it  I'm sure. 

[Casey]

This morning I went by a junkyard near my work.  There was a 300D I remembered but the motor was gone.  Found a W126 300SD, and decided to give it a go.  The front was damaged so this meant removing the radiator first.  There was no getting a rope into the tiny hole under the injector. or through the glow plug hole.  I tried sticking a piece of accelerator linkage in there but it just hit something about a half inch in.  Then I jammed a wiper arm into the space in the pulley from the upper right of the engine, which was quite effective at holding it.  Managed to get the big bolt loose with the torque wrench.  The pulley was still stuck on there, so I had a go at removing the six hex nuts.  Managed to get all of them free, but still the pulley was stuck.  Realized it was jammed behind the upper fan pulley.  Okay, no problem, I thought.  But one of the 4 screws stripped and I could not get it removed, so it was a no go.  Perhaps I'll head up to the junkyard with the 240D later today which might even have the proper pulley unlike the SD's...if I can sneak out of work.  It's a good 30 minute drive each way plus whatever time it takes me to tinker, so that'll be pushing things.

[Casey]

FWIW, the part on the 4-cylinder OM616's is NOT the same.  The pulley itself looks the same, with a single belt for the alternator, but the part it's attached to (is this the harmonic balancer?) is longer to compensate for the shorter engine block.  This time I managed to get the big bolt free, but a couple of the hex nuts seemed stripped out, or maybe full of crud I couldn't see.

The assembly did not simply pull free with the large center bolt removed, which I was surprised  by.  How do you remove it?

The part I need is not the pulley anyways, but the part between it and the engine.

[koan]

On petrol M-B engines a hub puller is required to get the harmonic balancer off, I assume diesels are the same.

On my engine the harmonic balancer is heated to 100C in an oven then slipped on.

Thought I saw some where here the balancer is drilled round it's edge to balance the crank/engine and can't be swapped and a new balancer should be drilled to match the old.

koan