I have a 1978 300D...

long story short...

Driving to work and I lost PS and all the lights came on, I drove home... found a bolt in the driveway... opened hood to see the balancer&pulley nolonger attached to the engine....

i put it back on and put all the belts back... but it will not stay tight...

after just a couple of minutes the lights some on and the pulley is loose, nearly fallen off. I cannot seem to make it stay on.... WTF!!!!!

thanks

Ouch, you may need to put a fork in the engine as the crankshaft snot sounds damaged. I assume you are referring to the “Crankshaft Balancer?” If so you might be able to do some things but I do not believe you will have any long term solution without changing the crank as well, the items that are currently broken.

the items that are currently broken what? What pulley are you referring to? Can you post or email a pic?

__________________
1982 Mercedes-Benz 300CD
1982 Mercedes-Benz 240D - stick

If you are talking about the front crank pully and harmonic balancer bolt I would try a new bolt (probably a dealer part) and blue locktite and make sure that you are toqureing it to the right specs my 86 SE specs are 250 lps "thats tight".................

William Rogers........

I will try to make it that tight and see, well Ill check my book and see what the exact torque is for mine.


The bolt threads looks okay, what signs should I look for to tell if the bolt needs to be replaced? (besides it falling out )

And just for fun, what could have caused it to come off in the first place? I have had many cars, and some were not in the best shape... but this is a first for me.

Thanks!!!

~Brian

HOLY CRAP!!!!!


My torque wrench only goes up to 150 ft-lbs ?????

well Ill give it a shot anyhow!

You need to confirm that you are talking about the heavy balancer that is held on with a 27MM head size bolt. If so, are you getting the pins in place? There are two pins about 1/4" dia. that pin the balancer in position. They are tricky to get properly in place.

Is this the pulley on the crankshaft or another pulley? Please be more specific.

Good luck,

The pulley is the one connected to the balancer. Then onto the crankshaft.

The balancer and pulley came off as one piece and went back on as such. I am assuming that everything is lined up because everything is lined up properly ( ie. the belts) and I can turn the crank by turning the pulley.

So I went back out tonight to try it again with the torque wrench... but I dont think I am doing it properly... I continue to block it and tighten... but once I get to a certain point it will not tighten.

While the balance is blocked from moving and I am tightening the bolt, the crank is turning the motor, they pulleys, etc., arent moving... but the crank is....


How can I stop it from turning the motor so that I can fully tighten it? Thanks

~Brian

You have to use a flywheel or starter ring lock.You can buy them from aftermarket MB tool sites online or improvise one . I used a very large screw driver and a pair of needle nose vice grips using one of the two holes in the front bottom of the bellhousing that is ment for the MB locking tool.........

William Rogers..........

so there are access holes near the bellhousing that I can insert a screwdriver to block the flywheel?

How do I access these holes, need I remove a cover or some kind of inspection plate? and do they face to the front, rear, driver or passenger side of the car?

THanks much, I cannot wait until I can drive her again!!!!


~Brian

Yes there is an inspection plate on the lower front of the transmission housing. The plate is sheet metal, is vertical and is held in place with a few small fasteners.

You have another problem, however, if you are blocking the balancer and turning the crankshaft, you do not have any pins in place. There are two metal dowel pins that key the balancer in place on the crankshaft. These keys are what prevent the balancer from turning on the crankshaft, the bolt just holds it firm rearward so that the pins are held in place.

Pull the balancer and look at the relationship between it and the crankshaft and I think you'll see what I mean.

It could be that the notches in the crankshaft and balancer are damaged so that you can't really tell what's going on.

If you will search harmonic balancer in the diesel discussion forum, you will find much information about this.

Good luck,

And its worse than that....

When examined closely one will see that there are two dowels keying the balancer. You will note engine timing marks on the balancer, there is only ONE right position and MB would in no way allow you to do it wrong, thus the two doewls are not 180deg apart. You have to know where the motor is and whether you are on the right stroke to chose between the two positions as it isn't obvious until close observation on assembly.

That was the good part, I can tell you that there is about one chance of solving the problem without a crank repair. That would be to start with a new balancer or atleast a used one that hasn't failed. This one has failed!

A proper fitting balancer will have to be pulled onto the crank with a puller. It will have to be done carefully as the two halfs of the dowel hole must align perfectly and once a few millimeters on the thing doesn't turn relative to the crank by hand. A long heavy punch and hammer can tap out a slight misalignment as the balancer approaches proper depth. Once in position the dowels should driven into the two aligned holes with a hammer and the large bolt properly torqued.

You stand little chance of a long term repair if you can turn or install the balancer by hand. It must be snug to down right tight. We have fixed ones with too little interference by drilling two new dowels at 90 deg to the pair already there. Using a bearing/stud mount type locktite might be a last resort, used on the crank to balancer fit, not the bolt.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Steve paints the picture pretty clear about the challenges you face if you choose to work with what you have. His suggestion about drilling new holes would serve well for a better repair that may work for an undetermined amount of time.

The color of loctite you would be looking for is Green.

Good luck