1992 W124 300 E Final drive unit

[ShaunD]

Hi,

I've owned my 300E for about 3 months now, my 1st ever Merc. I Bought it for towing a caravan and because I was told they are very reliable motors which go on for years. (Well they do have that reputation anyway)
It seems that the final drive unit need replacing because its making a real bad grinding noise. Is there anyone out there who can advise how difficult it is to remove and replace the unit if I do it myself?

Also I have an oil leak coming from the head on the front left hand side (looking into the engine). I've since been told that this is a common problem with these and if true, is it worth my while spending the money to get repaired?

Thanks,

ShaunD

 

[television]

Hi Shaun and welcome.

Its a matter of taking off the prop shaft and drive shafts, then dropping the diff.

Is your engine the 104,, if so the leak will be over the top of the timing cover and can be fixed

 

[Smudge]

You have a PM regarding the diff.
As for the head it may be the head/block joint. I have seen a few with slight leaks there.
My own leaked albeit slightly for 100k miles with no ill effects!

 

[ShaunD]

Hi Malcom,

Thanks for the welcome. Regarding the prop and drive shafts, is it just a matter of removing the flange bolts / nuts and they drop down or are they on splind shafts which need to be pulled out 1st before dropping? The reason I ask is because I will be on my back under the car and would like to know before hand was is involved.

I'm not sure if it is a 104 engine, all I know is that its a W124 type. The oil leak is quite heavy as it leaves a sizeable stain on the driveway each day but I only need to top it up once a week if that. In your opinions is it worth getting it repaired? I appreicate any advise you can give.

 

[television]

This evening I will print off a how to do it, and let you have it

 

[Richard Moakes]

The prop will have to slide forwards on the splines, for this you will need some very large spanners (41mm and 46mm from memory) to unlock the spline joint. You also have to loosen the support bearing mount to allow the whole prop to slide forward. You have to do this as there is a spigot on the diff coupling which projects forward about 1.5" which you cannot clear unless the propshaft is moved forward. You may also find that the flex disk will be 'stuck' to the propshaft coupling and will need persuasion with a hammer and screwdriver to come loose.

The driveshafts are bolted to the diff output flanges using multispline (XZN?) bolts, these will need the appropriate socket adapters to remove.

Finally you have to remove any electrical connections to the diff and then you can undo the front diff mount and the two rear diff mounts, be sure to support it before you undo these, as it's very heavy and you don't want it to fall on you.

Hi Malcom,

Thanks for the welcome. Regarding the prop and drive shafts, is it just a matter of removing the flange bolts / nuts and they drop down or are they on splind shafts which need to be pulled out 1st before dropping? The reason I ask is because I will be on my back under the car and would like to know before hand was is involved.

I'm not sure if it is a 104 engine, all I know is that its a W124 type. The oil leak is quite heavy as it leaves a sizeable stain on the driveway each day but I only need to top it up once a week if that. In your opinions is it worth getting it repaired? I appreicate any advise you can give.

 

[MercStraight6]

The engine is probably an m103 unless it is a 300E-24.

If it has a slim, black cam cover it is a 12v m103.

If it has a wider, sand-cloured cam cover then it's the 24v m104.

 

[Bolide]

If it's a 300E it has an M103 engine. The oil leak is therefore probably from the rocker cover and not from the cylinder head gasket

Nick Froome
www.w124.co.uk