weeping differencial

[DavidWeis]

HI,
I just had my 98 SL500 checked out at MB Dealer. They said I had a weeping differential, and that it should be 'watched'. I took a look at it, the main body is 'weeping' while the area near the crankshaft has an actuall drip.
What should I do..Is there a quick fix? This diff looks like its tough to get out.
And sorry for my ignorance, is this the tranny fluid thats leaking? , and should I check its level?

Thanks for your help.

Dave

[Duke2.6]

Small diff leaks can make a real mess, but over the mileage between maintenance visits they don't usually loose much oil.

The easiest thing to do is have the diff checked and topped off every time you have the engine oil changed, but you will have to specifically request that from your service provider, and make sure it is written on the work order.

If they have to add oil, the quantity should be listed in the parts breakout, so you will be able to compute the actual leak rate.

I'm guessing that the diff capacity is about 1.5 quarts (should be in your owner's manual under capacities), so if it just looses a few ounces between checks, there's nothing to worry about unless you plan to keep the car forever.

Duke

P.S. Diffs have a vent at the top with a lose fit cap to keep oil from being thrown out, and these typically weep, which will coat the diff with oil over tens of thousands of mile. An overfilled diff will also tend to weep more as will sustained high speed driving. If it were me I would spray down the diff with mineral spirits to clean off the oil residue, then keep an eye on it. It could be that it is weeping out the vent then migrating down to the low spot and finally forming a drip, but you could also have a pinion seal or side seal leak.

[placo1]

Originally posted by Duke2.6
P.S. Diffs have a vent at the top with a lose fit cap to keep oil from being thrown out, and these typically weep, which will coat the diff with oil over tens of thousands of mile. An overfilled diff will also tend to weep more as will sustained high speed driving. If it were me I would spray down the diff with mineral spirits to clean off the oil residue, then keep an eye on it. It could be that it is weeping out the vent then migrating down to the low spot and finally forming a drip, but you could also have a pinion seal or side seal leak.

This is an excellent suggestion! I had noticed oil on my tranny and differential when I purchased the car. I decided to have the undercarriage steam cleaned to help source the leak. Well it turns out the leak had been coming from my engine (oil cap, power steering hoses and breather hoses!!!) and had managed to migrate down the backside of the engine and onto the tranny and differential. After fixing the two items my engine and undercarriage have been spotless. You may never know where the leak is coming from unless you spent the time cleaning first.

[DavidWeis]

Wow..Thanks for the advice.
SO, I suspect that this thing is a pain to fix if it needs to be 'removed' and rebuilt.

David

[Duke2.6]

Years ago I inquired with my MBZ dealer about replacing the ring and pinion in my diff (wanted a shorter gear), and they said they didn't have the tools, parts, or tech data to rebuild a diff. If a customer (warranty or customer paid) had an internal diff problem, they just replaced it with a new one. Don't know what the situation is today. Diffs are very reliable and rarely go bad inside.

The pinion seal can be replaced with the diff in the car. I replaced the pinion seal in my '63 Corvette back in the sixties - on the car and me on my back - not fun! I got much more enjoyment out of rebuilding the whole diff on the bench in the seventies.

If the "leak" isn't just weeping from the vent, the most likely suspect is the pinion seal.

Duke