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Rear differential slow leak


wonderllama

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I’m looking for some suggestions as to what to check on my 1978 280Z 5-speed. The situation is, I just bought the car last week, and after inspecting it when I got home, I saw that there was an oily substance all over the rear differential that definitely was not there when I bought the car. However, it was a two and a half hour drive to get back to my house, and this is not my daily driver, so I just decided to keep an eye on it. To this day, it has not dropped an ounce of any liquid on my garage floor, where it spends all day and night parked.

But the other day I drove it to a friends house, and left the car running in his driveway as I was not going to be there very long. After what some would say was a “fast acceleration†out of his driveway, he later called to tell me my car had left a puddle of liquid near the rear tire. I’m guessing this was the rear differential, because of what I had seen earlier, and he confirmed that is where it looks like it would have come from.

Now, I know that the R200 is considered Bulletproof, and mine only has 115,000 miles on it, so I don’t think it’s shot. Furthermore, it really doesn’t make any noises or clunks. I’m guessing it could be a seal or perhaps even the filler or drain plugs themselves.

Anyone got any good ideas?

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The oil could be coming from the plastic vent tube on the top of the rear cover. It’s not unusual to get some venting after some spirited driving, especially if the diff has been slightly overfilled. You can check the level of gear lube by removing the filler plug and inserting your finger. The oil level should be just below the plug hole opening.

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Ditto on ZCARUT's advice. For a couple of years I always had a little oil vent out of the vent tube which kept the case greasy. I finally removed the fill plug, and watched about half a cup of oil drain out. I then realize too much oil was in the differential, so I then re-installed the plug, and never had an oilly differential from that time forward.

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  • 2 weeks later...
wonderllama' date='

I'm in Bradenton and have a lift if you want to take a look underneath.

You can email or pm me if you want to get together.

Brad[/quote']

 

that would be awesome, although the 280 is considered taller than the 240, man is it a low car. i put it up on ramps and i still needed to jack it up further.

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  • 4 years later...

I may be misunderstanding you; but if you're talking about replacing the diff cover gasket, it takes about as long as it takes to remove and reinstall the diff. I'm not familiar with any technique that allows you to swap gaskets w/o first removing the differential. Once the diff is out of the car, the cover unbolts and comes off (w/ a couple taps from a rubber or plastic mallet) pretty easily. You might be tempted to try to remove the mustache bar with the differential still in place, but that will probably become more trouble than it's worth (if it's even possible).

 

Probably not the answer you were hoping for. On the bright side, now you can do all that other rear end maintenance (that you may have been putting off for a while) at the same time!

Edited by jhm
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There is more than just the "Rear diff seal" There are pinion seals, there are axle seals, and then there is just a rear cover seal. Time may vary depending upon tools and which seals need replacing. Would recommend some dial indicators and a magnet mount to check backlash if the axle or pinion seals must be removed.

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