I just recently purchased a 95 rx7 and had to replace the rear seal in the differential, and had to get a drive shaft as well. seems as tho the u-joint on drive shaft froze, caused rear seal to blow.
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But I still see a small oil leak from differential, it looks like it is coming from the rear seal around the cover of the differential, where the filler and drain plug is.

My question is, is there a gasket that goes there? It looks like it just has sealent on it. Also, it appears that I may be able to drain the oil and take the rear cover off without having to remove the differential completely, true?
thanks for any help.
Chris.

 

I've never seen a drive shaft go bad. Where is Bel Air? Was it rusted or something?

The only joint in the diff is for the diff cover where the drain and fill plugs are. You can get an OEM gasket from Ray Crowe at Malloy Mazda. He gives us discounted parts. His number is in the 3rd gen FAQ: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/faq-3rd-gen-other-useful-links-68640/

The other possibility is a leak from the axles. You'll need to get under there and check.

Refer to the FAQ thread for good archived info on these cars.

 

Thanks for the advice.
the original leak blew from the front of the differential where the driveshaft/u-joint enter the diff...
the mechanic said the u-joint "froze up" and thus put strain on the seal into the differential; causing it to leak. we replaced that seal, stopped the massive leak. As far as we were told, Mazda doesnt sell a u-joint that you can replace with on the end of driveshaft, crimped down. so I had to buy a new driveshaft complete.
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the axles look fine with no leakeage.
I only see a small drop hanging now from under the drain bolt and where the gasket would be on the back cover of differential. I wasnt sure if it was sealent used or if i need to order a gasket.
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btw, it appears that they way they designed the rear cover, that you might be able to drain and pop off thru the rear bracing section of the car, true?
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Belair is a suburb outside of Baltimore, Maryland, eastcoast.. I just got the car last month. it was a florida car and was stored alot, only 36k orig miles.

 

I recommend you drain and replace the diff fluid too and look for bearing damage. If the driveshaft had an issue severe enough to deform the oil seal, it's likely to have abused the pinion shaft bearings. It's easier to fix that stuff now than wait for the diff to let go completely.

 

check the ventilation cap or whatever, on top of the diff itself, it could be plugged. that caused the pinion seal on my ford to blow out. as well the diff i picked up for my FC had that thing pretty badly plugged before i cleaned it out

and yea the u-joints are "non-replaceable" but any decent machine shop would be able to put new ones in for you. they are more like "non-user-serviceable"

 

i took the car back to my mechanic, he says it is dry.. he says that it appears at tho some fluid may have been coming out of the upper vent hole (there is no drain hose) of the differential, maybe it is running down and making it apper that the rear cover is leaking. gonna pick it up and bring it home.
I wonder how long this will go on? I had the rear seal replaced and diff refilled with oil 2 weeks ago, and have only put about 15-20 miles on it.. does it spit out some oil till it gets to a suitable level in the diff then stops???

 

Dry? Ouch. No, it's not normal for the diff to lose any fluid at all.

 

I meant to say that mechanic said that the front seal he replaced in the diff and the sealent around the back cover is "dry" of any leaking oil.
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there is a breather hole at the top of the diff that it spitting out some oil.
Hopefully it will stop once the oil gets down the norm amount in the diff...