9/16/10 7:57 p.m.

Hi, I have the tranny out of my '90 Miata to replace the slipping clutch. The inside of the bellhousing is covered in what smells like engine oil (not tranny, although I'm might replace the front tranny seal anyway), but I'm not sure if it's the seal or the half moon of the oil pan that's leaking (the CAS area is clean and dry).

Am I right in assuming that the seal seals oil that is under pressure while the half moon is not pressurized (by the oil pump)? And so it's more likely to be the culprit?

The seal I took out looked fine, but I don't think they have to look bad to leak.

Anyway, hate to take the pan off, even with the tranny out (although I'm not sure if that makes it any easier) so wondering if there is anyway I can figure out where the leak is coming from. Hate to put the new clutch in and have it slip as well. Any suggestions?

Thanks very much!

motomoron Reader
9/16/10 9:20 p.m.

Step 1 - consider what a bitch it is to R&R the transmission. Those 2 top bolts are sweet. I used my new 24" extension and 2 universals.

Step 2 - Think about this for another couple minutes.

Step 3 - order rear main seal, transmission front cover seal and gasket, tail shaft seal, and clutch slave cylinder boot.

Step 4 - Clean trans w/ a can of degreaser and a stiff brush, install parts listed above.

Step 5 - leave transmission in situ for the next 100k miles...

Seriously - I did all that stuff when my '90 was apart. Parts are cheap compared to my time.

amg_rx7 HalfDork
9/16/10 9:53 p.m.

It took some elbow grease but the inside of the bellhousing cleaned up easily with just paper towel. Using a degreaser and a brush just got everything all mushy and pushed it all around. YMMV.

Definitely do the trans seal and gasket as well as the rear seal. It was easy.

Not sure about that half moon gasket but I wasn't willing to pull the pan at the time.

Streetwiseguy HalfDork
9/16/10 10:22 p.m.

If the pressure plate was slimey too, its probably trans oil. If its flung around the bellhousing, buy not really on the cluth, its probably rear main seal. If its just running out the bottom, its probably pan gasket.

Do them all. Its way easier than dropping the trans again. And don't cheap out on the seals. You don't want a cheap part behind 5-6 hours of labor.

Garnet New Reader
9/16/10 11:11 p.m.

Thanks for the info. The inside of the bell housing is covered in black goo, as is the bottom of the car, but the clutch plate, pp and flywheel are all clean, bought new ones anyway (who knew Amazon had clutch kits?).

I plan on doing all the seals, although I hear the front trans seal can be problematic with shims or something. Searching for info....

Anyone experience on replacing the pan gasket with the tranny out? Haven't been able to find much info on this.

Thanks again.

mistanfo SuperDork
9/17/10 10:18 a.m.

In reply to Garnet:

Give FM a call at 970.464.5600 (tech line).

They always have (or quickly get) answers.

Then, when you feel the need to fly, call them and order something. There's a 1-800 # for that.

Jay_W HalfDork
9/17/10 10:38 a.m.

Yeah. While you're in there, do them all. Cuz if you don't the one you didn't replace WILL start leaking within weeks. Ask me how I know.

On second thought, maybe best don't ask...

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