Rear main seal, rear stationary gear o-ring

[scotty305]

Hi all,

I recently replaced the original (88k miles) 13B-REW from my 1994 RX-7 with a used 13B-REW from a 1996-1998 Japanese RX-7. I got the longblock from an importer, the compression tested good (I measured over 110psi on all 3 chambers of each rotor) although the engine appears that it may have sat for a while, possibly outdoors.


I've installed the engine in the car and it starts and runs well, good oil pressure, doesn't smoke, idles smooth, pulls hard, etc. The only problem I've encountered is an oil leak from the flywheel side of the transmission bellhousing. From what I gather there are two likely culprits: the rear main seal and the rear stationary gear o-ring.

One friend (who spent a couple years working at a rotary specialty shop) advised me that it's possible to replace the rear stationary gear o-ring with the engine still in the car, by removing the transmission & flywheel and then prying the rear stationary gear out carefully. I tried this on the car's original engine (which is sitting on a pallet and hasn't been disassembled yet), but so far I haven't gotten the stationary gear to budge. In the Mazdatrix rebuild DVD, the rear stationary gear is removed by hitting it with a soft mallet from the front, not by prying from the rear.

I've already ordered both replacement parts (o-ring and rear main seal) because they're cheap. The question is should I attempt to replace the stationary gear o-ring or just do the rear main seal and hope that will cure the leak?

[C. Ludwig]

It'll some out. Use two pry bars. Put one on each side and pry at the same time.

[rotor85]

i just did the same thing you are doing but i ran into a problem. after reaasembling the gear/flywheel/clutch assembly, my engione is hard as hell to turn. i had the engine running getting it ready for a tune when i noticed the leak and decided that it was no big deal and tackled the repair. the front assembly has not been touched but i am still afraid the front torrington bearing may have dropped somehow and is binding up the motor.

tap the gear with a mallet a few good times, put some penetrating oil behind it and it'll slide out. just make sure to clean up before putting it back in and lube up the oring with some vaseline to prevent pinching it.

[NoDOHC]

i just did the same thing you are doing but i ran into a problem. after reaasembling the gear/flywheel/clutch assembly, my engione is hard as hell to turn. i had the engine running getting it ready for a tune when i noticed the leak and decided that it was no big deal and tackled the repair. the front assembly has not been touched but i am still afraid the front torrington bearing may have dropped somehow and is binding up the motor.

tap the gear with a mallet a few good times, put some penetrating oil behind it and it'll slide out. just make sure to clean up before putting it back in and lube up the oring with some vaseline to prevent pinching it.


I really doubt that the spacer fell out of the torrington. Unless you removed the front pulley hub, the front assembly should have been locked in place.

It is possible that the rotor turned on the E shaft whiel you had the planetary out and now it is clocked wrong. I am not absolutely sure if the rotor can turn that far while assembled.

[TitaniumTT]

The rotor cannot be clocked wrong. There is a chance that the spacer fell. There is no chance to get a rotor and a stat gear in wrong. I would pull the front cover..... sadly.

It raises a good point though for the OP, if he tries this.... put something with some pressure against the front pulley.... just in case

[RETed]

First of all, it is very easy to determine which one is leaking.

If you got oil leaking right below the (rear) stat gear ONLY, it's the o-ring.
Oil leaks between the rear iron and the rear stat gear and drips down the back of the rear iron.

If you got oil ALL OVER THE PLACE back there, it's the (rear) main oil seal.
In this case, oil bypasses the gear and leaks onto the rotating assembly / counterweight / flywheel.
This is why it's flung all over the place.

If you don't need to remove the rear stat gear...DON'T.

If the stat gear needs to be replaced, it's a bitch to get it back in there if it does move - most likely it will.
By slowly rotating the engine (via the front - usually the front eccentric bolt) with the help of a friend, you can get the rear stat gear to go back in.

I doubt anything in the front cover (i.e. Torrington / thrust washer / etc.) fell out.
There is no way those things should get loose unless you remove the front eccentric bolt!
If the engine has significant resistance to hand turning, something is drastically wrong...


-Ted

[C. Ludwig]

What Ted said is right on. If you pull the rear gear out and don't move the assembly while it's out, it'll go right back in. There is no way to get the rotor/gear clocked wrong either. If I had to guess I would say you don't have the gear flush to the plate, somehow have it cocked in the plate.

The front bearing stack can not fall apart unless you remove the front pulley bolt. There is just no way that happens.

[scotty305]

Thanks for all the advice, everyone. I'm not a very experienced mechanic; removing & reinstalling the engine was the most involved thing I've done on this or any other vehicle. Luckily I have a good amount of local friends who have spent time wrenching on cars and building engines (mostly piston engines) and are willing to help.

We got the flywheel off this evening, it was cleaner than I expected. There was some oil on the inner lip where it slides on the eccentric shaft, I was under the impression there would be oil on the entire rear surface of the flywheel.

There is oil on one side of the rear housing, I suppose this makes sense considering the direction the flywheel will rotate.


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http://rotarycarclub.com/rotary_forum/attachment.php?attachmentid=9247&stc=1&d=1289886954

[scotty305]

Update:

The rotary expert had me spray the rear stationary gear with PB Blaster, let it sit overnight, then tap it with a hammer to 'wake it up.' Then he stopped by, used two pry bars exactly as described by C. Ludwig and got the thing out like magic. The old o-ring was pretty brittle, and when replacing it we used some Toyota OEM valve cover sealant (similar to black RTV) on groove and the new o-ring.


We reinstalled the transmission last week (plus a new Exedy clutch), the car has logged about 20 leak-free miles so far.

[Prodigy]

Good to hear...

It always feels great when one tackles a job, they are not totally sure they can handle, and they come out on top...


J.