Tranny is leaking, help diagnose

Chuck Moreland · 05-24-2004, 06:18 PM

73 915. On the track the tranny has been blowing a *LOT* of gear oil out. It may blow some on the street, but nothing like on the track.

The gear oil bath is concentrated on the passenger side, coating the exchanger, starter motor, rear portion of the tranny case, even the oil lines in the wheel well.

It got so bad that I was nearly black flagged at Cal Speedway due to the smoke coming off the exchanger.

Since the oil is up high and all over, I suspected the breather might be oriented wrong. But a quick check shows the vent is pointed forward.

I acknowledge the input shaft seal could be a problem, but I would expect the oil to be concentrated at the base of the case, not up high and not all over the place. And the clutch shows no slippage.

The case is not overfilled. I checked and found it to be nearly 1/2 quart down (it was full / changed 1 month ago). That 1/2 quart is all over the engine.

Any ideas?l

Jim Sims · 05-24-2004, 07:11 PM

Check the detent access hole plugs; loose or missing? There are three on the PS; one is towards the top. Jim

AFJuvat · 05-24-2004, 07:48 PM

Differential flange seal?

AFJuvat

Adam · Adam's Garage

Gear oil? Man, that must stink!

Chuck Moreland · 05-24-2004, 08:31 PM

Jim, I'll check the detents tomorrow.

AFJ, It does not seem to be leaking around the output flanges.

Noah, I did just that. 1/2 hour of street driving and there is very little visible fluid and it is all at the bottom of the housing (as if it was coming from the input seal). It is entirely possible that no new leakage has occured, simply some drippage that was not cleaned up in the pressure wash.

pete911 · 05-25-2004, 01:02 PM

I had this exact same problem on my track car. It only occured at the track, not during "normal" driving. It was the plug near the top of the tranny at the shift rod end. Under heavy braking the fluid gets thrown up there and leaks out. I cleaned the area real well with brake cleaner then globbed RTV over the area. This fixed my leak without having to drop the tranny. It is amazing what a mess this small leak can make.

Pete

Chuck Moreland · 05-25-2004, 01:29 PM

Pete,

I'm not sure what plug you are refering to? Not the fill plug?

I don't think the leaking is coming from the front (shift rod end) since that end of the tranny is dry.

Eugene at Pelican Parts · 05-25-2004, 02:56 PM

Quote:

Originally posted by Chuck Moreland
I acknowledge the input shaft seal could be a problem, but I would expect the oil to be concentrated at the base of the case, not up high and not all over the place. And the clutch shows no slippage.

Any ideas?l

If the input shaft seal is gone, the clutch will definitely fling lube in every direction. You'll definitely see a drip at the bottom inspection hole, and it will also fling out the top one, getting all over the parts you just listed. The clutch will not feel much different, except for occasional low speed shudder upon lugging. Reach your hand up to the top of the motor by the breather cover to see if it's wet. If it is, I suspect the input shaft seal is gone.

pete911 · 05-26-2004, 11:04 AM

It is a small press in cap for one of the detents. If you have a tranny out of the car you can see it easily. I'm TDY with the Air Force right now, but will be home this weekend. I'll post a picture from a spare tranny when I get home.

Pete

chrisp · 05-26-2004, 11:42 AM

Could the breather be partially blocked and when things get really hot the pressure builds and stuff comes out but only when really hot.....under high pressure?

Chuck Moreland · 05-26-2004, 11:48 AM

Pete

I checked the detent cover screws and the cap you are referring to. They are all in place and secure.

I found the breather vent can be rotated fairly easily, perhaps 10-15 ft lbs of torque reqiured. It also deviated about 5 degrees from pointing straight forward. I have since staightened it.

With the case warm, given the different expansion rates of mag and steel, this could well be loosening and rotating with much less force. Mix vigorously with vibration at 7500 rpm and it may in fact be rotating about.

I'm going to zip tie a shop rag over the vent, then monitor the rag for oil saturation.

chrisp · 05-26-2004, 11:58 AM

When I had my tranny out I removed and cleaned my breather. It turned as easily as yours. I had a 10" or so box wrench on it and it took veyr little force to turn. Definitely well under 20ft lbs.

RoninLB · 05-27-2004, 04:05 AM

Quote:

Originally posted by Eugene at Pelican Parts
If the input shaft seal is gone, the clutch will definitely fling lube in every direction.

my tranny shaft seal was easy to replace.