[dataway]

I was testing running the engine today and noticed a leak from the access cover on the transmission/converter. Wasn't leaking for the couple of months it was on the test stand, running now and then, not a drop. Only leaks when it runs. I rebuilt it a few months ago, functions and sounds normal.

Fluid shows about a pint high even when cold, so it does have too much fluid in it .... evidently the change in level between the stand and the chassis matters a lot.

What would be the most common source of a leak between the pump and converter? Outer pump seal, converter input shaft seal? Would high fluid level cause this?

[Schurkey]

There's two dozen points of potential fluid leakage on an automatic trans. Be sure the fluid is coming from where you think it's coming from.

How about draining the excess fluid and seeing if it still leaks?

[steve25]

Just because you rebuilt it and installed what you though where all new seals does not mean they where not already on the way out!

I have had new converter seals get hard in just 400 miles of driving and then drip some.

You may have overlook that the seal maybe just slightly cocked and not seated straight, and it does not take much of that to make for a drip to even a bad leak.

Also as posted the trans being over filled can make for a leak around the OD of the converter seal also!

[Cliff R]

Did you install a new oil pump/torque converter bushing and seal during the rebuild, or just the seal?

There are half dozen places to leak on the front of the trans, but none are typically problem-areas. Can't ever remember having a leak up there after a rebuild. Other very common leak points are the fill tube "O" ring (upgrade to a mulit-lip seal highly recommended) and the manual shaft seal.

Overfill by a pint or so often pushes some fluid out the vent on the top of the case after a hard run but usually doesn't cause any leaks elsewhere......

[Jim Moshier]

I agree with Cliff

Did you install a new oil pump/torque converter bushing and seal during the rebuild or just the seal?

There are half dozen places to leak on the front of the trans, but none are typically problem-areas

[dataway]

Total rebuild, all new bushings and seals from a complete Trans-go kit. Nothing coming out of vent, pan or dipstick tube, it's dripping a bit out of the bottom vent on the access cover, so I know it's coming from either the torque converter seal, or the pump to case seal ... or the new Hughs converter (doubtful I'd guess).

Had easily an hour run time on the stand and never leaked, but did leak after running for five minutes in the chassis.

I'll crawl under and pull off the access cover and see what I can see, and try to pull a pint or so out of the dipstick tube.

[dataway]

Do any of the pump mounting bolts typically need thread sealant? I didn't use any sealant on the OD of the converter seal ... but I assume it would have been leaking just sitting on the stand if that was the problem.

Trans was installed on the engine before it went into the chassis, so there was not a lot of chance for converter seal damage during installation, converter bolted the flywheel with no drama, about 3/16" slack between them. Again, all done before it was installed in the chassis and was test run on the stand several times before being installed in the chassis.

[dataway]

Pulled the converter access cover ... no definitive source of the leak, there was a small puddle inside the cover. Cleaned everything very well, I'll run it without the cover and see if I can locate the source. What I could see of the front pump showed no obvious fluid trail, but that synthetic fluid flows so nice it pretty much leaves no wet trail behind it after a few hours.

[Half-Inch Stud]

leaky Converter weld?
Real difficult to get a Front Seal leak due to the Front Seal generous internal drain path.

Could have been a temporary "high fluid level" condition due to sitting and Converter siphoned its fluid into the pan. I had 1 TH400 Converter like that...aggravating.

[Cliff R]

I've seen the seal spring driven off the seal plenty of times during installation. This is often missed during assembly. Pretty rare to leak at the pump outer seal provided the pump halves were correctly lined up during assembly. The pump bolts have back-up sealing washers on them but don't tend to leak in the first place......Cliff

[Schurkey]

Originally Posted by dataway

Pulled the converter access cover ... no definitive source of the leak, there was a small puddle inside the cover. Cleaned everything very well, I'll run it without the cover and see if I can locate the source. What I could see of the front pump showed no obvious fluid trail, but that synthetic fluid flows so nice it pretty much leaves no wet trail behind it after a few hours.

The low-tech leak-detection system works pretty well.

Buy a container of baby powder. Blow the powder around any suspected leak point. Where the powder sticks...is wet.

Works best if you thoroughly clean and dry the area first, run the thing long enough for it to leak again, and then use the powder. That way you know any oily-powder-trail is fresh.

[dataway]

Thanks for the suggestions. I'll get it started again in a few days ... waiting on a new oil pressure gauge line ... let the plastic one touch the exhaust manifold, copper this time around.

[Mister Pontiac]

Originally Posted by dataway

Thanks for the suggestions. I'll get it started again in a few days ... waiting on a new oil pressure gauge line ... let the plastic one touch the exhaust manifold, copper this time around.

Excellent plan. I recently did the same on my 71 GTO when the plastic line split spraying oil all over the hot exhaust manifold. Small fire, big smoke, bigger excitement. Don't want that again. Copper line was installed the next day. Planning to replace the plastic lines in my other cars in short order.

[Schurkey]

Don't forget that copper tubing work-hardens then cracks.

ANY oil-gauge plumbing--nylon tube, copper tube, "steel-braided hose"...ALL of it will fail if it's not routed properly. The failure you two experienced was not the fault of the nylon tube, it was the fault of the installation. If the copper was installed as carelessly as the nylon, it too will fail.

[Mister Pontiac]

Originally Posted by Schurkey

Don't forget that copper tubing work-hardens then cracks.

ANY oil-gauge plumbing--nylon tube, copper tube, "steel-braided hose"...ALL of it will fail if it's not routed properly. The failure you two experienced was not the fault of the nylon tube, it was the fault of the installation. If the copper was installed as carelessly as the nylon, it too will fail.

Old, dried out plastic tubing can split along the length of the tubing as it repeatedly heats/cools, ages/dries out. Not installation error failure. Time failure.

[Schurkey]

Originally Posted by Mister Pontiac

Old, dried out plastic tubing can split along the length of the tubing as it repeatedly heats/cools, ages/dries out. Not installation error failure. Time failure.

OK, I'll accept that in your case. Previous poster says his melted on the exhaust.

[dataway]

I've only done it three times so far I've got the test gauge panel just kind of laying on top of the engine so it's routing changes every time I move the panel around. Those exhaust manifolds are like plastic magnets.

My post wasn't meant to be a condemnation or praise of any particular oil pressure gauge line, just explaining why I have to wait till Tuesday to start the engine and look for tranny leaks again.