Leaking 4+3
Thread Starter
Intermediate
Joined: Jun 2007
Posts: 35
Likes: 0
From: Bandon Oregon
Leaking 4+3
After replacing the engine in my 84 (no more crossfire) the Doug Nash is leaking atf on the exhaust system when it gets hot. Never did it before.... I had the entire running gear out of the car engine all the way back to third member. Short runs it is fine but massive smoke when I run it more that ten miles.......
Le Mans Master
Joined: May 2006
Posts: 9,226
Likes: 9
From: Irvine Ca
There is that small vent tube on the back of the o/d Check to see if it got pointed in the wrong direction allowing atf to drip out.
Take a look at this pic
I was being funny when I snapped the shot but it shows a flaw. The Vent Tube was moved to the wrong bolt when it was reassembled. If you take that tube and move it just one bolt over, it now points upwards and leads to the top of the bell housing.
I think you need to take a peek at that tube and see where it is pointing.
Take a look at this pic
I was being funny when I snapped the shot but it shows a flaw. The Vent Tube was moved to the wrong bolt when it was reassembled. If you take that tube and move it just one bolt over, it now points upwards and leads to the top of the bell housing.
I think you need to take a peek at that tube and see where it is pointing.
Le Mans Master
Joined: May 2006
Posts: 9,226
Likes: 9
From: Irvine Ca
2nd, if it continues to leak.....it is going to be low pretty soon.....If it doesn't get low you better check your T10 gear box for oil.
That seal between the two may have taken a crap and gear oil is going into the o/d.
That seal between the two may have taken a crap and gear oil is going into the o/d.
Team Owner
Joined: Mar 2000
Posts: 83,381
Likes: 87
From: Boston, MA
Can you see where by any chance? Getting the RTV to seal on the pan can sometimes be a chore. I like to let the RTV set up a little to get a skin on it before installing the pan. The vent tube is another excellent one, but you have to ask yourself "damn... how much fluid is IN this thing?" for it to get that high. 
The O/D doesn't take much fluid.
If the seal between the units failed then you're soon to have a toasted O/D unit, so do some dilligence to ensure the fluids aren't mixing or you'll have an expensive rebuild coming. There is a pressure switch internal to the O/D so (in theory) if the fluid gets low and the pressure drops the O/D won't engage.
The O/D doesn't take much fluid.If the seal between the units failed then you're soon to have a toasted O/D unit, so do some dilligence to ensure the fluids aren't mixing or you'll have an expensive rebuild coming. There is a pressure switch internal to the O/D so (in theory) if the fluid gets low and the pressure drops the O/D won't engage.
Le Mans Master
Joined: May 2006
Posts: 9,226
Likes: 9
From: Irvine Ca
^^See, that was the deal with mine....it just kept on hemorrhaging oil from somewhere.
I never was able to find the leak. I do know that the seal between the two had gone as the gear oil was going down. The O/D pressure switch had never been starved for oil during that whole time.
But as the thing was sitting while I addressed other issues, during a three week period a constant drip from "somewhere" trickled all the way down the garage floor to the back of the car...
I pulled the whole thing out and went through it.
I never was able to find the leak. I do know that the seal between the two had gone as the gear oil was going down. The O/D pressure switch had never been starved for oil during that whole time.
But as the thing was sitting while I addressed other issues, during a three week period a constant drip from "somewhere" trickled all the way down the garage floor to the back of the car...
I pulled the whole thing out and went through it.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
I had to change all the seals on the trans to get mine to stop leaking. When I did, it just is better.
What I did though is pull off the factory vents, tap the holes to pipe thread, and use aircraft fittings and stainless braided aircraft hose, and found a mini K&N filter, and plumbed the vents to that filter.
Now the vents aren't restricted in any way, and the fluids don't mix either because the hoses are longer.
What I did though is pull off the factory vents, tap the holes to pipe thread, and use aircraft fittings and stainless braided aircraft hose, and found a mini K&N filter, and plumbed the vents to that filter.
Now the vents aren't restricted in any way, and the fluids don't mix either because the hoses are longer.
Last edited by coupeguy2001; Aug 11, 2009 at 09:50 AM.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
you know what the answer is, you have to put the car up on jack stands, and start it up and run it in gear up on the stands while someone keeps the throttle constant while you crawl under it to see where it's leaking. If you don't have a second person, you can tie up the throttle with some string, and just keep wire cutters in your pocket so you can cut the string quick if you have to.
That way, you will see precisely what you have to seal up.
In my case, the vent tubes were hit in transit when I bought the trans, and the vent tube in the rear wouldn't seat tight all the way.
Modifying the tubes to a non leak status took care of the biggest problem. I changed the rear seal, the gasket between the trans and Od, and the vents, and the seals on the shifter arms. THEN it stopped leaking for a while, then the pan bolts loosened up, then I made a gasket out of a cereal box, and then it stopped leaking. Now, the pan has started a slow drip, so a new gasket and sealant is required.
That way, you will see precisely what you have to seal up.
In my case, the vent tubes were hit in transit when I bought the trans, and the vent tube in the rear wouldn't seat tight all the way.
Modifying the tubes to a non leak status took care of the biggest problem. I changed the rear seal, the gasket between the trans and Od, and the vents, and the seals on the shifter arms. THEN it stopped leaking for a while, then the pan bolts loosened up, then I made a gasket out of a cereal box, and then it stopped leaking. Now, the pan has started a slow drip, so a new gasket and sealant is required.
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Thread Starter
Intermediate
Joined: Jun 2007
Posts: 35
Likes: 0
From: Bandon Oregon
Leaking 4+3
Great input, thanks to all. Looks like the problem was a leaking seal around the speedometer drive gear. we did check the vents and everything looked dry. Put it on the rack and noticed some seeping out of the drive gear hole......New rubber seal and it SEEMS to have fixed the problem........I may be back.......