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  #1  
Old 11-14-2012, 09:33 AM
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Transmission Leak {slight}

Trying to trace a small tranny leak on my 85 300TDT. Just did a complete fluid/filter change and now I'm seeing about 3 tablespoons of fluid on the garage floor after sitting all night. I cleaned everything up to help trace the leak and it seems to be coming from the area directly in front of the pan. There is an aluminum housing there that has several rectangular holes and one square hole in it. The fluid is dripping from these holes. I didnt do the fluid/filter change so dont know what this is called. I'm thinking that maybe the torque converter is up in there and the fluid might be leaking from the drain plug/copper seal?? Does this sound right?
Also checked the Bowden cable and it is slightly wet around the housing but not enough to drip the amount on the floor. I have a new Bowden and seal ordered anyway because mine is broken at the valve cover.
Thanks
John

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  #2  
Old 11-14-2012, 10:34 AM
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It does indeed sound like it is dripping from the area where the torque converter is - have you checked the tightness of the hex head torque converter drain plug?

The front seals "have been known to go" - which then means transmission out to fix it.

As for the Bowden cable to the best of my knowledge they are plastic bayonet push in fittings at the transmission - which if they've been removed and replaced might explain why that point leaks. I understand most people go for the dab of RTV solution for that kind of leak.
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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!
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  #3  
Old 11-16-2012, 04:45 PM
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Quote:
Originally Posted by Army View Post
It does indeed sound like it is dripping from the area where the torque converter is - have you checked the tightness of the hex head torque converter drain plug?

The front seals "have been known to go" - which then means transmission out to fix it.

As for the Bowden cable to the best of my knowledge they are plastic bayonet push in fittings at the transmission - which if they've been removed and replaced might explain why that point leaks. I understand most people go for the dab of RTV solution for that kind of leak.
Well Army; its not the torque converter drain or seal. I can see{with flashlight} red fluid up inside the "air vents" behind the TC in the area between the TC and the pan. It looks like it is on a shiny chrome looking ring way up in there. Front pump seal maybe?? How long to drop tranny and replace the seal and re-install?
If the trans needs to come out....what other seals/items should be replaced at this time?
Thanks
John
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Old 11-17-2012, 05:00 AM
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Assuming you've got a 722.315 (or a 722.303) installed in there (as you should have) you can see what to do in these threads =>

722.315 Pump Re-seal pictures

722.303 in bits photo shoot

To remove the transmission there are two schools of thought =>

1) Try to just remove the transmission by itself - so disconnect prop shaft - lift the car - remove transmission etc

2) Remove the transmission and engine together in one go


Option 2 does sound totally bonkers but in my opinion that's the way to go! The benefit is that you are less likely to damage the transmission when you are mating / de-mating it to the engine. To remove the transmission by itself I think it is safest to do so if you have a decent lift and a transmission jack etc. As a DIYer with axle stands and trolley jack(s) I think it is a bugger of a job to attempt option 1.

If you are entertaining option 1 I've written this which might help

How I took out my 1981 W123 300D (euro) non-turbo engine

You can see links to parts and parts lists via the second link I posted above.

Timing wise I reckon you're gonna loose about one weekend if it all goes well.
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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Last edited by Stretch; 11-17-2012 at 05:01 AM. Reason: Added a bit
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  #5  
Old 11-17-2012, 07:47 AM
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Army,
Thanks for the links. I'm not sure if I'm going to do this job myself or not. Its leaking maybe 5 ml's a night on the garage floor so its not bad yet and I have some time to think about it. Car has 313K on it. Has always been maintained since day 1 so other than the leak, the transmission works fine. With the high miles; I am wondering if it would be wise to just go ahead and have the trans rebuilt at this point even though it functions normally. It will be out of the car and I dont want to pull it again for a rebuild in 100K miles.
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Old 11-17-2012, 07:53 AM
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How much fluid do you have in there?

Full on the dipstick is at full operating temperature. Filled to "Full" cold is overfilled. You'll get leaks.

MM
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05 Passat TDI Wagon, 155k miles
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  #7  
Old 11-17-2012, 08:38 AM
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Originally Posted by mozark View Post
How much fluid do you have in there?

Full on the dipstick is at full operating temperature. Filled to "Full" cold is overfilled. You'll get leaks.

MM
Just serviced the trans with fluid/filter. It is halfway between the marks after driving and then at idle for 2 minutes. I'll check it again today to be sure its not overfilled.
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  #8  
Old 11-17-2012, 09:46 AM
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Quote:
Originally Posted by Jareb View Post
... I am wondering if it would be wise to just go ahead and have the trans rebuilt at this point even though it functions normally. It will be out of the car and I dont want to pull it again for a rebuild in 100K miles.
That kind of preventative maintenance is what I tend to do. It isn't really smart. I started out with a leaking oil cooler line (well I think it was that) and now look at it!



(You've got to have a sense of humour!)

So my message is - if it is a hobby and you don't mind driving the car for a while and perhaps you want to learn something then fine go ahead - it is great fun - I don't regret it for a minute. But if you actually want to drive your car...
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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!
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  #9  
Old 11-17-2012, 11:03 AM
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Quote:
Originally Posted by Jareb View Post
Just serviced the trans with fluid/filter. It is halfway between the marks after driving and then at idle for 2 minutes. I'll check it again today to be sure its not overfilled.

That sounds OK, if the fluid's hot. My 85 is sensitive to being overfilled. Just wondered, since it didn't seem as if it leaked before service from your 1st post.

MM
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05 Passat TDI Wagon, 155k miles
05 Tacoma, 135k miles
96 F-250 7.3, 225k miles
85 MB 300TD, 275k miles
52 Dodge M37, 4BTA powered
52 Dodge PW, 23k miles
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  #10  
Old 11-17-2012, 11:39 AM
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Quote:
Originally Posted by mozark View Post
That sounds OK, if the fluid's hot. My 85 is sensitive to being overfilled. Just wondered, since it didn't seem as if it leaked before service from your 1st post.

MM
Well Mozark....you were right. Drove the car this morning for a while and checked the fluid level when I got home. It is about 3/16-1/4 inch higher than the top mark. I used a "top sider" pump and pulled off enough fluid to get it exactly between the marks....check it several times while hot and running. I'm going to "gunk" underneath the car while I've got it up on ramps; then drive it all day and check again to see if it's still leaking.
Thanks
John
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  #11  
Old 11-17-2012, 06:36 PM
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Transmission Leak (slight)

I had a similar leak on a 722.315 transmission(83 300TD) about a year after I had it rebuilt, not related to any recent service on it, but after a 3000 mile drive across the plains at interstate speeds. Looking up into the "grate " on the bottom of the transmission, I could see drops of ATF on the bolt heads of the bolts that hold the front cover on the transmission. The rebuilder sent me a new radial seal and gasket for the front cover which I installed but still had the leak. There was no evidence that the radial seal was leaking--it was dry.
So I had to pull the transmission a second time( I am getting good at it) and when I removed the front cover again, there was ATF in 4 of the 9 bolt holes through the cover. Since the threaded bores for these bolts are blind, the only way fluid can get in the bores of the cover is if the gasket inner edge is not making a seal with the cover/transmission housing adjacent the bores. The lowest bolt in particular has only a 2.5mm wide section of gasket material to make the seal due a material cutaway behind the cover. Once the fluid is in the bores of the cover, there is only a spring or wave washer under the bolt head to seal it, against a non-machined surface of the cover. The torque on these bolts is only 13 Nm.
The rebuilder was very helpful and sent me a new(rebuilt) torque converter(just in case it was the problem) and I again replaced the front cover gasket, but also bought some Parker Stat-O-Seals (Google it), which are washers with a molded rubber seal on the inside diameter that is deformed as the bolt is tightened. These replaced the spring washers. This time I was successful and have no leaks. It is hard to understand why this leak showed up after a year from the rebuild, but it did. In your case, one would suspect that it is related to the recent service- an overfull transmission might exacerbate the problem.
Let us know if removing some of the fluid stops the leak.
Peter
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  #12  
Old 11-18-2012, 09:14 AM
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83TD/Army,
Still leaks but only a little. Drove it about 20 miles yesterday and parked it overnight. There was maybe a teaspoon of trans fluid on the floor. I looked up through the slots and it appears to be on the center of the case and not around the bolts or pump case edges. I'm thinking its the torque converter seal and not the pump seal. At 27 years old and 313K miles, its time to change them. I dont think it was due to being overfilled by 1/2 quart or less. Dont these transmissions vent anyway? I would think that the slight overfill wouldnt create enough fluid pressure to make it leak...but not sure with old seals.
The leak is small enough that I'm not going to rush to do this job.
Also in front of the TC{towards front of car} there was a little engine oil where the case joins together{couple drops}. What would this be....rear main seal?? Again a very small amount.
Cleaning the underside of the car with 4 cans of Gunk helped alot to see leaks. The rest of the engine/trans is dry so that is good!
John

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