ATF Leak

tmea · 05 October 2016, 03:51

Looking for some information and/or advice on an ATF leak. Last week my 68 AS started to leak ATF. I had replaced the seal 10 or 12 years and many miles ago so I figured it was just time. Pulled the engine and replaced the TC seal (black one) peened the edges over installed the engine and went for a test drive for 20 miles or so. No issues, no problems until I reached my neighborhood. It sprang a massive leak a block from my house. Blowing two seals in succession would be an oddity.

Doing some research and test before removing the engine and replacing the TC seal again. I removed the ATF pump prssure relief valve and found no problem. The spring was in good shape and the piston floats freely in its bore. This should rule it excessive ATF pressure as a cause. Reading Bentley it suggests that another cause for an ATF leak in the TC area is the one way clutch support gasket and seal. The seal and gasket are available but I cannot find a procedure for replacing them. Looking at it don't even see a way to take off the support from the TC side.

Anyone have experience with this? I've been on this forum for several years and never heard of a leak from this area. Opinions, advice, experiences? It is possible that I botched the TC seal installation but I doubt it. Held it in place and square with a pvc tube and lock bar while I peened the edge over. It was secure and worked for a couple hours with no issues. Trying to rule out other possibilities before I replace the TC seal again.

Thanks

Tom

volkenstein · 06 October 2016, 01:31

Tom,
Miserable in the extreme IIRC. Disassembling to get at that seal is a sweat dripper. You will destroy the bearing (or at least hurt it) unless you have specialized pullers and it is a special grade (C3 - close tolerance) - Ordinary size otherwise. Otherwise you have to tap the bearing out by it's centre, and this assumes you haven't ruined it already getting the clutch carrier assembly out. I will look at some exploded views to jog my memory and fiche- but it is a nasty job.

Check to see if your support tube is worn, or even if that replacement seal has the correct ID....

HTH
Sean

tmea · 06 October 2016, 17:44

Many thanks Sean,

I'm going to remove the engine tonight. I'm really hoping that I'm going to find a defective or dislodged TC seal. In the few hours after I replaced it there were no leaks at all. To me this may rule out the OW clutch seal leak as a cause (your thoughts?).

In my thinking this leaves me with three possibilities all relating to the new TC seal:

1. Somehow I failed to do a good job preening it on.
2. The seal is simply defective.
3. ATF over pressure blew the TC seal off. I have largely ruled this out. I removed the ATF pump pressure relief valve and found the spring to be fine and piston floating freely in the bore.

Any other possibilities I may be missing? I'll know more tonight or tomorrow when I get the engine out. I will either find the TC seal in place or off and it will either be due to my installation, seal defect or too much pressure. Aside from replacing TC seals I have little experience with these transmissions.

Appreciate any insights you have

Tom

nypater · 06 October 2016, 20:17

Do you have to replace the tc seal again, because you are pulling the engine? Or can it stay in place if it's okay?
I thought this was a replace every time seal. Keeps me from pulling the engine too often.

tmea · 06 October 2016, 20:39

It is new but currently leaking (lasted a couple hours and 20 miles or so). I'm definitely replacing it. I'll post pictures when I do. I'm hoping it is just a defective seal or installation error (by me) instead of some of the uglier possibilities.

sb001 · 07 October 2016, 02:56

I hope that is the issue as well, a pain to pull the whole engine just to replace that seal, but much better than disassembling the clutch support. BTW, I never knew there was an ATF pressure relief valve..

Where is it located? I only have the autostick section of the Bentley manual, and it briefly mentions it, but it mostly covers it in the maintenance section of the manual which I don't have.

In answer to the previous poster, NO you absolutely do NOT have to replace the torque converter seal every time you pull the engine. Only if it shows obvious signs of leakage, warping or other damage.

tmea · 07 October 2016, 16:27

Yes, it is on the pump on the r/s. small plug with Allen wrench socket. Easy to check but due to the angle of the bore you will have to remove the inlet pipe and blow the piston out with some c oppressed air (not much).

tmea · 07 October 2016, 21:06

I dismounted my engine and discovered the source of my ATF leak. The seal lasted exactly two hours and 30 or so miles. It was still on straight and peened in well. I had to pry it off from all four sides. What I believe happened here is that this seal failed (tore) due to excess friction. Even the black replacement one I have fits over the TC far too tight. It is difficult to turn even when lubed.

Comparing the black and orange TC seals aside from the obvious they are quite different in the way they seal against the TC hub. The black seal has a thick and wide contact surface that allows for no oil clearance. The orange seal by contrast uses a beveled contact surface that is like a knife edge (less friction). Additionally, it also has small oil displacement ribs like modern seals. It fits and turns with far less friction.

I'm installing with an orange replacement seal instead of the new black one I have on hand now. This has to be the reason VW discontinued the black seal. It appears to be a much better design. Therefore, since both seals fit the application I recommend to everyone that you opt for the orange one next time you install.

Tom

68autobug · 26 October 2016, 09:28

Terrible looking seal.. The black seal inner surface should look similar to the red seal with a V which I always lubricate with ATF. Being so tight isn't good either, but having a flat inner surface is terrible and being too tight only makes it worse. It seems that that seal has grabbed and self destructed.

Always replace the torque converter seal -
YES, but naturally, if the seal has only been in for a few months etc, and hasn't been affected by heat and gone hard, it doesn't need to be replaced.

Over the years, I remember virtually everyone who didn't replace the torque converter seal had it leak badly, due I believe, to the seal going very hard over a period of many years, and when the torque converter is moved, as when the engine is taken out, the seal center is moved slightly, and it cannot flex and reseal due to it being VERY HARD..... and not flexible enough to seal. So, it isn't worth the trouble of re-using an old seal if it has been in use for many years.

Lee in Australia

68autobug · 09 March 2017, 05:14

Well for the first time I had an ATF Leak for a few days...
I had taken the hose fitting from the bottom of the tank to drain the ATF as i thought Ihad to take the engine out due to a very bad oil leak but I took the fan housing etc off and found the seals on the new oil cooler were badly deformed and leaking...
maybe one or two of them???
Maybe the wrong seals were used originally with the new oil cooler... but I would have thought the seals would have come with the oil cooler??? But I didn't have to take the engine out.... which was a good thing...
I don't like to apply too much force on those brass fittings and the bottom of the tank and the leak stopped after a couple of days... The original washers are still being used... aluminium I think they are...

Lee in Australia

tmea · 13 March 2017, 19:55

Yes, my crush washers or original also and thankfully do not leak. Reference your oil cooler. Are you talking about the stock cooler or an add on one. Four our cars (1968) there are three different seals for the stock cooler.
1. 8mm case galley to 8mm original stock oil cooler. (Rubber tube type seal)
2. 8mm case gallery to 10mm newer style oil cooler (conical top 8mm flanged bottom)
3. 10mm case to 10mm original oil cooler? (Flat rubber disk with 10mm flanges

Can't recall exactly but the bottom line is that any cooler will work for a short time with any of the seals but will fail in short order. There is a good u tube video on it you can search.

Tom

68autobug · 14 March 2017, 18:33

Hi,
the oil cooler adaptor - New doghouse oil cooler - as this engine was a 1500 single port with small oil holes on top of the engine. I had used a 10mm rubber [soft] seal between the adaptor and the oil cooler [vertical]. The 8-10mm conical top with flanges may have been a soft rubber too as all the seals were compressed badly after only approx 3 years or 3,000 klms use.. I believe the seals may have all come with the NEW doghouse oil cooler. I normally use the HARDENED 8-10mm conical with flanges seal between the oil cooler adaptor and the case. I have had no problems with this type of oil cooler as they do NOT compress over time. I am lucky as the rear valance comes off My beetle, and the engine can be slid backwards with the car tires only just off the ground [so I can get under it]....

Lee in Australia

sb001 · 10 April 2018, 01:56

Quote from: tmea on 07 October 2016, 21:06
I dismounted my engine and discovered the source of my ATF leak. The seal lasted exactly two hours and 30 or so miles. It was still on straight and peened in well. I had to pry it off from all four sides. What I believe happened here is that this seal failed (tore) due to excess friction. Even the black replacement one I have fits over the TC far too tight. It is difficult to turn even when lubed.

Comparing the black and orange TC seals aside from the obvious they are quite different in the way they seal against the TC hub. The black seal has a thick and wide contact surface that allows for no oil clearance. The orange seal by contrast uses a beveled contact surface that is like a knife edge (less friction). Additionally, it also has small oil displacement ribs like modern seals. It fits and turns with far less friction.

I'm installing with an orange replacement seal instead of the new black one I have on hand now. This has to be the reason VW discontinued the black seal. It appears to be a much better design. Therefore, since both seals fit the application I recommend to everyone that you opt for the orange one next time you install.

Tom

I am bringing back up this old thread in part due to another poster having a similar issue with leaking ATF. If tmea (the original poster in this thread) is still around on this site, could you please re-post the comparison photos between the ill-fitting black TC seal and the good-fitting orange seal?? I only have a spare black seal on hand and would like to see the difference--thanks!

sb001 · 10 April 2018, 02:37

tmea or Lee or anyone else--

Is this the beveled edge you are referring to?

If so, it appears my new black TC seal I picked up at the VW show last year DOES in fact have the beveled edge as you can see in this photo. Is this then a suitable replacement, or should I be looking for something else?

Here are a couple more photos just to help me be sure:

Thx

tmea · 11 April 2018, 20:26

SB001:

Unfortunately all of my pics posted on this website are in Photobucket which is no longer functional. The seal in your pic is suspect to me and looks like a knock off. Both the black and orange OEM seals work fine in my experience even though they look different. The seal I had the issue with was a black knock off. The way to tell wheather a black or orange seal is OEM or correctly designed is the presence of oiling ridges along the sealing contact surface (TC hub in this case). The knock off seals are smooth around the contact surface and quickly become dry letting friction tear the seal in no time. I have seen the knock offs for sale in CIP1 and other sites. I informed them during that time and received no response. If ordering a new one I would do it over the phone and have them physically verify that the seal has oiling ridges. Hope this helps.

Tom