So here's my story and it's going on as we speak. Any advice would be greatly appreciated because I really want to keep my 71, but I've just about had it with all the problems I've been through lately. I'm so close to saying F-it at this point.

It started when I had shifting slippage/hesitation. I checked the fluid and it was low. Figured it needed a transmission service. Fluid looked good when I dropped the pan, not burned or anything. Its been many years since the fluid was changed so I did a transmission service on it.

Well, wouldn't ya know it...one of the bolts on the filter was totally stripped and I had to have a mechanic remove it. Figured he should just do the transmission service also since it's there. I bought 8 quarts of fluid although I know I probably only needed 5.

The mechanic fixed the filter problem and he put in 7 quarts of fluid. The mechanic told me that everything is fine with the transmission and it was just low on fluid. It shifted great for about 2 days but then I noticed it was leaking a bunch of tranny fluid.

I had it towed back to the same mechanic for a diagnosis. Just got off the phone with him and he says the front main seal went out on it. He mentioned that the seal is probably original, but I know for a fact it's not.

About 7 years ago the front main seal was replaced because I overfilled the transmission and blew the seal. A hard lesson learned. The transmission shop I took it to told me it happened because I over filled it.

My question is, is it possible to blow out a front main seal from over filling? Was the transmission shop correct? If so, how can I prove my mechanic caused the problem? He did use 7 quarts, but I would rather give him the benefit of the doubt.

Would a transmission seal go out like that only after 7 years? I have a feeling this mechanic caused the problem and is trying to cover up his mistake. He doesn't get too many old vehicles in there, but he should have RTFM. I can't make accusations unless I have proof of course.

What do you guys think? I could really use some help on this one. I think I still have the invoice for the transmission seal replacement by the way.

Thanks

 

Overfilling the transmission can not cause the front seal or any other seal fail.

Overfilling may cause it to leak out the vent or filler tube.

The only way to tell why the seal has failed is to remove the transmission and inspect the seal, bushing and converter.

The shop that serviced the transmission is not at fault for the leak out the front.

I would get a second option on where the leak is coming from.

 

I called 2 transmission shops today, one of which did the service 7 years ago and both said over fill can cause the front seal to blow out. I honestly don't know who to believe though. I wonder why they would tell me over fill caused my first leak? It makes sense why a vent tube would be on there of course. Maybe the transmission vent is clogged or plugged up some way? Would that be possible?

I spoke with the mechanic today and he says fluid was gushing out of the front when I brought it in. Wouldn't a vent tube prevent this from happening? I don't know what to think anymore really.

I am willing to be wrong if it means I can understand what really happened. Is there really any way to tell what happened by inspecting the seal and bushing? The seal has to be tore up and pulled out of there right? Doesn't that make it difficult to determine if the seal was bad?

 

I think that service writers will say things that make things fit even if they don't know what they are talking about, I even catch mine doing it sometimes. I guess its because they deal with the customer instead of the transmission.

Overfilling the transmission does not cause pressures to be higher or put stress on the pump or seals to blow out, it just doesn't work like that. The pump when running is completely full of fluid, there is no way to add any more. Pressures are controlled by valves, not by fluid levels. Overfilling may cause the fluid to aerate and foam but that is rare.

A clogged vent will cause the fluid to come out the filler tube.

There are many things that could be the cause of the leak from the front, it might not even be the front seal. I have seen cracks in the converters at the hub area and the studs, or a loose converter drain plug. Sometimes the pump bushing spins or "walks" forward and pushes on the back of the seal causing it to leak, this is generally a converter problem.

You can spot a failed or worn seal even if you damage it when it removed if you know what your doing and what to look for.

I would take it to another shop and have them find the leak, don't fill there heads with to much info up front, just find the leak, then let them in on the details. They should clean it and then drive it.

 

That's a problem. On the one hand you have a trans shop that you can talk to in person telling you one thing, plus another mechanic that agrees with them.

On the other hand you have someone you don't know posting on the internet who tells you they are wrong. The guy on the internet rebuilds transmissions and has nothing to gain or to lose by telling you the truth.

Now you also have a former automatic transmission engineer telling you the guy on the internet is correct and the guys you know are telling you the common myth about overfilling and blowing seals. It can't happen. Overfilling CANNOT make a seal leak.

Here is an analogy. Take a one quart container. Pour two quarts of water into it. Do the sides blow out? No, it just runs out the top when it is overfilled. The trans has a vent that will expel fluid if it is very much overfilled.

When I had service writers working for me I caught them doing that, too. And both of them were Master Mechanics. They knew better, but sometimes they just couldn't contain the verbal diarrhea. They had to say something, and anything could come out of their mouths.

 

Is it just coincidence that the time I over filled it myself 30K miles ago it started leaking from the front main seal, and then just after 7 quarts were put in last week it started leaking from the exact same place? I appreciate what you are telling me, it makes sense. I am just trying to figure out why I've had 2 front seal leaks after fluid was added. Would there possibly be another explanation besides coincidence? This has been very frustrating because I don't have a mechanical background, but I really want to understand what happened. Maybe something is wrong with the transmission? I should probably trade this 71 in for a newer Ford Ranger and save myself the aggravation! Thanks again for the information!