Transmission vent hose leaking fluid

Six months ago I started having problems with my 1997 Jimmy's transmission vent hose leaking fluid. I took it to a transmission shop in town. They said they would have to take the tranny apart to see what the problem was. They ended up rebuilding my transmission. Just in the past week the same exact problem started happening again. I took it to a different shop that I have heard from others to have an excellent mechanic. This new mechanic shook his head when he heard that I had the transmission rebuilt and informed me that he believed it was only the front differential case seal between the transmission and transfer case, and that the transmission should not have needed to be rebuilt. He removed the high level plug on the transfer case and sure enough, the fluid started puking out. The new mechanic is saying that it has taken the past 6 months for the fluid to leak past the bad tranfer case seal (my bill does not have anything on it in regards to the tranfer case, only tranmission parts) building too much fluid pressure in the transfer case causing the fluid to escape out the transmission vent hose where I have seen the fluid leaking. I understand that the transmission vent hose, the transfer case vent hose are both connected on the transfer case somewhere.
The vehicle has always shifted and run perfecly fine, other than the fluid leaking out the transmission vent hose. Has anyone else experienced this type of fluid loss, and does this new mechanic sound like he knows what he is talking about. If he is right, than I had my transmission misdiagnosed the first time, and spent $2,500.00 on a transmission rebuild when it should have only cost about $500.00 for a new transfer case seal.
Please help!!!!!!

2,500.00 for a Tranny Rebuild??

Good Greef

2,500.00 for a Tranny Rebuild??

Good Greef
The $2,500.00 is in Canadian funds. It is probably still alot. I have been kicking myself ever since. I was comparing this to going to the docter. They prescribe you medication and you should be able to trust their judgement.

Do you have a transmission cooler?

Yes, it has a trailer hauling package.

Typically a tranny wont vomit unless it is way overfilled and/or well overheated. You can usually overfill a 4L60 model 3 qts with no worries. (I myself always run at least1 qt over and I run coolers the size of toyota radiators.)

Yea, I think your are overheating because of a poor flowing transmission cooler.

What would explain the transfer case overfilling, transmission loosing fluid, and the fluid puking out the vent hose? It sounded like the seccond mechanic I spoke to had something going with the bad transfer case seal. But what do I know!!!

The tranny and the transfer case are not connected.

For some reason, transfer cases are overfilled from the factory.

Don't starting thinking the fluid from the tranny is magically going to the transfer case.

There is a seal between the tranny and the transfer case just as there would be a seal on the tail housing of a tranny without a transfer case. In either situation, if the seal leaks, fluid comes out. Without a transfer case, it falls to the ground or gets spun around by the yoke. With a transfer case, it goes into the transfer case. Wonder what happens in that situation?

I don't think if that was the case that it would get into the transfer case oil sump.

My transfer case was overfilled and very high and it wasn't because of the transmission, it was because it was overfilled from the factory.

This has been a complaint I have heard with even the Suburbans and full size also.

But I could be wrong.

Best way to find out is to drain the transfer case to the proper level, fill up the transmission to its proper level and see if this happens again.

Also, remember to check the tranny fluid level while in hot, idling in park.

Just to let you know BlazerLT, I definately have a transfer case mounted on the back of my transmission. That would be how I get 4 wheel drive is it not. Anyways, the seal between the transmission and transfer case has been replaced. If it was from factory overfilled, it would have happened within the last 150,000 kms that I now have on my venicle.

Why are you telling my about a transfer case for 4wd, don't you think I know that??!!!

What were you trying to say in that post?

You said that the transfer case and transmission were not connected! What did you mean!! Never mind. I was hoping to get a mechanics response to the bad seal between the transmission and transfer case that are connected.

This thread has gone astray.

There is a seal between the tranny and the transfer case just as there would be a seal on the tail housing of a tranny without a transfer case. In either situation, if the seal leaks, fluid comes out. Without a transfer case, it falls to the ground or gets spun around by the yoke. With a transfer case, it goes into the transfer case. Wonder what happens in that situation?

Kelvin8R -

My question was rhetorical - "Wonder what happens in that situation?"

What happens is, is that if the seal is leaking, the fluid will be captured in the transfer case and overfill it, exactly what you described.

If the seal has been changed your problem should be over, if I understand you correctly.

Yes, I have replaced the seal. However, the last time it took 5 to 6 months. According to my new mechanic, it took this long for the transmission fluid to seep into the transfer case through the bad seal. Seems like a logical explanation. The future will tell. Since I am new to this transmission game, I was looking for other opinions. Thank you.

They are connected, but the two fluid sumps are not.

Just because one is attached to the other doesn't mean the fluid leaking from the tranny will go into the transfer sump.

That is what I am saying and it is on topic.

Of course the two fluids are seperate, that would be why the seal is between the two. If the seal was damaged, where do you suppose the fluid will go. The tranny was loosing fluid and the transfer case was severely overfilled. It wasn't magic like you might suggest. It is common sense. Anyways, the problem should be resolved. Thanx for your ideas.

OK time for me to chime in.
ALL K TRUCKS AND S-10 Trucks that are 4 wheel drive Have a transmision connected to the transfercase and then the driveshaft to the rear diff. AND the sec drive shaft going to the front diff.

The transfercase being over filled is CAUSE BY A BAD rear trans seal. The trans fluid goes down the trans output shaft and into the transfer case imput shaft. There are a bunch of old TSB talking about this problem. There are 2 seals and 1 gasket that must be replaced. Beleave me on this 1 .
I have done a billions of them . EVERY S-10 and K truck will have that happen to it. Its just a matter of time.
Fireplug

I guess I stand corrected.

I just couldn't see how that much fluid could escape directly to the transfer case like that.

I am with you Fireplug, thankyou! So how do I get my money back from the transmission overhaul that they sucked me into? Just kidding. I am kissing that $2500.00 good by. I had to learn the hard way about trannies I guess. Thanx guys!!