LYKOS

I did a couple searches and couldn't get a thread that addressed this.

My 01' had major overheating issues as of late.

I thought it had a cracked head as every time I got to 220 degrees smoke started pouring out of the back.


Changed all the cooling stuff then saw the smoke again, but this time it continued to smoke while I was sitting still. I look underneath ad it's tranny fluid leaking all over the exhaust from the top of the transmission.

A quick search tells me the breather in on top the bellhousing.

It all adds up.

I do a total fluid swap. Disconnected the trans line from the radiator and let it pump out yadda yadda yadda...

The transmission fluid was black as coffee.

New tranny fluid in, bottom of Jeep steamed off. We are ready to go.

Still spewing tranny fluid out the top when the Jeep gets warm or I go on a long drive.

No slippage, no grinding no nothing not now and not before.


I got a used transmission available if this one blows. But if this is a common AW4 issue maybe I can avoid that?

ColoradoCorey

Hey I was born in Roanoke Va.

Anyway so there are a couple other things I would check. First thing is, is there a crack on the top (I assume its an automatic) another thing may be the modulater valve (not sure where or if you have one). The modulator valve will look like a bell with a vacuum line running into it. And last thing is make sure the dip tube's gromet isnt bad making it spill out.

These are just a few things I would check before shelling out the dough.

jtodaro

Is it coming out the vent/dipstick? Check for a blocked/partially blocked transmission cooler line. It ups line pressure and in turn will cause this to happen.

LYKOS

Nope, not coming out of the dipstick. Where EXACTLY is the breather tube? I want to eyeball it and make sure I'm not telling lies on here. At the moment I'm making an assumption.

ColoradoCorey

tbh if it is an auto than Im not sure it would have a breather tube beings that is is a presure type system. I could be way off base. there are several things that connect to the trany like speedo, shift linkage. I am not seeing in the chiltons a mod valve but that doesnt mean its not there. Do you happen to know what model trans you have? On diesel versions there is throttle valve cable that appears to go into the top of the tranny.

Radi

It's fairly common for an overheated AW4 to puke it's fluid like that. The cooling it gets from the radiator cooler is marginal at best, if the engine is running too hot, the trans isn't cooling either.
Over 200 deg is bad for the trans...and you're actually heating the fluid to 220 deg with the 'cooler'.. Fix the hot engine and the trans will probably settle down.
An aux cooler is always helpful too.
And change the fluid if it's been overheated, of course. It turns into a pretty bad lube when it's been cooked. Oh, and be careful to not overfill it. That can bring on on the spewage smoke show too.

LYKOS

That sounds about right. This didn't start until I had overheating issues. And it only does it when I'm running hot or on a pull.

I've replaced the radiator, tstat, fan clutch all with stock style parts.

Operating temp now runs a tick under 210 and maxes out a tick under 220. Which I thought was about normal...

I've not checked the efan. Ill do that today if the rain holds off. I'm assuming a malfunctioning efan could contribute to this issue??

Franks93Cherokee

I have a 1995 Jeep Cherokee Sport with the 4.0 inline and 3 speed automatic. 150,000 miles. I can go all day hitting around 210 on the temp and think I'm in the clear and then be on the way home and look up and see this giant puff of smoke where it's hitting the exhaust when it blows out. It looks like it is coming from the bell housing to me I have not looked on the top.

Now I also just bought this jeep a few weeks back and this has become a everyday problem for me with it. I called a transmission shop and got a price for front seal and the guy asked me if anyone had over filled it? I told him I just bought it and he said the reason he asked was the vent was in the bell housing and if it gets to full when you run it hard then it comes out of this vent.

Now here is the real messed up part I have started checking the fluid everyday once it gets good and hot and it always shows right on the full mark on the hot side of the stick. So for about three weeks now doing this everyday I'm not missing any fluid? Could it be my tork converter is over filled? When this thing gets good and hot and you look under it it's dripping hard off the pan like many areas dripping. I have climbed under it and cleaned it all off and found it was coming from the bottom of the bell housing. So I'm real confused how long would a over filled transmission do this?

Radi

you sure it's trans fluid leaking? 4.0 has no shortage of common oil leak spots that all seem to end up near the rear of the engine/bellhousing bottom.

It reads correctly on the dipstick while warm, running in N or P...so I doubt it's overfilled. More likely you might have a front or pump seal going south when it heats, or a trans that heats excessively.
Might check to make sure your trans cooler is operating, the lines are not kinked or damaged, and that your TCC lockup is operating. Could also pop a thermometer (IR works well) on the output line to the trans cooler. Don't want to see much over 220.

Franks93Cherokee

Well it's red in color so I think it's transmission fluid and it smells like it. And when you Google this problem it seems to be a very common problem from Jeeps with no one that I have found fixing it.

ZINGGG

Are you lifted with bigger tires?

If so, may want to consider adding an auxiliary transmission cooler. And also consider regearing in the future.

If you're stock height with stock tires, something else is going on. As Radi said, you may have a damaged tranny line where the flow of fluid to the radiator is restricted in some way

PUNISHER

My 97 had the same issue. I chased my tail thinking it was motor oil. I replaced every gaslet, seal and o-rings on and in the engine! Run it at 55mph all day and no leaks or smoke. Ran it on interstate at 75mph and bam, let off the gas and the smoke rolled out the back. The tranny oil looked like motor oil so I had it flushed and checked and all was fine. Then ran it hard and the smoke rolled out and nice red tranny fluid from front to back! Bought a B&M cooler, installed it and all my problems went away! Best money I have spent!

Franks93Cherokee

Ok I purchased a transmission cooler today should I do away with the way it runs in the radiator or should I just tag into one line and use both the new cooler and the radiator?

ZINGGG

People have done it both ways. But I would suggest doing it IN ADDITION TO the factory transmission cooler in the radiator. There's a small portion on the transmission return line that is a soft line and can easily be cut, which is where I added my tranny cooler.

LYKOS

Really? I'm on the fence about this. I've talked to at least one transmission shop who says that Jasper wpon't honor a warranty if an aux cooler is run inline with the factory cooler.

Is the logic behind running them both simply that more is better?