Leaky Tranny Seal

R

RokeeChick

NAXJA Forum User
Location
Raleigh, NC
If its not one thing with my Rokee its another - Went out on a long drive (5 hours) this weekend and noticed that there was smoke coming from underneath the Jeep...got out and took a look and saw that something was leaking onto the exhaust which was causing the smoke. Checked all my fluids and everything looked okay - finished the drive and had a friend take a look at it. He said that it looked like the rear tranny seal is leaking. We rechecked all the fluids and the tranny fluid was a little low.

I don't have the tools (or know-how) at my disposal to fix the seal myself - what type of damage (financial) am I looking at? I don't want to walk into a transmission shop and get raped just because I'm a chick - but at the same time I want to go into it knowing *something* about whats going on with Jeep...

Any advice would be greatly appreciated (or if you know of a good (not too expensive/but good workmanship) transmission shop in the Raleigh, NC area)
 
It's a pretty simple operation. The seal itself is about $4 +- and shouldn't take more than about 30 minutes with but one 'specialized' little puller ($12 for the deluxe one at Harbor Freight if you want to try it yourself). Someone here might have an official labor book to give an exact number.

I also tell folks that go to shops to either LOOK at the part in question, or mark things (especially wheels for rotation and balance). That way you can SEE if it was replaced. Especially tire shops - I've seen people pay for rotate and balance on 4 and they do 1 (or just lift it and drop it later). Even with the customer looking! About 80%+ of the time! Maybe ask to see your driveshaft while they have it out... I would probably trust a small local shop recommendation before any chain, especially a tire based operation.

Just because you're paranoid doesn't mean they're not out to get you! ;-)
 
You may first want to check your oil sending unit/oil pressure sensor. Sometimes a leak from that point will dribble down or be blown backward down the tailpipe & simulate a tranny leak. The unit I'm referring to can be found on the left side of your engine below the spark plugs & distributor. It may not look like it's leaking, but if you see oil on the top of the tranny case bellhousing, it's probably coming from the oil sending/sensor unit. If I can find a picture of it, I'll try to post it.

Mechanics often damage or otherwise break the unit when doing an oil change, since it is located directly above the oil filter.

You should also look closely at the color of the fluid that is being leaked -- if it is reddish, then it is tranny fluid -- if it is brown or black, then it is engine oil from the oil sender/sensor.
 
Man, that filter looks brand new, doesn't it?
I just paid $17 (at AZ I think) for the oil sending unit on one of my '87 Cherokees.
MoFo
 
I had a similar problem...might still have it :-) I was instructed by tranny shop to put on a separate tranny cooler and remove the check valve from the trans line going to the cooler. I did it today and am awaiting the results. I got a cooler($45) from Advance Auto and bypassed the radiator trans line inlet and outlet. I was told the check valve was part of the lines closer to the radiator...so I did away with them. I'll keep you posted on outcome. So far, so good.

BTW, my leak was in the front of trans and appeared to be coming from under bell housing. Upon closer inspection the leak was coming from above - the vent tube and dripping down the housing and spraying all over the undercarriage. It would happen when the truck got hot - above 210 degrees. Below that...no leak.
 
FrankDV1 said:
I had a similar problem...might still have it :-) I was instructed by tranny shop to put on a separate tranny cooler and remove the check valve from the trans line going to the cooler.

BTW, my leak was in the front of trans and appeared to be coming from under bell housing. Upon closer inspection the leak was coming from above - the vent tube and dripping down the housing and spraying all over the undercarriage. It would happen when the truck got hot - above 210 degrees. Below that...no leak.
Click to expand...
Not recommended to take the radiator/cooler out of the loop. Rather, put the cooler after the radiator. The add-ons by themselves don't dissipate enough heat.

The overflow sounds like an overfilled trans. The fluid expands as it heats up, and it should have enough room to expand at all temps. If overfilled, it comes out the vent.
 
skipc said:
Not recommended to take the radiator/cooler out of the loop. Rather, put the cooler after the radiator. The add-ons by themselves don't dissipate enough heat.

The overflow sounds like an overfilled trans. The fluid expands as it heats up, and it should have enough room to expand at all temps. If overfilled, it comes out the vent.
Click to expand...

I would have done the loop method, but there was a blockage somewhere in the raditor and/or lines(check valve). The tranny guy called Jeep and was told to do away with the check valve. As far as fluid level...I would run it a quart low and it would still get to hot and leak. Besides, wouldn't a stand alone 6-pass cooler dissipate heat better than a radiator that is trying to cool 210 degree coolant from the engine? Just asking.

Thanks for the advise Skip :-)
 
Unfortunately, I've not seen dissipation numbers for trans coolers like you can get for some radiators. It would be interesting if you could put a temp sensor inline with it. I know the old guys used to talk about heating up the transmission faster as a good thing as well as cooling it. Not sure if that's still valid with today's designs, or if it's just a northern thing. I never saw anything in writing about that. The most compelling argument was in the case of starting, especially cold in cold weather, and letting it idle to warm up. You get very little heat generated in the trans (it's just pushing fluid through the lines) but the engine heats up to it's temp of 195 or whatever. The trans only really contacts the block through the bell housing (it's only good heat transfer contact that is) and it isn't very efficient. So, the tail might be at 20 or 30 or 40F (outside temp) and the bell at 190F. Aluminum has a big coefficient of expansion, and it is made of several sections that are bolted together. This could make for big stresses as one part expands much faster/longer than others, especially at the bell housing, leading to cracking.

I always run all my engines at 160. The 4.0 CAN run cooler and mine gets to 180 in stop-and-go traffic with AC on in 98F ambient temps. That's all. Rubber parts don't last as well, and neither does a trans at higher temps. I used to have a trans temp on the return line of my Explorer. It would run at approx engine temp until a faster acceleration or accelerating while towing, then it would spike up to 30F higher, after the coolers, then come back down. That's all from heat made in the TC, so there's a lot. I also had a separate fan just for the cooler. You may want to do that too. Air flow is everything, and thickness reduces flow, so stacking another thickness in front of an already marginal design may not be well. I'd maybe put it on the electric fan side, with an add-on fan as pusher in front. That would help the current elec fan too. The other fan is much higher capacity to begin with.

If you want a cheap way to test temp, get a couple of thermistors (Radio Shack or other elec shops) and just hook them to a resistance meter (VOM, DVM, etc). Tape it to the input and outlet of the cooler (metal tube part), keeping the leads insulated. It's not very impressive for day-to-day looking cool, but you can get a reading on temp and convert the resistance to temp from a chart, or just remember what's a bad number and watch for that... You can unhook the meter when you're done, but leave the thermistors if you ever want to spot check later. Run some thin wires into the truck to read on the road (even out the hood and in through the door jamb).

Report back if you get to test it. I'd run some sort of gauge either way if you go solo cooler.

On the fluid leak, I know some Fords will cause the fluid to foam up if slightly overfilled. This, more than expansion, causes blow out on them. That also means the fluid can foam (also causes other problems when it does that). Maybe your leak is letting air in and causing foam too.

The other more obvious possibility is that if your cooler was faulty, and you had to take it out of the loop because it didn't have much or any flow, your fluid was getting REALLY hot from no flow! It'll keep expanding while it's still liquid. I reread your post and it said Jeep said to remove the valve, not bypass the cooler. You may want to keep that as an option after monitoring your temps.

Hope that helps.
 
Again, thanks for the info and suggestions Skip. That's what i like about these boards...so much pratical info and experience.

I wasn't clear on my post. The trans mechanic told me Jeep told him to bypass the radiator and put in a stand alone cooler. The one I got is for a Fuul-size truck towing 4000 pounds(heavy duty). Since I was doing that I should also give the valve the old "heave ho" because it was probably adding to the problem. Will see...got my fingers crossed :-0
 
Okay, I'm mooching off of this thread because it's close to my problem. I'm going to look tonight if the fluid is coming out my vent as well but my difference is that I'm pushing all of the fluid out of the transmission. I'm not 100% sure it's a seal leak or blockage.

If it's the front seal... Can I replace it with out tearing into the tranny? Or do I have to pull it apart to replace the seal? I know I have to drop it out of the Jeep at least.

I'm going to take a close look at the vent tonight and see if that's my problem.
Thanks.
 
I know most of this thread is old news, but for all the people finding it that suspect front seal failure, before you do anything...remove the inspection cover (talking about aw-4 here) and check the four bolts that affiz the t-convertor to the flexplate.

I'll bet a good number of you that have a fluid leak in this area actually have this problem.
 
I was hoping after reading your reply Beezil that you were right. That would have been an easy fix. All four bolts were good and tight. The vent is not where my leak is coming from either. My next question is "Can you replace the front seal without tearing down the transmission?"
 
Overdriven said:
I was hoping after reading your reply Beezil that you were right. That would have been an easy fix. All four bolts were good and tight. The vent is not where my leak is coming from either. My next question is "Can you replace the front seal without tearing down the transmission?"
Click to expand...


what ever came of your leak? whats was it and did you have to lower the tranny?

i have same prob right now... thanks
 
Greenlantern - if it's truly the front seal that's leaking you will have to drop the tranny to replace it.
 
Yucca-Man said:
Greenlantern - if it's truly the front seal that's leaking you will have to drop the tranny to replace it.
Click to expand...

i know!!! this is gonna suck.. gonna take it to a shop.... checked the tranny fluid level today and at running it showed empty, and when engine is off, fluid level was fine....


dont know anymore!!! :gonnablow
 
Greenlantern said:
i know!!! this is gonna suck.. gonna take it to a shop.... checked the tranny fluid level today and at running it showed empty, and when engine is off, fluid level was fine....

dont know anymore!!! :gonnablow
Click to expand...

You do know you're supposed to check it with the engine running right?
 
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