engine warms up jeep leaks

I know that the heat from the engine can cause the tranny fluid to boil and thus cause a leak. What I need to know is how to stop this.

did you over fill the trans?

Thanks for the fast responce...
I was thinking the same thing at first.
But this happened before I put a qt of fluid in it.
I took it on the freeway and when I got home it was a mess underneath.
I checked the levels and they were a little low, but didn't smell burnt so I added a qt.

Back or front of tranny? Try using some cleaner to get rid of as much residue as you can. Then drive around for a short while and see if your can narrow down where the leak is coming from.

Also check the cooler lines to the rad.

start it an look for the leak, if need be drive it around the block then hop out to look, i would clean up before i drive it to find the leak

Its the front. I did use some conditioner with that qt and it slowed the leak down quit a bit, but the next time i hit 70mph it did the same thing. I've read a lot about the lines from the radiator, but I'm not too sure where it is located. :doh:

The 97 I just sold was having that same problem

I had it at a tranmission shop and they guy said the torque converter was most likely bad and was heating up causing the seal in the front to expand and thus letting it leak, I wasn't paying the money for him to drop it and be certain though

I assume it doesn't leak anything overnight or when you take it on short trips?

Whats your engine temp? if the transmission is getting too hot it will prob cause the engine to run a little warmer, it did in mine

no my engine doesn't seem to be getting hot unless my thermostat is shot too
but it doesn't leak overnight only when engine warms up

ftwxj said:

Its the front. I did use some conditioner with that qt and it slowed the leak down quit a bit, but the next time i hit 70mph it did the same thing. I've read a lot about the lines from the radiator, but I'm not too sure where it is located.

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Are you checking the fluid level when the engine, tranny and tranny fluid are hot like the manual says to do. The level rises, a lot, as the fluid heats up. Also the hot tranny fluid level from low to full is a lot less than a quart, more like a pint at at most from the bottom of the low mark to the top of the full mark, so you may have way overfilled it. Also check the fluid level with the tranny in park, but only after a good warm up drive to get it hot.

Overfilling it will make it blow fluid out all over the place, and over filling can damage transmissions.

Hmm, dipstick, what year is yours? Is it the original AW4 that came with that year jeep?

Mine is an 87, but I am not sure my AW4 is the original, as I am not the original owner. My dipstick says to check it in park while hot.

There is very little difference between the AW4s, if any, between 87 and 2002, but I guess the dip stick could have changed somewhere along the line. Perhaps after posting your year, someone else can check their dipsticks to see if it was a year change along the way.

Have you checked for any loose (the obvious) drain pan bolts or speedometer cable conection. Mine was leaking when I bought it and as I recall it was just a loose dipstick/o'ring seal at the tranny connection for the dip stick holder and a loose speedometer cable connection on the tranny from a prior flywheel replacement just before I bought it.

ftwxj said:

I am aware of over filling causing problems but like stated earlier it started leaking before i put fluid in it and I am checking it after it is warm and on a level peice of ground. The only difference is I check it idling in nuetral like it says to do on the dipstick. Could this cause me to think my fluid is low?

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its a 2000
all original from what i can tell
do you know by chance where the radiator hose connects to the tranny

My '00 XJ: dip stick says to check idling in "N". It's 25 3/8" from the base of the plastic down to the tip.

The proper way to check the tranny fluid, per the owners manual, is to bring it up to operating temp, set the emergency brake, and run it through each gear (RND...I do 1-2 and 3 as well), then put it in Neutral and check the level.

As far as the problem goes, mine is doing the same thing and its about to drive me crazy! I can drive it 35 miles down the highway, let it sit at work for 8 hours, and drive it the 35 miles back home at 100* temps and not have a problem. However, If I go to run any errands on the way home from work, or get stuck in stop and go traffic, it will begin to leak and coat everything underneath, as well as make a mess in the driveway. It will also start to do this if I drive the highway trip and turn around and come right back (with no break, or very little of one).

For now I just deal with it, and degrease everything underneath as it happens, so that it doesn't drip all over the driveway for days.

edit: ebxjbob, did the 97 you had also seem like it "slammed" or "jerked" out of OD when you took your foot off the pedal? Mine will do this if I take my foot off too quickly, and I believe this is aiding in the fluid leak.

There is no radiator hose attached to the tranny. There are two apx 1/4" ID metal tubing lines (plus some hose for flexibility) that go from the tranny to the radiator. They attach to the drivers side radiator tank, the cooler side of the radiator. Tranny fluid is pumped to the radiator for warming in the winter and cooling in the summer, and returned to the tranny through the second tubing line. They run under, near the engine oil pan. Might as well check the coolant and tranny fluids to make sure one is not leaking into the other!

ftwxj said:

its a 2000
all original from what i can tell
do you know by chance where the radiator hose connects to the tranny

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You might have the wrong tranny fluid in those AW4s. I would need to look it up, but as I recall chrysler tranny fluid does not work right in the AW4s as the AW4s are not chrysler trannys, they are Japanese as I recall! 5-90 has written about this in several threads in this forum. Just search if you need the details on the right fluid to use.

Are the engines running hot?

Did you have them flushed recently by a transmission shop? If yes, they might have used the wrong fluid!

I had an interesting experience with my 87 AW4. Ran it for 2 years with it overfilled by a full pint with no problems. Then I finally solved a low power, way too early upshift problem (with no down shift even at WOT), with a new TPS. The TPS on the tranny output side was bad. Then my tranny suddenly wanted too leak due to the higher revs of the engine and tranny. Pulled out 16 oz of fluid, got it right to the full mark while hot (idling in park in my case) and it stopped leaking.

Anyway, the TPS and TCU control the tranny fluid pressure and TC lock up so it might be a TPS sensor or electrical wiring control issue causing too much fluid pressure or no TC lock up causing trany fluid overheating.

are you serious about the TPS controlling the tranny fluid levels?
if so that is great b/c when my check engine light came on i had it scanned and they said I had a faulty TPS shortly after that my xj started pissing like racehorse
I hadn't gotten around to fixin that b/c I was dreading an expensive re-seal job on my tranny
if this is the case then it won't cost me much at all to fix

I sure hope you're right about this

In my case, the engine is running on the low side of 210 (208-210), even in 100* temps with the a/c on. Just did a tranny fluid and filter change back in the spring, and put in Mercon/Dexron III. Fluid level is perfect....as of now. If this keeps up much longer i'll probably have to top it off.

Dont think the tranny itself is overheating, but I guess it's still a possibility. I've been wanting to come up with some sort of guage(s) to monitor the tranny temp on both the tranny cooler lines.

TPS was replaced in December due to a separate problem (erratic shifting).

And yes, Chrysler ATF (ATF+3 or +4...whatever it is they're up to now) is murder for the AW4. Mercon/Dexron III is the required fluid for them. Actually, if you want to get technical, I believe it's Mercon/Dexron II that's called for in the book, but since Dexron II isn't made anymore, they've made Dexron III to be completely compatable where Dexron II was used.

edit: If it starts doing it again in the next couple of days and I have my camera with me, i'll see if I can grab a short video so you can get a better idea.

When it comes to Jeeps and life, there are no guarantees (except death, and Taxes, LOL).

The TPS does not control tranny fluid levels, but the tranny fluid expands as it gets hot, thus it occupies more volume. If it gets hot enough, or foams, it runs out of room and leaks out any openings it can find like a vent. What I discovered was that with the TPS fault I had (there are many different failure modes or types of TPS failures, and they cause different problems and show up as different symptoms) my tranny would not ever get over 2000 rpm, so it never really got warm, much less hot. With a good TPS I can do WOT and see 4000 rpm easy before it upshifts, so it heats the tranny fluid much faster. So my thinking is if your TPS is doing the opposite of what mine was doing, and is making late shifts, keeping the engine and tranny at higher rpms for too long, it might be increasing tranny pump pressures and overheating the fluid in the process, making it expand and thus making it leak. Since you had a TPS error code, its possible that is part, or if your lucky most of your problem. But there are no quarantees.

If it was me, I would replace the TPS!

ftwxj said:

are you serious about the TPS controlling the tranny fluid levels?
if so that is great b/c when my check engine light came on i had it scanned and they said I had a faulty TPS shortly after that my xj started pissing like racehorse
I hadn't gotten around to fixin that b/c I was dreading an expensive re-seal job on my tranny
if this is the case then it won't cost me much at all to fix

I sure hope you're right about this

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