Radi

Is your torque converter lockup working? If it isn't it will contribute to higher trans temps on the hwy.
You should be able to tap the brake slightly while cruising >45 and see the rpm's jump up by 200 or so then back down again. That's the TCC. It should unlock momentarily then lock right back up.

Franks93Cherokee

I'm not sure I have noticed a few strange things going on in the area your talking about however. I was on the Interstate the other day doing about 60 and going up hill it felt like I had the cruise control on in the pedal. I would take my foot off slightly and I could feel it still sinking down a little just like the cruise was on and the RPM's jumping up and then back down.

I went to Atlas Transmission today instead of buying the new radiator and he said it was in the transmission and that it would need to be taken out and taken apart. I asked him if he could maybe blow out the transmission cooler and lines for me and he said it wouldn't help that it had a internal blockage and would cost around $1,200.00 to fix it.

Here is the best way I can explain this. It's heat related without any doubt. I can drive it around town and sit in a few red lights and as long as I keep it a little hair below the 210 mark it has no problem if it goes on up to 220 or 230 then things start getting hot and it boils over transmission fluid out the vent in the transmission.

If you jump on the interstate with it then your screwed for sure a few exits down the road it starts creeping on up in temp and before long your doing 210 down the highway no matter how fast or slow your going. And then when you get off a exit and sit the temp just keeps going a little more and little more to 230 and then when you take off it blows it out.

Radi

How long since the trans fluid has been changed? Once it overheats it starts to lose it's lubricating properties...which adds more heat to the trans. You go in circles from there.

If it's been a while, I'd consider disconnecting the trans cooler lines and blowing the coolers out with a compressor. Make sure you don't have any restrictions. Then drain the trans and have a good look around in there for varnish buildup or discoloration. If you find sticky goop, the trans guy may be correct...although you could try a bottle of Trans-X as a hail mary before pulling it for repairs.

I personally think 220-230 is too hot. That's the limit for the trans fluid, and when the radiator is that hot it isn't cooling the trans at all.
Has the water pump ever been replaced? Any hot or cool spots in the radiator itself that would indicate a blockage?


Forgive me if you've already answered those questions, I'm having a bit of trouble keeping the two jeeps separate, lol. More than one guy with the same problem in this thread.

Atomic Citizen

That temp is your engine and not your tranny temp. At best you are keeping temps that low in your tranny but expect higher. I have the same problem and experience with those corporate transmission shops. Any excuse to open them up without determining what is causing it. Hell, I can open the tranny and inspect it, but do you know what is wrong. I'll take that NO is NOT another corporate answer, if you know what I mean. Those experiences for me seem like redneck mechanics using buck shot when hunting for quail.

I don't believe the vent plunger is opening up due to heat but pressure built up too high pushing it open. I wonder if the heat is pushing the PCM to boost the pressure or sticking a solenoid not acting correctly when over heated. I don't believe the DTC will come up until it finally fails and throws some funky shifts. From mechanical inspection I haven't ever have anything or anyone pinpoint a cause and they work on them more than I do, but what is happening inside the torque converter? Is it getting air, is it worn out and generating much more heat in overdrive or by an intermittent solenoid preventing a constant lock up. The fluctuating RPMs are worth looking at to determine if the distributor or pick up failing with the heat throughout the whole engine compartment. The worn Distributor was the one that caused that for me, not the cap, rotor, pickup, or wires or tcc lock up. The PCM was asking for an advance but getting whatever the Distributor shot out. I was able to see the wear on my old distributor when compared to a new one Or you can borrow a known good one. I suspected my TCC isn't locking up is why I looked somewhere else besides the tranny. Right now, I'm waiting for a tuner to see if I can freeze a frame of the PCM's PIDs when Puff the Magic Tranny comes out to ride. In addition, I suspect a lean condition in your engine at peak HP. I pulled my vent tube away from venting onto the exhaust and the smoking will stop but not the tranny fluid covered rear end.

I'll be back to add to this. This topic is a complete mystery to most tranny shops who only want to change parts unnecessarily. The key to this mystery is that not at any time during any load on it did it puke out fluid while cold, only when the heat is so high you feel it when you park and open the door is when you know the underside is wet.

Atomic Citizen

Broke down the elec on my tranny, all looks good. With a cold engine changed out tranny fluid which looked dark but not burnt and still very slippery. I recommend all coolers to be flushed not being connected to the tranny: disconnect tubes to cooler and flush chemically and forcefully by blowing out all the fluid in the cooler and then filling pumping through a cleaner. With today's tech water or oil based cleaners will do as long as you completely blow out and let dry before changing out fluid still left in tranny, very important to let dry. While doing that, check your fans, if a clutch type with over 80,000 miles change out, with elec type check the resistance of your motors while HOT. Very important for weak motors will show good cold but borderline bad HOT. Now with my tranny, 4l60e with same problem and no CEL, all electronics checked fine and no metal in the pan. reassembled the cooling and pan and filled with new fluid. Mine took 6 gallons to get fluid to come out of the cooler clear. Then to the computer. Put on HPTuner, yours will be different as of this post, found someone enabled torque management where a complete lock up would not happen under extreme load. Not good for MPG but good for creating lots of heat. I don't know which shop did that, wish I could tell. I would have a website up showing how that mechanic intended on burning up my transmission for they all knew I towed, and I knew the torque management was off and specific towing parameters were put in to keep my shifts quick and lock up in 2nd, 3rd, and 4th, when speed was hit. Now I will have to get my old tune back and set up, but with the cooling system cleaned, new fan clutch, and still towing, new fluid and temp never got over 198 even after a highway run without the trailer.

I do not know what can be done to the Jeep computer and knowing that would be helpful, but so far I have not puked out any fluid. I won't tow at highway speeds until my tune is back to where I specified my truck to be. Conclusion, you are not cooling much and the heat is causing the fluid to come out your vent. Suggestions would be to get a Cold Air Intake, CAI, add coolers wherever you can, increase your fan speeds or new clutch to maximize Cubic Feet of air over the cooling fins. Without towing, I haven't had a puke out of tranny fluid after doing every thing I could afford to keep the tranny cool. If you cannot do much now, change out your tranny fluid every 6000 miles to keep viscosity high and fluid level high. It will help to save your tranny until you can find out what is wrong, for me it was improper cooling to my engine and to my tranny. You will be surprised how much sludge will come out of an old radiator.

jon71203

I'm having the same issues, whats interesting is that this started about 2 years ago and I only noticed it when i would drive from home (indy) to louisville, about 130 miles. after months of it not leaking/smoking, i drove to louisville a few days ago to visit family, sure enough, by the time i had been on the road about an hour and a half there was construction and i had to let off the gas and behold, puff the magic dragon. unfortunately, since i've gotten back to indy, i'm getting smoke pretty soon after I'm out and about at street speeds.

one other interesting note, i had the tranny replaced about 4 months ago. like i said this has been ongoing so it's not the tranny itself.

any ideas? thoughts? help? really tired of my 97 sport blowing smoke.

thanks guys,
jon

jon71203

more smoke today....sucks

sthon

I had this issue a few months ago, usually at highway speeds and going up hill. My trans would heat up and dump ATF out the breather/vent all over my exhaust. The worst time it happened I was going up the hill to the mountains and passed about 60 cyclists just as it started to smoke like crazy. Turns out the return line on my transmission cooler was crimped almost shut. Replaced the line and all is well. If you have an aux cooler check your lines and flush it out. If you don't have one get one.

jon71203

hey sthon,
any how to's on checking the return line on the transmission cooler? just need to know what and where I should be looking.
thanks a ton

sthon

Just look for any kinks or damage. The transmission lines run into the radiator, if you have a cooler it's likely connected in series with the radiator. In my case the rubber hose from my cooler ended up wedged under the radiator pinching it almost shut.

Kbrew

Reading through what everyone has done and thought I would share on the same issue. Replaced the entire cooling system: Mechanical fan, Radiator, Thermostat, and water pump. Transmission died about a month ago and swapped for a new to me with under 100k on it. Ran fine in town with better performance. Highway over 60mph, smoke every time I let off the gas. Bypassed the original trans cooler with with a small after market with better success. Still over 65mph, same smoke and fluid. Added a much larger and nicer to the system. Took a 4 hour trip in the mountains with no problem, got braver on the way home with the speed and had on small smoke with minimal fluid loss. Brought speed to 68 and below and was just easier on the hills with no more problems, just don't like driving while looking behind me and want this fixed. Only thing next is to check to the breather tube for a clog that i can think of.

Jeep is lifted with 32x11.50 BFG's. Stock '97 4.0 motor and trans. I do have ARB bumper with winch which i feel is hurting my cooling to some degree with air flow. Removed the lights on the bumper and received some relief on the cooling for the engine at speed.

Thanks for any help!

sthon

I to have some cooling issues, I've replaced the entire cooling system but I also have a winch blocking a good part of my radiator



I've relocated my solenoid box under the hood and I'm going to change my bumper.

One thing you can do to test if it's coming out the vent is to attach a hose to it and attach the other end to a an empty soda/gatorade etc bottle. Drill the cap and put a nipple on it to attach it to the hose. Attach the bottle somewhere underneath your XJ keeping it near the same level of the breather tube attached to the bell housing. Once you have it set in place poke a few small holes for air to escape where you wont have fluid leaking out.

Now you can go mash on it on the highway. If it's spewing out the breather tube it'll end up in the bottle.

Kbrew

Thanks I'll try that. Also ordering a trans temp gauge to monitor temp change with speed. Trans seems to work flawlessly minus the fluid at speed.

If knew how i would post a pic of the set up i have

jon71203

can anyone take a quick phone pic of the vent/breathing tube?
i'm going to try to run a hose to it like sthon suggested, but not sure what I'm looking for.
thanks

sthon

It's bolted on top of the bellhousing and curves to the passenger side. I'll try to find a picture.