Automatic Transmission; Bypassing the radiator.

[Mudderoy]

I have had a heat creep problem with my cooling system since I lifted and put larger wheels and tires on my XJ.

After many modifications to the cooling system I have managed to solve the problem that many XJs have with overheating at low or no speed.

I have NOT solved the problem of it running hot at highway speeds.

One of the things that was recommended to me long ago was to remove the AW4 cooling lines from the radiator. I have not done this because I have had no way to monitor the temperature of the transmission fluid.

That has changed. I recently received a B&M transmission temp gauge and my plans are to install it this weekend. To have a good idea as to what the normal operating temperature of my transmission is I will be running the gauge with the stock radiator and OEM transmission cooler.

Then the following weekend I'll install the 13k BTU B&M transmission cooler that I removed a couple of months ago to find a leak.

Finally I will be removing the transmission from the radiator.

I have already asked, Which line is the input and output of the transmission. I need to know this so I can put the gauge on the proper line.

Now I need to know, when you disconnect the lines to the radiator, what do you do with the connection points on the radiator? Just leave it open?

[bigjim350]

you can just leave em open. It will drip a little tranny fluid out from time to time until it completely empty in there.

[Mudderoy]

you can just leave em open. It will drip a little tranny fluid out from time to time until it completely empty in there.

Could this cause a problem later, like say when winter time comes, and I may want to hook it back up?

[bigjim350]

Don't see how it could cause any problems. This is what your stock cooler looks like inside the tank. There is no way for coolant to leak out of it or anything like that. But like I said it will just take a bit for all the fluid to drip out of it. So dont be alarmed if ya see a few drops in the driveway.
http://img13.imageshack.us/img13/1894/img0347ibs.jpg

[Mudderoy]

Don't see how it could cause any problems. This is what your stock cooler looks like inside the tank. There is no way for coolant to leak out of it or anything like that. But like I said it will just take a bit for all the fluid to drip out of it. So dont be alarmed if ya see a few drops in the driveway.
http://img13.imageshack.us/img13/1894/img0347ibs.jpg

Hey great picture, I was wondering what that looked like, thanks!

[LizardRunner]

X2 on what Jim said.

[msmoorenburg]

ok this if for info purposes. I had to scan the wifes van for a abs issue so i said why not do the tranny to for temps. Here it is the van was warmed up (well 10+ miles later) the outside temp was 102 so here it is

http://i7.photobucket.com/albums/y299/msmoorenburg/IMG_20110612_162959.jpg

[Mudderoy]

http://i168.photobucket.com/albums/u196/chasdwitt/ALL%20JEEP/TransLifeChartfromHECATInc.jpg

[Mudderoy]

http://mysite.verizon.net/%7Echris83803/trans_cooler.jpg

[Mudderoy]

http://jeepin.com/features/tranny_temp_gauge/DSC01100t.jpg

http://jeepin.com/features/tranny_temp_gauge

[4.3LXJ]

That is how it works Tony. Just plumb one tube in and the other out. Does yours have a fan and thermostat in it. I can't remember.

[Mudderoy]

That is how it works Tony. Just plumb one tube in and the other out. Does yours have a fan and thermostat in it. I can't remember.

No it does not. Just a static cooler.

[Mudderoy]

There seems to be some disagreement (from what I have read on the Internet) whether the gauge temp sensor should go on the outflow line or the inflow line.

B&M's instructions says inflow (after the cooler(s)) but many people have installed it in the outflow line which would be the hotter of the two oil temps. Yet others say the only true measure is to put the sensor in the transmission oil pan.

I know I'm not putting it in the pan. :mad:

So one lets you know quicker if your transmission is heating up but the other lets you know how well your cooler(s) are working.

What do you think? No I'm not buying a 2nd gauge. :P

[4.3LXJ]

No it does not. Just a static cooler.

It doesn't matter which line goes in then.

[4.3LXJ]

There seems to be some disagreement (from what I have read on the Internet) whether the gauge temp sensor should go on the outflow line or the inflow line.

B&M's instructions says inflow (after the cooler(s)) but many people have installed it in the outflow line which would be the hotter of the two oil temps. Yet others say the only true measure is to put the sensor in the transmission oil pan.

I know I'm not putting it in the pan. :mad:

So one lets you know quicker if your transmission is heating up but the other lets you know how well your cooler(s) are working.

What do you think? No I'm not buying a 2nd gauge. :P

Put it in the outflow line so you know what your tranny temp is.

[Mudderoy]

Test fitting of a-pillar pod. I think it's going to fit ok!

https://lh3.googleusercontent.com/-prNUuYqnZuY/Tf0IkthbOoI/AAAAAAAAA7c/vJ0klVEEk9g/s576/2011-06-17%25252022.29.05.jpg

Should I leave it black, or paint it gray to match the interior? Can I paint it, or will it flake off the flexible plastic?

[oderdene]

black looks good, it is add-on item. you have black things inside door :)

[Mudderoy]

Installed. Holy crap! It was very easy installing the sensor into the line but then I spent the next 6 hours getting the a-pillar pod mounted, gauge to fit, and finding all the wiring points I needed, but it's done.

Oh I also fixed my tilt steering wheel. The lever went limp last Thursday. The end of the cable came off. Lucky I had a spare steering column so I just pulled that cable out of it.

I didn't get to the power locks. They unlock but won't lock. Just dead.

[Mudderoy]

I'm amazed at how quickly the transmission oil temp changes. It seemed to build up over time. At first it was staying below 160, then stayed on 160 like glue. As I would come to a stop it would move up midway between 160 and 220. Once I got moving down the road, near instantly the temp would drop to 160 again.

After a few "jack rabbit" starts the temp rose to the 160 to 220 midpoint again, and pretty much stayed there for the rest of the drive in.

https://lh6.googleusercontent.com/-8iQJF_DHw3k/Tf9Pb-97A7I/AAAAAAAAA8E/ANBGSevrMX0/s912/2011-06-20%25252008.26.53.jpg

I checked for leaks on the nice white concrete at work. I'm good (or out of transmission fluid :shocker:)

[Mudderoy]

I hit 220 on the transmission oil temp this afternoon! It's really weird, at least to me never seeing this information before. You can watch the needle move to 220 when I come to a stop, and you can watch the needle move when I hit about 40 mph. It damn near goes from 220 to 160 in the matter of 30 seconds!

:out:

[LizardRunner]

somethings you need to keep in mind when watching that gauge. what is the ambient temperature outside? what speed are you going? The rapid reduction in heat shows how good (and important) a trans. cooler really is. I would say your temp running higher at speed is probably more due to high ambient out side temp than to a lack of airflow over the fins. the fact that it goes down fast at 40 mph shows that you are getting good cooling effect.

yes indeed it looks weird when you've never seen that data before. if you really wanted to freak out, you could do a temp gauge for exaust gasses.

the increase while at idle shows you why racers get every fluid up to temp before they race and how effective sitting still is for heating up most of your fluids. the static fluids, read that rear end, are also warmed up by jacks and putting the tranny in gear and letting the wheels spin.

[Mudderoy]

somethings you need to keep in mind when watching that gauge. what is the ambient temperature outside? what speed are you going? The rapid reduction in heat shows how good (and important) a trans. cooler really is. I would say your temp running higher at speed is probably more due to high ambient out side temp than to a lack of airflow over the fins. the fact that it goes down fast at 40 mph shows that you are getting good cooling effect.

yes indeed it looks weird when you've never seen that data before. if you really wanted to freak out, you could do a temp gauge for exaust gasses.

the increase while at idle shows you why racers get every fluid up to temp before they race and how effective sitting still is for heating up most of your fluids. the static fluids, read that rear end, are also warmed up by jacks and putting the tranny in gear and letting the wheels spin.

I may not have explained it correctly. Sitting still the trans temp goes to 220, moving at 40 mph or more (up to 60 mph) the temp drops like a rock.

[jeepxj95]

ive herd that it drops like that when the tourqe converter locks up.

[Mudderoy]

Well here is what I have learned so far. It takes quite a while for the transmission fluid temps to get up to 160 degrees. I'd say at least 5 miles. Then even longer for it to start getting close to 220.

Now you need to understand that I drive the back roads to and from work. Speed limits from 30 to 40 miles per hour. That means I drive 45 to 65 miles per hour. It is stop and go but usually several miles between stops.

According to Google maps my trip is 20.3 miles one way.

I don't see the 220 temps (only stopped at a light) until I'm over half way home, so in excess of 10 miles.

Now I do need to see what the temps are driving my standard test down I-10 about 12 miles and back.

Now certainly I see a somewhat correlation to the engine coolant temp and the transmission fluid temp in as much as by the time the transmission temp is getting up to 220 the coolant temp is past the 210 mark, however the transmission fluid temp varies greatly as I speed up and stop where as the engine coolant temp remains relatively steady. It will drop as my speed, and air flow, increases.

The temp of the transmission drops to I'd estimate about 170 while driving at 50 to 60 mph, even after it was just 220 sitting at a light.

I'm wondering how much this rapid fluctuation is caused by having the temp gauge on the OUTPUT of the transmission instead of the RETURN.

[LizardRunner]

well, only one way to find out about that, swap it to the return line. Looks to me like you have plenty of tranny cooling going on. Since your getting readings of the fluid at its supposed hottest temps. Looks like sitting still it gets up to a good temp then with movement it cools right down, saving wear on the internal moving parts. your transmission should last a good long while.:D:thumbsup: now we gotta get more flow moving through that radiator to stop that nasty overheating problem. Have you re-installed your front pan (skid) yet? or is it that it won't fit quite right?

[Mudderoy]

well, only one way to find out about that, swap it to the return line. Looks to me like you have plenty of tranny cooling going on. Since your getting readings of the fluid at its supposed hottest temps. your transmission should last a good long while.

Yeah, or add a second gauge! lol not. I'm just going to proceed with doing a highway test, making note of the readings, then add the B&M 13k cooler this weekend. I may go ahead and take the transmission off the radiator at the same time. Then I'll see how hot it gets on just the OEM cooler and the B&M cooler.

If the highway heat creep goes away I'll do a little dance. Otherwise I'm thinking about that all aluminum radiator now!

[LizardRunner]

Truth is on the tranny, the B&M would probably be all you needed. I ran one a long time ago on a lola with automatic trans. we had problems with to much cooling when they put two of them in. I still think your main problem with the highway heat in the engine is from air flowing under/over instead of through the radiator, but an all aluminum radiator is never a bad idea.

I abhore plastic in a radiator, just way to many problems can come up. I am going to be swaping to the olympic unit and perhaps going with just electric fans with a good shroud. I am not a proponet of a fan stealing my hp. so I'll set up with electric fans all the way.

[Mudderoy]

Truth is on the tranny, the B&M would probably be all you needed. I ran one a long time ago on a lola with automatic trans. we had problems with to much cooling when they put two of them in. I still think your main problem with the highway heat in the engine is from air flowing under/over instead of through the radiator, but an all aluminum radiator is never a bad idea.

I abhore plastic in a radiator, just way to many problems can come up. I am going to be swaping to the olympic unit and perhaps going with just electric fans with a good shroud. I am not a proponet of a fan stealing my hp. so I'll set up with electric fans all the way.

Yeah well I still need to do the air damn under.

[Mudderoy]

I haven't put the B&M 13k BTU transmission cooler on yet, but I did drive on the highway today. Maintained 70 mph for 15 to 20 minutes. Peak was 75 min was 65. I didn't quite make it to hash mark after 210. The transmission temp never hit 160, very close but not quite there. This was during the hot part of the day, 2:30 to 3:15pm

[jeepxj95]

? have u tryd turning on ur e fan in traffic to try to keep the temps down??

[Mudderoy]

? have u tryd turning on ur e fan in traffic to try to keep the temps down??

Yes. Under 60 mph no issues, over 60 mph it starts getting up close to the hash mark after 210.

[Mudderoy]

I had to drive to my Aunt's memorial service the other day and the transmission temp never got about 160, at least not on the freeway. So I don't think disconnecting the transmission from the radiator will be any benefit to the overall cooling of the engine.

I'm going to hook up the 13k BTU aux cooler though and see if I can drop the temp on the transmission a bit. It does get up to 220 when idle after everything is heated up (at least during the summer).