Engine/Transmission (1998.5 - 2002) Transmission getting real hot while towing in Stop and go traffic

[tractorface]

While towing about 7,000lbs in stop and go the transmission gets to about 250 and puts the transmission into limp mode. Any idea how to keep it cooler?

Thanks

 

[RHARVEY]

If it is stop and go traffic... pull it down in 2nd gear to force the convertor to lock up. . According to Bill @ DTT this will cause it to cool down. .



Rick

 

[paulb]

While towing about 7,000lbs in stop and go the transmission gets to about 250 and puts the transmission into limp mode. Any idea how to keep it cooler?

Thanks

Putting the trans in neutral when stopped will help, but the one thing that concerns me is that the transmission is going into limp mode. Is it actually doing second/third gear starts? It should not be doing that at 250. I had a faulty govenor pressure sensor that was causing second gear starts when it got hot, and it was actually at about that temp.



Paul

 

[RustyJC]

I added a B&M Supercooler to the hot line of my 1996 47RE between the transmission and the radiator tank cooler and left the factory oil-to-air cooler in place. As much as cooling the transmission, I wanted to get rid of some heat before the transmission fluid dumped it into the engine coolant in the radiator tank cooler. Transmission and engine temperatures both dropped during stop-and-go towing in Houston summertime weather (13. 5K GVWR 5th wheel).



I went with this transmission cooler because it had 1/2" NPT inlet and outlet ports - one of the few I found that was sized to handle the 1/2" tubing used on the 47RE transmission lines.



Rusty

 

[tractorface]

Yeah starts at 250. (My temp sensor is in the hot line) I am going to call Dave and se what he says.

Dropping it into 2nd is what I do to cool it off and it does help a lot.

Always shift into neutral when stopped for more than 10 seconds or so.

Thanks guys.

 

[steved]

Almost sounds like the cooling line is plugged... I wonder if your check ball has lodged in the line??



I towed very heavy traffic with about 8k on once... the transmission went to 180*F in the PAN and leveled off... never gave any issues... and this was running regular DexronIII. Never offered to go any higher... and as soon as I got back under constant motion, it cooled right back off...



steved

 

[klaybus]

Shifting the trans into 2nd gear DOES NOTHING unless you have 2nd gear lockup. (Smart Controller or Mystery Switch) Kick it in & out of gear as much as possible & do no FAST starts while in heavy traffic.

I live in the Seattle area & fight this all the time in commuter traffic if I'm pulling my 5vr. As Rusty mentioned, a cooler would probably be your best bet. It's a pain the the arse, I know. I too fight it! Although I have never went into LIMP Mode. I suspect a faulty electrical prob in the trans for that one.



Good luck!

Clay

 

[stownsend]

I've noticed this too. It definitely helps to shift into neutral at the stops. I also noticed improved cooling efficiency after I flushed the radiator and put in fresh coolant.

 

[Vaughn MacKenzie]

I wonder if an electric fan running constantly would help keep good air flowing through the trans cooler.



Another suggestion, always manually downshift to 1st when taking off and letting it rev to at least 21-2200 RPM before going to second. Letting 1st gear do most of the work getting you going instead of the trans quickly shifting to 2nd and making the TC do it should help.

 

[steved]

My whole problem with everyone's suggestions is that HIS TRUCK SHOULD NOT HAVE ANY ISSUES IN TRAFFIC WITH 7,000 POUNDS!!!!



There, I said it...



The OE cooling should be sufficient... I'd be looking into something that is causing the condition... it is NOT normal.



As I stated above, I towed 8k, in 108*F weather, in Philadelphia traffic, with 3. 55 rears... it never went above 180*F in the pan.



I'd be looking for a root cause, not just adding coolers as a bandaid.



steved

 

[tractorface]

I don't think I have any cooling problem. My sensor is in the Hot line so it is very sensitive. Senders in the pan are not much help at all. No way to really know what is going on with the large volume of fluid in there. Remember my sensor is installed before the fluid goes to the cooler.



Temps come down quickly once out of traffic. Sounds like the real problem is that it goes into limp mode (3rd gear starts) when hot. Hoping dave can help me when I talk to him.



To anyone running a temp sensor in the pan, buy a first gen line with a port in it and install your sender there. It will surprise you how hot things get when backing up or sitting in traffic.



My father is the person who keeps having this problem, I seem to be able to avoid it by doing the same things suggested above. He says he is but I have to wonder.



FWIW I opted for a valve body without second gear lockup and do not run a mystery switch. Maybe I should talk to Dave about changing that. 2nd gear starts seem to cool better than first for some reason. Stock Trans always had similar trouble maybe even worse. I don't worry about the heat in this one except for the limp deal. Dave has told me several times that 250 won't hurt it.

 

[steved]

And again, you should not have a overheating problem in any condition towing 7k.



But what do I know.



steved

 

[tractorface]

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[SCosgriff]

I just experienced similar problem while running empty in stop and go traffic. A quick check around and found that I had a bad water pump.

 

[tractorface]

Everything i tried to post was typing backwards. WTF? Back to normal now.



For the guys with sensors in the hotline. What temps do you see while towing in stop and go. Do I have a problem?? Never had any other temperature related issues.

 

[y-knot]

In my opinion anyone with a automatic that tows, should install a auxiliary transmission cooler. Your simply fooling yourself it you think you and your 48RE do not need one. it is just that simple!

 

[Partyat33]

The trans does get over 200 degrees in heavy traffic even if I am not towing. I wonder if this has something to do with a very tight torque converter. I only have the aux cooler in front because I swapped a auto in for a manual. If you are going to be sitting a while you could throw it in neutral AND lockup the torque converter. Of coure you WILL get a suprise if you throw it back in gear without unlocking the TC. (Don't ask me how I know). Talk to Dave.

 

[Mhannink]

well fwiw my buddies 99 ext cab shrt bed 4x4 would get hot empty. he put his guage in the hotline and soon after called me asking why his temps are so high. thats the point at which i realized why these trannies are tore up so easily when stock. THEY RUN TOO HOT. im sorry i dont agree w/ 250 being fine for the transmission i think its too hot and my buddy can hit that easily in stop and go traffic and his truck is completly stock. heat kills these trannies and even stock they run far to hot for my liking. id like to see no more then 200 in the hot line under a heavy load, such as pulling a trailer or hammered down. this 250 putting around in traffic stop and go is not right. ive looked over his truck too the water pump is fine and they only problem we have had is the vp has failed and that took a while other then that his truck runs perfect and so im sure its just a poor design of the trannies cooling system.

 

[Hahn007]

Hmmmmmmm... ... ... ... ... ... ... . I installed the BD X-monitor with a transmission temp reading, boost pressure reading, and exhaust temp reading. It simply taps into the factory (variable resistance) sensor that controls the idiot light for trans temp. My converter is also very tight, about 400-500 rpm lower stall speed than stock, and I only see about 128 deg while cruising on the freeway and if I really abuse it while towing in town I might see 140 deg. As soon as I get into lockup the temp comes right down. If I remember correctly the manual that came with my X-monitor said when using the factory sensor location to monitor trans temperature, the temp should not exceed 200 degrees. It is either 200 or 250 degrees, I can't remember for sure. The external cooler attached to the radiator is not the only cooler in the system. There is also a shell and tube heat exchanger mounted under the exhaust manifold that cools the transmission fluid as well.

 

[steved]

Hmmmmmmm... ... ... ... ... ... ... . I installed the BD X-monitor with a transmission temp reading, boost pressure reading, and exhaust temp reading. It simply taps into the factory (variable resistance) sensor that controls the idiot light for trans temp. My converter is also very tight, about 400-500 rpm lower stall speed than stock, and I only see about 128 deg while cruising on the freeway and if I really abuse it while towing in town I might see 140 deg. As soon as I get into lockup the temp comes right down. If I remember correctly the manual that came with my X-monitor said when using the factory sensor location to monitor trans temperature, the temp should not exceed 200 degrees. It is either 200 or 250 degrees, I can't remember for sure. The external cooler attached to the radiator is not the only cooler in the system. There is also a shell and tube heat exchanger mounted under the exhaust manifold that cools the transmission fluid as well.

Exactly... towing 7k SHOULD NOT pose any overheating problems as he is having... I restate, I think you have a problem in the system, adding a cooler will simply apply a bandaid... it will not fix the problem.



steved