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Stratman50th · 10-20-2015, 03:11 PM

Question for those of you that have a side radiator DP. I have a 42' Country Coach, 525hp CAT and a 6 speed Allison with a side radiator. The transmission radiator is at the bottom half of the engine radiator. The transmission tends to run hot. Especially in heavy stop and go traffic. It operates at around 212 degrees normally on the open road. I've had it climb up to around 219-221 on mountains (east coast, no Colorado Rockys yet). In heavy stop and go traffic I've had it get up as high as 236. It's also popped out of gear when it's running hot. I can hit N then D and it reengages, but that's not the way it's supposed to work! I can manage the temps ok at red lights by shifting into N while I'm sitting but not much I can do on the interstate or beltway. I am going to take it in to Allison for service, but just wondering if anybody else has had this issue?
Oh, I forgot to mention the engine temps are good. Between 194-204degrees.

C-PHartley · 10-20-2015, 03:58 PM

Fluid level OK? Verify your electronic sensor by checking with the dip stick. Have you changed the filters? If not, I would have the fluid analyzed and change the fluid if necessary. I would also change the filters. These are relatively inexpensive compared to an overhaul. I hope this helps.

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Stratman50th · 10-20-2015, 04:23 PM

Quote:

Originally Posted by C-PHartley

Fluid level OK? Verify your electronic sensor by checking with the dip stick. Have you changed the filters? If not, I would have the fluid analyzed and change the fluid if necessary. I would also change the filters. These are relatively inexpensive compared to an overhaul. I hope this helps.

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I Have not checked with the dipstick. Will do a full service soon. Thanks for the suggestions my friend!

Randyman1 · 10-20-2015, 04:57 PM

Mine is similar to yours in the cooling department even though I have a Cummins ISX. I would recommend the fluid and filter change as soon as possible, especially if it has not been done before. Jumping out of gear sounds to me that the transmission is low on fluid. That could factor in to the running warm as there is less fluid to be cooled. My temps run at engine temp or less depending on the terrain. Be sure to have an authorized Allison service facility do the work. The Transynd fluid is expensive, but the transmission overhaul is more expensive. Randy

C-PHartley · 10-20-2015, 04:57 PM

I would also invest in a laser gun to verify that your gauge is accurate. Maybe do this first as it is also very inexpensive at Harbor Freight.

IASM · 10-20-2015, 08:53 PM

the cooler in front is likely the hydraulic cooler for the fan. The trans I think is plumbed thru the radiator so you might confirm. My inspire would warm up at stop lights or any time the torque converter is slipping so I tried to not sit in gear so much. In stop and go traffic once trans temps get high it takes some time to lower.

Steve n Jan · 10-20-2015, 10:40 PM

What is the temp of your engine coolant when you're having these high trans fluid temps? I have an 05 Magna and my tranny temps are in the 185-190 range almost all the time

IASM · 10-20-2015, 11:07 PM

Also checking the fluid level at the shift panel is more accurate then the dip stick

Randyman1 · 10-21-2015, 07:19 AM

On mine, i have both the hydraulic cooler and the transmission cooler in front of the radiator. I would bet that a big Cat engine would be the same. The OP will have to verify this to be sure.

Stratman50th · 10-21-2015, 12:24 PM

Quote:

Originally Posted by IASM

the cooler in front is likely the hydraulic cooler for the fan. The trans I think is plumbed thru the radiator so you might confirm. My inspire would warm up at stop lights or any time the torque converter is slipping so I tried to not sit in gear so much. In stop and go traffic once trans temps get high it takes some time to lower.

That's exactly what I get. I've trained myself to put it in neutral as soon as I'm stopped for a red light. We were in 4 lanes of stop and go traffic on the Washington Beltway and it lasted for a good 15 miles. Even when we started to move again it didn't cool below 128ish. I pulled off at rest stop and it was reasonable again after about 8 minutes. Like 118.

Stratman50th · 10-21-2015, 12:28 PM

Quote:

Originally Posted by C-PHartley

I would also invest in a laser gun to verify that your gauge is accurate. Maybe do this first as it is also very inexpensive at Harbor Freight.

What am I checking with this? There's the engine coolant radiator, the transmission coolant, hydraulics, and I'm not sure where the coolant from the turbos go....

Stratman50th · 10-21-2015, 12:29 PM

Thanks everyone for responding.

gsander1 · 10-21-2015, 02:26 PM

Allison would tell you that those temps are not a problem. Especially if you have synthetic Transyn fluid. Running down the road the transmission temp is sensitive to speed, ambient temperature, cooling fan run time and weight. IF you are diring at 75 MPH, towing a heavy toad on a hot day 212 is really not bad. Also, the highest transmission temp I have seen via Silverleaf is in stop and go traffic. When driving the torque converter is locked and not generating much heat. Stop and go creates heat via torque converter slip.

Jumping out of gear is a separate problem that needs attention.

Larry Young · 10-21-2015, 03:00 PM

In heavy stop and go traffic the allison transmission will run hotter than driving on the highway. Your torque converter will slip in 1st and 2nd gear generating a lot of heat.