Skip to main content ↑ ↓
Topic: Transmission temp question (Read 1833 times) previous topic - next topic
0 Members and 1 Guest are viewing this topic.

Transmission temp question

Yahoo Message Number: 66255
We are traveling to SoCal from Ohio and, as always, I love watching the engine & transmission temps cycle between 188 and 206 (engine) and 180 and 196 or so for the transmission. That was in cool to cold temps from Ohio to Texas. Yesterday we hit NM and AZ and the transmission temps rose to 201, and stayed there for a relatively long time. The outside temp was probably 75. I was not going any faster (usually run 65-68) and so the only difference that I can think of is the air temp. Could that make a 10-degree difference in the normal transmission temp?
Just thought one of you mechanical whizzes could help this old history major figure things out! :>)

Scott Laidig

2004 Magna 6354, Suburban Toad

Re: Transmission temp question

Reply #1 –
Yahoo Message Number: 66256
I would think that result likely. The cooling system will shed excess any heat better in colder temps. With the increase in outside temps, your thermostat stays open longer due to slower cooling and a higher coolant temp before operating the engine.
The range of 188 to 206 degrees probably approximates the range of your thermostat from closed to fully open.

Dean

95 Magna 5280

Re: Transmission temp question

Reply #2 –
Yahoo Message Number: 66258
Scott aka...the "old" history major ....
I did notice on our Affinity with long steady running hours the operating temp would climb up slightly, but remain in the comfort range. When we pulled over the temp would drop down. With the side draft radiators cool air can sometimes be compromised.
I see your toad is a heavy weight so taking all in to account, all normal.
How much cargo on board ?
AL

00 Affinity..no bidet

Re: Transmission temp question

Reply #3 –
Yahoo Message Number: 66263
Don't know what route you took but here is a thought. You are steadly going uphill until you cross the continental divide in western NM. Southern NM and AZ is warmer than where you came from so could make a difference.

Phil C

Re: Transmission temp question

Reply #4 –
Yahoo Message Number: 66271
Thanks for the replies.

Did not think about the steady uphill climb past the Continental Divide in NM, but of course it was downhill into Tucson and the temps were highest during the last phase of the trip, when it was both downhill and at slower speeds. So not sure that climbing affected the temps.
We weigh just under the gross carrying capacity of the 2004 Magna, about 53000 lbs. And the Toad weighs in at about 6400.
These "systems" are much like living organisms in my opinion. No one seems to be able to predict why some days the temps will be absolutely within a set range and then, for little or no apparent reason, they will deviate +/- 10 degrees or even more. Of course, lacking knowledge, deviations cause me to be very sensitive to impending disaster, though I realize that transmission temps of 208 degrees are well within reason... heck we used to have 300+ degrees before we got our 5th radiator replacement and our separate transmission cooler (under warranty of course!) :>)
Hope to make it to Indio tomorrow, and looking forward to seeing what the transmission temps do!

Scott Laidig

2004 Magna 6354, Suburban Toad

Re: Transmission temp question

Reply #5 –
Yahoo Message Number: 66272
The transmission is cooled by the engine cooling system, it will run close to engine temp under normal loads. Somethings to check, make sure transmission is full. Make sure radiator is clean. Check hyd. system oil level. Can you hear the cooling fan kick in at high RPMs. Do you have a PTO driven pump? If you have unexplained swings in temp, might be wise to do basic maintenance, change hydraulic filters. Hose down radiator. If you have a pto driven pump, maybe time to have it checked. What about your engine cooling systems condition, i.e. full and correct mix. Check belt that drives water pump. Do you have any leaks underneath? Lost your original post, but seems the transmission was running 10 or more degrees hotter then the engine for an extended time. Once the transmission oil gets hot, it takes some road time for all that oil to loose the extra temperature. Probably do not have an issue, keep watching. Don't be afraid to manuel downshift to keep the engine RPM and fan speed up when pulling extended grades. If the transmission runs hotter then the engine on regular basis under normal loads, i.e. not pulling a grade, then time to dig deeper.

Leonard Kerns
97' Magna 5418

Re: Transmission temp question

Reply #6 –
Yahoo Message Number: 66275
Leonard,

That was my take on our coach and really didn't get to concerned about a slight increase in temp when the area temp was relatively warm. Always the back up was to drop a gear or slow down. When I converted to Transynd from DexII there was a 10 degree reduced operating temp. I' am sure by 2004 that was standard Trans fluid for Allison.
What is your take on the synthetic fluids as it relates to performance in the heavy duty applications. More or less failures ? AL

00 Affinity ...no bidet

Re: Transmission temp question

Reply #7 –
Yahoo Message Number: 66278
AL,

I a very strong believer in synthetic fluids. Changed our trans over to the Amsoil for Allison. It also runs cooler. That drop in temperature says there is less internal friction causing less heat. Less friction, less heat = longer life. Like you, I thought by 2004 it would be the standard in Scott's transmission. What we do not know is the history of his rig, how many miles, when was it serviced-filters changed, was it changed back to standard fluid, etc. He needs to continue to watch it longer.

Leonard

Re: Transmission temp question

Reply #8 –
Yahoo Message Number: 66280
If the engine is not overheating or showing any signs of running hotter than usual, then there are a couple of things I would do before the goose chase below. First confirm the engine temp with a gun thermometer, to confirm the temp gauge for the engine is still accurate, the best place to do this is where the temp sensor is located on the engine, Then check the trans temp the same way, the cooler lines are probably the best one will be cooler than the other. The trans temp gauge is a good place as well if it is in the pan for the trans. This will confirm if is a gauge or something else. This is assuming your trans cooler is part of the radiator. If it is a separate cooler (air to oil) then be sure the air flow over it is not restricted by dirt on the exterior. If all of the above is okay, then confirm the trans is going into lockup It should go into lockup from 2nd gear up. If it is staying in the convertor mode it will run hotter. If you are not familiar with what it feels like going into lockup, it is very subtle, you may want to go to a good Allison facility and get it checked. The trouble shooting efforts will involve pressure gauges etc.
Are you using trans fluid or synthetic oil ( Transynd)?
All of this being said 10 degrees is not something to cause alarm, but you should continue to monitor it for further changes.

Mikee

Re: Transmission temp question

Reply #9 –
Yahoo Message Number: 66289
Thanks Leonard, Mikee, Al (and anybody I missed)- my coach started life with a very uncertain future. 2004 was not CC's best year for quality control and we had numerous - better said countless = issues, especially with engine and transmission temps. We literally replaced 5 different radiators the first 18 months we owned the coach. After #2 we also were fitted with an add-on transmission cooler, and we also switched to Transynd. As a result, our transmission temps dropped from 310 degrees (in FL traveling 62-64 mph) to 180 -190 degrees (going up western mountains.)
I do regularly check for leaks and look at external fittings (that I can see without going under the coach,) we have the coach regularly serviced by pros (most recently at Oregon Motorcoach Center last spring, where we also had the PTO fixed,) and try to stay ahead of problems... but, it is always something! But that's RVing, right?
Leaving in a couple minutes for SoCal, and will watch with interest what occurs. Thanks for the reminder about manually downshifting, that was something lost in my memory bank (with lots of other "stuff.")

Safe travels,

Scott Laidig

2004 Magna 6354, Suburban Toad

Re: Transmission temp question

Reply #10 –
Yahoo Message Number: 66295
Scott,

With the history of running 310 degrees, I'm very much with Mikee and wonder if it is locking up as it should. A couple of times I have had to stop on steep grades, road construction, then traffic moved slow and I was struck in first gear. Transmission temp climb like a rocket until we could get enough road speed to shift and get it locked up. Then temps started dropping. Does your Allison control panel show trouble codes? Have to dig in manuel to find out how to access the codes. Might be worth the trouble to see if it has thrown trouble codes. If so, time to find a good allison shop sooner then later. if not then keep trucking and watching.

Have a safe trip.

Leonard Kerns
97' Magna 5418

Re: Transmission temp question

Reply #11 –
Yahoo Message Number: 66298
Scott..."old history major"

Reading your post, about 5 different radiators. There must be a story there finally getting to #5 for a keeper.

AL

00 Affinity no bidet
original radiator

Re: Transmission temp question

Reply #12 –
Yahoo Message Number: 66299
Coaches built after Jan.1 04 had transynd. My coach was built during the fall of 03 and I had to pay $435.00 extra to have the system flushed and transynd installed. At that time Allison was delivering the tranny to CC with transynd, but CC was filling the system with Dexron, thus down rating the Transynd.
TWI 2004 Intrigue 11731

Re: Transmission temp question

Reply #13 –
Yahoo Message Number: 66313
Scott

My Allison frequently creeps up to 310 in traffic and congested city steets. Allison said not to worry if the temperature gets the point where is could cause damage the unit will derate and shutdown. He said they are almost impossible to damage.

Dan 2006 Allure 31348

Re: Transmission temp question

Reply #14 –
Yahoo Message Number: 66315
Dan, the reason it is going to 310 maybe from not locking up in slow in town traffic. Have seen mine go up as well, but when it is start and stop grid lock all in 1st gear, around 220. Hard to keep it cool. My concern at 310 is the breakdown of the oil. Saw a chart on heat and transmission oil life. The hotter the oil gets the more often it needs changed. Even with synthetic, excess heat shortens it's service life, just not near as fast as non-synthetic. 310 is very hot for oil from my understanding. Will see what I can find for better information. If mine was getting that hot of a regular basis, I would add an outside, air to air cooler with an electric fan and change the oil more often considering the cost of an Allison swap or rebuild.

Food for thought.

Leonard 97' Magna 5418

Re: Transmission temp question

Reply #16 –
Yahoo Message Number: 66317
There are two things at work heating the transmission fluid in stop and go situations. One of course is the failure to lock-up as mentioned. The other is the reduced engine heating reduces the cooling fan run cycle.
I learned when my fan controller failed that a fulltime fan cools both the engine and the transmission.
Before I went to an expensive aftermarket cooler I would simply install a switch to open the power lead to the fan controller. This would force the fan to full speed and cause a dramatic drop in transmission temps. The cost and effort is minimal.

George in Birmingham
'04 Allure 31038
George in Birmingham
2003 Magna 6298

Re: Transmission temp question

Reply #17 –
Yahoo Message Number: 66318
Good ideal George. Another trick is to shift to neutral when at a light or stopped and rev the engine. But it takes time to pull off all that heat.

Leonard

Re: Transmission temp question

Reply #18 –
Yahoo Message Number: 66319
Scott:

I assume you don't have a Silver Leaf, because the temp reaches the 300 deg area. The Silver leaf sensor will read in the low 200 deg.verus the 300 due to the location of the sensor. To reduce the temp, put the transmission in N when sitting at a signal light.

John Beach

06 Allure 31309

Re: Transmission temp question

Reply #19 –
Yahoo Message Number: 66326
Dan

I think you need a second opinion.
AL

00 Affinity
 

Re: Transmission temp question

Reply #20 –
Yahoo Message Number: 66333
Leonard

Thanks for the info and thoughts. I am running synthetic and I do the oil analysis hopefully that will give a heads up to the oil breakdown concern. We try to stay out of the congested traffic areas so the issue does not raise its head too often.

Thanks

Dan 2006 Allure 31348