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Transmission Temp range


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In the past my transmission temps would climb when climbing hills etc.  Not sure the highest it eve got to but on my most recent trip I noticed it climbing to ~210/15 periodically during my 5 week trip out west. In the mountains of KY and TN coming south on I75 I saw the same thing.   So now I've started to become paranoid.  I did take the time to hose out the radiator stack after I got back from my trip. 

This week I was doing some work on the coach and decided to go ahead and change transmission filters.   I have about 35K miles on it, although I had not changed filters for 5 years (Covid).  Nothing unusual noted, the filters did not have signs of contamination, I caught the couple quarts of oil in a large paint roller try and had put a white plastic bag over it so I could take a good look at the oil, again I didn't see any problems with the oil.  I measured out the oil that I had drain and then added the same amount to the transmission. 

I then took it on a drive to get it hot and check oil.   It checked out OK.   I did climb a couple short grades and by the time I got back to the my house the temps were ~210F.  I have to back my rig into my garage, backing up a short slope.  It took me a couple tries and by the time I was in the garage the transmission temps was +220 F (I had set an alarm on my Silverleaf for 220 and it had started to go off).  By the time I shut the engine down it was 229F.  During this time the engine temps were normal ~183F

So the other day I went and pressure washed the radiator stack, climbing underneath and spraying with an oscillating type head working around the fan blade and shroud the best I could.  I then sprayed from the outside in through the CAC.  I did check the temp sensor wiring, it was barely on so I pulled it off and slipped it back on tight.  I then took the rig for the same drive and this time by the time I was in the garage the temps were ~210,  but it only took one attempt to get in the garage.  Do I have a problem coming on?

What kind of temps to other see, specifically a Windsor or Dynasty of this vintage 2002 model year with the 350 ISC.  

Is there a way to check if the cooling stack is not plugged?  My radiator is ~6 years old with ~12K miles on it.  But when it was installed Cummins must have had the B team on it.  Had several problems that I had to fix after I got it back, driveshaft out of phase, sheet metal screws missing from radiator shroud, thermovalve screwed up because the left of piece of rag in it.  No telling if they may have left something in the radiator. 

I have ordered a lube test kit from JG Lubricants and will pull a sample and send it in.

Any suggestions on what else to do?? 

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This is a good opportunity to remind coach owners that when they are picking up their coach after having work done, to take a test drive with the shop foreman or technician before paying the bill.  That way any questionable items can be addressed.  Otherwise you are going to get the used vehicle salesman guarantee, guaranteed until he sees the taillights leave the driveway.  Chuck B 2004 Windsor

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Jim,

I believe our CG&J radiators have the transmission cooler built into the main coolant radiator.

My original factory radiator system would always run fairly low temps for both the coolant and the transmission. They were in the range of 180F to 185F unless climbing a grade. Then they would approach 195F - 200F

The new CG&J radiator for whatever reason is giving me higher transmission temps but coolant temps have remained the same. On average the transmission temps are now running 5F-10F higher.

However I have never seen coolant and transmission temps in the range you are now experiencing. I would be looking to see why.

What were the temps of the coolant and transmission right after having the new radiator installed? Are they significantly higher now than back then?

1 hour ago, Rick A said:

Like medical, taking a vehicle to the mechanic can’t result in dire consequences and unexpected surprises. 

I agree, especially if they are not a reputable service center with knowledgeable service techs.

That's why when I find a shop that has an owner and service techs that turn out to be the best, I will ALWAYS take my coach to them no matter how far away I have to drive to get there.

I am very fortunate to have found a few places near where I live in Florida. Josam's for chassis work and Action Mobile for engine work both located in Orlando.

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On my 2004 Windsor the transmission cooler is Not in the radiator.  The cooler is mounted on the left side of the engine.  That cooler is about 6 inches square and about 4 feet long.  The transmission fluid cooler runs in a pipe that is on the inside of the cooler.  The radiator antifreeze is plumbed through the cooler and surrounds the pipe the transmission fluid runs in.  Send me a PM at jbee99807 @ gmail.com remove the spaces.  I will send you a picture of it.  Chuck B 2004 Windsor

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My transmission cooler is built into the coolant radiator.

I really can't remember what my transmissions temp ran with the old radiator, nothing that would raise any alarms in the back of my head.   Now it seems that the transmission temps run higher then the coolant temp.  Normally ~190 vs 183, but then as soon as I get onto any types of grade it goes up and/or stop and go traffic. 

I'm going to take a coolant sample and see what it shows. 

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  • 2 weeks later...
On 9/16/2021 at 9:37 AM, Chuck B said:

This is a good opportunity to remind coach owners that when they are picking up their coach after having work done, to take a test drive with the shop foreman or technician before paying the bill.  That way any questionable items can be addressed.  Otherwise you are going to get the used vehicle salesman guarantee, guaranteed until he sees the taillights leave the driveway.  Chuck B 2004 Windsor

Good point!  I will remember that.

 

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I've been chasing an issue with my temps. I use a Silverleaf VMSpc and my transmission temps seem to have crept up some from what I remember but my just be me being paranoid.

My last trip I noticed temps on the Silveleaf while driving going to ~210F when climbing grades. When i got back home I decided to change filters. Took it for a run to get it to temp and check oil level. While backing into the garage (took me 2 attempts) the temp reached 230F. Don't ever remember it going that high.

Took an oil sample and sent it in, came back fine.

Decided to flush the cooler, which is internal to the radiator, all looked good.

So took it for another drive but this time I compared the temps on the Silverleaf to the dash. During the drive the Silverleaf got up to ~193F the dash was below 180F
When I backed into the garage the temps reached 210F on the Silverleaf and the dash was ~185F.



Is this pretty much normal as to the dash vs any type of other display. I know that Monaco uses a separate temperature sensor, it is mounted in and aluminum block on the cooler port, this may cause enough of a difference as to what I'm showing.

Still trying to figure out if I've got a problem or not.

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Jim,

I gave up on most of my analog gauges as I learned on my very first trip to Alaska that they were NOT accurate. That's why I installed the SIlverLeaf while in Alaska back in 2010. The only gauges left of the dash that I will use and glance at are the large Speed & Tachometer as they are fairly close to the SilverLeaf.

My analog coolant gauge is at least 20F off or more from the SilverLeaf.

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Does anyone know which port on the Allison Transmission is the feed and/or return line from the cooler.  My temperature sensor is mounted in an aluminum block on the passenger side port.  Is this the correct port?  

Since I did have my transmission changed not sure if Cummins reversed the lines or not.  If the didn't remove the lines they would have had to put a union between the two lines, possible but not easy since one has a 90 degree elbow.  

Just trying to eliminate all possibilities. 

 

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Thanks Ivan, that's where mine is.

Do you know if the hose with temp sensor goes to the bottom port of the oil cooler? 

Been doing some reading and  you'd want the transmission out port going to the top of the cooler since that would be hotter then the bottom.  The oil would cool before it returns to the transmission.   Mine goes to the lower port.  Not sure how much difference it wold make but any little bit helps. 

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Heat is what ruins transmissions.  All my race cars had transmission temp gauges.  Transmissions are expensive to replace especially Allison DP type transmissions.  From your explanations you have very (not extreme) high Trans temps assuming your water temps are normal.  I have driven those high hills on I-75 many times and my trans temps rarely go over 200 Deg F if that.  I monitor my trans temp from start up to trip end as part of the three extra digital sensors on my dash.

Hopefully you can get a good result on your trans fluid sample saying it is still good.  Trans fluid does wear out but can last a long time with proper filter changes.  I hope you are successful in finding what is causing the high temps of the trans fluid.  Myself, I would spend the time and money to take it to an authorized transmission dealer.  In my case that would be an specialty Allison Trans shop, not a Freightliner/Allison shop.  They would do an analysis of the fluid, change the filters if necessary and take it for a test drive to verify the trans itself is ok and that the cooling system is the problem if there is a problem.

It is always nice to be able to do things by ourselves but there are also times to let the experts do the job.  Good luck and let us know how you make out.  Stay well, Stay safe

  

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