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Trans temp range?


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Hey guys 01 signature with ism. Trans was running at about 200° on the way home today. Usually remember it running 180 or 190°

Whats your normal range for Trans temp. @ or around 65mph?

200° just seems on the higher end.

 

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My trans generally runs under 200, in the 190-200 range driving 65mph in 100 degree temps. A lot of viables. Ambiet air temps, load, length of the climb or downgrade. I think the highest temp I've seen was actually on a long steep downgrade in 110' temps and trans was locked in 4-5 gear using the engine brake for 5-10 minutes off & on. Temps up to 215'.

Temps over 200 for short periods will be fine with the right atf. I think the allison ATF is good to over 240

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Transmission temps can have a huge range depending on ambient outside temps, terrain, condenser cleanliness, mountains, etc.

It took me a while to learn what the "average normal" operating range for the 40-foot 2002 Windsor I had owned for 18+ years was over time which has a Cummins ISC-350 with the Allison MH3000 Transmission. It turned out to be about 185F for the Cummins engine and 180F for the Allison. Then I had to have a new aluminum radiator built and installed by CG&J in Gadsden AL. After that new installation the transmission temps increased to 190F for whatever reasons.

Now I own a 42-foot 2006 Dynasty which has a Cummins ISL 400 with an Allison MH3000 Transmission. The engine runs about 190-195F and the Allison runs about 200-205F depending on grades. I have been running 55-62 mph which gives me the sweet spot for the ISL. It will actually stay in 6th gear below 55 mph which amazes me.

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Posted (edited)

Thinking maybe give the radiator a good flush. Looks like a lot of gunk on the trans as well. Possible leak so ill clean that as well.. Electronic diagnostic on the shifter indicator says fluid temp and level are ok but manual check I think it's high. 

Allison 4000 series manual says 180-200 is normal with 200-230° normal for towing +90° or hills. I was pushing 65mph most of the way.. maybe dropnit down to 60 and see.

  I really don't want to say wait and see as I though 200 was high but...

Edited by Romeo84
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This is all good info, and I’ll add another tidbit from personal experience: the “normal” temps for a given Coach will vary depending on how Monaco chose to install the sequence of coolers in the radiator “stack”. We have friends with a similar Exec, ours being 2005 and theirs 2006. We have a Detroit and they have an ISX. My oil temp will tend to run 7-10° warmer than the coolant while the transmission runs 10-12° cooler. Theirs is the exact opposite. A little examination in the engine compartment found that their oil and transmission coolers were in the reverse position to ours. Go figure.

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Posted (edited)
On 5/30/2022 at 7:00 PM, Romeo84 said:

Hey guys 01 signature with ism. Trans was running at about 200° on the way home today. Usually remember it running 180 or 190°

Whats your normal range for Trans temp. @ or around 65mph?

200° just seems on the higher end.

 

I have the Allison 4060 transmission and a cummins M11 450 HP engine. The Allison owners manual online says normal operating temperature is 160F to 200F and the danger zone is 230 degrees F. Mine runs in the mid 190s normally, but will go up to 200-205F on a long pull on a warm day.

karl ‘98 Signature

Edited by Karl Hampton
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Only time I've seen my trans temp climb was crawling along the interstate at walking speed for miles, with a 7 vehicle pileup ahead. 

Traffic never really came to a complete stop, which would have given me a chance to shift to neutral.

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Coming down a long 6+% grade is Colorado yesterday I did see 197 for a short time near the end of the grade.

Tim 

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Looking into it further and after a little chat with Allison tech... I pulled an extra 2 and a half gallons out of the transmission...that's what was causing the mild increase in temp. Lucky guess when I saw a 10° spike. 

No idea where who or how. Had to make sure the trans cooler doesn't mix with the hydraulic tank because that's a lot of extra fluid. 

Now the stick and shifter diagnostic match up and are both happy. 

Allison did say at some point it would heat up and burn a lot off or leak out somewhere.  They said it's common for service stations to add too much when doing filters. The initial fill capacity of my trans was something like... 36 quarts but the refill after filter change is only 26...

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2 hours ago, Romeo84 said:

Looking into it further and after a little chat with Allison tech... I pulled an extra 2 and a half gallons out of the transmission...that's what was causing the mild increase in temp. Lucky guess when I saw a 10° spike. 

No idea where who or how. Had to make sure the trans cooler doesn't mix with the hydraulic tank because that's a lot of extra fluid. 

Now the stick and shifter diagnostic match up and are both happy. 

Allison did say at some point it would heat up and burn a lot off or leak out somewhere.  They said it's common for service stations to add too much when doing filters. The initial fill capacity of my trans was something like... 36 quarts but the refill after filter change is only 26...

Did you have the transmission serviced?  When was it done. 

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Posted (edited)

I checked when i came home and the temp was up in 200s. I don't remember the specifics. I know the stick was about 8 inches over the full line.. the pad did say ol hi don't remember the number that followed. But 2 gallons over will cause an "aerate" or foam  problem I guess which won't allow the trans fluid to cycle properly and eventually increase temp.

 

Checked running in neutral

Edited by Romeo84
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Hey folks I have and Allison 4000 and Cummins ISX/15Liire/525HP in "03 Sig.........my "normal" operating tranny temperature range is 210F to 230F / no issues - ever, that's why I changed to Transynd Synthetic, to ensure it I don't have issues and of course; verified all of this with my Allison authorized factory representatives.

Big Engine, Big Tranny, Big Coach (47,000Lbs)......lots of heat and I didn't want issues \ in mountains or flat-landing, I watch trans temps carefully while traveling to ensure I never do have issues!

Remember when asking the question about "normal" operating conditions: everything is relative, OK? Malcolm

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