BAC Forum

General Boards => Technical Support => Topic started by: Don Colapietro on January 11, 2020, 03:26:36 PM

Title: 2006 Monterey trans cooler
Post by: Don Colapietro on January 11, 2020, 03:26:36 PM
Has anyone replaced the the engine coolant to trans fluid heat exchanger with an air to fluid cooler. My trans fluid has always seemed high, 188-194 and occasionaly over 200. fluid and filters replaced with no change. when it does heat up, it takes forever to come back down. I have a brand new aluminum trans cooler, just not sure where to mount it. Thanks, Don Colapietro. 2002 Beaver Monterey Lagoona III C9 400Hp 239 940 6199
Title: Re: 2006 Monterey trans cooler
Post by: Gerald Farris on January 11, 2020, 04:46:09 PM
Don,
At 188-194 your trans fluid temperature is not too high. That is the within the preferred operating temperature range for an Allison trans. Installing a fluid to air cooler can cause your transmission to run too cool, especially in colder climates, and that can be detrimental to the very long life that Allison transmissions are noted for. The need for an Allison to run at its preferred operating temperature is the reason that virtually all applications use a liquid to liquid cooler in the engine cooling system. This type cooler not only prevents the trans from overheating, but it also helps the trans warm-up faster.

Gerald   
Title: Re: 2006 Monterey trans cooler
Post by: Joel Ashley on January 11, 2020, 07:27:51 PM
Don, not that Gerald needs backing up, but we have a setup similar to yours and he’s absolutely right as usual.  Your numbers are right where they should be from what I’ve read here on the subject over the last 13 years.  In fact my similar coach has always run at those same tranny temps.  I don’t know what criteria you are judging by, but for your current application they are not too high.

Your question states yours is a 2002 model year, but I’m assuming you meant ‘06 as per your profile at the bottom and your post heading, and I’m not sure there was a 400hp C9 option in ‘02.

Joel
Title: Re: 2006 Monterey trans cooler
Post by: Don Colapietro on January 11, 2020, 07:43:31 PM
Thanks guys, those temps just make me nervous. yes, it is an 06. what is the max safe temp??




Title: Re: 2006 Monterey trans cooler
Post by: Joel Ashley on January 11, 2020, 10:50:08 PM
Allison trannys are pretty stout and these days pretty self-protective.  If you have Transynd fluid then that’s even more protection from overheating. 

When reading others’ tales I see all kinds of temps being tossed around.  It varies because everyone drives differently, have different radiator setups, different loads, different radiator cleanliness, and different fluids.  And they may read the temp from different sensors at different drivetrain locations.

Allison would likely tell you that 170-205 is normal, at 230 have it checked if that stays a consistent number, but don’t fret much unless it approaches 250.  Even then Transynd would protect things.

Joel
Title: Re: 2006 Monterey trans cooler
Post by: Steve Huber Co-Admin on January 12, 2020, 04:54:20 AM
Per Allison, normal fluid temp at sump is 160-200 and at converter 180-220. I read in an Allison blurb a while back  that up to 240 is OK. Mine consistently runs at 210-220 (per Aladdin) in summer and cools down slowly while engine runs at 204 nominal. Others with the same engine/tranny and year coach report same while some report tranny runs within 5-10 degrees of engine temp. Fluid samples on mine indicate no issues.
Steve
Title: Re: 2006 Monterey trans cooler
Post by: LaMonte Monnell on January 12, 2020, 06:21:28 PM
My Contessa with a CAT 3126 runs with a transmission temp of 200. Occasionally climbs to 210-215, but thats in the hills in July and August when its 100 degrees outside. Engine coolant stays at 195-199 until its time to clean the Radiator and CAC, then its up to 215!
Title: Re: 2006 Monterey trans cooler
Post by: Al Anderson on January 13, 2020, 07:09:32 PM
Don, I agree with everyone that these temperatures sound normal.
If you want to give yourself some added protection, assuming you haven't already, change out your fluid and filter to the Allison Transynd Full Synthetic.  By it nature it will have less breakdown at the higher temperatures and give you that added safety margin.