Tranny cooler failures

[The Prez]

Just curious if there were any other people out there that have had EXTENSIVE failures of their tranny coolers. I'm in a 2003 Kountry Star 39' DP w/3 slides and a 330 CAT/ Allison 6 spd/Freightliner set up. I took delivery 5/1/03 and am now on my FOURTH Tranny Cooler! They keep developing pinhole leaks and eventually seep into the cooling system to the point where the Low Coolant Sensor in the rear of the radiator tank gets "coated" with the tranny oil that it "thinks" there is no coolant and activates the buzzer alarm up in the dashboard instrument cluster. I'm fortunate that that circumstance happens or I'd just be merrily going down the road some day and start overheating due to EXCESSIVE oil in the cooling system. So far, Freightliner has not given me an explanation as to why I'm experiencing so many failures on my particular chassis. Anybody got anf pregnant ideas?

[The Prez]

Just curious if there were any other people out there that have had EXTENSIVE failures of their tranny coolers. I'm in a 2003 Kountry Star 39' DP w/3 slides and a 330 CAT/ Allison 6 spd/Freightliner set up. I took delivery 5/1/03 and am now on my FOURTH Tranny Cooler! They keep developing pinhole leaks and eventually seep into the cooling system to the point where the Low Coolant Sensor in the rear of the radiator tank gets "coated" with the tranny oil that it "thinks" there is no coolant and activates the buzzer alarm up in the dashboard instrument cluster. I'm fortunate that that circumstance happens or I'd just be merrily going down the road some day and start overheating due to EXCESSIVE oil in the cooling system. So far, Freightliner has not given me an explanation as to why I'm experiencing so many failures on my particular chassis. Anybody got anf pregnant ideas?

[rebelsbeach]

Mr. Prez, WELCOME to iRV2!!

In my former life a few months ago, I owned a 2006 Vectra that was delayed from delivery to me as they discovered a leaking tranny cooler....
Sounds like three years and they still have an issue,although my coach was the 400 Cummins...

Glad to have you on board iRV2!!

Keep us posted on your issue and let us hear more from you...

["007"]

Welcome George to irv2.
Sorry to hear of your problems I thought the trans cooler was a separate cooling unit not built into the main radiator. Have you seen the one they removed when they changed it.
Some of the FL owners should be along to help, enjoy the forums and post often.

[The Prez]

The cooler is separate and apart from the radiator. But it is mounted to the crossmember that goes east and west underneath the radiator and the coolant is routed THROUGH the cooler to cool the tranny fluid! That's how the fluid is finding its way into the radiator.

[Cruzer]

4 coolers sure is a lot of coolers. I can see a defective one, or I can see one that wore out, and I can even see the remote chance of the 2nd one being defective but I can't see 4. If they were all bad you'd be hearing screams from all over the web from other RVers too. I'm thinking that there has to be something that's causing them to fail. Being a simple enough system there aren't too many things that could affect it. My guesses?

How about transmission pressure. The fluid pressure is regulated in ther Allison. If it's too high, the extra pressure may tend to "pop" things.

Is the coolant fresh? Have the SCA (PH) levels been checked? If the coolant is heavily acidic it may be eating at the cooler tubing causing it to corode and weaken.

In the same manner, is the tranny fluid clean and no contamination found in it? If anything acidic is in the fluid it could have the same effect.

Other than that, I can't think of anything else that could posibly affect it and cause pinholes to appear.

[The Prez]

Hey Mark: I must say that you've offered up some "new" possibilities. Never thought about the pressure being too high coming out of the tranny to the cooler. This thought has merit. Although I've hed the tranny serviced twice at the local Allison shop here in Mobile and they've never said anything about that- - - but why would they, right? I'll be stopping by their shop next week to discuss this very thing and give them the complete history.
The ideas on the coolant are probably "not a factor".Each time we've replaced the cooler the Freightliner people have flushed the cooling system TWICE ( at my request ) and reloaded with BRAND NEW coolant right out of the cardboard case- - - and I'm talking a BUNCH of it!
As regards the tranny fluid, it's still got 15,000 miles to go on the last changeout. So I'm guessing that it's not the culprit since I had a cooler go out with old fluid AND with new fluid. Thanks again for taking the time to get the gray matter "in gear" for me.

["007"]

Just asking a question if the anti gets trans fluid in it, wouldn't the Alie trans get anti within it infecting the trans fluid.

[The Prez]

Hey 007: I know that seems like the likely happenstance- - - however, thru the 3 failures there has never been any coolant in the tranny fluid. My guess would be that pressure and viscosity have something to do with it. Pressure when the engine is operating and viscosity ( thickness ) when the engine is not operating. I could be sorely mistaken here, but it's the only LOGICAL thought I can muster.

[Cruzer]

Your Alllison's fluid pressure is much higher than anything the cooling system could muster up so the oil would leak into the coolant, not the other way around.