Radiator keeps taking my Transmission out

[BG1988]

I never looked in to this because I did not regularly build transmissions in my shops. What is too high a temp for the trans? Just when it gets to red on the gauge? Lower temp for a prolonged period of time? Since I have my trans temp gauge, even when I am driving the crap out of my rig, has never exceeded 180 degrees.

158F is normal on my tahoe... i think the highest i have ever seen was 165F in the summer when it was 110 outside..

it takes about half hour of driving to get it to that temperature.

varnish starts to form around 220F

 

[OR VietVet]

Yes, it takes quite a while to get the temp up to that. The 180 degrees was after 3 hours of heavy driving with a lead foot. I get to the point where I don't notice it at times because it never climbs higher.

 

[swathdiver]

2006 Chevy Tahoe LS 5.3 engine

Sooo.... been dealing with multiple transmission rebuilds since last June. Truck has 242,109 on it right now. Tranny last year started to go bad so I had a reputable local shop rebuild it. Couple months later the torque convertor went bad again. They replaced it. Couple months later, same thing happened along with another gear busting going up a mountain. Had to tow 100 miles back home. They rebuilt again and the same results. However..... this time when they opened it up the tranny fluid looked like stawberry mix fluid. They said the radiator tranny cooler had failed and dumped coolant into my tranny cooler lines. They would not cover it under warranty. I get it.... pissed, but I get it.

Took the tuck to AAMCO and had them rebuild it. No offense to the other company, but I wanted someone else to rebuilt.. just in case. Not gonna keep up with the same story, but the same scenario above has just happened again. This time though, AAMCO installed a new radiator and cooler lines so it is under warranty.

It is currently being rebuilt again. This will be the 2nd radiator AAMCO will install. We decided to bypass the radiator this time, as I don't tow a lot of stuff and quite frankly I am not gonna have the tranny die from coolant again.

My question is this.... is there something lurking and hiding in the coolant system that is causing the radiator cooler to fail and take the tranny out? Water temp has been spot-on and never any issues.

The radiator is the most replaced item on this truck with a grand total of 5 since I have owned it. Bought it with 125,000 on it. The other radiators just busted around the drivers side and leaked radiator fluid.

Any help with this would be great.

If the fittings for the internal transmission cooler are not installed correctly, it will leak. Use only GM OE radiators or the ones approved by the guys on this here forum, they've learned painful lessons and shared their experiences with us.

Are you still running GM Dexcool in your radiator (red or orange fluid) and not the old green stuff?

 

[newtek007]

The radiators that have gone in this truck came from Oreillys several times and one from NAPA. None of them lasted. Went up to the shop today to do some talking. They state that pressure tested the lines and everything was in spec. Not really sure about what brand they used, but it was not OEM. Think they are getting an OEM this time.

As for the Core, I am also suspect of it.

The person that had the Astro van, what led you to determining the ECU was bad? This has been on my mind also. I have replaced the entire drivetrain since last year. Honestly, I have put too much money into this truck, but I really like it...

 

[newtek007]

If the fittings for the internal transmission cooler are not installed correctly, it will leak. Use only GM OE radiators or the ones approved by the guys on this here forum, they've learned painful lessons and shared their experiences with us.

Are you still running GM Dexcool in your radiator (red or orange fluid) and not the old green stuff?

Yes. It has the orange GM Dexcool.

 

[Mudsport96]

The radiators that have gone in this truck came from Oreillys several times and one from NAPA. None of them lasted.

Bingo found it. Oriellys rads are junk.. put one i my dads 02 hd and it died and took the trans with it. Was a known issue. Local oriellys paid for a new gm 4L80e and GM rad to be installed no question asked

 

[Jimmyy]

The radiators that have gone in this truck came from Oreillys several times and one from NAPA. None of them lasted. Went up to the shop today to do some talking. They state that pressure tested the lines and everything was in spec. Not really sure about what brand they used, but it was not OEM. Think they are getting an OEM this time.

As for the Core, I am also suspect of it.

The person that had the Astro van, what led you to determining the ECU was bad? This has been on my mind also. I have replaced the entire drivetrain since last year. Honestly, I have put too much money into this truck, but I really like it...

The company that rebuilt the transmission twice and replaced it twice (2 different shops) figure it out. It was something to do with OD and 3rd trying it engage at the same time or something like that. It was a work truck so I never seen the paper work I just had the pleasure of being stranded a few times. It did end up with over 300k on it.

 

[newtek007]

Soooo.... Still dealing with the transmission. I decided to take it to AAMCO and have them rebuild the tranny. It worked and then another strawberry fluid issue. They put a new radiator in and we decided to bypass the cooler all together. The tranny lasted about 5 months, and then it threw a slipping code. Took it back and they got it apart and said water was again in the transmission!!! I still have a warranty on it, but the shop called me and said they have no idea how water is getting in the transmission. They stated there are only 2 ways for it to get in: 1. drive through high water, 2. or someone is putting water in it on purpose. Needless to say, I wans't too happy with this news as neither of these events have happened. The truck is driven on the road... period. No off roading or water fording. Anyway, they have agreed to rebuild the unit under warranty and now they are telling me that they will not cover anything from this point forward due to them thinking funny business is going on.

Does anyone have any ideas why water would still be entering the transmission?

-The stock radiator has been bypassed
-They routed the cooler line to the small OEM cooler on the front. (AAMCO stated they installed a new cooler, but it is indeed the unit I installed, not them). Not fighting that battle.
- I have orded another cooler and will be replacing it when I get the truck back.
- I have heard that rain water could get into the dipstick tube. I know the 2500 trucks fron 04-06 had this problem. TSB 05-07-30-017B.

 

[rockola1971]

There are only 3 ways for water/coolant to get into a tranny. Via the transmission cooler that is built into the radiator, someone is purposely putting water/coolant into your tranny or you are driving through deep water and it is entering your vent because your vent hose is off. Or the shop is lying to you for whatever reason.

 

[newtek007]

Well, 1. nobody is putting water in the transmission. 2. It has not been driven through any high water, except when it rains on the street. 3. no real reason that I see for them to be lying other than they can't figure it out and they have already made their money off me. I would have assumed they would have been able to figure this out as they ARE a transmission shop.