Auto Tran Faliure due to Radiator Fail?

Heys Guys,

(2006 V6, Double cab, 101,000 miles, A750E(?) automatic trans)

Wondering if anyone has had similar issues... Last Thursday about 200 miles into a 300 mile trip the Truck started jerking on down shifts from 5 to 4 while under load. At highway speed 65+ uphill and when tranny downshifted it felt like you ran over 5-6 speed bumps at speed. The whole truck shook and rattled. The truck was not overloaded... my wife, daughter, dog and a couple suitcases. It only did this on downshifts, not up shifts on the highway. After getting off the interstate I noticed it was doing it at all shifts. Took it to the Toyota dealer that my brother uses (we are now 300 miles from home) and they diagnose it as bad transmission. They suggest A) trade the truck in, B) $3600 for Toyota Remanufactured Tranny, C)$2600 for a used Tranny with less than 50k on it. I looked a new 2012 but they really low balled me on the trade.

So I took it to another independent shop for a second opinion. They have now concluded that the Tranny cooler internal to the radiator has leaked tranny fluid into the antifreeze and antifreeze into the tranny. Thus trashing the Tranny. So I'm looking at a new radiator, an engine flush, and rebuild the tranny.

The second shop said this is relatively common on the Nissan Frontiers, except the only difference is the transmission ECM is inside the Nissan's transmission so it gets trashed too, to the tune of another $1000 just for the ECM. The Toyota ECM is external to the transmission and can be re-used.

Scarry thing is Toyota Tech never mentioned the radiator.... So I don't know if knew to look there or if they even looked at the tranny fluid. Additonal note: I'm religious about the maintenance and don't overload the truck. 98% of that 101k is highway commuting to work and back. Tranny was seviced at 60k like the book says and would have been due again at 120k.

Anyone else had similar issues? Anyone seen or heard of similar?

Thanks, Chuck

 

WOW--never heard of anything like that before-.
I have replaced radiators on cars and realized the tranny cooling--just never heard of it trashing the tranny--

 

I just had my transmission replaced because coolant was found in it from the radiator. It cost $4,700. I only had 54,000 miles on it. Dealership said it was a freak happening. I'm not so sure as I've found radiator leaks in first generation tacs and in sequoias.

 

Sorry to hear of your troubles, I can't offer any technical advice other than that sucks. What dealership and where did you have it checked on your trip?

Unfortunately, you know they're gonna low ball you on the trade. Regardless, weigh the loss in trade in to the price of repairs. If you do trade you're going to have a nice new truck with no worries for a few years.

 

This was an issue on the 3rd gen 4runners.

 

I seem to recall this as well.

I know I have heard of auto trannies in general meeting this fate.

 

Thanks for the condolences....!

It looks like two weeks before I'll be able to get the truck back. Due to the holiday week it will take a couple of days to get the new radiator. The Tranny rebuild is a two day job. So that is going to put me into next week. I've got to make the 600 mile round trip to pick it up and can't afford a day off right now. So I'll make the trip next Friday night and return on Saturday. I'm lucky to have family in the area and can have one of my brothers or Father-in-law go check on it if needed. Untill then I'm in a rental car.

When I get the truck back I'll have to decide what to do....keep it or trade it. I am particularly enjoying not having any car payements at the moment. So it will be a tough decision. I've run most of my Toyotas (this truck is my 9th Toyota) to 130-150k before even thinking of trading them in. With a kid in college I might hold on to this one for a while.

BTW... Toyota dealer was/is in Wheeling,WV. (Near the Cabela's) The service writer James was really cool about getting the truck in with virtually no notice on a Friday to check it out. Can't fault his mechanic for not noticing the antifreeze/transmission fluid mix. I can only assume they would have caught it once the job started. The salesmen on the other hand were doing what salesmen do.... ehh no big deal. I did have them price out a 2012 Pyrite Mica double cab.... It was sweet! I just did not feel comfortable with the trade in offer. Even facing the $3600 Tranny replacement I felt the 2006 was worth a lot more than they were offering.

Chuck

 

Seen this a couple times. Trans fluid looks like a pink milkshake. Trans cooler inside the radiator ruptures. Like the idea of independant trans cooler.

 

So here goes an update.... The tranny has been rebuilt, radiator replaced, engine flushed. I picked the truck up last week and still had a shudder at the downshifts. Took it back to the shop and one of the mechanics rode with me. No disputing it, it's still there. So the following Monday back at the shop they get a newsletter from Sonnax (aftermarket transmission parts co.) and there is an article about our very transmissions, the Toyota A750E. And this article talks about this shudder! The concensus is the "main pressure regulating and boost valve assembly" has worn out. This is not neccesarily due to the antifreeze contamination. We believe the shudder may have been there and the introduction of antifreeze only made it more noticeable. Admittedly the shudder is not as prevalent as it was before the rebuild. I've had a drive line vibration when under light load since way back around 35,000 miles. (I'm at 101,500 now) It will be interesting if it is gone when this is all done.

Unfortunately (for me) this is a pretty reliable transmission and parts are not all that common in the aftermarket. My mechanic searched for a used one or a remanufactured one but could not track one down. They are apparently that rare. A new assembly is $650+.

And yes the secondary transmission cooler was suggested. I opted for the whole new radiator since it had 100k on it and had been contaminated with the transmission fluid. The price difference was only + $200. Oh and yes Pink milkshake was the exact description of what came out of both..the transmission and the radiator.

Google Sonnax and go to their page.... isn't it kinda ominous that the A750E/F transmission is featured on their front page?

Another week in the rental car and I hope to be back on the road. you just don't realize how much you use the truck until you don't have it.

Chuck

EDIT: to Add: The nationwide transmission shop's tech dept who gathers input from all over the country says no one knows for sure how long the transmission will run with antifreeze contamination. So my cooler could have been leaking for a while. They assume it takes a while for the antifreeze mixutre to destroy the clutch pads and o-rings in side the tranny. So my advice is to pop that radiator cap every once in a while and take a look inside there. The coolant was foamy in mine.

 

Hey ya'll,

Final update... picked the truck up yesterday. Took it on a 340 mile test drive back to Northern Virginia. It is running great! Shifts are smooth and barely noticeable at any speed or load. Looking back I think it has been having issues for a while. We suspect that pressure regulator/boost assembly had been failing for a while. The antifreeze contamination just brought it to light. In a week or so I will stop by an Aamco here locally so they can take a look underneath for any issues and I'll have the engine/radiator flushed one more time just to make sure we've got it all cleaned out.

I can't say enough about the Jeff and the guys at Aamco Transmission in Wheeling, WV. These guys are true mechanics, they put a lot of time into rebuilding this transmission and doing the research to learn about this transmission and it's issues. Then fixed it right! (rather than just throwing parts at it like a lot of guys do now a days) They were also great about keeping in touch and were most sympathetic to my concerns about being so far away. They were conscious of my time in the rental too. But also not willing to give the truck back until it was done right. Great guys!

All told I'm in it for about $3800. (Rebuild, New Radiator, Pressure/Boost Valve, Engine flush) I'm a happy camper. I'm not so happy to have had to put that much into a Toyota vehicle. This truck is my 9th Toyota since 1989. I've never had to put much more than tires, brakes and oil, and a couple O2 sensors on the 2000 Sienna and run them all to well over 100k with no major mechanical issues. I guess my luck finally ran out.

Strangely something else of possible note.... I did not detect the drive line vibration that I have had since way back around 36-40k. I originally thought was the front differential bearing vibration or the center carrier bearing. I will have to drive it a bit more on my more familiar commute to know for sure. After all it's been over a month since I last drove the truck regularly. And the roads between here and there do not always lend themselves to a smooth surface to test it on.

My advice to everyone....check the condition of those fluids more often as these trucks age.... hopefully save yourself the same fate.

Chuck

 

Your gallery photo shows you pulling a trailer. Did the truck have the factory tow package? Should be a separate transmission fluid cooler like this one:



(Photo from OZ-T)

 

Glad things finally came out good for you. Sorry that you had to experience that but at least its not a mystery any more.

Thanks for the tip, I'll be checking the radiator fluid regularly.

 

The internal trans cooler warms as well as cools the trans fluid. It makes for better drivability in cooler climates. The aftermarket cooler goes before the radiator to lessen the cooling load of the radiator.

Glad to see you got it taken care of OP.

Older vehicles(15+ yrs old) experience your problem on a frequent basis. Some because of improper maintenance, some because of age. It shouldn't have happenend to you so early. They usually corrode on the outside before an internal failure.

An experienced tech, who works on late model vehicles would have caught it easily. Sounds like your dealer's tech was not.

 

Yea, it does have the tow package and the external trans cooler is still in place. Unfortunately I have not pulled the trailer in over two years. The transmission "warming" issue was the other reason for not abandonning the internal cooler. We discussed it at the time. But I'm one of those "essential employees" who have to report no matter what the weather, I felt I should keep it in the radiator.

 

I'm confused. wouldnt it be one or the other, not both, Either external or internal?

 

The output from the trans goes to the external/add-on cooler first. Then, it goes into the internal/radiator cooler. The external cooler sheds what heat it can, then the internal cooler either finishes the job, or keeps the trans at engine operating temp. It ensures the best trans operating temp. Too cool=too thick of fluid. Too hot=burned/too thin fluid.

 

Ok gotcha, thank you so Vury much for that explanation, I was feeling a tad slow on that one.

 

This is unexpected. I thought the tranny fluid heated up quickly enough on its own by working through the tranny. I also didn't know there was any kind of "intercooling" in the radiator. I thought the top portion of the radiator held antifreeze, while the bottom few rows held tranny fluid for trucks w/o the tow pkg. Learn something new every day.

 

I am trying to find data that shows the Toyota radiators or radiator lines have faulty composition. So far I have found evidence of Seqoias and some Tacomas having this radiator leakage into the transmission. I need more to push for a recall. Toyota investigated my situation, declined reimbursement, and said this was the only way to get some money back on the the $4,500 (dealership) to replace my radiator, transmission, and clean the lines, etc. It is a situation that is already catastrophic when you take it in to the shop. Radiator fluid simply should not leak into the transmission like this.

 

This is all too common on 3rd gen 4runners.