My wife has a 2005 GX 470. We bought it new and its been in great condition. Although I normally look for a more economic solution, we have had it serviced by the dealer since we got it. It has approx 140k miles on it and we have never had any major issues. We recently took it to the dealer for a minor service (oil change, fluid level cks etc). When my wife got it back she noticed something wrong immediately. The car was surging and sputtering. I did not drive it but at the time it sounded like a fuel filter issue. She called the dealer to get back in but couldn't until a few days later. In the meantime the car overheated bigtime ultimately causing a crack in the engine block. I did not know at the time the engine and transmission are both cooled by the radiator. Apparently the surging was caused by something amiss in the transmission which seems to be related to the cooling issue. It appears that something happened when it was serviced that disrupted the cooling of the engine and the transmission. The dealer says that they didn't do anything and it is normal wear and tear and just coincidental that it occurred right after it was in their shop. I beleive that something they did or did not do caused the problem. I know a little about cars but can't figure out what could have happened that would have caused this issue. It is very clear to me that the issue occurred on their watch and was not "coincidental" wear and tear. I need your help and thoughts as to what could have occurred. The dealer and I are still talking......

 

wow. if you can check the tranny fluid while engine is hot and running that would be a start to see if overfulled or underfulled

 

So if if the transmission fluid was over filled would that have caused the series of things that resulted in the engine overheating? I can't start the car, the engine is ruined and sitting at the dealership. The dealer told me that the transmission is cooled by a separate compartment in the radiator . How would the engine have overheated if there was a transmission fluid issue.? Clearly there is a connection but its not clear. We definitely had a transmission problem immediately after the service. But how would this lead to an overheated engine?

 

Yes there is a transmission cooler and I believe it is interconnected to your radiator.

It is impossible to tell exactly what caused the problem over the internet - it's probably difficult enough to diagnose in person.

If you are talking about potentially coming out of pocket for a new engine and transmission, you may want to consult with an ASE certified master mechanic at an indpendent shop that has experience working on Lexus/Toyota vehicles. I would even go so far as to suggest "buying" some of his time to come look at your vehicle at while it's at the dealer - say he's your Uncle Fester. He could poke around with a flash light, from above and underneath to check connections etc, which may lead to some clues as to the cause.

Curious, w/140k miles on your truck, when was the last time you had your radiator flushed and fluid replaced?

 

Since we have had it serviced by the Dealer at every interval, if it was scheduled maintenance it would have been done. I have kept the invoices that reflect the service history but haven't gone back to double check if the radiator was flushed. I'm pretty sure it has been.