ATF Boiling over?

[JHZR2]

Hi,

My girlfriend has an older 4runner. A few months back, the radiator went bad, and there were a bunch of other problems.

Twice now, there have been situations where, when going up very steep hills, where there is high load, all of a sudden the trans will stop transmitting power, a hissing sound will devellop, and ATF will being bubbling or seeping out past the seals of the transmission pan, onto the ground. When it cools down a bit, the transmission will work again fine.

The ATF is a light pink/brown murky color. This I suppose is indicative of water contamination, and what I believe is happening is that there is water in there, and when it gets hot enough, the water starts to boil, causing the internals of the trans to not work, and the vehicle to go nowhere.

There is no sign whatsoever of crossover of ATF into the radiator, which I would assume would also occur if coolant was getting into the ATF.

I plan to drain it from the plug, refill as best as I can, drive a bit. Drain again, drive some more, drain, drive, etc. This way the contaminants get slowly washed out (Ive read this is better for ATs). After cleaning it thuroughly this way, then drop the pan/filter and replace all the fluid I can.

Is this the best method? Is there anything else to check? It shifts fine and operates great until the hissing, etc starts. Unfortunately there is no fluid exchange device available, as my gf lives on an island...

Thanks,

JMH

 

[Chris142]

Check to see if the trans lines got kinked when the rad was changed.

 

[keval85]

If I owned it I would get the transmission flushed and install a good aftermarket trans cooler.

 

[jorton]

Does this model have a drain plug on the torque converter?

 

[Matt_S]

Contaminated fluid is one of the best reasons out there for getting a transmission flush. Wherever you take it, they should do a pan service first as well, even if it costs extra. You could change it 3 or 4 times, but that's not a very good use of fluid, you won't get 100% of the bad fluid out and it'll probably cost you the same in the end.

But first, I'd recommend following Eddie's suggestion about getting the cooling system pressure tested. You don't want to flush the trans, only to find out you still have the original problem.

 

[Eddie]

Since the cooling system runs at 15-18 psig I suspect the water is coming from the radiator via the transmission cooler portion of the radiator. Do a radiator pressure test at maximum pressure. Keep pressure on the radiator for say a full 5 minutes.

 

[crashz]

It sounds like the coooler lines were capped off with the installation of the new radiator. Check for that first. Make sure there is a clear fluid path for the transmission fluid across the cooler circuit. This can be found simply by disconnecting the cooler lines at the transmission and using a little hand pump to pump clear transmission fluid through. This can be done in tandem with the coolant pressure test. If nothing comes out the other line, there is a restriction. If coolant comes out with the atf, you still have a radiator problem. If the fluid comes through easily and clear, then you'll want to drain and fill the transmission a few times to clear the old fluid out.

It may be a good time to add an addtional cooler, but the stock system should be working correctly first.

 

[Jim Spahr]

What was done when the 'radiator went bad'? Was it replaced or repaired. It sounds like the problem lies in the radiator which also supplies cooling for the auto trans as well as the engine coolant. First, find out if the ATF is contamenated with engine coolant or is it just 'burned', as in over heated. Both conditions will cause the ATF to discolor. If the radiator was replaced, did they replace with the correct rad. with the auto trans cooler? Was the trans cooler correctly connected to the trans cooler lines? Sounds like you need a new rad and then get a complete flush of the ATF.

 

[mechtech]

Sure sounds like coolant in the ATF.
Pressure test your cooling system first.

 

[Mike_dup1]

You said you had radiator problems and I think you still do. You don't say who repaired it but its safe to guess they did something wrong.

Did the radiator gets repaired or replaced.

If repaired, then get rig of it.

If a new one or used, go back and make sure you have the correct one for the car. With radiators, cheap is almost always bad, go for quality and stay away from cheap parts.

There has got to be something wrong in the cooling. The fluid is most likely getting hot and is the trans cooler does not appear to be doing the job. There could be a bent line, or a kink that appears under pressure. Or the radiator is defective.