Transission Overheating?

[kenc195]

1997 Honds Passport (alias Isuzu Rodeo) I have noticed on 2 occasions within the past week that when accelerating from a stop, some slippage then sudden connection of the transmission.

In the same period I have been running well above normal coolant temperature. Just below the red zone.

Can my tranny be cooking itself and heating the coolant in the radiator since the tranny fluid uses the bottom of the radiator for fluid cooling?

Also, 181,000 miles and I don't know if the tranny has ever been serviced. Would a system flush help it or kill it?

[amigo-2k]

It is most like the other way around the radiator fluid cooked the tranny fluid and now the tranny is slipping.

I would change the tranny fluid and see what happens.

[Ramblin Fever]

Agree with Amigo, if you overheat your engine, you're overheating your tranny at the same time.

You'll kill them both in nothing flat, if you keep driving it that way.

I'd personally do a full radiator flush, with new thermostat, also have your radiator checked for blockage. I have the same year of Rodeo with 170k miles, I changed out my radiator last summer as they typically only last 9-10yrs before their cooling abilities are shot.

As for your transmission, if the fluid's never been changed, I would NOT change all the fluid at once, i.e NO transmission flush; but what I would do and do VERY VERY soon, is drop the transmission pan, clean the pan, change the filter and do a partial fluid swap.

Then, if your tranny's still functioning in 1k miles or so, do another partial fluid swap, wait about 1k, then if you want, have the transmission flushed and get ALL of the burnt fluid out.

What's happening now, is your transmission is connected to your engine and they are BOTH overheating through the cooling system.

Don't just dump all of your old tranny fluid out though, cause the gunk, if you will, in the old fluid is holding that transmission together.

Park it til u fix it, that engine's all aluminum, you'll blow it's top in nothing flat.

[trooperbc]

some good points.
agree with the heat transfer likely engine coolant to trans fluid...
agree from reading that full-on trans fluid flushes can be problematic with automatic transmissions...
agree that you don't want to be risking your rig by driving it with the described conditions...

but ... ANOTHER POINT of VIEW on a couple of points:

Originally Posted by Ramblin Fever

....they [radiators] typically only last 9-10yrs before their cooling abilities are shot.

that's not been my experience, nor have i seen that trend. some like to changeout parts just in case. if you're taking a summer trip through south america to patagonia, yes for sure. my radiator only went because i tended to overtighten the old upper radiator hose and eventually got that stress fracture on the top 'plastic'.

the lifetime of particular parts are dependent on many factors, and my problem with 'premature' replacement is that all too often the replacement is actually of inferior quality to the original, and this would be the case with the radiator (since the dealer price is astronomical).

...

Then, if your tranny's still functioning in 1k miles or so, do another partial fluid swap, wait about 1k, then if you want, have the transmission flushed and get ALL of the burnt fluid out. ...

...Don't just dump all of your old tranny fluid out though, cause the gunk, if you will, in the old fluid is holding that transmission together.

well a little hyperbole is fine, perhaps, as long as you understand the reasoning and experience behind not doing full on trans fluid flushes. the problem occurs because the small metals and clutch materials and other 'gunk' tend to get flushed through the whole transmission and then lodge in those very fine passages, and that's what ends up causing severe and serious operational problems.

this apparently happens no matter if you use some 'power' flush or the more common flush that uses transmissions' own pump. i can only assume that the new fluid being introduced under pumping pressure and velocity is using it's cleaning properties and that is the problem.

so-called partial fluid changes (partial mainly because your not emptying a significant amount of fluid captured in the torque converter.

one would think that after 2 or 3 or so partial fluid changes, then most if not all the material will have been removed and a complete fluid flush would be ok. however, anything i've read seems to indicate not to do this. btw, after 2 or 3 or so partical fluid changes, essentially *all* the burnt fluid will have been drained out, or it will be so diluted as to be inconsequential.

i'd be interested to hear what 2eye.... and JLEMOND have to say about this.

anyway, it's good kenc195 that you are getting on this before it's too late.


//bc

[surferfletch]

At 140K I swapped my radiator. It clearly had white deposits in the interior which were affecting flow, even after a flush with the Zerex rad flush product. It takes half an hour, less than 1 beer. I'd recommend getting the cooling system squared away (no leaks?), then do a fluid swap. That fluid needs more attention than just a single swap, though. If it shifts well after that, I'd drop both pans, change the filter, and get a lot of new fluid in there.

[surferfletch]

Oh...and I'm thinking that my all metal replacement radiator, which costs a bit less than the dealer part, will last the life of the vehicle.

[Ramblin Fever]

Originally Posted by trooperbc

but ... ANOTHER POINT of VIEW on a couple of points:

that's not been my experience, nor have i seen that trend. some like to changeout parts just in case. if you're taking a summer trip through south america to patagonia, yes for sure. my radiator only went because i tended to overtighten the old upper radiator hose and eventually got that stress fracture on the top 'plastic'.

the lifetime of particular parts are dependent on many factors, and my problem with 'premature' replacement is that all too often the replacement is actually of inferior quality to the original, and this would be the case with the radiator (since the dealer price is astronomical).
//bc

Whatever

I give, doesn't seem to matter what I say in trying to help someone. Obviously my own experience with having owned/currently own 2 Isuzu Rodeo's and a Trooper obviously doesn't amount to much when I attempt to give info to people on the prevention of major repairs. You undermine everything I ever attempt to help assist people with, and it's getting old.

My experience with EVERY vehicle I have owned is that typically the radiators are only 100% reliable for roughly 9-10yrs, they frankly just wear out. And if you re-read my original post, I did NOT tell him to change his radiator, I simply told him to have it checked for blockage.

FWIW - to anyone reading this, at 9-10yrs of age on BOTH my Isuzu Rodeo's, I had their original radiators pulled out and looked at, and both radiators at 9-10yrs of age were showing a build up, even though I had regularly performed radiator flushes.

Take it for what it's worth - trend or no trend, I don't care, not every vehicle follows the stupid same trend of another; simply mentioning it as a cautionary measure.

Adios - may this thread be owned to TrooperBC, he obviously knows better then I.

[kenc195]

ok, We all overlooked the simple cause of overheating. Bad thermostat. Tranny was over 1 quart low though and that has me concerned. Added a quart and all seems well now but I have a service planned for later this week.

[trooperbc]

Originally Posted by kenc195

ok, We all overlooked the simple cause of overheating. Bad thermostat. Tranny was over 1 quart low though and that has me concerned. Added a quart and all seems well now but I have a service planned for later this week.

cool, kenc195. that's a nice bit for the 'databank' on overheating transmissions....

so if you are 1 quart low on the atf, do you have any apparant leaks?

//bc

[surferfletch]

I'd imagine it's either a leak or a prior underfill. Glad you got the source of the overheating solved.

[pharm_rodeo]

Originally Posted by kenc195

Also, 181,000 miles and I don't know if the tranny has ever been serviced. Would a system flush help it or kill it?

I'd be concerned with that. Perhaps you're very lucky.