Transmission Fluid Flow Rate through Radiator problem?

Hi Toyaota MDT,

I have inserted comments.

> I would like to know what you mean by "overheats". Do you mean that
> the trans temp light comes on at a certain point in your drive?
Yes... the tran temp light comes on. When doing 60+mph for about an
hour.

> If so, I would be suspicious of the ATF level. If it is a hair too
> high in a A340F transmission/transfer unit, the fluid will readily
> aerate and cause that symptom.
Yes we found that we were way over filled... about 1.5 inches over the
high mark. And yes a Toyota guy told me that too much fluid would
aerate the t-fluid leading to overheating. I told this to tranny
shop... was certainly unhappy that his guys overfilled the tranny but
was skeptical that overfilling would cause tran temp light issues at
just 60mph. So he did some checking and found the raidator had low t-
fluid flow.

>I would also be suspicious of what
> fluid additive a trans shop uses. They are often not as knowledgeable
> about transmission practice and theory as one would expect.
I do not know what t-fluid product they use. I was not in a position
to have an opinion then... but now I know that what the Toyota guy
told me; Dex2 is what that 1993 4Runner tranny was designed for...
Dex3 replaced it a long time ago and on "really long multi-hour drives
there is sometimes a problem". He suggested Texaco havelin AFT as
most problem free product.


> The original equipment aux cooler is very small, but it is adequate
> for any use I have run across. One problem with it is the location; a
> careless butcher can easily rack the left front lift arm on it and
> crush it trying to lift the vehicle. Has this cooler been bypassed in
> favor of an aftermarket one? If so, is the aftermarket unit inline
> with the airflow created by the mechanical fan?
My 93 4Runner just had radiator t-fluid cooling. I had a shop put in
an aux cooler a few years ago when I first noticed tranny waring
signs. Size? I let the shop pic it out and they located it above the
skid plate... no extra fan.


> I do agree that your original flow specs through the radiator cooler
> sound low, but that is a guestimate based on other similar experiments
> I have done at work, not your exact test.
>
> Toyota MDT in MO

So thanks for your comments/questions... all things I will cover the
tranny shop owner on Monday.

Thx
Dave-in-Denver

> wrote in message
oups.com...
> My new transmission is (still) overheating on long highway drives.
>
> Transmission shop tested the t-fluid flow rate through the radiator at
> 1 quart every 30 seconds.
> The transmission itself however will push times that amount, 3 quarts
> every 30 seconds, all by itself and also through an aux t-cooler.
>
> My radiator is only 2 years old. When I first started having
> transmission overheating I found the radiator was shot and had it
> replaced and later put in a tran cooler too.
>
> So the questions is...
> What should be the t-fluid flow rate through the radiator?
> In other words... is my radiator restricting t-fluid flow rates below
> spec?
>
> 1993 4Runner, V6 3L, Auto, 4x4, 170K
>
> Thx
> Dave-in-Denver
>

95 4Runner, V6 3L, Auto, 4x4. I had a trans overheating problem also.
After a heated discussion with my dealerships service manager, where I told
him that my trans was overfilled and I thought that was my problem, he
called Toyota. The fix was to check and make sure the trans was not
overfilled. It needs to be checked after idling for 15 minutes. If it's
overfilled it will cause the clutches to slip and overheat. On my last
service they had overfilled it. They changed the fluid and filled it to the
correct level and the problem went away.

Ron

Ron

>
> 95 4Runner, V6 3L, Auto, 4x4. I had a trans overheating problem also.
> After a heated discussion with my dealerships service manager, where I told
> him that my trans was overfilled and I thought that was my problem, he
> called Toyota. The fix was to check and make sure the trans was not
> overfilled. It needs to be checked after idling for 15 minutes. If it's
> overfilled it will cause the clutches to slip and overheat. On my last
> service they had overfilled it. They changed the fluid and filled it to the
> correct level and the problem went away.
>
> Ron
>
> Ron

Hi Ron,
I think you are right... glad to have found someone who has the same
picky tranny. If tranny fluid level was spot on... may never have
found or noticed the poor flow problem.

The overfilled tranny was an important part of the problem. Then
layer onto to that Dex2 vs Dex3 issue, then finding my radiator had
restricted flow in it t-fluid section. This all did add up to some
finger pointing... all had some ownership of the problem.

Thx
Dave-in-Denver

"Ron(Tx)" > wrote in message
...
>
> > wrote in message
> oups.com...
>> My new transmission is (still) overheating on long highway drives.
>>
>> Transmission shop tested the t-fluid flow rate through the radiator at
>> 1 quart every 30 seconds.
>> The transmission itself however will push times that amount, 3 quarts
>> every 30 seconds, all by itself and also through an aux t-cooler.
>>
>> My radiator is only 2 years old. When I first started having
>> transmission overheating I found the radiator was shot and had it
>> replaced and later put in a tran cooler too.
>>
>> So the questions is...
>> What should be the t-fluid flow rate through the radiator?
>> In other words... is my radiator restricting t-fluid flow rates below
>> spec?
>>
>> 1993 4Runner, V6 3L, Auto, 4x4, 170K
>>
>> Thx
>> Dave-in-Denver
>>
>
> 95 4Runner, V6 3L, Auto, 4x4. I had a trans overheating problem also.
> After a heated discussion with my dealerships service manager, where I
> told him that my trans was overfilled and I thought that was my problem,
> he called Toyota. The fix was to check and make sure the trans was not
> overfilled. It needs to be checked after idling for 15 minutes. If it's
> overfilled it will cause the clutches to slip and overheat. On my last
> service they had overfilled it. They changed the fluid and filled it to
> the correct level and the problem went away.
>


Ron,
He has confirmed that the fluid does not flow efficiently through the
radiator.

>
> Ron,
> He has confirmed that the fluid does not flow efficiently through the
> radiator.

Hi Jeff,
Yes... my radiator will only flow 1 quart in 30 seconds (a third of
what the tranny fluid pump wants to push) and that it did not improve
after spending the nigh on the flush/cleaner machine.

4Runner is still in shop... owner working on this himself on a hit/
miss basis rather than one of the his usual guys. So tomorrow he
expects to tell be result of the flow test through a NEW radiator.

Thx
Dave-in-Denver

>
> Hi Jeff,
> Yes... my radiator will only flow 1 quart in 30 seconds (a third of
> what the tranny fluid pump wants to push) and that it did not improve
> after spending the nigh on the flush/cleaner machine.
>
> 4Runner is still in shop... owner working on this himself on a hit/
> miss basis rather than one of the his usual guys. So tomorrow he
> expects to tell be result of the flow test through a NEW radiator.
>
> Thx
> Dave-in-Denver

Picked up 4Runner yesterday with new Radiator (and same aux cooler).
T-fluid Flow rate through the radiator was great... "over a gallon in
less than 45 seconds" according to the shop owner. (Wish he had done
an apples to apples time/volume test... but the flow was "so huge"
compared to the bad radiator the tranny shop knew the problem was
solved.

AND they did not overfill it... in fact the t-fluid levels are at the
mid mark on the dipstick... not the high mark.

I have a 6 hr drive in the mountains tomorrow with temps in 80's...
will be a good test.

Thx
Dave-in-Denver

> wrote in message
oups.com...
>
> Picked up 4Runner yesterday with new Radiator (and same aux cooler).
> T-fluid Flow rate through the radiator was great... "over a gallon in
> less than 45 seconds" according to the shop owner. (Wish he had done
> an apples to apples time/volume test... but the flow was "so huge"
> compared to the bad radiator the tranny shop knew the problem was
> solved.
>
> AND they did not overfill it... in fact the t-fluid levels are at the
> mid mark on the dipstick... not the high mark.
>
> I have a 6 hr drive in the mountains tomorrow with temps in 80's...
> will be a good test.
>
> Thx
> Dave-in-Denver
>
Thx for the feedback...
Ron

> Picked up 4Runner yesterday with new Radiator (and same aux cooler).
> T-fluid Flow rate through the radiator was great... "over a gallon in
> less than 45 seconds" according to the shop owner. (Wish he had done
> an apples to apples time/volume test... but the flow was "so huge"
> compared to the bad radiator the tranny shop knew the problem was
> solved.
>
> AND they did not overfill it... in fact the t-fluid levels are at the
> mid mark on the dipstick... not the high mark.
>
> I have a 6 hr drive in the mountains tomorrow with temps in 80's...
> will be a good test.
>
> Thx
> Dave-in-Denver

No OVERHEATING TRANNY!!!

Drove 300+ miles yesterday in the Colo mountains and not one blink
from the Tran Temp Light. So the radiator was in fact the the bad
guy.

Checked fluid level 6 times. Had everything from half an inch under
the low end of the "hot range" on the dipstick to half an inch over
the high end of the "hot range".
- The highest level was observed one block from the highway after a
hard fast mountain pull.
- The lowest level later observed was later in day on the return
trip home after power costing nearly an hour back down into Denver.

Thanks to everyone for there comments/suggestions!

Dave-in-Denver