over heating tranny stumper for u guys???????????help

bling

bling

New member
Joined
Nov 30, 2009
Messages
287
ok here goes... forgive me for the long post but i want to really explain whats happened

the issue: tranny in drive with the parking brake set and just sitting still will over heat in about 5 minutes.


like i said i can sit with the truck in drive at idle and hold the brake or set p brake and the tranny will heat up all the way to 250.

now my gauge is hooked up via the old firstgen tranny hot line part so its coming right off the tranny.

The tranny has been rebuilt but it has done this ever since iv had gauges in the truck well before it was ever rebuilt.


now driving down the road or interstate she is ice cold 100 to 130 degrees. but if i get into traffic or stop and go she climbs right back up to were i have to pop it into neutral.

things ive done to try and solve this : replaced the stock tranny cooler with a larger unit and the results are still the same it just taked longer for it too over heat.

ive talked to my tranny guy and we drove the truck. it drives fine just like it always has. no slipping no shudder.


im honestly kinda baffled at why its acting like this. low stall speed in converter so i know that wouldnt casue it. any ideas fellas


fluid is clean no smell no debris. red and clean.


i replaced my fan clutch recently so i know it works. iv deleted my heat exchanger so its just from tranny to cooler and back.

i need some help tranny guru guys.:nail:
 
I'm far from a transmission expert, but I've heard of a check valve that is used to keep fluid in the TC. Supposedly it gets plugged up with stuff.

Dunno anything else about it or it's whereabouts, just that it exists.
 
Doing away with the water exchanger can be an issue that needs to be driven around. Water will cool much faster than air, even if the water is 180*. If nothing else the fluid is hitting the air cooler at 40 degrees less when in traffic. May be a huge factor, I could be wrong also.
 
Chris Mallett said:
Doing away with the water exchanger can be an issue that needs to be driven around. Water will cool much faster than air, even if the water is 180*. If nothing else the fluid is hitting the air cooler at 40 degrees less when in traffic. May be a huge factor, I could be wrong also.
Click to expand...

i see ur point but far too many people run with out it and have no issues what so ever. i live out in virginia. it doesnt get that terribly hot out here and its like 40 degrees out tonight as i ran this test again with the new trans cooler i installed and still the same results only it took twice the amount of time for it to over heat as thr stock cooler did.not sure about a check valve but ill look into it and ask my tranny guy. i still feel there is an underlying issue that is causing this.


hope somebody can help on here
 
You have an independent fan on your trans cooler? That is what we had to install on a 12v 1500 when the exchanger was removed. Would get hot quick with no real air across the cooler. And we are in the mountains of WV.
 
I'd want to have fans if it doesn't. Could possibly be size of trans line also. Or you need a new trans guy, lol.
 
Not having the heat exchanger is not your problem. Whàt size are your trans lines. They should be atleast -8.
 
At idle disconnect the return line from the transmission and let it pour into a bucket. A minute should get you at least half a gallon... Make sure you have flow.

Do you have control over lock-up? Perhaps it's okay when the clutch is engaged, frying itself when it isn't. I don't know what that'd mean, though...
 
You're reading the hotline. Of course it's gonna get hot when idling in D..... The question is: Does it get hot in the PAN idling in D? That's the temp you really need to know... You're reading the temp at the hottest point in the transmission. I have a customer with a tranny temp gauge in the hotline and it will peg the temp gauge nearly instantly when you floor it from a stop sign..... But the pan will still be just warm.......
 
As a side note, I too only have an air fluid cooler. It's mounted horizontally under the cab with a fan. No natural air flow over it ever... I never see much over 130 pan temp in cool weather in stop and go... Once I got it to 170, but that's still very safe. Doing reverse/manuvering with a trailer though will send 'er right up to 190 to 200.....
 
If you're reading on the hotline directly off of the front of the tranny, you're not monitoring tranny temp you're monitoring converter temp. The converter is the source of all the heat in the tranny. When you get on the interstate it cools down so much because you're in lockup and the converter is essentially a clutch, not creating any fluid heat.

Move your temp probe to the pan where its supposed to be, if your tranny flashes over 200 with the probe there then you actually have an issue, otherwise party on wayne.
 
While in gear with no movement...TC coupling will cause fluid temp to rise dramatically.

My 3rd gen CAN do the same, however I wont let it...when i see converter temp getting over 200* I put it in neutral to keep the fluid temp down.

Perfectlty normal and doesent indicate a trans problem...I wouldnt recommend doing it, but its your truck.
 
maybe someone who works at a reputable trans shop will reply


EDIT: ^^posted



I've always read/been told to put the thermocouple in the outlet port.... this is news (from post #11)
 
Last edited:
Hurley said:
maybe someone who works at a reputable trans shop will reply


EDIT: ^^posted



I've always read/been told to put the thermocouple in the outlet port.... this is news (from post #11)
Click to expand...

I was about to say.. Do I not count!? But you posted a minute after I did :Cheer:

You can read outlet port temp too but thats just monitoring converter temp. We only monitor pan temp in all of our trucks, let em run after a pass in neutral with fans on the tranny cooler until pan temp is below 150. There's been talks of doing a standalone pan cooler on a pump setup in one of our trucks... one of these days

Reading converter temp and calling it tranny temp is like reading EGT and calling it engine temp.. make sense?
 
deerefanatic said:
You're reading the hotline. Of course it's gonna get hot when idling in D..... The question is: Does it get hot in the PAN idling in D? That's the temp you really need to know... You're reading the temp at the hottest point in the transmission. I have a customer with a tranny temp gauge in the hotline and it will peg the temp gauge nearly instantly when you floor it from a stop sign..... But the pan will still be just warm.......
Click to expand...

Sorry but no. I ran my gauge in the hotline for 10yrs and my built dtt never went over 200* sitting in rush hour traffic in 110* weather. And it never went over 210* doing boosted launches or making multiple back to back runs on the dyno with no air flow over anything. Cruising down the highway it was around 140-150*.
 
Last edited:
BgBlDodge, did you maintain your factory heat exchanger?


And Krazeeun, I'm with you
 
it appears that the factory hx pulls a pretty good amount of heat from the trans fluid.


This makes me want to add a second trans temp gauge to monitor pan temps hahahaa
 
I think it'd be gucci to monitor hot line, cold line and pan temp.. just for funsies, but for my truck already looks like a cockpit with 5 gauges
 
You must log in or register to reply here.
Back
Top