What temp should they run at with an external cooler? Takes a while to warm up and then seems to like about 180-190 but after a while of running temp creeps up to about 230 and seems to stay there. This happens cruising at 80-90mph for 20miles. First 10miles it's about 180-190 then last ten miles it went to 230. When I got off interstate and cruised at about 30-40mph temps seem to drop a little bit at times like to 210~220 but not back to 180-190 and would mostly stay up there at around 230*. So what should be reasonable and would a bigger cooler help?

 

This will probably get me flamed but what the hell, I asked this same thing (having similar issue but with higher temps),so i asked muiltiple trans shops and the chevy dealership. To sum it up i was told by them that the trans temp shouldnt be no more than 20 to 25 degrees above engine temp.

 

From the Bowtie Installation Guidelines:
"When you touch the return line, do so with caution, use a quick, light tap to determine if the line is scolding hot. You should be able to touch this line without burning your hands. Even the outgoing line shouldn’t be hot enough to burn you if you touch it momentarily. If you feel very high temperatures on the return line you should add a cooler. A transmission temperature gauge will help determine what is occurring. If you error on this topic, please do with too much cooling. The temperature gauge is recommended even if you don’t plan to tow. 150 degrees F or less should be indicated with a temperature probe (sender) positioned in the pan. The fluid can be seriously overheated if pan temperatures exceed 150 degrees F. This happens because overheating is occurring in the converter, not the pan. What they don’t realize is the temperature that we are observing is the fluid temperature after it has returned from the cooling system! People are confused about this because they know that Dextron III can withstand higher operating temperatures than 150 degrees F. What they are failing to realize is the gauge is reading the fluid after it has gone through the cooling system. While it is impractical to probe the inside of the torque converter when it is operating, it’s known to be the hottest component in the system. The converter is the heat source and the main reason a cooling system is essential to automatic transmissions. So we have learned though years of observation this transmission is doing fine at 150 degrees F and overheating when over that if you are sensing the fluid temperature in the pan."
Avner

 

ALL well and good, but seriously doubt you will find any tranny to stay at 150f pan temp in FLORIDA heat when it's 100f ambient in my shaded back yard, and stuck in traffic . that road heat has to be 140f easy, if not higher....engine running 200f now how in hell your tranny going to be 150f...that info is flat out RONG.....

 

Here is a pic of the guage. I am waiting for Bowtie to open up (West Coast) and ask them their thoughts.

 

Just spoke with Bowtie. The temp should run around 140~160 according to them. They said about 180 on a really hot day and if I am getting up on it hard maybe 200. I have their medium sized cooler. Looks like I will have to get a bigger cooler. Also will need to buy an infared heat gun and zap the pan to see what it says as they say the guages can be off also by as much as 20* sometimes reading too high. Something ain't right. Ugghh!!!

 

where is your cooler mounted?

I'm interested with your resolution

My next mod will be a 200r4 install

Does your cooler have a fan mounted to it?

What size is your cooler?

I'm running a Hugh's TH350 with a 2800 stall and I have a trans cooler with a fan mounted to it with a T-stat controlling it. The fan runs when I push the car hard or when its hot out (90* plus). I have the fan stat set at 160* so it runs when it needs to.

I had a little digital thermometer mounted to the inlet of the cooler and it will stay at 170* to 180* when I drive it hard on hot days. I bypassed the radiator so the oil only goes to the cooler.

Neal

 

I have measured it both ways....the infra red reads lower than the thermocouple on Fluke meter says....how much lower, I forget....

but I KNOW the Fluke is right....

 

How could it run this cool if it was plumbed through the cooler integrated into the radiator, which is probably running at least 180.

 

from the radiator to the external cooler back to the trany

 

I'm talking about a stock set-up with no external cooler.

 

First off, my 78 L-82 is a 4 speed, not an automatic, thank god! HOWEVER, I have been adding external tranny coolers to automatics on other cars for 30 years and have never had a tranny failure.

Going back to my 73 Nova SS, I added 2 tube and fin coolers (not the much more efficient double stack coolers I use today) and had a B&M external trans filter (just a passenger car oil filter) in addition to the internal trans filter on the Turbo 350 and beat the snot out of during high school and college and it was running fine when I sold the car in 1990 with 168,000 miles on the trans. I have always run the cooler outside and separate from the radiator, not inconjuction with the OEM radiator cooler.

Currently, I run 2 18,000 GVW double stack Long coolers separate from the radiator in my 2001 Pontiac Grand Prix automatic 4T65E and the trans has 100,000 + miles on it and runs great. On my 1994 Mustang GT with the AODE trans I run 1 28,000 GVW cooler outside of the radiator and I am considering running another smaller double stack cooler with this trans in addition to the 28,000 GVW cooler since the fluid still is very hot in the summer. No issues in the winter with either car-just takes longer to get warm.

Remember, that physics here, that if you cool the trans fluid using the radiator, the fluid can never get lower than the temperature of the coolant in the radiator if the radiator does all of the cooling. If your cars coolant is 200-210 degrees the trans fluid cannot get reduced to below that temperature-that is the mimimun threshold.

Run the biggest cooler that you can outside of the raditor for the best cooling and don't worry about the fluid running too cool. I have never had a tranny failure in 30 years. Just my 2 cents!

 

I am slowy getting to the bottom of all this.

Called Bowtie this morning (me) and they said 140-160 should be the temps.

Called mechanic asking him WTF as Bowtie says 140-160 and you drop off a car that is running way hotter.

Mechanic says he spoke with Bowtie and "asked" if it was okay put the temp sensor guage in the pressure line fitting vs. the pan and the temp guage will now run hotter since it is not the temp coming out of the cooler.

Mechanic calls Bowtie and they now say its not okay to run temp sensor in the high pressure line and to re-route it to the pan as per the instructions to make sure the temp should be around 140-160.

Ugghh...I am about to scream!!! The mechanic I had do the work is back at my home town where I grew up which is 650 miles away. Not an easy solution for him quickly re-route the temp sensor. He dropped off the car via a trailer and offered to come get it tomorrow and redo the work which is a LOT of driving being 10hrs each way but at this point I am going to think about it and most likely have a local person re-route the temp sensor.


I have an external trans cooler that is mounted in front of the radiator and ac condensor.

 

Mounting the trans cooler in front of your radiator is just putting all of that tranny heat back into the engine. Why not install it so that it gets a different airflow path?

 

What other is there,?? without having a dedicated fan....

with dual spals, C4 blower, a/c etc....just where to put it so that heavy traffic is not a problem with cooling...

 

On all my cars that I have installed trans coolers outside of the radiator, no cooling by the OEM trans lines into the radiator, every one of them shows a significant water temperature drop since the radiator only has to cool the engine and does not have flaming hot trans lines running in the radiator which will significantly increase the water temperature. While mounting the coolers outside of the radiator airflow would be nice, on a C3 that would be difficult as it would be on most cars. On my cars referenced previously, both double stack coolers (GP has 2 Long coolers) are in the radiator airflow and the water temp decreased once I got the lines out of the radiator which indicates that removing the trans lines from the radiator is more effective than allowing some of the cooled (heated air from the coller removing the heat) air to reenter the radiator. Hope that helps!

 

Typical radiator will have a 20* plus temp drop from the inlet to the outlet of the radiator. If the T-stat is 190* than the outlet of the radiator will be around 170* or cooler if the radiator is functioning correctly.


Neal