Bypass the in-radiator cooler?

[UncleDave]

I have an aluminum rad that has a nasty leak in the bottom fitting, and nothing anyone can do will stop it from leaking. Would there be any problem with bypassing the in-radiator transmission cooler completely, and relying solely on an external cooler?

Thx

 

[GNeric]

I did that on mine since the F-body radiator cooler chose to block itself off once in a while and cause me major front seal leaks. I have not noticed any trans temp differences. I run a 19,000 GVW cooler with a fan on it under the front of the car mounted horizontally with the fan pulling air downward. It gets it's "fresh air" from the headlamp holes in the radiator support.

 

[87lc2/wo2]

Try teflon tape

I had the same problem. I just changed radiator hoses then my original radiator had broke while placing the upper radiator hose (upper outlet cracked). I replaced the original unit with new Aluminum unit, but installed a B&M supercooler. Next problem was my transmission feed-line was so corroded that it snapped off. I was hopeless at this point, so I replaced it with Bowtie-Overdrives replacement (easy to install) transmission cooler lines. Now more to the point, I called many transmission repair shops and asked the professionals here on this site and "not one" would recommend going to the auxiliary cooler itself then back to the transmission. If its a street car, then yes, a "track car only" then NO. In a hot day in traffic wouldn't cool your tranny enough with that extra cooler all by itself, without the exception of one of those coolers with a fan. That's when I learned from the experts at the shops and here that running it thru the radiator-cooler, then the auxiliary cooler itself. I too had a leak with new "lower" feed line and a new radiator, and I reiterate it was leaking too. I put teflon tape after inspecting the threads on the fitting, then cleaned it with a clean shop towel, then inspected the radiator threads, cleaned the inside-threaded area, put the teflon tape (went twice around), then to my surprise I had no leak. Mind you it took a month, new radiator and lines to get it up and running. It was a test for patience. I now thank all the men on this site and transmission shops for advice. Hope this helps.

 

[Just a Six??]

I had the same problem. I just changed radiator hoses then my original radiator had broke while placing the upper radiator hose (upper outlet cracked). I replaced the original unit with new Aluminum unit, but installed a B&M supercooler. Next problem was my transmission feed-line was so corroded that it snapped off. I was hopeless at this point, so I replaced it with Bowtie-Overdrives replacement (easy to install) transmission cooler lines. Now more to the point, I called many transmission repair shops and asked the professionals here on this site and "not one" would recommend going to the auxiliary cooler itself then back to the transmission. If its a street car, then yes, a "track car only" then NO. In a hot day in traffic wouldn't cool your tranny enough with that extra cooler all by itself, without the exception of one of those coolers with a fan. That's when I learned from the experts at the shops and here that running it thru the radiator-cooler, then the auxiliary cooler itself. I too had a leak with new "lower" feed line and a new radiator, and I reiterate it was leaking too. I put teflon tape after inspecting the threads on the fitting, then cleaned it with a clean shop towel, then inspected the radiator threads, cleaned the inside-threaded area, put the teflon tape (went twice around), then to my surprise I had no leak. Mind you it took a month, new radiator and lines to get it up and running. It was a test for patience. I now thank all the men on this site and transmission shops for advice. Hope this helps.

Good info but each car has a purpose so he must decide what he needs. I run a big aux cooler with no fan & no engine oil cooler at all. It see's a few thousand miles a season cruising or at the track some weekends. In my case I believe thats all I need. he maybe a daily driver in Arizona so that would change everything. Gotta build for the use of the car.

 

[cdr.performance]

I have an aluminum rad that has a nasty leak in the bottom fitting, and nothing anyone can do will stop it from leaking. Would there be any problem with bypassing the in-radiator transmission cooler completely, and relying solely on an external cooler?

Thx

Should be not issue at. Don't skimp the the size of the cooler. Keeping the trans cool enough is important to it life.

 

[UncleDave]

I live in CT, and only plan to drive the car 2000 miles per year max, from late spring to early fall. It does get into the 90's (this year has been brutal), so I got the biggest cooler I could find and mounted it to the radiator X-brace where it gets full frontal airflow. No leaks detected, but I have not been able to drive the car anywhere yet.

Thanks guys!
~Dave

 

[Roger]

I live in Florida where temperature gets to 100* & 100% humidity. Temperature also gets below freezing.

Before installing an aux cooler, on a cold day, I often had to drive 2 miles to get it to shift into OD.

I run a very large aux cooler with a fan & then run the fluid into the rad cooler. My theory is: The rad has a thermostat. On cold days the thermostated rad keeps things at a good operating temp & on a hot day precooling (aux cooler) helps the rad cool the car.

 

[HighMileage]

I've got external coolers on almost all of my cars. My GN is next!

I don't use the radiator in the circuit at all. Some have warned me not to use this system in the dead of winter here in upstate NY. Never have I had a problem.

On one of my cars,I even installed a tranny temp gauge in the outflow line from the tranny. The gauge has never went above 200'F. ...and that is with a slightly higher stall converter. Most of the time the temp is in the low 100's.

Excess heat kills trannys.

Then we have the issue of if the factory cooler inside of the rad springs a leak. Strawberry milkshake time.

Isolate the tranny cooler circuit from the engine coolant. ...that's what I do.

Steve. '87 GN,t-tops. <-soon to get an external cooler.

 

[cdr.performance]

The only time we have seen issues in cold weather is if the trans has issues. One of the Daily drivers has over 3 gallons of HTF and runs only an external cooler and no issues driving thought the winter.

 

[bmackinnon]

Before installing an aux cooler, on a cold day, I often had to drive 2 miles to get it to shift into OD.

I run a very large aux cooler with a fan & then run the fluid into the rad cooler. My theory is: The rad has a thermostat. On cold days the thermostated rad keeps things at a good operating temp & on a hot day precooling (aux cooler) helps the rad cool the car.

Well, the trans will shift into 4th gear (OD) at any temp.... the ECM controls the CONVERTER LOCKUP permissive based on engine coolant temp... not trans temp... 2 miles for the engine to reach 150*F is reasonable... sometimes more...

Your second paragraph makes perfectly good sense... yes... hotter engine coolant temps will increase the trans temp... and vice versa....

I've got external coolers on almost all of my cars. My GN is next!

I don't use the radiator in the circuit at all. Some have warned me not to use this system in the dead of winter here in upstate NY. Never have I had a problem.

On one of my cars,I even installed a tranny temp gauge in the outflow line from the tranny. The gauge has never went above 200'F. ...and that is with a slightly higher stall converter. Most of the time the temp is in the low 100's.

Excess heat kills trannys.

Then we have the issue of if the factory cooler inside of the rad springs a leak. Strawberry milkshake time.

Isolate the tranny cooler circuit from the engine coolant. ...that's what I do.

Steve. '87 GN,t-tops. <-soon to get an external cooler.

Better have a hell of a dedicated trans cooler if it's a driver in hot weather... my trans runs 230-240* steady state, locked-up, on the interstate on a warm day... 260-280* on a hot day in the hills with a few little boost squirts unlocked..... when the lockup solenoid died on a 600 mile trip, it was running about 300-325 thru some hilly terrain... having a trans temp gage, yes, I was being gentle!!!

If your trans outlet never hits 200*, I'd say the gage is crap.... low 100's my a$$.... no way....

 

[JDSfastGN]

Better have a hell of a dedicated trans cooler if it's a driver in hot weather... my trans runs 230-240* steady state, locked-up, on the interstate on a warm day... 260-280* on a hot day in the hills with a few little boost squirts unlocked..... when the lockup solenoid died on a 600 mile trip, it was running about 300-325 thru some hilly terrain... having a trans temp gage, yes, I was being gentle!!!

If your trans outlet never hits 200*, I'd say the gage is crap.... low 100's my a$$.... no way....

You really should not be running that hot... 260-280 is way more than Ive seen as being "normal" Even stock setups with no external cooler shouldn't be much hotter than than the engine coolant temp.... just what I have seen. Seals don't tend to last long at 250+ I do agree that low 100s is not really doable, but 175-210 is in the right range imo.

 

[HighMileage]

Better have a hell of a dedicated trans cooler if it's a driver in hot weather... my trans runs 230-240* steady state, locked-up, on the interstate on a warm day... 260-280* on a hot day in the hills with a few little boost squirts unlocked..... when the lockup solenoid died on a 600 mile trip, it was running about 300-325 thru some hilly terrain... having a trans temp gage, yes, I was being gentle!!!

If your trans outlet never hits 200*, I'd say the gage is crap.... low 100's my a$$.... no way....

The temps you are describing are the same temps my '69 Chrysler NY'er with 440 and 727 TorqueFlite had when towing 5,000lbs.

The low-100's I mentioned was with a '90 GM A-body with a 440t4,3300 Buick V6 and fairly large cooler. I thought the temps were not believeable also. Then I checked the outflow line with an infra-red heat sensor. Plus,I could actually grab the line with my bare hand.

As mentioned in the beginning of my last post,my '87 GN is yet to receive a cooler.

 

[Alky V6]

Trans temp should be allowed to reach over 160 degrees F every once and awhile just to burn off condensation buildup.

Normal trans temp is the same as normal engine temp. 180-210 degrees F.

Trans temps over 250 F should be avoided. Over 250 is cooking the trans. As was already mentioned, seal and plastic parts don't like temps that high.

If at all possible, keep the in radiator cooler in the circuit. It is a far superior cooler to an external air cooler. You will never see an auxiliary cooler manufacturer suggest that you bypass the in radiator cooler.