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I feel kinda silly asking this but I've forgotten which way the fluid goes to the cooler inside the radiator. I'm installing a transmission cooler bypassing the radiator alltogether and also installing an inline filter which is directional.
Is this diagram below accurate for the 4l60e?
EDIT: I think I might not have been clear.
The inline filter I'm installing is directional. The transmission cooler line that attaches to the top of the stock radiator, is that bringing hot fluid FROM the transmission TO the radiator? The fluid needs enter the "in" side of the filter and exit the "out" side of the filter.
The radiator in the picture below is the stock radiator for the engine that also has the internal transmission cooler section. I'm trying to confirm that the picture below is correct for the stock setup.
EDIT part II: This is a daily driver, stock engine, with a Circle D TC with about a stock stall, so there's not really an overheating issue. I know there's different opinions on bypassing the stock radiator or doing stock radiator combined with a separate transmission cooler, but that shouldn't be an issue for me. And I live in Texas, so there's not an issue with the fluid running too cool during the winter.
EDIT PART III: Turns out this picture is backwards for the 4l60e. In the 4l60e, hot fluid enters the bottom of the radiator and the cooled fluid exits the top of the radiator and heads back to the tranny
Last edited by coryforsenate; Jul 26, 2015 at 10:19 PM.
I do not believe so.
If you want the cooler to do more work, ..., the hot should go in the bottom & out the top. Makes the fluid get better BTU removal. And using both the OE heat exchanger & an aftermarket unit will get the best BTU removal rate. (Yea, here come the people who tell you to just use an aftermarket cooler only, ...)
It seems to be 50/50% on opinions whether to use the aftermarket trans cooler in addition to or instead of the OE cooler. I think that 51%+ will agree that if you run a lower temperature engine thermostat (e.g. 180F) and live in a cooler climate, then using both coolers will be best, with the hot line going first to the OE cooler.
However, there have been a few posts about these nearly 20 year old OE radiators springing a leak in the trans cooler portion and thereby instantly ruining the trans.
In short, even if using both coolers might be best for heat removal, issues such as reliability, plumbing complexity and a few other issues prompt many people here is only use the aftermarket cooler with complete success.
IMHO, it is more important not to use rubber lines anywhere for the trans cooler as there are dozens of stories of rubber lines leaking. Keep in mind that the 100 psi and 240F+ hot trans fluid will quickly deteriorate rubber lines, even fuel injection lines.
The inline filter I'm installing is directional. The transmission cooler line that attaches to the top of the stock radiator, is that bringing hot fluid FROM the transmission TO the radiator? The fluid needs enter the "in" side of the filter and exit the "out" side of the filter, which is why I'm trying to figure out which cooler line brings fluid FROM the transmission and which line returns the cooled fluid to the transmission so that I get the directionality right.
Last edited by coryforsenate; Jul 26, 2015 at 01:24 PM.
And I live in Texas, where for six months out of the year it's too hot to do much outside before 7pm. Right now it's 100 degrees with around 60% humidity.
I defer to you guys as the experts, and from what I've read on here it seems that bypassing the radiator is recommended when a person lives in a climate where it's hot most of the year. The coldest it ever gets here is about 25-30 degrees a few days during winter during a "big freeze".
I was hoping to avoid that, but it is the surefire way to figure out the "to" and "from" cooler lines. I can always attach some hose and set it in a bucket to minimize making a mess.
I'm planning to do it this evening, so if I don't get a definitive response then I'll do that method.
The lower cooling line fitting is the "hot out" line and the upper fitting is the return line.
The stock lower hot line goes to the bottom of the OE radiator, just like PontiacFan explained.
The lower cooling line fitting is the "hot out" line and the upper fitting is the return line.
The stock lower hot line goes to the bottom of the OE radiator, just like PontiacFan explained.
Ah, thank you sir. Looks like the picture I posted in the OP is backwards. I'll update the OP so that if somebody happens upon this thread they don't have to read a whole page to figure out the answer.
I actually didn't wind up doing it this evening. By the time I finished washing and waxing my truck it was starting to get dark. At least my truck is shiny enough to use as a shaving mirror.
The lower cooling line fitting is the "hot out" line and the upper fitting is the return line.
The stock lower hot line goes to the bottom of the OE radiator, just like PontiacFan explained.
I feel kinda silly asking this but I've forgotten which way the fluid goes to the cooler inside the radiator. I'm installing a transmission cooler bypassing the radiator alltogether and also installing an inline filter which is directional.
Is this diagram below accurate for the 4l60e?
EDIT: I think I might not have been clear.
The inline filter I'm installing is directional. The transmission cooler line that attaches to the top of the stock radiator, is that bringing hot fluid FROM the transmission TO the radiator? The fluid needs enter the "in" side of the filter and exit the "out" side of the filter.
The radiator in the picture below is the stock radiator for the engine that also has the internal transmission cooler section. I'm trying to confirm that the picture below is correct for the stock setup.
EDIT part II: This is a daily driver, stock engine, with a Circle D TC with about a stock stall, so there's not really an overheating issue. I know there's different opinions on bypassing the stock radiator or doing stock radiator combined with a separate transmission cooler, but that shouldn't be an issue for me. And I live in Texas, so there's not an issue with the fluid running too cool during the winter.
EDIT PART III: Turns out this picture is backwards for the 4l60e. In the 4l60e, hot fluid enters the bottom of the radiator and the cooled fluid exits the top of the radiator and heads back to the tranny
Hi, thank you for posting this thread. I too was curious about the direction of flow.
Seems the diagram is correct in conventional engine design.
That is to say that the water pump is forcing hot water from the top of engine through the thermostat, to the top of radiator inlet cooling the water as it travels down and finally exiting the radiator from the bottom outlet back into the bottom of the engine block.
I do not believe so.
If you want the cooler to do more work, ..., the hot should go in the bottom & out the top. Makes the fluid get better BTU removal. And using both the OE heat exchanger & an aftermarket unit will get the best BTU removal rate. (Yea, here come the people who tell you to just use an aftermarket cooler only, ...)
the only advantage to using both coolers is in extreme cold areas,the vehicles radiator helps heats fluid faster,but in less friged areas along with extreme hot areas best to just use external cooler
the only advantage to using both coolers is in extreme cold areas,the vehicles radiator helps heats fluid faster,but in less friged areas along with extreme hot areas best to just use external cooler
Old thread.
But you can get an external cooler with a thermostat in it
IMHO, it is more important not to use rubber lines anywhere for the trans cooler as there are dozens of stories of rubber lines leaking. Keep in mind that the 100 psi and 240F+ hot trans fluid will quickly deteriorate rubber lines, even fuel injection lines.
Interestingly though, the factory installed rubber portions on both the high and low pressure side, presumably for the purpose of system flexibility I would guess. I have not experienced any quick deterioration of these rubber sections on mine (now 25 years old and original), nor the Goodyear brand trans cooler hose that I used to plumb in the aftermarket cooler (in series) back in 2005.
But I guess it's always a good idea to keep an eye on this rubber, especially in heavy duty and high mileage applications. Mine rarely leaves the garage so it hasn't really seen much heat in all those years.
Darn, I feel funny closing an old thread on which the Administrator just posted, but I do think that threads started 8 years ago and dead for years, should be closed, so closed it is.
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Fluid flow to and from transmission and cooler 
