External Trans cooler

Im gettin ready to do lift/tires and Im also going to plop an external trans cooler in. My question is will mounting the cooler out in front of the radiator and ac condenser affect my engine temp??? If so, about how much?
Second question...are most of you with externals running them in series with the stock cooler (radiator), or as stand alones? If running them in series, which line goes from the tranny to the rad...and which from the external cooler back to the trans... I tried to find a tech article on it but I couldnt, so if anyone has a link that'd be awsome. Thanks in advance.

Justin

Well...

There is a small increase in temperature due to the airflow over the radiator being blocked, but that is offset by the heat load taken off the radiator with the external cooler - and then some. You'll be coming out ahead on that score.

I've always preferred to plumb the cooler separately from the radiator, and just leave the internal cooler disconnected. There is a slight issue with some transmission taking longer to reach operating temperature, but my 87 didn't seem to care. If you are worried about this and haven't bought your kit yet, there are a few with a "thermal bypass valve" that will recirculate the fluid, bypassing the cooler, until the fluid reaches 190* and then open to cycle cluid thru the cooler element. As I recall, these valves also "fail" to the open position, meaning that the cooler will be in circuit if the valve decides to quit working.

Either way, I've always thought that the benefits of getting the internal cooler out of the circuit and cooling the engine offset the slight disadvantage of the transmission taking longer to cool - and the availability of the thermal control valves has solved that problem as well.

While you are doing the cooler, do yourself a couple other favours -
Check your speed shop for M14x1.5 to -6AN adapters, Russell and Aeroquip both make them (and I think Earl's does as well.) This will allow you to get rid of the silly little "Ford-style" QD fittings and use proper plumbing. The OEMR fittings for QD are M14x1.5 threaded, so these should work. The houses will have them in aluminum, but I'm working on a batch in brass. You'll be able to use "push-in" -6AN fittings with regular hose - just make sure they're compatible. A speed shop can help you with that.
Add in a "remote" spin-on filter so you have proper filtration for your transmission. The AW4 "filter" is usually just a metal screen, and won't catch much. Mount the filter boss so that it will be open end UP, and remember to fill the new filter before you put it in to minimise "dry time" when you start after your oil change. Plumb the filter between the transmission and the thermal valve.

I didn't look to see where you were, but I'm available for assistance if you're in the Bay Area...

5-90

5-90 said:

Well...

Add in a "remote" spin-on filter so you have proper filtration for your transmission. The AW4 "filter" is usually just a metal screen, and won't catch much. Mount the filter boss so that it will be open end UP, and remember to fill the new filter before you put it in to minimise "dry time" when you start after your oil change. Plumb the filter between the transmission and the thermal valve.

I didn't look to see where you were, but I'm available for assistance if you're in the Bay Area...

5-90

Click to expand...

Questions? I have an extra remote filter bracket on the shelf somewhere, I´ve been thinking of installing between the tranny and the cooler. Have a external cooler and the radiator cooler hooked up in series (no thermal valve). Gets cold here and the tranny shifts late, until it gets up to temp.
Which type filter do you think, a standard motor oil filter, think my remote filter bracket is threaded for early Dodge.
Second guestion, I´d think the out (hot) line for the tranny is the one that used to go to the top of the radiator. But never fired one up with the lines disconnected to find out for sure, for obvious reasons. Though I did flush a Chev, once and discovered the out line from the tranny actually put pressure to the bottom of the internal radiator tranny cooler. Always made me wonder a bit.
Last question, if the filter becomes plugged does the tranny cooler line have enough pressure to compress the bypass spring? I´d imagine so, but assumptions have bit me in the rear before.

5-90: Yeah Im about 3000 miles away. But if youre up to the drive you are more than welcomed to freeze your butt off over here in PA and help! The beer stays cold while youre working anyway! Thanks for the advice. So...running the external cooler will cool the tranny a little too much? Im putting 33s on stock gearing...only for a short bit...so will that cause enough extra heating of the tranny to equal things out? Thanks for the tip with the AN fittings. I hate those QD things. I struggled for hours with my rusty one while changing my radiator. One more question. I think Im going to try to run it in series with my radiator. Will that help the fluid heat up faster or slower? I assume faster since it has warm coolant and less airflow than the external cooler out front. Thanks again. Im finally getting all the little things I need taken care of!

Justin

Yeha - it seems the jury's still out on the "series v. bypass" debate - but I'd go with the thermal bypass valve and take the load off the OEM radiator (which will also decrease warmup time - running the transmission fluid through the coolant bath cuts both ways - if the coolant is cold, it will take the transmission longer to heat up anyhow.)

You can use regular "spin-on" filters for the remote - mount them open end UP like I mentioned, and fill the filter just before you install it. In fact, if you do a remote oil filter, you'll want to do it the same way, and for the same reason.

Since transmission fluid is considerably thinner than engine oil (even and especially when hot,) there is usually no blockage of the filter element. Maintain change intervals, and you'll be fine.

5-90

There is a little place to mount a fan powered transmission cooler under the radiator, behind the bumper, it's a good 20 inchs long and 7 or so inchs wide!
I have a 91 cherokee without a tranmission cooler and am trying to figure out ways to encorporate it into the system...mine doesn't have one, any suggestions?