I have a 1971 F-100...390 C6 2000 rpm stall just a street truck not towing heavy loads.... I want to eliminate using the radiator cooler and mount a cooler under the truck..... How big of a cooler do I need...???

 

You will get a variety of answers for this question. The most often given answer is to not bypass the radiator cooler, but to run your cooler through that then through an external cooler.

However, I'm running a stand alone cooler and have bypassed my radiator cooler. Others here have done the same with no complaints as well.

I had my tranny recently rebuilt as the previous rebuild took a major dump and sent metal throughout my system. On the new rebuild I used the largest stand alone cooler I could find. This was what the Rebuilder told me to do, and since he is giving me a 24,000 mile warranty on it, I did as he instructed. The main reason for this was because the only way to be sure to get the metal out of my radiator tank was to have it cut out and replaced. He said that this was not needed and to just run a large stand alone cooler and bypass the radiator, just plug up the radiator inlet/outlet. Given his 40+ years of rebuilding experience, I did what he said. This is on a built up C6 behind the built 400 in my '53 F-100.

If you live in a cold climate and drive it alot in the winter months, you should not bypass your radiator cooler as it will warm up the fluid quicker. This will prevent condensation buildup and "not so hard" shifts. However, I'm running a stage-2 shift kit and wouldn't know the difference between hot and cold fluid shifts, feels the same to me...........but, never-the-less, I have read that in previous posts in this forum (in response to my question, which is the same as yours).

If you are like me and primarily don't use it as a daily driver, but mostly just cruise around in the summer months (it is a hot rod, not for snow and ice), just install a large cooler. I installed a flex-a-lite (flx-4126) cooler. Works great In addition, I installed a fluid temperature gauge, this way I can monitor the tranny temp as well. For the most part, it stays right about 150-175 degrees. That is with the outside temperture ranging from fairly cool, low 50's to over 100 degrees. The temp does climb up on the big, BIG hill climbs though. Probably because I'm pushing it a bit though

I'm not sure what else to tell you other than this is what I have done.

 

53fatfndr

thanks for the reply...yes it's very similar to what and how ur using ur truck..... where did you mount the cooler.....I'd like to mount a cooler without a fan but I can't mount it in front of the radiator..... I was looking at a 24" long 2 row cooler that mounts along side of the frame but I don't know how effective that would be maybe I could use that along with the radiator cooler.....???

 

You will need air flow, that's a given. In front of the radiator is usually the best place, or somewhere else with an externally mounted electric fan. There are models available that include a cooler and fan. Just make sure that you are buying a large enough cooler. However, if you use the radiator cooler then the external cooler, you should be ok. Again, you are still going to want air flow to dissipate that heat away from the cooler.

 

If you use the radiator cooler, you can get away with a sighnificantly smaller cooler. Good reasons to not use the radiator cooler are leaky or blocked/dirty radiator cooler. For many people, a mere 10 - 15 degrees reduction in temperature is more than enough.

 

it needs to be infront of the radiator. i use a 25k one on mine. it is 27 1/2'' x 12'' x 1'' its 330'' of cooling space.

 

When in doubt get a tranny temp guage. I installed a tranny cooler with a dedicated fan and I'm still having problems with the tranny temp. I've been brainstorming to come up with a solution but the higher the stall and the more you like the gas pedal the harder they can be to keep cool.