Too hot and too cold?

[rmfreeze]

Hey guys, I just got through putting a '68 back together and put some trail time on her today. She probably doesn't have 200 miles on the rebuild yet. I put a 351w/C4 in replacing the 200 6cyl / 3-spd.

I used a triple pass radiator but it doesn't have the tranny cooler (or heater if you want look at it that way ;D ). I ran the tranny lines up to the passenger inner fender well and ran them into a B&M cooler with fan. It's mounted with about 1/2" of clearance off the fender.

I had my doubts about the tranny cooler working well in the engine compartment. After doing several test drives I noticed the B&M fan never comes on (175* switch). So I put in a tranny temp gauge and noticed it doesn't heat up AT ALL. It took lots of stop and go driving for it to get above 80* on a 75* day. I knew the radiator helped heat the fluid but I figured it would eventually heat up on it's own. I drove 30 minutes to Superlift ORV Park today and in 65-70* air this morning it never got above 80*. After wheeling for 30 minutes it was around 100*. After 2-3hrs it was 140-160*. If I ever got on a main road and got to 10mph or so for a few minutes it would be down to 100* in no time. It got down to 87* on the way home in 78* air.

Now the motor is another story. I'm using the triple pass radiator and a big electric fan. It's the highest CFM I could find at the time (can't remember what it is). If I'm doing 5mph+, it keeps it 180-190* no problem. But after an hour or so of wheeling it gets into the 200-210* range.

I'm thinking of adding an engine oil cooler and sticking it up front with a small fan. I guess I'll also keep an eye out for a radiator with a tranny heater. I had no idea it would stay that cool without the radiator.

 

[Broncobowsher]

Where did you mount the tranny temp gauge?

 

[rmfreeze]

Where did you mount the tranny temp gauge?

In a pod attached to my roll bar.

LOL. Or do you mean the sender? The sender is in the line feeding the inlet of the cooler immediately preceeding the cooler. It should be the forward most line coming off the tranny. I would have to double check but when I mounted the tranny cooler I checked at that time to make sure that line entered the cooler where the temp sender for the fan was located. Basically, the sender for the fan and the sender for the tranny temp gauge are on the same line relatively close to each other.

I also forgot to add that I slightly overfilled the tranny and need to drain a bit off.

 

[Bronchole]

I think you discovered why tranny manufacturers will not warranty a transmission that has not been plummed thru the radiator!

 

[Amac70]

200 210* is not running hot for the motor. That is fine temp to be running at especially with a new motor.

 

[Mark]

200 210* is not running hot for the motor. That is fine temp to be running at especially with a new motor.

Especially a 351W

 

[rmfreeze]

Well, it was only 78* degrees today, too. When it's 98* out it may be a different story. 20* hotter air being pulled across the radiator may not cool it as much or as quickly. I was fine with the temps when not wheeling andit cooled off quickly when I could get the rpms above 1000 and get some air moving through there.

I also cut out the inner fender panel close to the header. A couple of times I'd let the fan run with the engine off when I'd get out to look at a trail and noticed I could feel the air/heat being pushed through around the tire/under the rig from the electric fan.

 

[rmfreeze]

I think you discovered why tranny manufacturers will not warranty a transmission that has not been plummed thru the radiator!

I always thought they were plumbed through the radiator to cool the tranny just like the coolant is plumbed through there to cool the engine. I figured if I supplied an adequate cooling alternative I would be fine. %) Obviously I need a heater for the tranny fluid, too.

So anyone know the operating temp for tranny fluid? Let me guess ... 160-200*?