ZF-5 temp gauge and cooler

JCart · Mar 6, 2020

Hey Fellas,
Need comments on this notion. Periodically tow moderate weight in some steeper terrain here in B.C. Western Canada. Have the bits to install a temp probe. How hot is too hot for the ZF-5? I know they are a robust tranny and the ZF-6 comes from factory with a cooler. So the plan is to install on drivers side (probe) inspection plates using a brass bulk head fitting.

Got me thinking what if I install two more bulkhead fitting one on each side (in inspection plates). Then run from say drivers side using 5/16 rated hose to cooler in front bumper then on return through spin on filter then through SD 7.3 fuel pump then to passenger side inspection plate. When the gauge indicates hotter temps, flick the switch....

Thing is I have all the parts kickin around in the shop, including true cool tranny cooler (even has a puller fan on it and fits inside stock bumper).

Appreciate any feed back.
j

Zeb · Mar 6, 2020

Eh, I don’t think I’d go thru that much hassle.

If you do, I’d put the pump pre filter. I don’t think it’d last very well trying to pull trans fluid thru the filter.

Garbage_Mechanic · Mar 6, 2020

I think the real issue is the operating temp limit of the oil. I’m thinking a basic limit of 250 but need to research that #. Your plan is cheaper than the Fasr Coolers I was thinking of.. Not sure how long a fuel pump will keep working but there are pumps made for this, I have seen them for diff coolers for racing.

co04cobra · Mar 6, 2020

I agree that I don’t know how long a fuel pump would hold up. The other concern I would have would be the fluid capacity needing increased to compensate for when the pump is on and lines, cooler, etc...are filled.

Fluid capacity on the zf-6 vs 5 is almost double.

Patrick Feeley · Mar 6, 2020

Not sure a fuel pump would handle it (both temp and viscosity). I could get my ZF-5 up to 250F when I owned my 94. Here's some stuff I wrote a long time ago regarding a cooler and pump:

You can put an external pump on the ZF-5, but it won't be a cheap endeavor! I thought about it on my 94. You will need to modify the PTO covers for inlet/outlet ports (or find a couple of Fabcraft Metalworks billet covers that have the ports), get a pump (Weldon 9200-A, Tilton 40-525, or Mocal 17-522HT ... $200-$400, get one with Viton seals), Temperature Switch (don't want to pump when its below temp), decent stacked plate Cooler (I don't think it needs to be huge either), and of course all the fittings and lines. The pumps are usually around 0.5-2.0 GPM.

Cheers!

JCart · Mar 7, 2020

Zeb said:
Eh, I don’t think I’d go thru that much hassle.

If you do, I’d put the pump pre filter. I don’t think it’d last very well trying to pull trans fluid thru the filter.

Redline MTL is pretty thin, just the same good call on filter placement if the pump packs it in least I’ll catch the bits.

JCart · Mar 7, 2020

co04cobra said:
I agree that I don’t know how long a fuel pump would hold up. The other concern I would have would be the fluid capacity needing increased to compensate for when the pump is on and lines, cooler, etc...are filled.

Fluid capacity on the zf-6 vs 5 is almost double.

Great point about capacity, I typically fill my ZF-5 with 5 litres of Redline MTL as the synchros seem to like it best. So overfilled just a little. Never really thought of gravity drain back into the tranny though, guess there must be a check valve made I could install. True cool in the front bumper will be a smidge higher then tranny maybe, I’ll have to measure that as I’m thinking the bottom 1/2 of the inspection plate will be just lower.

JCart · Mar 7, 2020

Patrick Feeley said:
Not sure a fuel pump would handle it (both temp and viscosity). I could get my ZF-5 up to 250F when I owned my 94. Here's some stuff I wrote a long time ago regarding a cooler and pump:

Cheers!

Thanks Patrick, other thing I am probably overthinking was internal tranny gear train rollover and if it pulls all the fluid away from inspection plate location(s) E.g., facing towards front of truck while at back of tranny, gears mostly roll clockwise? Mmmm guess more research is needed here... just for fun.
Thanks guys,
j

78-79fordman · Mar 7, 2020

I have thought about the pump and stuff my self I bought the fabcraft pto plate it's nice. But I have yet to take time to install it with a sending unit .

JCart · Mar 8, 2020

78-79fordman said:
I have thought about the pump and stuff my self I bought the fabcraft pto plate it's nice. But I have yet to take time to install it with a sending unit .

Yup those are nice for sure, think they also make a cooler that mounts in front of the cover too right? Thanks for sharing.

Garbage_Mechanic · Mar 10, 2020

The coolers are called Fast coolers...

Patrick Feeley · Mar 10, 2020

The Fast Coolers increase the fluid capacity, but they really don't do much (IMO) other than increase the time it takes to get hot. There will be a little cooling, but not like using a pump and decent cooler. Cheers!

JCart · Mar 10, 2020

Patrick Feeley said:
The Fast Coolers increase the fluid capacity, but they really don't do much (IMO) other than increase the time it takes to get hot. There will be a little cooling, but not like using a pump and decent cooler. Cheers!

Thanks Patrick, agree with you on the Fast Coolers possibly a good idea, however prices here in Canada for a set are unrealistic. Especially so when I have all parts save for some tranny rated hose. Have the temp sensor installed on driver’s side inspection plate in bottom corner. Drove 20 miles and gauge didn’t even move, mind you it’s just above freezing at the moment. Changed out the fluid and added through the top shift tower as I wanted to put in 4 litres. Now just gotta come up with a better way to fasten the shift twin covers.... sigh challenge to not wreck the cover(s) and hit the same screw holes in the floor pan. Guess I should order new cover assembly mine is a little rough, the inner white cover is boogered up a little at the corners.
j

78-79fordman · Mar 10, 2020

Fast coolers are $99 a pair on ebay . Dont how that works in Canada though . I'm going to buy a pair . But sadly I will install all at one time sending unit coolers and covers . So I will not have a pre temp to see if they help .

JCart · Mar 11, 2020

78-79fordman said:
Fast coolers are $99 a pair on ebay . Dont how that works in Canada though . I'm going to buy a pair . But sadly I will install all at one time sending unit coolers and covers . So I will not have a pre temp to see if they help .

Thanks 78-79fordman price seems lower then when I last looked. For me guessing $250 or more for a pair, shipping, x border duties and taxes.
j

JCart · Mar 18, 2020

So driving around a bit this afternoon for 25 miles or so ZF temp went up to 130 degrees F. Ambient air temp was 11C or about 54F. Mostly city driving, just thought I’d toss this up for anyone’s interest.