Thread: Can I run w/o trans oil going into radiator???

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Pat,

I run mine mostly in 3rd, because most of my trips are short an local. When it's in 4th, running at speed, it's locked up (either automatically or manually with my switch).

Dave,

I've had a few delays, and some time in traffic, but none of the park n' idle for 10-miles stuff yet. We'll see as this summer progresses. Last summer, I was mostly suffering tune-up woes, and didn't drive a lot.

Related question: I have a tranny cooler built into my radiator and a buddy suggested running an additional cooler on its way back to the tranny. Should I use the radiator connections at all. I am worried about the radiator temp and the tranny temp. What is the right balance? Thanks

Many Schools of Thought on this subject. Some advocate using only the one in the radiator (their logic is that if Detroit does it there must be a reason) some say that the radiator cooler actually does no cooling to speak of but is used to keep the transmission fluid warm enough. Others say "why would you want to run hot fluid into a radiator, further diminishing the radiators ability to cool the engine." And still others say to run BOTH an external cooler and the one in the radiator. Take your pick.

For the reasons I mentioned in my previous post, I do not like to run the tranny fluid into the radiator and only use a double pass external cooler. Am I right or wrong? Who knows. But I have yet to have a heat related transmission failure in any car I have done this to. My Jeep truck has this setup and I have pulled trailers with way over the limits a few times to Daytona and other places, and there were never any problems.

I had a long conversation at Turkey Run with one of the guys from PRC radiators a few years ago, and he said that they do not like putting the transmission coolers in the radiator either, and he also suggested an external one.

Flip a coin.

Don

thats why i put mine in the trunk with a fan on top of the cooler and a small hole cut next to and below the cooler to allow for air circulation when it needs to warm up i leave the fan off and when its warm turn it on

By putting a transmission cooler in the bottom of the radiator you are potentially introducing even more heat into something that is already hot - the ATF. The water returns to the top of the radiator with a temperature that could be as high as 250*, depending on the pressure cap. It is cooled during its' flow thru the radiator to the bottom tank and that cooled to (whatever temp is, I don't know) water that then surrounds the transmission cooler. Transmissions like ATF at 175* or less. Will that coolant temp in the bottom tank on a 99* day in South Florida do a good job? I like Jack's idea of a switch and monitoring the tranny's temp. I also like the idea on NOT introducing more temp in the ATF by the radiator cooler.

Here are my transmission coolers.
A skin effect radiator in front, 120 sq inches of cooling area . . .


And a DeRale trans pan.


One thing that will impact trans cooling is the stall speed of your converter.
It needs to be low enough to lock up at highway speeds.

Mine is a 2400 rpm stall, but it flashes to 2800 rpm.
Depending on engine size (mine is 462") the converter will stall at different rpms due to available torque.

This setup works pretty good and the only time the trans has gotten warm was on the slow, winding switchbacks going up into Sequoia National Park running in 2nd gear below stall speed.
A 20 minute cool-down did the trick and the rest of the way up the hill, no problems.

I understand the cast aluminum trans pans do as good as the DeRale vis a vis trans cooling.
I may use one of those on my 31 on 32 rails roadster, but am also thinking of using one of Summits small trans coolers with electric fan.
Only trouble I see with aluminum trans pans is they break and steel dents.
Probably a moot point since I've never dragged my trans pan.
The DeRale trans pan hangs down equal to the oil pan fwiw.

You won't know where you're at unless you have a transmission temperature gauge.
I prefer mechanical for their wide needle sweep and accuracy as well as reflecting changes right away.

I see questionable trans cooling setups quite often, no temp gauge and when I ask the owners how the trans does set up like that the answer is always, "no problem, cools great."

It's obvious they don't know and I don't argue with them, but a trans failure is surely in the future of some of the creations I see....

First of all, Denny, what I was referring to, of course, is a non-stock engine, suffering with a radiator that is marginal for the engine, then adding the heat of a transmission. They will both suffer and I will not knowingly allow that to happen to either. I have a big radiator for this engine and really an oversize cooler for my transmission. Since it had completely slipped my mind to add a temp sensor to the transmission and with Jack's saying he uses the same gauge, will install a sensor in-line as soon as I can figure out the plumbing changes. C9 - while I do like mechanical gauges for most reliability will be using strictly electrical units on this car.

I am all to well aware of grounding oil pans - I happened to be rummaging around my 'trophies' a couple of days ago and came across the pan from my last 351W - with an oops that wept oil. I replaced that pan. The C4 pan that was on the trans behind it was worse but it of much heavier steel. Like I said above, I would have liked a DeRale pan but they don't do a C4/C6 though it doesn't appear to difficult to do my own - (and with how many tube welds(??).... The aluminum version is a bit lower then I would like but it isn't lower then the engine pan

okay, I think I made sense of all this. Please check my work. I have a 454 TBI engine out of a 92 Suburban; it is now in a 37 Cadillac Sedan. I live in very hot AZ and therefore don't have any need to warm up my transmission fluid. So I should run a transmission cooler and not use the cooler in the radiator at all. Ideally I should use a tranny cooler with a fan that I can switch on and off and I should get a gauge to monitor the tranny fluid temperature.

In order to keep a tranny cooler away from the exhaust I was thinking of mounting it under the front fender. Good or Bad idea??

Thanks for all the insight.

Denny,

Isn't 180 a pretty high temp for the fan to turn on?

This thread is a few months old but I ran into a new but related problem. My Brookville frame is pretty narrow and now I have the mufflers installed so I am installing the fuel line along the right outside frame rail hidden under the Model running board apron. So far so good EXCEPT I already have a fin type external trans cooler on that outside of the rail. First it is not clear to me that the air flow will be good enough there, although the shape of the '29 front fender may act as a large scoop? I discovered I do have fittings in the radiator but for reasons several of you have discussed above I prefer not to plumb the transmission cooler to the bottom part of the radiator when the small radiator may be marginal for the engine coolent. So what I have now is the fuel line coming up to the front alongside the 24" double pass fin-type external cooler. Another problem is that there is a 60" section of fuel line which is unsupported under the apron which will probably vibrate. So I put a small zig-zag into both ends of the fuel line to offset it to the outside about two inches away from the 24" trans cooler and I covered it with a sleeve of 3/4" heater tube to damp vibration and maybe insulate the fuel line from the trans cooler. I also have another double pass trans cooler like the one IC2 shows above. Does anyone know whether the fin type or the solid aluminum type cools better? I also have a steel DeRalle tube trans pan as shown above but it is clearly the lowest part of the underside of my car with barely 3" of clearance. I like the idea that steel will dent as compared to a cracked aluminum trans pan but I would like to go back to the stock pan to get more ground clearance. Any comments on whether the fuel line will pick up much heat from the trans cooler and whether the rubber hose sleeve gives any insulation effect? I have thought of adding an additional sleeve of aluminum over the hose to reflect heat rather than absorb it by the black rubber hose. Maybe what I should do is wrap wrinkled aluminum foil around the fuel line to reflect heat? I am looking into a gauge for the trans fluid temp.; sounds like a good idea. Comments?

Don Shillady
Retired Scientist/teen rodder

As I posted some time ago in another thread, here is my 700R4 transmission cooling problem: First, when you are driving down the road, you probably will not have a cooling problem. In overdrive, the converter is locked up so there is not much heat being generated. Where the cooling problem will show is at slow speeds....putt-putting around the fairgrounds, etc.

I did the following steps with my 350 Chevy/700R4 with no radiator trans lines:
1. First used a flat Derale cooler with a fan mounted horizontally over the rear axle. Blew the air downward. Long pulls in lower gears made trans temp go to 260 deg.
2. Added finned aluminum cooler (long skinny tube with fins) outside of frame rail. Zero change.
3. Added high velocity boat bilge fan blowing down tube cooler. Zero change
4. Moved Derale cooler from under car to above rear tire (this is a 4500 lb jeep). Helped some but long pulls still got hot.
5. Removed bilge fan. No change
6. Changed to Torco synthetic fluid...figured if it was going to get hot, then I should use a fluid that would take the heat. This helped probably 30 degrees on the long pulls. I am at 11 quarts in the system right now.

As soon as I quit the slow pulls (unlocked converter), the temperature falls to under 200.

From what I can tell, you cannot predict the performance of a system by asking other people...it is a personal thing that is related to the air flow on your car...it's not like a radiator cooler....the airflow under the car is so different between cars that it is mostly unpredictable. From what I found, you need to experiment with a transmission temperature gauge installed. I highly recommend the synthetic fluid...costly but apparently effective.

By the way, the trans pan with the little tubes works at speed when there is air going thru the tubes but at slow speeds, there is not enough air mass being presented for it to do much.

mike in tucson

the rubber hose will help to keep the fuel from cooking off.

If you are on a budget look at the external cooler from 90s Ford F and E series.

You can also install a switch to lock it up in any gear.

I am kind of discouraged about this since I really do not like the external cooler next to the fuel line even with the rubber hose shield. I am considering using the bottom of the radiator after all with the needed plumbing but down on the floor again gave me the usual sinus infection. I had swept the garage out pretty well when the car was in the muffler shop and thought I had solved the dust problem, but here I go again needing a few days off! Thanks for the suggested Ford external cooler.

Don Shillady
Retired Scientist/teen rodder