PS/AT cooler question... What would you do?

[agirgen]

I am in the process of chainging out the radiator, power steering system and transmission on my 74. When I got the transmission, I ordered one of those fancy electric fan powered remote coolers with it. Yesterday, I got my new four core radiator from Wild Horses and (I didn't think of this when I bought it) it has a transmission cooler on it as well. I was under the impression I was getting a trans-coolerless radiator. So, now i have two coolers and two systems that need to be cool... Should I run the transmission through the radiator and use the remote cooler for my power steering box or vice versa? The original stock P/S cooler is in pretty sad shape and I am a little leery what it looks like inside... the last power steering box pretty much turned itself into a grenade!

Thanks in advace for any advice! ;D

Later,
Girg

 

[Steve]

One of those fan coolers is way overkill for PS fluid. Since you live in the south, you don't have to worry about adding heat to your ATF (yes, it can be too cold.) Personally I'd run the ATF through the separate cooler with the fan and not hook anything to the radiator cooler, and I'd get a smaller (and cheaper) cooler for the PS fluid and mount it in front of the radiator.

 

[Landshark]

I am in the process of chainging out the radiator, power steering system and transmission on my 74. When I got the transmission, I ordered one of those fancy electric fan powered remote coolers with it. Yesterday, I got my new four core radiator from Wild Horses and (I didn't think of this when I bought it) it has a transmission cooler on it as well. I was under the impression I was getting a trans-coolerless radiator. So, now i have two coolers and two systems that need to be cool... Should I run the transmission through the radiator and use the remote cooler for my power steering box or vice versa? The original stock P/S cooler is in pretty sad shape and I am a little leery what it looks like inside... the last power steering box pretty much turned itself into a grenade!

Thanks in advace for any advice! ;D

Later,
Girg

Use them both. I've read either way, but I lean towards this way. Run it through the seperate cooler first, then run it through the radiator. I've always been told that you could cool it too much with just a seperate cooler.

 

[cbearly]

I agree with Steve. I'd skip running it through the radiator, and use the trans cooler with the fan. Get a thermal switch for the fan so that it only comes on once the tranny is up to temp. I also have a smaller cooler with out the fan that I mounted infront of the radiator that I use to cool the power steering.

 

[HotWheels]

Run them both, Run the forward line to the radiator and the rear (return) line from the radiator, thru the aux cooler then back to the tranny. This way u get a good tranny warm up and no heat transferrence. I have the B&M which has the thermal switch already on it. If you need a hand or tranny fittings for the Earls fittings I believe I have some spares. Here's some pics:

hth,

Mick

 

[BlackHorse]

Don't forget when it comes to the auto trans the "cooler" in the radiator is also a heater. It's used to bring the trans up to operating temp fast. I know auto trans rebuilders that require running through the rad because of this. I'm of the opinion you should run through the rad and then an additional cooler if necessary.

 

[OX1]

Don't forget when it comes to the auto trans the "cooler" in the radiator is also a heater. It's used to bring the trans up to operating temp fast. I know auto trans rebuilders that require running through the rad because of this. I'm of the opinion you should run through the rad and then an additional cooler if necessary.

So what about charts like this.

http://www.txchange.com/heatchrt.htm

Running a 195 stat, means the radiator is surely running hotter and hence the trans fluid is also.

and this

http://www.worldsbestoil.ca/Amsoil-Image-Files/atf-amsoil-synthetic-product-comparison.gif

Surely Amsoil would, if anything fudge the numbers on the stock ATF chart, but they still claim it's performance is OK down to 10 degrees. They also claim over 170 reduces life, so why do you want to heat it up to 195+.

On 10 degree days, my 95 F250 would take so long to warm up, the trans temp never went over 88 degrees (had a cyberdyne digital trans temp guage with sender in the line out of the converter) and even with the stock "cooler", could take 20 miles to even approach that. With a 10 mile commute on multpile cold days, it sometimes never reached that for many days @ a time.

I'm not a big fan of the stock radiator cooler. I think it does more harm in hot temps, than it helps in cold temps. Obviously if you live in Canada or similar climate, then that may be different.

If your worried about heating up the trans fluid quick, get one of these thermostats and hook it up to a large stand alone cooler. Provides no cooling until it hits 165.

http://ox.users.superford.org/MISC/TRANS_THERMOSTAT.JPG

 

[Broncobowsher]

There is a big flaw in your cooling logic...
If you run a 195 thermostat, that is the temp at the thermostat when it opens, not the temp of the whole cooling system. Trans coolers are usually placed on the outlet (cold) side of the radiator. If your thermostat is letting 195 water into the radiator and you are getting 195 out again, you need to replace your radiator with one that actually cools. Radiator outlet temps are typically 20 to 40° cooler then inlet temps.

That is why trans coolers are located there. The need for remote coolers before the rad cooler is when an auto is working too hard and the fluid is getting hot. This heats the rad water too much before it enters the engine again. Basicly the rad is working fine but the trans is defeating it's cooling ability. Not a problem in a normal car, but when things get worked hard then it becomes a problem.

 

[OX1]

There is a big flaw in your cooling logic...
If you run a 195 thermostat, that is the temp at the thermostat when it opens, not the temp of the whole cooling system. Trans coolers are usually placed on the outlet (cold) side of the radiator. If your thermostat is letting 195 water into the radiator and you are getting 195 out again, you need to replace your radiator with one that actually cools. Radiator outlet temps are typically 20 to 40° cooler then inlet temps.

That is why trans coolers are located there. The need for remote coolers before the rad cooler is when an auto is working too hard and the fluid is getting hot. This heats the rad water too much before it enters the engine again. Basicly the rad is working fine but the trans is defeating it's cooling ability. Not a problem in a normal car, but when things get worked hard then it becomes a problem.

So your saying it's still possible for that in radiator cooler to heat my trans fluid to 175?? 175 is when I just start getting concerned and keep a good eye on the guage. Not really fond of my radiator heating my trans fluid up right to the edge of acceptable operating range just so that it can get 30-40 degrees hotter inside the converter and massively break down. You also assume that everyone has perfect cooling and no one ever runs hotter than what their thermostat says. Anyway, to each his own, but I believe the minimal initial warming benefits to having the fluid run through the radiator are negated heavily by the damage the fluid can receive from the constant heating. ;D

 

[4x4xTOR]

I personally don't use the radiator to cool the tranny although I have and still have the option. I did however, add a cooler in front of the rad. and I did add the same fan cooler you mentioned. I have a hood scoop and I made some rails to mount the cooler to the underside of the scoop. Now the fluid goes thru both coolers then back to the trans. No problems and I think it helps to keep the engine cooler, also. It isn't such a heat sink anymore.TOR

 

[Broncobowsher]

So your saying it's still possible for that in radiator cooler to heat my trans fluid to 175?? 175 is when I just start getting concerned and keep a good eye on the guage. Not really fond of my radiator heating my trans fluid up right to the edge of acceptable operating range just so that it can get 30-40 degrees hotter inside the converter and massively break down. You also assume that everyone has perfect cooling and no one ever runs hotter than what their thermostat says. Anyway, to each his own, but I believe the minimal initial warming benefits to having the fluid run through the radiator are negated heavily by the damage the fluid can receive from the constant heating. ;D

If you are running a 195 thermostat and have a radiator that can only pull off a 20° drop (a marginal radiator) then the outlet temp would be 175°. Depending on where you live, 175 is a cold tranny temp. Out here we start at 115° in the summer just sitting in the parking lot. Keeping tranny fluid under 190 in the summer can be a challange. But amazingly there are thousands of vehicles that run around for well over 100,000 miles without even the transmission fluid level ever being checked there entire life. That 175 is a pipe dream number that sells transmission coolers. If you are going to be that paranoid when are you going to start watching the engine oil temp? And if you do any towing you can be amazed at how hot a diff can get and people don't even know that they are doing it. And for the most part they live long happy lives (there are always the few that do fail).

And if you actually get in and read some of the real information from the people who make the clutches for the transmissions, the fluid needs to be warm for the clutches to work and not self destruct. Much like an engine, transmissions are designed to operate at normal operating tempertures, not super cold temps. What temp does the transmission operate at in it's intended application? what was the cooling in that intended application? Does the sales pitch that you need a tranny cooler come from someone who sells you transmission coolers?

 

[clayne]

I run a separate cooler with its on fan and have a small cooler for the PS mounted below trans cooler. I did this so radiator would get pently of air through it for cooling. We all know they aren't the best known for cooling. I have in-line thero control (from summit racing) that works great. The temp stays around 185 degree but gets 210 if I run it hard but it seems to cool alot faster with its on fan. I am running a small stall and that with cause alittle more heat too. I ran my transmission for 4 years and when I decided on putting a stall in I freshened up the C4 and it looked great. I did put better clutches in it to withstand higher temp just incase heat was a problem after I added the 2000 stall. WORKS GREAT!

 

[72Sport]

There is a big flaw in your cooling logic...
If you run a 195 thermostat, that is the temp at the thermostat when it opens, not the temp of the whole cooling system. Trans coolers are usually placed on the outlet (cold) side of the radiator. If your thermostat is letting 195 water into the radiator and you are getting 195 out again, you need to replace your radiator with one that actually cools. Radiator outlet temps are typically 20 to 40° cooler then inlet temps.

That is why trans coolers are located there. The need for remote coolers before the rad cooler is when an auto is working too hard and the fluid is getting hot. This heats the rad water too much before it enters the engine again. Basicly the rad is working fine but the trans is defeating it's cooling ability. Not a problem in a normal car, but when things get worked hard then it becomes a problem.

The subject of inlet and outlet temperature was brought up a few months ago. Then like now I couldn't believe the large temperature difference as you describe. Twenty degrees to forty degrees difference would be hard on an engine if in fact it were true. The thermostat serves as a temperature controlled flow device. Its purpose is to keep the entire engine operating at the same temperature. It does have it limitations so there is some difference between water going into the block and water temp out of the upper radiator hose.

I decided to see what it really was so I hooked up a thermocouple on the lower radiator hose (Todd Z pipe). See pictures. I then went for a 30 mile ride and recorded temperatures as I went. The greatest difference was my first reading when the temperature gauge on the dash read 176.9 (est) the bottom hose read 166.9 by a handheld thermometer. I have previously verified the aftermarket temp gauge reading with the handheld thermometer. They read within .5 degrees of each other if I remember correctly.

This is what I found:

Engine temp xxxx 176.9 180 185 186 189

Lower Hose temp 166.6 170 175 178 182.6

As the engine warmed up the differences became much less. It was only in the 90's that day so the hottest I could get the engine temp was 189. Actually that is where it always runs even in Lake Havasu when it was between 113 and 115 and the ac on high.

I don't run an automatic in my Bronco but I do have one in my 33 year old RV. Art Carr did my tranny work many years ago and he suggested not running the radiator cooler. Like you have said it heats up the engine. I run two aux coolers in series. One with a temperature controlled fan and the other in free air. The only time it sees a temp above 170 is when pulling a long hill with the Bronco in tow. I had engine problems about ten years ago and while I had it down I took the tranny back to Art Carr for a check up. His response was why did you bring it back it looks like new inside. There was no wear on anything.

 

[Broncobowsher]

I have done OEM testing of cooling systems, that is where my general data comes from. As for the thermostat regulating, theory and operation are not always the same.
Imagine this torture test. Run an engine at normal operating temperture then switch the water inlet with water at -40°. Repeat.
When questioned about it I found out it really does happen. Up in the cold north the rad is chilled to -40 when driving and the water stays stagnit. When the thermostat does open it flushes that hot water out and the cold in. I know this is a test that one of the OEMs does to there engines.But this is the stuff that I do for a living. Last thing I feel like doing when I come home from work is take 100 channels of data on the cooling system on my bronco. I could do that and dial in my cooling system perfect, but it works good enough right now I don't want to mess with it.

If you want to do it right, you actually need to play with your cooler arangment based on where you live, where you go, your driving habbits, and even the season. When I finally ditch my old rad and go modern I will probably toss my in rad cooler as well, but not without placing a thermostat in the cooler lines first. I don't like running the trans too cold

 

[spieser]

What is a normal operating temp range for a C4? Acceptable range.

 

[COBlu77]

What is a normal operating temp range for a C4? Acceptable range.

My understanding is 90 above the ambient temp outside, so on a 90 degree day 180 would be normal. A good range would be between 140-190. Mine normally runs about 160 with an external cooler not going through the radiator. If it gets close to 200 I start to watch it and never let it get over 220 without changing the fluid. Without the A/T lines routed through my radiator it has kept my engine temps lower, but the A/T temps aren't as consistent. It goes up to 190 and then down to around 100 very quickly, but generally stays around 160.

Some of the newer AT coolers come with a temp bypass valve. Here's a good one that I have on my F250 http://www.dieselsite.com/index.asp?PageAction=VIEWPROD&ProdID=205 . For our Broncos you would need the one with the "Thermal Bypass Valve". Here's another one I found with temp bypass http://store.summitracing.com/partd...&N=700+4294924500+4294839034+115&autoview=sku . This is the one I'm going to switch to.

Here's my .02. It's debatable how much it affects engine temps having an aux cooler out in front of your radiator, but I've found little difference with or without one in front and I think you could avoid expensive coolers with fans by just going to a bigger plate cooler in front of the radiator.