Bypass radiator/tranny cooler combo?

It has electric fans so it's definitely not fan noise.

This does sound like a bearing in the drivetrain to me. When I apply the brakes harder going down hill it gets louder/more whining/higher pitched.

When I throw it in neutral it goes away.

I experienced the front end whine again but it was quieter this time, and didn't last as long. After I got to less grade/more flats with hills, it generally goes away slowly.

Fan clutch kicking in making a whine noise ?? However fan noise may still be going on even when stopped. After a while the fan clutch kick out and noise stops.

My wife old '06 1500 chevy crew cab 4wd right front hub bearing went bad but gave more of a hum (it might be called a whine) at speed especially while turning maneuvers out on the open roads.
Ten months later the left hub bearing went out with no noise at speed but just a slight high speed vibration in the steering wheel.

A older '84 1500 chevy transfer case bearing went bad but it was more of a rumble noise.
Might check with some of the many GM truck websites....there not all HD diesel types.

I and mostly the wife has owned several 1/2 ton GM trucks. We live out so we put lots of miles on a vehicle like 235k miles on a '90 chevy. Non of them had a radiator issue.
The '90 model was the 4L60 tranny/5.7 engine 4.10 gears. I put a small external rad cooler out front as this truck towed doubles (26' 5er/3400 lb bass boat).
Ran one temp gage with a 3 way toggle switch for two senders....one in the return line and one in the sump.
Interesting watching temp changes and differences when pulling hard.....when stopping at the top of say LaVeta Pass or Monarch Pass/etc.... fighting 35-40 mph headwinds....in 110-113 degree outside temps. Separates what gets posted theories and what actually happened.

Now that I think about it more, most transmissions now a days have some sort of thermostat built into them (or into a cooler hose like my truck). So the rad would never play a part in warming the fluid. Fluid is just never cycled to the rad cooler for the transmission fluid. It's just short-circuited and kept inside the transmission. I remember FCA getting an award for their transmission cooling setup in their 8 speed, can't remember what it was, but it was in an engineering mag, not "Ward's" or anything like that.

Another thing is that water has more thermal mass than air, so it's able to absorb more heat/energy from an oil/cooler exchange. This is why dunking yourself in a 30 degree ocean will result in hypothermia much quicker than standing naked in a 30 degree freezer.

ktmrfs wrote:
One thing that somewhat baffles me is using the radiator to warm AFT fluid at startup.

THE RADIATOR COOLER *NEVER* WARMS THE TRANSMISSION FLUID. NOT IN HOT WEATHER, AND CERTAINLY NOT IN COLD WEATHER. EVER.

ktmrfs wrote:
radiator doesn't really start getting warm until the engine is warm enough to open the thermostat. by then in most cases I'd guess the torque converter slip has already warmed up transmission fluid, especially in any stop and go driving. and in the meantime your running hot fluid through a cold radiator.

In cold weather the cold side of the radiator, where the transmission cooler is located, only gets a few degrees above ambient tamperature. The thermostat isn't open for a long time, so the coolant has a long dwell time in the radiator. That gives the cold air flowing through the radiator plenty of time to get the coolant almost down to ambient temperature before it gets to the trans cooler.

ktmrfs wrote:
Now maybe in extremely cold weather it will help keep the fluid warm enough once the thermostat opens,

No. See above.

Mark Kovalsky wrote:

Turtle n Peeps wrote:

I didn't disagree with Mark at all. I didn't know where his temps were taken and still don't for that matter.

When I was doing cooling tests at Ford I had anywhere from 50-200 thermocouples throughout the powertrain. I had thermocouples in the ATF line into the radiator cooler, out of the radiator cooler, and out of the aux cooler. I also had thermocouples inside the radiator reading engine coolant around the transmission cooler. I had about 20 throughout the trans so that I could map the temperature gradiant inside the trans. I had them in the radiator's upper and lower coolant hoses. I had a series of them mapping the air temp into and out of the radiator. I had them outside the trans to get an idea of the air temperature around the transmission.

Turtle n Peeps wrote:
Let me say it one more time. "If" ATF temps are higher than the ECT's "at all times" we are all in agreement.

I can't say that.

What I can say is that after extensive testing in ambients from -40°F up to +115°F I never found a condition where the temperature inside the radiator around the transmission cooler where the coolant was warmer than the ATF. ECT often was, but that's irrelelvant. What matters is the temperature near the cooler, and I maintain that it is ALWAYS colder than the ATF.

If radiator surround is cooler than transmission fluid, then I guess in hot weather it is doing it's job, cooling the transmission fluid. One thing that somewhat baffles me is using the radiator to warm AFT fluid at startup. radiator doesn't really start getting warm until the engine is warm enough to open the thermostat. by then in most cases I'd guess the torque converter slip has already warmed up transmission fluid, especially in any stop and go driving. and in the meantime your running hot fluid through a cold radiator.

Now maybe in extremely cold weather it will help keep the fluid warm enough once the thermostat opens, but what I've found on all the vehicles with transmission temp guages, the transmission fluid temps and coolant temps tend to track each other pretty consistently. Now they all have had the cooler in the radiator along with a big external cooler.

Mark Kovalsky wrote:

Turtle n Peeps wrote:

I didn't disagree with Mark at all. I didn't know where his temps were taken and still don't for that matter.

When I was doing cooling tests at Ford I had anywhere from 50-200 thermocouples throughout the powertrain. I had thermocouples in the ATF line into the radiator cooler, out of the radiator cooler, and out of the aux cooler. I also had thermocouples inside the radiator reading engine coolant around the transmission cooler. I had about 20 throughout the trans so that I could map the temperature gradiant inside the trans. I had them in the radiator's upper and lower coolant hoses. I had a series of them mapping the air temp into and out of the radiator. I had them outside the trans to get an idea of the air temperature around the transmission.

Turtle n Peeps wrote:
Let me say it one more time. "If" ATF temps are higher than the ECT's "at all times" we are all in agreement.

I can't say that.

What I can say is that after extensive testing in ambients from -40°F up to +115°F I never found a condition where the temperature inside the radiator around the transmission cooler where the coolant was warmer than the ATF. ECT often was, but that's irrelelvant. What matters is the temperature near the cooler, and I maintain that it is ALWAYS colder than the ATF.

Mark,

I'm glad you chimed in here and it still baffles me when one provides as clear as I think is possible the FACTS and folks still try and twist things to try and fit their prior incorrect/erroneous information using often at times what I can only best describe as red herrings left and right like this drivel over the laws of thermodynamics or conditions completely out in left field over what is actually being discussed.:R

It will be interesting to see what sort of counter arguments at now made with you above post:E

Larry

Turtle n Peeps wrote:

I didn't disagree with Mark at all. I didn't know where his temps were taken and still don't for that matter.

When I was doing cooling tests at Ford I had anywhere from 50-200 thermocouples throughout the powertrain. I had thermocouples in the ATF line into the radiator cooler, out of the radiator cooler, and out of the aux cooler. I also had thermocouples inside the radiator reading engine coolant around the transmission cooler. I had about 20 throughout the trans so that I could map the temperature gradiant inside the trans. I had them in the radiator's upper and lower coolant hoses. I had a series of them mapping the air temp into and out of the radiator. I had them outside the trans to get an idea of the air temperature around the transmission.

Turtle n Peeps wrote:
Let me say it one more time. "If" ATF temps are higher than the ECT's "at all times" we are all in agreement.

I can't say that.

What I can say is that after extensive testing in ambients from -40°F up to +115°F I never found a condition where the temperature inside the radiator around the transmission cooler where the coolant was warmer than the ATF. ECT often was, but that's irrelelvant. What matters is the temperature near the cooler, and I maintain that it is ALWAYS colder than the ATF.

hey guys, I can tell there are quite a few tranny/gear heads in this thread so I'm going to post this here.

I have another towing update and figured I'd get your thoughts on the results.

I towed my camper again over the weekend but this time I went up highway 285 in Colorado. It's still steep but not nearly as long and drawn out as i-70 here. It was a bout a 2hr drive and ended up stopping around 10,000ft.

Result:
I experienced the front end whine again but it was quieter this time, and didn't last as long. After I got to less grade/more flats with hills, it generally goes away slowly.

On the way home last night, I was heading from 10,000ft elevation down to about 5,000ft. I payed close attention to the temp gauge for the tranny and it never got above 180-190. The outside temp ranged from 45 degrees to a max of about 65 as I got down in elevation, however I did start to hear the same "whine" sound coming alive after I was using the gears to hold down a 5-7% grade (usually 2nd gear with minimal braking)

Given that the transmission wasn't hot, or wasn't nearly as hot as previous runs, I'm now wondering if it's my transfer case/front diff making the noise and not necessarily the transmission?

I generally start to notice the whining noise when I touch the brakes even lightly, the noise only comes from the front and it seems that it's due to the braking stopping the wheels....which are connected in the AWD to the diff/case...then the tranny.

Temp wise it doesn't seem like it was nearly as hard on the transmission to use it to brake down the pass, but I'm sure it was equally as hard on the transfer case/diff as going up hill.

Any thoughts or speculation?

Turtle n Peeps wrote:

LarryJM wrote:

Turtle n Peeps wrote:
No theory's here. The law of thermodynamics is a LAW.

"My" tranny gauge stays at 160 solo where my ECT stays around 190. Which way do you think the heat is going to go according to the 2nd LAW of thermodynamics?

The heat is going to go from the ATF that enters the bottom of the radiator which is probably close to 250 deg and with the temp at the bottom of the radiator being in general at least 20deg cooler than you 190 ECT reading the ATF will be cooled by that in tank OTW cooler NOT WARMED.

I think you would be best to just believe what MARK who is the TRUE EXPERT here and if you were to appreciate that the 160 you are quoting is generally the pan temp of the ATF and the ATF going into that OTW cooler has just left the torque converter and can typically run anywhere from around 220 to well over 300 deg along with the fact that the coolant temp in the bottom of the radiator where the OTW cooler is is cooler than what is typically measured as the ECT temp (the 190 in you example) the thermodynamic laws are being followed, it's just you are applying them with incorrect temperature where they actually apply.

I'm thru and if you want to try and convince someone, you need to be talking to MARK and not me since I completely agree with him and my understanding of what in general the various temps of both the ATF and coolant are in each system at the points of interest as they apply to this discussion, they make complete sense to me and are consistant with what MARK has proven.

Larry

I didn't disagree with Mark at all. I didn't know where his temps were taken and still don't for that matter.
I'm going off of what "my" gauges read and the laws of thermodynamics.

Let me say it one more time. "If" ATF temps are higher than the ECT's "at all times" we are all in agreement.

what one reads for temperatures is going to be highly dependent on WHERE the sensors are. ECT is usually measured somewhere in the block, not the radiator. Transmission temps are usually measured somewhere in the transmission. So one could have a difference one way or the other as to which reads higher.

now if one measures the transmission temperature at the outlet of the radiator cooler and coolant temperature in the water jacket around the radiator transmision cooler at the transmission line exit , then ECT should be lower or possibly very close to the transmission temps once the system has stabilized and run for long enough for the engine thermostat to open. E.G. when driving after warmed up.

LarryJM wrote:

hotpepperkid wrote:

LarryJM wrote:
Bypassing the OTW cooler in the bottom of the radiator is the worst thing you can do for maintaining tranny temps especially when towing. It it always the first cooler that the hot tranny fluid goes thru since it is the one that can extract the most heat due to the temp differential and is not dependent on the speed of the vehicle like the OTA cooler is. You examples of light weight non towing vehicles and any comparison of turbo intercoolers is comparing apples to oranges and IMO your worries about cooler failures is basically not founded on any data or reliable reports I have ever read.

Even the gaggle of engineers at FORD failed to appreciate this in the original design of the SD series when all they initially had was the OTA cooler and started loosing trannys from heat especially for those who were towing. They had to put out a service bulletin to replace or add the OTW cooler in the bottom of the radiator to solve the issue.

My recommendation is not to MUCK around with the engineered design of your OEM cooling system and definitely DO NOT bypass that OTW cooler in the bottom of the radiator if you want to keep your tranny.

Larry

My 2000 F-350 has an OTA only. I have 225,000 mile on the trans. It does just fine as far as temps go. It heats up when going light to light when them air temps are over 100 but it has never been over 225 deg. The up grade a lot have done is put a cooler from the 6.0 on. It is about 3 times the size of the OEM cooler

I would say you have been fortunate and the vast majority of 7.3L owners generally never see temps above 2000. I work the snot out of my PSD towing and have only once seen my temp go to 200 and it's max is generally 190. With only around 200hp and towing at 17.5K GCW I routinely have pre turbo EGTs staying above 1000 and often have to turn off OD to keep EGTs under 1300 which can even happen on a lot of the more significant Interstate hills. The TSB I mentioned is 00-24-4 and only applied to SDs made before 6-6-2000.

You are correct on the 6.0 cooler (not sure if it's actually 3x the size, but is bigger) and my understanding that is now a standard addition that Brian Thompson does for all his built 4R100 trannies now.

Larry

Going down the road temps hang around 150, where it get warmer is in town with lots of stops and goes and 110+ outside temp. Don't know if you have bigger than stock exhaust but your EGT's will go down about 200 deg. My EGT's were hotter stock than now