how hot is to hot for an A4ld tranny?

[huntman58]

. Dose any one knows what the temp for an A4ld tranny is at the out put line before the coolers should be under normal driveling and or what it would be when it’s hitting hot to starting to burn the AFT fluid? I know it would not be a set temp but more a so much over air temp deal. I have a gauge on it but it reads right before it hits the first cooler at the radiator and in the summer in stop and go on a 100 or better deg day it hits 210 to 220 easily but drops down to 160 , 170 if I get on open roads and let it run.

Reason I am asking is after burning up two tyrannies do not ant to do it again. I do have a large B and M stacked plate cooler added to it with a pusher fan besides the stock cooler out front and it still hit them temps but I know the gauge is reading the fluid at its hottest point as it comes out of the torque converter

 

[MrQ]

(provided by Transmission Exchange Co.)

 

[arco777]

I would move your temp sensor. One mounted in the pan would be a better indicator of the fluid temp that the trans is actually seeing.

 

[Maniak]

200F right before it hits the first cooler is actually pretty low.

You really want to read it at the pan. Thats the temp the transmission itself is seeing. Once it leaves the torque converter it is as hot as it is going to get and heads out of the trans.

We also kept killing a4lds.. I don't think it was just heat.. It was probably the off-road use and we were towing 2000 lbs or so 3 times a week for a year (that spread across 2 transmissions).

We were running a plate and a tube/fin cooler with the a4ld. Since then I have gone to two plate coolers and a pusher fan from a geo metro..

This is our setup.. The fan runs whenever the trans is not in lockup. We are running a 700r4 now so that control was easy to do. I never tried to do the fan setup like that on the a4ld but it should be possible since lockup is controlled by a solenoid in the pan..

Transmission-cooler-misc 005 by maniak_az, on Flickr

With the current setup, and a high stall torque converter the highest in pan temp I have seen is 200F and that was towing 3500 lbs across town in 105F+ temp.

~Mark

 

[sportblack99]

200F right before it hits the first cooler is actually pretty low.

You really want to read it at the pan. Thats the temp the transmission itself is seeing. Once it leaves the torque converter it is as hot as it is going to get and heads out of the trans.

We also kept killing a4lds.. I don't think it was just heat.. It was probably the off-road use and we were towing 2000 lbs or so 3 times a week for a year (that spread across 2 transmissions).

We were running a plate and a tube/fin cooler with the a4ld. Since then I have gone to two plate coolers and a pusher fan from a geo metro..

This is our setup.. The fan runs whenever the trans is not in lockup. We are running a 700r4 now so that control was easy to do. I never tried to do the fan setup like that on the a4ld but it should be possible since lockup is controlled by a solenoid in the pan..

http://www.flickr.com/photos/10384420@N03/3454387446/
Transmission-cooler-misc 005 by maniak_az, on Flickr

With the current setup, and a high stall torque converter the highest in pan temp I have seen is 200F and that was towing 3500 lbs across town in 105F+ temp.

~Mark

700r4 in a sploder...didn't know it was possible

 

[Maniak]

700r4 in a sploder...didn't know it was possible

Advance Adapters makes the kit for the engine/trans and trans/1354 xfer case. Search for 700r4 on here (search only the title or you will get too many hits).

I think there are 10 or so conversions on here (EF). I'm not positive Adance Adapters is still making them (I didn't see it on their site when I just looked).

~Mark

 

[R&T Babich]

200F right before it hits the first cooler is actually pretty low. ....

If it's 200F before the first cooler and the first cooler is at 195F (radiator) it's not going to cool much. With those 2 large coolers in front are you still going thru the radiator?

 

[Maniak]

The 195F coolant at the radiator (give or take some) is at the top of the radiator. The Coolant is much cooler at the bottom. When I was calibrating my electric fan switch on the Van I was seeing 20F+ difference between the top and the bottom of the radiator..

As I understand it, the OP has it going from the Trans to the heat exchanger in the radiator to the external coolers. That is the way to route it to get maximum cooling effect for the trans fluid.

~Mark

 

[R&T Babich]

The 195F coolant at the radiator (give or take some) is at the top of the radiator. The Coolant is much cooler at the bottom. When I was calibrating my electric fan switch on the Van I was seeing 20F+ difference between the top and the bottom of the radiator....

If the coolant is at 215 at the top and 195 at the bottom it's not going cool trans fluid at 190 at all. If the the trans is at 240 that is not good for the engine. I've never liked tying the 2 systems together because a problem with one overheating can take out the other. If the trans needs more cooling add larger radiators, same for the engine. Our engine radiators are limited in size/capacity because of physical restrictions. The only reason I can think of for running the trans fluid thru a radiator cooler is to keep the trans fluid above a minimum temp. Which really comes down to cost. Large trans coolers and a thermostatic bypass valves aren't cheap.

 

[huntman58]

Thanks every one
Yes I run it threw the radiator cooler but I am also running a 180 stat with a temp reading on the Heater hose about 1/2 way between the motor and heater core of 170 now. Did not have it both gauge and lower stat this summer but were the Dash gauge was to be it is now I would say it was running about 195. The reason I have run the tranny temp were I did is it’s a mechanical one and the probe is large is size. I in ways would rather see the highest temps its throwing then the average. maybe I will add another gauge or change mine to a electric and run two probes one on the hot side and one in the pan and see how both do for a better idea. I know the stock tranny luster over 150,000 miles and the 2 owners before me used it mainly as a tow rig for there winter toys such as snow machines. my towing has been limited but when its done it has been on the heavy side so I know I helped to kill the first tranny the next one will it was flat out a bad rebuild nothing more and the one in it now just proves that as about all that was reused was the case on the last one.

 

[Maniak]

If the coolant is at 215 at the top and 195 at the bottom it's not going cool trans fluid at 190 at all. If the the trans is at 240 that is not good for the engine. I've never liked tying the 2 systems together because a problem with one overheating can take out the other. If the trans needs more cooling add larger radiators, same for the engine. Our engine radiators are limited in size/capacity because of physical restrictions. The only reason I can think of for running the trans fluid thru a radiator cooler is to keep the trans fluid above a minimum temp. Which really comes down to cost. Large trans coolers and a thermostatic bypass valves aren't cheap.

I do agree, the heat exchanger in the radiator just isn't enough.. I can see it helping since the very hot trans fluid goes into a cooler (maybe not enough, but some) to bring the temp back down to 195F or less.

Ideally you want as much cooling as possible in summer and "enough" cooling in winter without over cooling.

Some of the newer transmissions have the thermal bypass built in the trans. The a4ld doesn't so you need something to let it get warm enough in the cooler climates (which I do not live in).

On our tow rig I am only using an external cooler. I have enough room to put in a 40,000 gvwr cooler. I have it installed close to the radiator and use an electric (Mark VIII) fan. The highest pan temp I've seen in the c6 on the tow rig was while towing (rig and trailer total weight of 14k) and heading uphill outside of Yuma, Az. I saw 170F (pan temp) there and it was close to 100F outside.

cooler-installed 002 by maniak_az, on Flickr


You can get the Tru Cool 40k gvwr (45k btu) cooler with thermal bypass for about $170 via bulk part (http://www.bulkpart.com/2/product/tru-cool-hd/4739.html).. But its not a small cooler. Its 8.5" by 22.75" by 1.25" thick..

I haven't seen proof that I can understand, but from what I've read, liquid to liquid heat exchanging (radiator exchanger) is more efficient than liquid to air (aux cooler).. Even if that is true, I think the aux cooler should always be there on an auto trans vehicle..

I almost forgot. The scenario you are worried about (over heat x and have it overheat y) is something we ran into. We cracked a head, lost the coolant and the temp gauge didn't show it overheating (no coolant on the sending unit). We got things hot enough that many parts in the trans got cooked too. After that trans rebuild we put in the temp sender for the trans.

I am also running a 180 stat with a temp reading on the Heater hose about 1/2 way between the motor and heater core

I do like how the OP has his coolant sender in the heater hose. That is where we have ours. It shows real coolant temp and not engine temp.

I in ways would rather see the highest temps its throwing then the average

Also, the OP mentions wanting to know the highest temp of the trans fluid. That is good to keep an eye on the trans fluid but I want to keep an eye on the transmission itself and know what temp fluid it is getting..


~Mark

 

[R&T Babich]

... The highest pan temp I've seen in the c6 on the tow rig was while towing (rig and trailer total weight of 14k) and heading uphill outside of Yuma, Az. I saw 170F (pan temp) there and it was close to 100F outside....

We had an E-150 351W/C6 for towing our boat and had similar results for temps. I also added a standard Ford oil filter in the return line. Changed the screen once when I got the van with 80k and fluid/filter regularly. The trans spun a tail housing bushing at 214k, but was otherwise fine. The shop said it was due to be rebuilt soon as the clutch surfaces were paper thin, but he had never seen an original C6 go that long.

......I almost forgot. The scenario you are worried about (over heat x and have it overheat y) is something we ran into. We cracked a head, lost the coolant and the temp gauge didn't show it overheating (no coolant on the sending unit). We got things hot enough that many parts in the trans got cooked too. ...

Another scenario - a friend has a really clean original 1966 Mustang and had the radiator replaced. The trans cooler fittings must has gotten over tightened and cracked the cooler tube. Ruined the trans. Fortunately the shop covered the repairs.

 

[huntman58]

Mark I am thinking after doing some research and reading here allot about going from the mechanical gauge to an electrical one, then running two senders. one in line pre coolers and one in the pan next time I drop it. Then a switch so I can read both temps at will with one gauge. This should give me a better understanding of how much things are being cooled and what the average tranny temps are. The one question I have seen asked over and over and never have seen answered is how hot is to hot or what is a good average hot line pre coolers temp. The temp charts are worthless to me as they do not say were there from, what the air temps are, nothing just a temp and that’s it! All of them with an A4ld would scare a person to death as the hot line reads over 200 a lot when it’s over 90 here in stop and go or when getting on it to get to freeway speed. (Lots of shifting)

 

[Maniak]

I've never really seen a good chart for max transmission fluid temperature, only for transmission temp (fluid in the trans). All I can really find is that same chart that everyone uses that has been around for years.

Since I couldn't find good number I just went by what was "normal" for my transmission when not in extreme temps or load. If I started to see higher temps I would worry.. I don't even want to see my "hot temps" when I'm going across town and towing.. The Pan temp will be around 80F or so above ambient so if its 190F pan temp I "guess" my hot temp is well in the the mid to high 200F's.

~Mark

 

[huntman58]

Interesting. I find my hot line temps average around 120 deg F above air temps in town stop and go

Freeway or open road locked up over drive I see about 80 over air temps give or take a few degs F.

Have not towed but once and have not done any offroading in a long time so can not say what it is with them. The one time towing (a move with a car trailer) it stayed bout 110 above air temps in stop and go city driving. And about 85 degs F above air temps when on the freeway. All with air temps of about 90 deg F.


When I have hit hot line temps of 270 I have stopped driving but left the truck running raised it to around 1500 to 2000 RPM in park or neutral and with in just a short time it will drop down to 190 or lower.