Jim Lane

If there isn't enough airflow I could always add another fan to the bottom of the cooler,

But I should not be having this problem, even if I had the temp probe post cooler, the reality is, it is still hot but I just won't know about it.

I have another Autometer sender ordered and then I will have the ability to read both Pre and Post cooler circuit to see how efficient it really is.

I have no doubt the returning ATF is probably between 160* to 180* mirroring the coolant temps.

Quote:
Will the second cooler be able to remove the same BTU as the first in it's discharge air? I'm guessing half? 15,000 BTU

This I am not yet sure of, I just got an add from BD of a Double Stacked Transmission cooler that has an 800 CFM fan and rated at 40,000 BTU they are claiming to be a big thing, but I am thinking mine should be somewhere as efficient.

http://www.xtremediesel.com/BD-Power...030606-DS.aspx

At what temperature does the overdrive cutout on a A-518 transmission?
This should give some indication of the temps it should be running.

I am going to take it back to the transmission shop as soon as I get some time and am able to collect some more stats first.

Sadly I think Detroit did not want you to know how hot your transmission gets or they would have provided a temp indicator, even an idiot light at a critical temperature would have been better than nothing.

Out of sight, out of mind

Jim

YOREL

The FSM says that the thermal cutout switch opens at 273*. Yikes!!! (its on the electrical schematic page showing the transmission wiring). Thats just before toast!!!

Jim Lane

How much air does this cooling fan flow?

I picked up a hitchhiker from Mc Donald's today, just came along for the ride. (about a mile down the road)

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Jim

hdguage

Let's start with your temp sensor. You want that to read your fluid temp coming out of your trans. Then you really know what is going on inside. I have a 518 trans in my truck and the normal temps run below 160. I don't see temps of 180 until I put 15,000 lbs on it. If you are seeing temps higher than that you have internal problems. I would start with the converter and would then check the clearances of the clutch packs. I just went through a couple of trans from heat due to improper clearances on the clutch packs. One minute it was 180 and the next it went past 240 at which time the tranny was shot. I took the trans to a guy with 30 years exp. in Dodge trannies and he explained it all to me. I then had him rebuild it and it never has been so good. Trans temps run about 140 now empty.

user name

I was thinking clutch issue from reading this too. How does boost and RPM compare to before during a stall test? If boost is down and RPM up then less load on engine probably the converter. If boost and RPM are about where it started pushing the truck before than I would think clutches are dragging or partially applying from a hydraulic problem or mechanical binding inside. That said at full operating temp you are putting 200 degree trans fluid back into the trans after it passes through the factory f/f cooler so that might just be the temps you see.

Jim Lane

I took it to the Transmission shop end of the week and had them look at it, and they could not believe the fluid was discolored so badly for only 4600 miles since the rebuild, he said it doesn't smell burnt but it just looks like old well used fluid, the transmission shifts OK although I would like it to shift a bit crisper.

It has always felt like I was loosing power through the converter.
I cannot check the stall speed because I do not have a tachometer yet but it defiantly felt different than the last one.

Looking under the truck he said that I defiantly have enough coolers in the circuit
I am going to take the truck in next week and they are going to a flow test and then drop the pan and valve body and then he said they will probably have to pull the trans and go through it again.

I am wondering it anything else happened to the case after it self destructed itself and took out clutches, drums, output shaft, valve body, torque converter, if you recall it now has a radial thrust bearing for the output shaft instead of a bushing, and what would cause the check ***** to get hammered through the separator plate?

I used to work on Allison transmissions that would come in from a 10 hour run that were overheating, the retarder would stick and engage FF and DD at the same time, the only way to cool the transmission down was to cool it with the steam cleaner so you could even stand to be near them, the cases would be so hot they turned gray.

He said whatever it takes he will make it right.

I guess I will find out next week.

Jim

Jim Lane

I had to take a trip out to Costa Mesa today, I was cruising at 75 MPH with about 8 PSI Boost.



Jim

deanhinsley1963

Really seems to be running hotter than it should.