Hey guys so i posted a little while back that my trans is getting hot after i had a shop rebuild it. i had gotten the temp up to about 220 UNLOADED.
here is what the truck is running right now.

I replaced the 26 row cooler (OEM)

I bypassed the rad cooler for the trans so now its just out of the trans to the 26 row cooler and back

I also have a diesel site external trans filter which has a brand new filter and the lines have been blown out.

The truck was dropped off to the shop that rebuilt the trans and he is saying nothing is wrong with the temp reading.

The line coming out of the trans is HOT and the line coming back is ICE cold. Even my external filter is ice cold. Before my trans let go I always felt some heat coming off of the external filter so I knew it was circulating. Could it be that the bypass valve is no good and its just circulating fluid through the body of the trans?

Once i get the truck back i have two temp probes i will install on the feed and return lines and insulate them, take it for a drive and see what i am reading.

When i read the 220 it was on my scanguage but i was advised that the OEM temp prob isnt an accurate reading by the trans shop????? basic knowledge would say if one line is really hot and the other isnt at all lukewarm than something is going on.

Any help is greatly appreciated
AJ

 

Have you checked to see if it's slipping
You should be logging that data. That is what would most likely cause it to heat up.

 

I would pull the line off going to the cooler from the transmission and direct it into a bucket and see what flow you have then check it coming out of the cooler and see if it is plugged.

 

Did you replace the cooler prior to the overheating or because of the overheating? Anyway I would check to see if you have anything flowing to the cooler.

 

the trans shop said the flow is perfect. But I still don't understand the HOT line and the ICE cold line. I've never seen a cooler work that well but that doesn't make sense about the temp reading.

as soon as I get my external temp readings I will post back

 

The OEM sensor is the most accurate reading. The shop is wrong.

 

They are full of crap. You can't have a HOT and ICE COLD line and have sufficient flow thru a cooler. They just aren't that efficient.

 

Exactly! I wasn't born yesterday. I've worked with diesel engines for 16 year and never saw a radiator work at 100 + efficiency! Same thing goes for the trans cooler. Once i have the truck back ill chck it myself. I believe it may be that bypass valve.

 

How long does it take to get up to 220F?

Is your clutch fan running? Do you hear it roar?

What does your EOT say when the trans temp is at 220F?

 

it takes about 40 min to get around 200. Fan is running. Oil temp is right with coolant so like 180 190. This isn't normal for my truck. Before I had issues the truck would run no problem at 160 unloaded in the dead of summer. Once I put the 26 row cooler my temps dropped from 190 normal to 160 165

 

Maybe they didn't put the guts back in the bypass. I know when I removed my bypass to rebuild it it had not been assembled correctly by the previous rebuilder.

 

Well, sounds like you have the needed data to back up the proper operation of your truck.

Might be time to have another talk with your trans builder.

Failing that, here's and idea. What if you took your output line and connected it to your input line, bypassing the cooler? Then see if the return line gets hot as well- to match the output line.

If it doesn't there is no flow. If it does, check your cooler for obstructions.

But wait for Mark K to weigh in on this idea first. Transmissions can be picky and I am not a transmission expert.