Trans won't stay cool

[smitty4605]

Have you done all of the flow tests as Mark suggested? If I recall correctly, the TCC (converter control) valve is a priority valve and when operating correctly, is a fine balance between apply flow pressure and cooler flow.



Im not sure that your trans guy has got you on the right path yet.

Yes he checked the flow already




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[gnxtc2]

You only have the external oil to air cooler? My truck is this way too.

Gnxtc, i thought you could use cooler kleen on the radiator circuit because its just tubes running though the tank?

I thought the trans cooler in the rad is a honey comb type but I can be wrong. I know my Mishimoto Rad has a honey comb type trans cooler. If it's a tube type, then it could be flushed.

Billy T.
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[mandkole]

You only have the external oil to air cooler? My truck is this way too.

yeah, plumbed just like stock. Its pulled 3 mile grades in excess of 6% with the trailer in 85F ambients and saw 185F. Go down the other side and to top gear and it goes right back to 165-170.

 

[smitty4605]

Do the TCC valves go bad often? How would it be checked?


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[mandkole]

The TCC valve was just a wag based on some earlier reading I did when I had my earlier issues (which was mostly TC). Read all the Sonnax pages, there is a ton of stuff in there. If your flow out of the cooler and back to the trans is within range, its gotta be something else that is heating the oil beyond the coolers' ability to remove.

Sonnax also suggests for overheating to check the bypass assembly for cracking too early.

From their page..
Sticking of bypass components, spring relaxation or poor ball seat will allow the bypass to open at lower cracking pressure. This reduces TCC apply pressure, cooler flow at the overdrive section, and radiator flow responsible for heat transfer. The Sonnax kit allows the bypass valve assembly to be rebuilt and maintains cracking pressure at 70-75 psi.

try this page..

http://www.sonnax.com/parts?utf8=✓&units[]=4R100&order=&symptoms[]=Overheating&commit=Filter

 

[TyCorr]

yeah, plumbed just like stock. Its pulled 3 mile grades in excess of 6% with the trailer in 85F ambients and saw 185F. Go down the other side and to top gear and it goes right back to 165-170.

Good deal. Mine was typically hotter in mild weather, ie, 70 degree fall weather than 85 or 90. But in IL that 85 or 90 is carrying humidity in excess of 90%.

 

[Mark Kovalsky]

Humidity doesn't have much effect on cooling a vehicle. It has a big effect on people because we rely on sweat for cooling. Trucks don't sweat, they only rely on the difference in temperature between the hot parts and the ambient air.

 

[gnxtc2]

Just like wind chill. It only affects humans.

Billy T.
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[TyCorr]

Well then i had something else wrong. I made note of it in my daily journal.

 

[smitty4605]

I meant to reply a few days but I noticed that my trans temp sensor was moved from the side of the trans to the built in spot in the mag hytec pan. Could that be the reason why my temps are reading higher?


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[Mark Kovalsky]

They will read differently in the pan than in the test port.

 

[smitty4605]

They will read differently in the pan than in the test port.

Do you think it would be higher in the pan?

I spoke to Brian from BTS and he said that the deeper pans don't do anything because the pumps don't move the fluid fast enough to circulate it through the cooler and the stock pan is better.


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[Mark Kovalsky]

Usually it's lower in the pan. I agree that a deeper pan is only useful to spend more of your money. It doesn't cool the transmission at all.

 

[Arisley]

Just takes a little longer to heat up.

 

[smitty4605]

Just takes a little longer to heat up.

That is what I found out


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[kingbilly68]

I've been having similar problems with mine. I just ordered a 6L cooler, John Wood valve body, bypass de1ete kit and new seal kit for bypass. I'm afraid my tc may be the problem though. I just don't wanna put a new tc in at 175,000 miles when a new trans is probably in my near future. At least these upgrades will be reusable with a new/ rebuilt trans.

 

[Mark Kovalsky]

The bypass ****** is a transmission failure waiting to happen.

 

[TyCorr]

The bypass ****** is a transmission failure waiting to happen.

Is there a test procedure for the bypass? Or does the bucket flow test rule it out?

I guess I really dont understand how it works. I know ehat it does but not how it works.

 

[smitty4605]

The bypass ****** is a transmission failure waiting to happen.

I read that John woods brazes the holes on the bypass when he rebuilds transmissions


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[Mark Kovalsky]

The bucket test will show if the bypass is working or not.

I have heard John does that. I think it's a bad practice.

The bypass is there to open a circuit for fluid flow in case the cooler or cooler lines get restricted. That's important because the return from the cooler is first sent to the rear lube circuit. If there is no bypass and the cooler circuit gets restricted, the result is no lube to the rear half of the trans. That means in a very short distance the rear half of the trans will self destruct. If the bypass is in place it opens and lube flow is maintained. The trans will get hot, but not self destruct.