2008 Explorer thermal bypass

[Francisco Blanco]

Hi,

My name is Francisco Blanco an i recently purchased a 2008 Ford Explorer XLT,
i started to have an issue wich a connect to the transmission and after some research on the problem i found a thread in here with the exact issue. the problem is when accelerating from stop, the revs go up and the vehicule slowly moves forward, some times it doesn't accelerate at all with revs up to 2000 rpm.

The thread i found says it's the thermal bypass in the transmission and the final post was this:


FINALLY!!! We figured it out. Bit of a story though. I finally got it to do it at the dealer. The Service Manager, Lead Tech and myself went for a ride. They agreed that the fan clutch was locking up and felt that a simple R&R would fix it. However at the last minute the Service manager decided to call Ford Engineering and he talked to an Engineer who explained that the fan clutch is controlled by the PCM (Module) and that replacing the fan would not solve the issue. He explained that for some reason the PCM thinks the engine is overheating and it is trying to increase air flow through the radiator. Makes sense. However there are no codes showing an overheating problem. Hmmmm…… Upon further investigation it was found that the trans was throwing of an overheat code! I’m not sure why that was not apparent from the beginning. The laptop showed the trans temp at 270!. No way! So up on the lift, and physically check the trans temp and fluid temp. Well, 160 all day long! Turns out that the Thermo Bypass was faulty and was misinforming the PCM that the trans was overheating and the PCM was locking up the fan clutch to pull more air to compensate. Replaced the Thermo bypass and so far problem solved.


The problem, now, is that i can't find such a valve up for sale online nor a valve listing with that name.

If someone could point me in the right direction i would appreciate ir very much.

thanks in advance

 

[Ronin8002]

Is your truck the 4.0 V-6 or 4.6 V-8?

If it is the V-6, you have the 5r55s transmission. You can actually eliminate the thermal bypass entirely on that tranmission. Here is a thread with instructions on how to do it:

http://www.explorerforum.com/forums/showthread.php?t=338261&highlight=fluid+cooler

 

[Francisco Blanco]

it's 4.0 V6

 

[Francisco Blanco]

thanks a lot, this might solve my problem, i think!
i will post my results!

Francisco.

 

[jbwilli]

thanks a lot, this might solve my problem, i think!
i will post my results!

Francisco.

I am aware this is a 7 year old post. I have the exact same issue on my 2009 EB and my daughter does also on her 2007 XLT. It happens rarely, but both are begging to occur a little more often. No sure if you will see this Francisco, but I do wonder how your issue worked out. It does make sense that the thremostatic valve inside the tran valve body could cause this problem AND an easy work around the real cause would be to flip the spring force the thermostatic valve to remain open ALL THE TIME! Before I consider doing that, I would first want to explore the source of HOW THE PCM DETECTS A FALSE OVERTEMP signal. Could it be as simple as the water coolant temp sensor (or its wiring) is defective? Any information on this subject would be greatly appreciated! THANKS!