How To: Eliminate Cold-Start Valve in 5R55W/S Valve-Body for Full Trans-Cooler Flow

According to Pat Barrett of Level 10 Performance Transmission Hamburg, New Jersey in Muscle Mustang & Fast Fords article. Cold-start valve failure is one of the most popular failing points of the 5R55W/S, there is a special circuit in the valvebody that restricts fluid flow to and from the trans cooler. This is done to bring the trans up to operating temperature quickly.

It was designed for extreme cold weather startups, like 20-30 below zero. In a perfect world this valve works perfectly, but we don’t live in a perfect world, adds Barrett. Level 10’s overhaul eliminates the valve to prevent any problems because 99 percent of these cars aren’t going to be fired up in that extreme weather.

According to Barrett, he would rather have the fluid flowing all the time so you can pull into the burnout box with full fluid flow.



Read more: http://www.musclemustangfastfords.c...ansmission_rebuild/viewall.html#ixzz1fqxHvizN




I emailed Pat Barrett asking him, how to do this modification? And this is what he sent me

In order to modify cold-start valve to remain locked:

http://www.ratiotek.com/5r55w-complete.pdf

• Disassemble cold-start valve on the bench.
• Relocate the big spring to the other side as it shown in the attached photo for full trans-cooler flow.

So what do the experts of this forum think about this modification???

What if I combine it with AP dipstick-deep-pan and an extra auxiliary trans-cooler

I am no expert but I think in your climate in particular this will be a very beneficial modification.

You might see if your existing transmission cooler is sufficient after performing it.

Were you ever able to get your scanguage to read your transmission temperature? That will tell you for certain what your temps are now vs after the modification.

Now I'm doing a complete overhaul and waiting for the parts to delivered, and I'm applying this modification and hope to finish by next Monday

From the past, I know that the existing transmission cooler combined with AP dipstick-deep-pan ware insufficient to cool down the transmission during extreme off-road conditions and dunes-bashing abuse. due to the cold-start-valve was keeping a minimum high-heat level.

I hope this time I'll get better results.

The Electrician said:

now I'm doing a complete overhaul, and I'm applying this modification

from the past, I know that the existing transmission cooler combined with AP dipstick-deep-pan ware insufficient to cool down the transmission during extreme off-road conditions and dunes-bashing abuse. due to the cold-start-valve was keeping a minimum heat level.

I hope this time I'll get better results.

Click to expand...

What temperatures were you seeing before?

I couldn't get the temperature readings from scanguage II

but the transmission kept over heating to the level that it spills ATF from the breathing vent. and I always had to add ATF after each time I go off-road.


also I forget to mention that I'm installing a catch/recovery can to solve this problem

The Electrician said:

I couldn't get the temperature readings from scanguage II

Click to expand...

Hmm did you try all of the following XGuage inputs?:

TXD RXF RXD MTH Name

07E0221674 046205160674 3010 000100080000 TFT
07E1221674 046205160674 3010 000100080000 TFT
07E0221E1C 0462051E061C 3010 000900500020 TFT
07E1221E1C 0462051E061C 3010 000900500020 TFT

One of those should work. I can double check and see which one I am using.

I'll try the codes once I finish the overhaul. Now the transmission is dissambled on the bench waiting for the Level 10 overhaul kit.

The Electrician said:

I'll try the codes once I Finish the overhaul. Now the transmission is dissambled on the bench waiting for the Level 10 overhaul kit.

Click to expand...

Sounds good

For your reference:

I typically see 160-175 degrees F most of the time regardless of ambient temperature though it rarely gets over 95 degrees where I live.

I have never driven mine in the sand or dunes but I would expect the temperature to go up above that.

I can tell you that during a several mile climb on a mountain road at 65mph with OD off I have seen temps up to 205 degrees for a short period.

This is because of the cold-start valve. It is based on old style mechanical solenoid, it is very slow to respond well to the rapid variation of tepmerature. And always cause the transmission to over heat.

Yes I have thought this too.

I just put those numbers up so when you get your transmission completed you can compare it to see if your average temperature gets lowered. If it works well for you I may also do the cold-start valve mod.

I'm very happy with this mod.

the first XGauge code worked for me

now I'm seeing 130 - 145 F degree most of the time

excellent!! I will definitely need to do this.

Are you running just the stock transmission cooler or did you add an auxiliary?

Yes I'm running the stock trans-cooler + AP deep-pan with dipstick

for now I don't think I need an auxiliary cooler, I went for dune bashing and I abused the trans so much. The highest temp I got was 200 F which is still cool and ATF does not spilled out of the trans breather assembly any more

Thanks for providing your finding on this topic. I'm considering having my transmission rebuilt. My question....Does it make sense to make this modification to my 5R55S? I have the factory tow package on my 2002 which means it has a factory tranny cooler added. I live in Florida but potentially can see temperatures down to around 10 degrees F when I travel but that is VERY rare. I do tow a couple of horses in a horse trailer at times. Is there a downside to making this modification?

the trans cooler line passes through the radiator, which means even in cold weather the ATF will reach the normal operation temperature.

this modification make sure that ATF will have a full flow through the trans-cooler all the time

I'm not an expert but from my experience, I notice that the transmission does not over heat any more (before this mod, it was over heating even with the factory trans-cooler)

for me I think this modification is a must.

Can you remove the thermostatic valve on a 5R55S while the valve body is still in the tranny or does the valve body have to be dropped?

Have to drop VB. Retainer is on top side.

I have the same problem with my 2008 Ford Explorer Eddie Bauer, fan clutch activate loud at 230 degree transmission temp, I did this fix to the thermo valve and definitely solve my problem, now I have 150 degree. Thanks

Last week I had a clogged cooling line problem, I think the valve was blocked or sg, so I'm planning to eliminate this valve in my 5R55E.
The colling thermostat and the valve body is a bit different than the 5R55S/N/W.
Does anybody have experience with the 5R55E transmission with the same issue?

Sorry, this is the only way I can show a picture about the E type thermostat, picture insertion not working:
5R55E thermostat and valve