There is...their thermostat (along with the other three or four just like it on the market...PermaCool, Mocal, etc) is intended for use with engine oil. Like other fluids, engine oil you do not want too cool. The majority of guys running an oil cooler of some type (be it looks, occasional track day, towing rigs, whatever) only "needs" the cooler on occasion. If you didn't have a thermostat, it would run too cool with a cooler...and trust me, it's easy to get oil too cool. Around 200 is a good temp for oil to maintain. Remember, an oil isn't even at its rated viscosity until 212*...an industry standard. So your 5W20 is a 20 weight oil at 212*. Below that... I will guarantee you once again your oil 95% of the time does not run that hot, nor anywhere close to it, unless you're doing some towing or maintaining a heavy load/high rpm's for extended periods. 180* is a good point to start opening and letting fluid flow to the cooler for engine oil, not for a tranny. They just say you can use it for that. Heck, you can use it on what ever you can make fittings to fit...they don't care.

 

I had a conversation with Darrin at BC Automotive about this back in Oct. Running 10psi and a 3500 stall will generate some heat. He told me the thermal bypass opens around 190. I was shocked. He said yeah its way to late to start cooling the fluid by then. Especially if you're at the track or towing. His advice was to bypass it all together. And so thats exactly what I did.

 

So you're saying that it's better to just cut it off completely, and run your transmission line straight to the radiator?

 

That seems to make sense. My ScanGauge II, after about an hour of driving, will show my tranny temp in the 180's & 190's for the rest of the day.

 

Correct.

 

OK...got the thermostat in today, so first things first. It is a little warmer than the 90 I predicted, but it's no where near 190 twinskrewd, so you can tell Darrin he was wrong.

The valve starts to open right around 138 and was full open by 150 at the latest. During cooldown, it seemed to have a different profile and was not full closed at 138. Seemed to reach full closed around 130ish. From what I observed, it is my conclusion that this thing moderates, and it trying to maintain a temp right around 140. If this thing is full open by 150, that has little to zero bearing on what you're reading on your scangauge.

Kinda like the theory of the guy with a 180* thermostat but installs a 160* thermostat to try and fix his overheating problem. If the radiator wont cool it to 180, installing a 160 thermostat ain't gonna fix anything. So if you're seeing temps of 180's, this thing is wide open/full flow to the cooler anyways and would have literally zero effect on making your fluid hotter. It's not this items fault.

Which begs another question twinskrewd...what were your temps before and after bypassing this thing??? Or would it be safe to assume you don't know and was just going off what Darrin said since you didn't mention anything? I'd like to know how your temps reacted to removing this, cause it would be my guess it may warm up a tiny bit slower, but will still reach the same overall temp.

But here's what I found interesting in my test...

When cold, fluid should flow in line A, up through port Z, and back to the tranny through line D. But, even when full cold and using ice cold tap water with the thermostat fully closed, there was a substantial amount of flow through port Y to the coolers. Best educated guess is there is always some flow through the cooler and as it warms up around 140, the valve begins to open to further increase flow to the cooler. This fact further proves my statement that this thing has none if any bearing at all on you seeing 180* temps.

Port X is just a wide open channel with nothing in it blocking/restricting/directing flow at any valve position. My further educated guess is during full cold, some percentage of fluid (probably the minority [but I can't confirm that with my water tests]) flows through port Y as mentioned to the coolers and then makes its way back through port X to the tranny. The majority of the fluid flows through port Z and mixes in with the fluid returning from the coolers and goes back to the tranny.

As the fluid heats up around 140 and the valve opens, this process is almost swapped and the majority (guessing almost all [but once again, can't tell with my bench test]) of the fluid goes to the coolers and back. As mentioned, port X is wide open and is larger than the ID of the lines so there is no restriction to flow...just in case you wanted to make the argument this limited flow and contributed to your 180* temps for some reason.

I guess this thing works like I thought it would overall, just surprised how much fluid can flow through Y at full cold/valve closed.

Fifty...can you do me a favor though just to double check me on something. I don't have a truck to look at right now. Can you confirm a couple of things?? Confirm for me:

1--Line A goes to the bottom port on the tranny.
2--Line D obviously goes to the top port on the tranny.
3--Most importantly, line B goes to the radiator (not the cooler) first
4--And line C returns from the cooler (and not the radiator)

(Just a FYI note to aide you in this experiment if you didn't already know (it helps me picture it)...fluid flow is from the tranny to the radiator first, (A to B) then to the tranny cooler, and then back to the tranny (C to D).

 

 

Does that help?

 

OP:



From Q himself - 'nuff said

https://www.f150online.com/forums/2580700-post16.html


MGD

 

Hell no...that makes it worse!! LOL. It completely ruins my understanding of how this thing operates

Is there any chance I cold get you look under your truck and just confirm visually (and not using this schematic as a reference) steps 1 through 4 from above that I asked you to check...or anyone reading this I guess can do it.

After that, I'll explain why this schematic doesn't help, but I want to confirm something first. Sorry for being such a pain, but guess that's why this site is so great...guys helping each other out with stupid *** projects like this!!

 

Sorry MGD, you're a little off with that link...I've already disproved that number...or did you not read my post and just jumped on in here?? This thing clearly modulates to maintain something between 130-140.

 

Nah - I read it - I think you got the unit from a '09+ truck (they run hotter)

Thing is, I also was of the mind ( or years) that it opened ~ @ 140. But - do you think I can find where I first read that?

I'll go with yer empirical observations - thanks for doing that.

Now we have TWO experts in error (Darrin and Qunitin) ...


MGD

 

OK, so...based on the schematic, had to make some theory adjustments (disregard that photo and use this one);

Fluid flows from the tranny through the thermostat through X at full flow hot or cold to the radiator/cooler. As it returns from that journey in line C, it hits a road block at the temp valve inside Y. This restriction forces the majority of the cold fluid to flow through Z, but there is still quite a bit of flow through Y even when cold. As the fluid warms, the valve starts to move accomplishing two things; is increased flow through Y, and closes off the port in Z. Now when hot, you have a full loop of flow through X and back through Y with little if anything going through Z.

Remember I said the valve was full open absolutely no later than 150? That means you have full flow through this thing with no restrictions at a minimum by then. It closes much slower, meaning it doesn't begin to restrict flow until way below 140. There's no way what-so-ever this thing will keep or maintain a fluid temp of 180+ degrees. It's shooting to maintain something in the 130-140 range.



So there's been a couple of post throwing out this 180-190 number...where's that coming from? I talked to the guy at the Ford place and Patman even indicated it above, there's nothing written on the operation of this thing...and I just gave you a somewhat solid way of confirming it's temperature.

Fifty, or anyone...I would still love it if you guys could confirm my theory for me using this drawing (same instructions/different labeling):

1--Line A goes to the bottom port on the tranny.
2--Line D obviously goes to the top port on the tranny.
3--Most importantly, line B goes to the radiator (not the cooler) first
4--And line C returns from the cooler (and not the radiator

MGD...it's all good!

If this all pans out, 140* will be pretty darn good with my big *** cooler in mid west winter.

 

That sounds about right to me.

I can confirm that when I look under my car, it looks like the diagram. The diagram is from the Ford service manual. What is it that you are looking for that I'm not seeing? I can't "see" the fluid flow inside the lines.

 

Wait two wrongs make a right so there you go. lol

Yeah thats exactly what I'll do. Call a professional who builds these trannys everyday and tell him he's wrong. I don't think so. So one valve opened sooner and now this one test on one valve is to be the standard for all? Could it be a revised valve? Could it be a freak valve? Could be Ford changed the spring in it cause trannies are burning up at 100,000 or less. I would consider the possibilities before calling people wrong or telling them there seeing higher temps is a result of an inadequate cooling system. Its been known for sometime these trannys run in the 150-190's and even hit 200. It seems to depend on the truck the location and use. For what its worth the fluid needs to be above 95F and thats not hard to do or maintain with just normal driving even in cold climates.

As for your other question about my temps. I have yet to install a tranny guage and I'm still debating whether or not I want to invest in one. Darrin built my tranny and it is warranted through him. If he says bypass it I bypass it. He says use Mobil 1 ATF I use Mobil 1 ATF. As for your theory about the cooling capacity. I have the towing package and its capable of cooling it just fine. I have been assured of that by Darrin and Troyer. By bypassing the thermal bypass I'm simply not allowing my fluid to hit 180 190 or 150 as you say before it is allowed to flow through. I'm also not allowing that stupid valve to close and prevent my fluid from cooling down to less than 140 or whatever the actual closing is on it.

And has anyone given thought to what happens when this thermostat sticks closed? Thermostats do that you know. It would be interesting to know how many of these burn up trannies are a result of this. I mean t-stats stick and overheat engines all the time and theres a gauge on the dash for that. You're not gonna know this things stuck until you've got a $3000 repair bill. Another great reason to bypass it.