Transmission Coolers Install

[Jim Brown]

Trying to beat the heat here in Phoenix, I started to track trans temps on my '01 4x4 Expedition with 5.4 and 4r100. Trans temps were routinely above 200f driving around town with OEM trans cooler (towing pkg). Hit 220f and higher driving slow speed off-road up steep hills in D. Such high temps were alarming so I decided to try to get it under control. Modified my driving habits and that helped considerably, and decided to add a trans cooler.

Added a Hayden 679 cooler after the aux cooler and that helped, dropping temps about 20 degrees average. On the freeway trans temp was stable around 190f, and every now and then went above 200f on steep hills off road in D.

Considered adding a 33 row cooler from 2000's F350 6.0 turbodiesel, but decided it wouldn't fit without a lot of modification. A 25 row cooler would fit, they're cheap at used auto parts but it's hard finding one in good condition.

Since I already had one Hayden 679 I decided to add another. This dropped trans temps 30-40f which I consider satisfactory. Ambient temps have been above 110f for the last 30 days here and the trans rarely goes above 170f and maxed out at 192f on a long steep hill that formerly would push temps up to 220f.



The trans coolers are mounted horizontal with tee fittings at the inlet (lower fittings) and outlet (upper fittings). I used two 1/2 x 3/16 x 36" steel straps to mount the coolers. They're bolted to the front of the radiator support, to existing bolts that happen to be the right distance apart to span the oil cooler mounting holes. I put foam insulation tape between the coolers and steel bars to reduce chafing the coolers.


The steel bars bolt between the grill support brackets and radiator support. Only needed to drill holes in the steel bars, not the vehicle. Only vehicle parts that needed to be modified were cutting the transmission lines to the aux trans cooler, and the ambient temperature sensor bracket, had to bend it straight and angled downwards to clear the cooler fins and leave clearance for the big plastic cover over the condenser and radiator.

Foam tape hopefully will reduce chafing for the cooler plates against the steel bar.

The cooler fittings are facing each other, connected with tee fitting. The lower is inlet from aux cooler, upper is outlet, goes to transmission. Covered the hose with plastic wire loom to hopefully protect against chafing.

The aux cooler was retained, the rubber strain relief on the OEM transmission lines were cut and spliced to the coolers with 3/8" connectors.

 

[Don Hall]

Well done.....

 

[adamsdaddy]

A couple years ago my 2016 XLT pulling a 3,000 lb trailer in 100 degree temps up hills, and crawling around hills hit 238 for the tranny temp. Last year I paid to have our mechanic install the Ford auxiliary tranny cooler. It doesn't have a lot of rows to it so I'm curious as to how it'll do pulling the trailer with similar temperatures. We haven't taken it on any long trips for quite some time. Most everyone online said they don't see temps about 205.

Your setup does make me curious as to how much more oil you had to add?

 

[Jim Brown]

It took a quart after loss from disconnecting lines and adding the two coolers.

There are three places to get trans temp, from internal sensor, from test port, and from return line after cooler. Makes it hard to compare trans temps between vehicles if the temp is taken from different locations.

The torque converter makes a lot of heat. Keeping the TC clutch applied reduces slippage and trans runs cooler. On rolling hills I found it's useful to switch off OD so trans stays locked up in third gear. If it wants to shift into 2nd on steep long hills, then slowing down, downshift to 2nd while keeping RPM above stall speed (1600rpm?) helps reduce slippage. I found that driving strategy to avoid heat buildup.

My next project is to repurpose the cruise on off switch on the steering wheel, to manual TC clutch lockup.

 

[AZShawn]

Jim - what are you using to monitor your trans temp? I'm considering getting the ScanGuage II, but open to suggestions...

I like your dual Haydens. I just installed a 6.0 cooler over the weekend.

 

[Jim Brown]

It would be interesting to see how that 6.0 cooler works out. That's a big cooler I believe same as ExplorerTom's The 25 row is still bigger than my two haydens combined.

OBDLink MX bluetooth OBD-II adapter ($80-$100) and Torque Pro android app ($5 from the android play store), adding the Ford PID data set (free with the app).



You don't have to spend $80-100 on an adapter. TXFishin, a member of this forum, has the adapter at this link that works with Torque app. It's $22. He said he also uses Forscan.
https://amzn.to/3hTDbue

I like Torque Pro a lot. Not all OBD-II adapters work with the app, avoid the cheap chinese knockoffs.

The trans fluid temp sensor on the 4R100 takes temp of oil in the pan.

Torque Pro will display a bunch of PIDs for our vehicles. You can have multiple screens and types of display like dial meters or digital. You can also create custom displays like showing delta between two PIDs, e.g. difference between ECT and TFT. Other PIDs in the Ford data set (that our PCMs will report) include fuel injector parameters, cylinder misfires, knock sensor retard and others.

Since I have been concentrating on getting LTFT as close to zero as possible (tracking down rotten vacuum hoses, might replace O2 sensors next, have injectors tested/ cleaned after that), and observing the transmission, I created this screen. I start the app on my phone and put it in the console where I can see it.



I thought about getting one of those double din android touch screens to replace the radio, it could also run and display the Torque Pro app. But good ones are kind of expensive and I have other plans for that area of the dash.

Also thought about adapting a 7" android tablet to a double din mount, and using android radio and hotspot from my phone. But I think I'll put in a single din radio and use the remaining space for a set of Superduty upfitter aux switches and maybe in-dash trailer brake from an F350 I got at the junkyard last week.

Drove up to Payson today, TFT stayed below 190f on the big hills doing 75mph with lots of shifts between 3rd and 4th. Quite pleased with that.

 

[ExplorerTom]

Jim - what are you using to monitor your trans temp? I'm considering getting the ScanGuage II, but open to suggestions...

Look into the UltraGauge. Cheaper. Looks better. Displays twice the number of gauges. Does all the same stuff as the ScanGauge.

 

[AZShawn]

Jim - I've also thought about a double din head unit, you're right though the good ones do get expensive. Maybe something down the road.

Tom - thanks for the suggestion, i'm going to look into the UltraGuage also!

 

[tekrsq]

I've also got a single Hayden 679 installed in my 99 and I've been debating about whether to add a 2nd Hayden or do the 31 row 6.0 cooler. The Hayden is like 30 rows, but only about 1/2 the size of the 6.0 cooler. So in theory, dual 679's should be about the same as the 6.0 cooler.

Jim, after re-reading your post, you just tee-d both coolers into the trans lines ? Did you try, or have an opinion on, piggybacking the coolers in series ? Do you think having the coolers tee-d reduces flow any ? Have you had any issues with the trans running too cold during the winter ?

 

[Jim Brown]

I did tee both coolers to the trans lines. The 6.0 coolers are thicker (1.25") than the Haydens (3/4"). If I remember, the frontal surface area of a radiator contributes most to cooling, but thickness matters too.

Putting the coolers in series would eliminate two tee fittings, thereby eliminating two minor energy losses lowering head pressure, but flow at the outlets would still equal the inlets.

A cooler, or coolers, whether in parallel or series, can be considered as a network of pipes, the outlet or sum of outlets having same flow as the inlet (Hardy Cross method). Internally, flow is reduced as the fluid splits at each junction and flows down different pipes. The sum of flow in the pipes leading to the outlet(s) equals the flow of the inlet. Head pressure decreases due to friction and junctions. The pressure differential is what drives direction of flow.

So... yeah flow is reduced in the coolers, increasing dwell time within the coolers for heat exchange, which is a good thing. Further down the return line to the transmission (after the cooler(s) outlet) the flow should be the same. The thing I don't know is the pressure back into the trans, is it enough to do whatever it's supposed to do.

I did leave the radiator cooler connected so the fluid will warm a little with the engine.

I just bought this Expedition beginning of June so I haven't had it thru the winter. I'm in Phoenix, AZ, winter daily low temps average mid to low 40s F. I researched the possible effects on the transmission and discovered a few considerations for extreme cold weather environments. Oil viscosity, the rubber bits get less pliable, and condensation within the transmission. The first two shouldn't be a problem, Merc V is good down to nearly arctic conditions, and the trans will warm up, just slower. The biggest threat would probably be moisture, which could be chased out by a good long drive to warm it up.

It shouldn't be a problem in VA, either. I think ExplorerTom lives in Colorado and he has a 6.0 cooler on his Expy. It would be interesting to know trans temps he gets in winter.

If you read the internet you'll find various testimonials about ideal transmission temperature, 160f, 175f and so forth. But they don't provide any info to back it up. Merc V is at 20w at 40 degrees C. So anything over about 110f is fine in my opinion. Extended operations at lower than room temperature, maybe 70f, could have detrimental effects on rubber bits since they may become less pliable.

 

[tekrsq]

Interesting. Like you said there are tons of information regarding the "ideal temps". I've been wondering about what temps are actually safe for the 4r100. I know they have the trans behind diesels, and they are pulling heavier loads then we'll ever pull with our Expys. I know the diesel versions have a "cooler bypass line" that commonly have issues with the bypass valve, which causes high temps...and frequently get deleted. I haven't been under mine recently to see if it has the bypass cooler line. If it does, I'll probably delete it, and see if that helps any with temps. In the mean time, I think I'm going to order another Hayden. Due to several arm surgeries, I haven't been doing a lot this summer, so I haven't been pulling what I normally do. I need this thing to last me for a while, so I need to take care of her.

 

[craig sargood]

So what the verdict??? To tee or no to tee??

 

[Jim Brown]

Craig I think it doesn't matter, they're about equal. I chose the tee's because shorter hoses.

I found 10 bar oil hose for 2 bucks a foot at AutoZone. Made in Thailand, seems like good stuff.

 

[Jim Brown]

Just checked, my 4r100 has the bypass line. I think I will replace it with new OEM Ford part or rebuild it with the sonnax kit. No idea if the checkball is leaking, but after reading all the different ways to test it, the cost and time to test would be at least equal to replacing or rebuilding.

 

[tekrsq]

I looked at mine earlier too. It is UGLY. Very corroded line, AND it looks like it's going to be an absolute joy to replace or delete. UGH !!! I guess it's time to do research.

 

[Jim Brown]

I think there's not much room at the forward fitting because of the heat shield. Should be an adventure reaching up there. Maybe a metric tappet wrench would be long enough to loosen the banjo bolt. Cleaning around it, if I can't reach my hand up there I'll tape a brush to a stick to scrub the area clean before removing. And getting the banjo bolt started gently to avoid cross threading.

I'll remove the back line first and check flow thru the coolers. 10' of clear 3/8 plastic line is $5 at home depot so I'll try the hose into funnel method and look for the proverbial 1qt in 15 seconds. The radiator is a year old, aux cooler is original, maybe there's a clog somewhere, and I'll find source of overheating, if it's not the bypass valve itself.

Too bad you found rust, but maybe fortunate to replace it now to avoid a pinhole leak later. Searching
2C3Z-7H322-BA shows two variants for the forward end. One style has a separate branching connection for the transmission pipe, the other they're stacked with a longer banjo bolt. I'll have to confirm but I think mine has the stacked style.

It makes sense the spring would take a set and cracking pressure would be less after many years. Same as gunsprings, leave a mag loaded for a long time, mag spring takes a set, and the stack of loaded ammo won't advance fast enough to feed next round.

I think this is the one I need


https://www.ebay.com/itm/Ford-Motor...202937&hash=item1a841e6654:g:E~YAAOSwXhRdek44

 

[tekrsq]

Yeah, I can't even see my front fitting because of the heat shield. I found a couple of older truck forums that talked about the bypass tube, and said they had to drop the exhaust to remove the heat shield. I'm not sure I want to screw with that much...especially since I'm still not 100% yet from rotator cuff surgery. They also talked about the different tubes. Supposedly, there were at least 3 versions of the 4r100 during 99-01yrs. Supposedly, there is a plate of some type near the shifter linkage with a serial # that ID's which version it is.

If it ever stops raining, I'm going to see if I can evaluate the tube further. Hopefully it's just surface rust. The rest of my undercarriage is fine. I'm not sure why that one tube would look like that. Anyway, I'm going to check for restrictions as well

 

[craig sargood]

Just checked, my 4r100 has the bypass line. I think I will replace it with new OEM Ford part or rebuild it with the sonnax kit. No idea if the checkball is leaking, but after reading all the different ways to test it, the cost and time to test would be at least equal to replacing or rebuilding. View attachment 37643

I did the removal kit, it doesn’t really get too cold here. The kit doesn’t come with much other than a couple sleeves and gaskets. Haven’t had any problems yet. Hopefully never.

 

[craig sargood]

I looked at mine earlier too. It is UGLY. Very corroded line, AND it looks like it's going to be an absolute joy to replace or delete. UGH !!! I guess it's time to do research.

Mine wasn’t too bad to do, but I do have a body lift, so I’m sure that helps.

 

[craig sargood]

Be careful with that banjo, it really sucks balls when it break in the trans. Got extremely lucky to get this out of my new transmission.