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How To: Transmission Cooler Install


Slartibartfast
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I installed my trans cooler the other day, and didn't remember seeing a write-up on it, so I made this. Hopefully this'll help someone else with theirs.

 

Installing a Trans Cooler

 

Let's start with the reason to bother with all this. Automatic transmissions change a fair amount of power into heat, especially if you're pushing them hard. Heat degrades transmission fluid, and degraded transmission fluid kills clutch packs. There's a stock cooler in the radiator which is mostly adequate, but a larger transmission cooler reduces fluid temps further, which helps the trans live longer, which is nice, because these things are awfully hard to push.

 

I used:

P1010008-19_zpse148d485.jpg

1x Transmission Cooler. I found a no-name aftermarket stacked-plate cooler in a WD21 at the junkyard. I think I paid $10 for it. A trans cooler from a wrecking yard might be full of crud if the trans it was hooked to failed, but the truck this one was in had a blown out bottom end, and someone had actually bothered to pull the trans, so a lunched trans was clearly not what sent it to the wreckers. What little fluid was left in the lines looked good and red. I washed the cooler out with alcohol and let it dry fully before installation. If you're going the junkyard route and don't see any aftermarket ones, Ford Explorers apparently have easily accessible tube-and-fin coolers that aren't bad. The GMs I scoped out had weird connectors on theirs, so I wouldn't bother looking in them. If you're buying a new one, look for a high vehicle weight rating. (There's a thread about sizes/ratings somewhere on here.)

3x Hose Clamps. You really only need two, but I had a handful from the junkyard trip, and I didn't like the look of one of the stock clamps.

5' or more of 5/16 Oil Hose. Hose is cheap and it doesn't stretch. Get more than you think you'll need. (Yes, I left the old hoses in the junker... I'm not that cheap.)

1x Transmission Cooler Mounting Kit. These are zip-tie like things that stick the cooler to the A/C condenser. If you want to screw it to something or build custom mounts, go for it. I used Carquest #77008 but the clips said Hayden on them, so it's probably the same stuff you'd get with a new Hayden cooler.

One quart of ATF (I used generic Carquest Dex/Merc). This wouldn't be a bad time to do a full flush if it's due for new fluid.

Paper towels... and a trashcan to put them in. Preferably one that doesn't leak. (Mine did.)

If you want to install a trans temp gauge and/or trans fluid filter, now would be a good time to do those too.

 

To start things off, I crawled underneath and located my trans lines. The lower line is the return (the same line you can use for flushing the trans fluid) and on mine it was held in by an odd wire clamp that came off easily enough. If the hose gives you trouble, shoot a little WD40 around the end, it should slide right off once that wicks in.

 

My radiator is fairly new so I left the factory cooler in line with the new one. This meant I only had to pull the lower line. There's some dispute as to whether the stock coolers clog up over time and kill transmissions or whether dying transmissions spit up clutch material and clog the coolers, or whether cooler clogging is even a thing that happens at all, but if you don't know how long your stock radiator's been in there it's probably best to pull both lines and bypass it.

 

P1010004-22_zps86fe8950.jpg

 

Incidentally, that top line (which connects to the driver's side of the factory cooler) is the supply line (ATF pumping out of the trans into the stock cooler). If you disconnect that line and bump the starter to see if you've got the right one, you'll spray fluid all over everything and the front crossmember will drip on you for the rest of the night. :doh:(Video may be nsfw if your coworkers are nuns or faint at the sight of transmission fluid.)

 

The other end of the lower hose is kind of a bugger to get to from behind. I ended up using a miniature open-ended wrench (1/4" should do it, and a ratchet screwdriver with the bit removed should fit) to loosen the hose clamp to the point where I could turn it around with vise grips and get a nut driver on it. If you lay under the car and rest your head on the centerlink you can see what you're doing, and your neck doesn't get sore. You can put your elbow up by the alternator if needed. Anyway, get that clip loose enough that you can pull the lower line out. Keep track of the clamps, as you'll be needing them later.

 

Here's the return line that we're retiring. I kept mine just in case.

P1010005-10_zps8877b554.jpg

 

Now the new cooler needs to go in, but the grille's in the way. Remove the corner lights, undo the clips along the top (or cut the zip ties, depending on how many times the grille's been off), undo the grille screws below the headlights, and pull it back. My driving lights and bumper got in the way and prevented me from removing it completely, but no worries, you just have to be able to get your arm back there. If you have big arms, or a thick cooler, or if you need to do other stuff back there anyway, removing the grille and bumper completely would make this next bit a whole lot easier.

 

P1010006-20_zps5ab90361.jpg

 

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The next thing you need to figure out is where exactly you'll mount your cooler. I put mine on the passenger's side of the condenser, in front, with the fluid ports coming out the side, mainly because this was the only place it would fit. (It would've fit the driver's side but then I would've needed longer hoses.) Trial fit it (don't mount it up yet) to make sure it'll fit how you want it to without fouling on wires/hoses/radiator support/etc.

 

P1010022-7_zps1d02489b.jpg

 

Once you know where you want it, identify where you'll route your hoses. The donor car I pulled the cooler from had both hoses routed through the headlight hole. I decided to put one line through the sheet metal beside one of the lines from the A/C tank (the cylinder bit on the passenger's side of the condenser), and push the other through the foam under the radiator. Routing is up to you, this just looked good to me. I've read that you should have the output be at the top to help the cooler purge air. I did it the other way and it seems to work fine (I can't imagine the fluid coursing through there would leave a lot of air bubbles hanging around either way). I can't think of a reason not to have the high side be the output; I just wasn't thinking when I hooked up the lines. I may swap them before I put the skid plate back on.

 

Hook the hose to one of the cooler's ends (doesn't matter too much which, but I'd go with the harder one to get to just to get it out of the way). I had some trouble installing the lines on the cooler due to some sharp ends on the cooler tubes. I rounded off the sharp bits with a file and smoothed them with sandpaper (being careful to keep the aluminum shavings out of the pipes) and then greased up the pipe ends. Installing the hose clamps and pushing them down with vise grips finally got the hoses fully seated.

 

P1010010-11_zps297435c2.jpg

 

Yours may be better built and put up less of a fight, but still, don't mount that cooler until you've got the pipes fit to it or your knuckles and your A/C condenser are gonna have a bad time together.

 

Once the hose was on I threaded it through the front end and trimmed it to size. Then I pulled the hose and cooler back out and attached the piece of hose I'd just cut off to the other pipe on the cooler. My hoses ended up being about 20" on the top and 39" on the bottom, but these measurements will of course vary with hose routing and cooler size/location.

 

Speaking of hose routing, an easy way to get the hose past the foam under the rad is to stick a big Phillips driver through from the back, wherever you want the hose to come out, sleeve the hose onto the driver, and then pull it out the back. This is from the back (the pipe end is the passenger's side of the factory cooler and the thing above it is the fan shroud):

 

P1010013-11_zps7d1d88de.jpg

 

And here it is from the front after pulling it through:

 

P1010017-7_zpsd80b3802.jpg

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I installed the cooler with the little zip-post things. The posts are absurdly long, so I trimmed them to clear the radiator. The kit also came with foam vibration pads, which I applied to the cooler before slipping it in. I could only get my hand behind the condenser to put the clips on the top two posts. (You can't see the clips too well, they're in the top holes of the mounting flanges on either side.)

 

P1010035-3_zps006b422a.jpg

 

I pulled the turn signal/fog lamp out to try and attach it from underneath, but I couldn't get my hand in under there either. It did feel quite secure however so I left it alone.

 

Next I connected the hoses underneath. If there's excess hose, trim it off with garden pruners (unless you've got something better lying around). I stuck one to the return line from the trans and the other to the factory cooler (with the 1/4" wrench and a lot of swearing). If you aren't using the stock cooler just hook the new one to the two trans lines. Make sure those hose clamps are tight! I swapped a proper hose clamp I took off the donor Pathy for the weird wire one just so I wouldn't need two different drivers to put it all back together.

 

P1010034-2_zps69a10a90.jpg

 

If your cooler is meant to flow one way or the other, make sure you aren't plumbing it backwards! Some are apparently directional. Mine wasn't.

 

If the hoses seem like they're going to flop around while you drive, consider zip tying them to something.

 

Button the front end back up. To get the upper grille clips back in, unclip them from the sheet metal, hold the sheet metal end with vise grips, and put them in the grille like you removed them (twisting the head with a screwdriver). Then clip the grille back on. Replace the missing/busted ones with new zip ties, and don't forget the two screws under the grille.

 

One last thing to do, and that's topping up the ATF. The new hoses and the cooler add space that fluid has to fill, and in my case, I'd spewed some of the fluid out onto the floor. Start the truck and let it warm up. It's probably best to just let it idle since the fluid's low, but I drove mine slowly up and down the street with no apparent ill effects. I'm sure you can at least back it out of the garage so you don't carbon monoxide poison yourself. Once it's warm, park it, cycle through the gears, and (with the engine running) check the fluid level. The dipstick's behind the passenger's valve cover, kind of buried down in there. Wipe it off very well with a clean paper towel, stuff it back in, pull it out, and yeah, mine wasn't showing fluid at all. I didn't want to pour ATF all over everything so I improvised a funnel with the top half of a plastic bottle and the left-over chunk of new hose. This plugged right into the dipstick hole and worked quite well.

 

P1010007-13_zps342a222d.jpg

 

Pour some ATF in, idle the engine/cycle through the gears, check it again, repeat until the fluid level's somewhere in the crosshatched bit on the 'hot' side.

 

P1010001-23_zps911fa1b6.jpg

 

By blind luck I got right into the middle of it after dumping about half a quart of ATF in there. Repeat the reading a few times to make sure you're reading it right, then put the dipstick back in.

 

Make sure it's holding its fluid. Take it for a test drive, make sure it's still not leaking. I drove to the car wash and hosed off the ATF I'd spilled so that I'd be able to see any new leaks. It wouldn't hurt to keep an eye on the fluid for a few days to make sure it's not getting out anywhere.

 

And that's about it! Let me know if this is helpful or if there's anything I can do to make it better.

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Very thorough and detailed guide, thanks!

 

A B&M 70268 should fit alright between the grille and A/C condenser and it comes with a mounting kit and some additional hose. It's fairly inexpensive too, I believe you can get it from Advance Auto Parts for very cheap after discount code. 70268 is rated for 19k GVW. I run one on my R50 now, though due to the abundance of room I would like to eventually upgrade to a 70264 which is thicker and rated for 24k GVW.

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I just installed this one in pretty-much the same fashion (not my pic).
8c_1.jpg
Fluidyne CR-10029-MC-BRB. It's big, but it fits well in front of the A/C condenser.
I got it for around $50 (shipped) on eBay.

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I could have sworn this has been covered, but perhaps not or it is simply hard to find. Good job, and the more the merrier for certain! :aok:

I took the liberty of changing the title to the full name of "Transmission cooler" so it will turn up easier during searches. I will also be moving this into the Garage/How To section.

What size is that cooler?

 

I'll add a few additional items:

1)If you are worried about the stock tranny cooler clogging, install an in line filter between the tranny and the radiator cooler, that will solve the problem regardless. I believe there is a thread I posted which explains how to set up a screw on type inline filter for about $30, and I believe TownCivilian wrote up an install on a Magnafine in line filter. These should probably be linked...

2)There are 3 basic types of tranny coolers (if I have all this straight); plate type, stacked plate type and fin and tube type, the order listed is also the order of efficiency and durability. What Slarti is showing is a stacked plate type. Due to the limited mounting space a 3/4" thick plate or stacked plate design is recommended.

3) A good idea before install is to pick up a can of tranny cooler flush from your local dealer and flush both units prior to installation, I'd argue it is worth the effort.

 

This is a plate type I pulled off of a Ford Exploder at the local P&P, I think it cost me $14-18. Yes, my P&P is expensive. The dimensions are 11x7.5" which roughly matches up to the B&M cooler #70268.

 

  • 19,000 GVW
  • 13,000 BTU
  • 11'' x 7-1/2'' x 3/4''

 

046_zps6aa38b3b.jpg

 

B

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Thanks all. :) Yeah, I think this has been covered, but the only other writeup I can find is Dr. Bill's (linked below) and he took the whole front end apart.

 

Mine is about 6" x 11" x 3/4," excluding brackets. I have no idea what it's rated at.

 

B, I remember seeing those threads, but I can't find them now. Anyone with good search-fu want to find those?

 

I did find these however:

 

http://www.nissanpathfinders.net/forum/topic/23280-replacing-the-timing-belt-adding-an-at-cooler/

 

http://www.nissanpathfinders.net/forum/topic/33650-dont-know-if-this-has-been-covered-tranny-coolers-tube-and-fin-vs-plate-style/

 

http://www.nissanpathfinders.net/forum/topic/30565-more-automatic-transmission-cooler-questions/

 

http://www.nissanpathfinders.net/forum/topic/32541-is-adding-a-tranny-filter-really-a-good-idea/

 

Also, can a mod correct my statement on the Ford cooler? I didn't know they were plate type.

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I know the stock cooler is known to clog and cause problems but after seeing one out of the radiator I really don't see how it could clog, it's basically a straight tube, this is a picture someone found of one:

 

I believe this is from a Nissan rad and it's just sitting on a Toyota box:

 

ofuf43.jpg

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I'm not sure that's off a Pathy. Mine has big hose barbs on it and I could swear it's a bit thicker too (full rad thickness).

 

Anybody have a buggered radiator to tear apart and verify what the guts look like?

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I decided to swap the cooler lines around so that the high side is output and the low side is input. The hoses were fun (nothing like a splash of ATF to the face) but refilling the fluid was weird this time. Trans fluid level and temperature seem to be related more strongly than I would've believed was possible. What looked like a good level at 1/3 temp (roughly) was off the scale at 1/2 temp (fully heated up). Because of this I'm not sure how much fluid it actually needed and whether or not the cooler had air trapped in it.

 

Anyway I'll recheck it tomorrow after doing the warmup like the manual suggests.

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Best to check it hot a few times after cycling through all the shifter positions (as per FSM instructions) and average the results. The auto trannys can be quite sensitive to fluid level from what I have read, yet 1 pint can move the dipstick reading from low to good from my experience. Best take the average approach and add only when convinced.

 

 

Thanks all. :) Yeah, I think this has been covered, but the only other writeup I can find is Dr. Bill's (linked below) and he took the whole front end apart.

 

Mine is about 6" x 11" x 3/4," excluding brackets. I have no idea what it's rated at.

 

B, I remember seeing those threads, but I can't find them now. Anyone with good search-fu want to find those?

 

I did find these however:

 

http://www.nissanpathfinders.net/forum/topic/23280-replacing-the-timing-belt-adding-an-at-cooler/

 

http://www.nissanpathfinders.net/forum/topic/33650-dont-know-if-this-has-been-covered-tranny-coolers-tube-and-fin-vs-plate-style/

 

http://www.nissanpathfinders.net/forum/topic/30565-more-automatic-transmission-cooler-questions/

 

http://www.nissanpathfinders.net/forum/topic/32541-is-adding-a-tranny-filter-really-a-good-idea/

 

Also, can a mod correct my statement on the Ford cooler? I didn't know they were plate type.

I'll go and see if I can't link them.

 

I'm not going to edit it yet, because there may be more than one type depending on year/model, or even an aftermarket install.

I can't even tell you what year I took mine off of as I didn't care/think to check. :shrug:

 

awesome write up...i need to do this soon

If you have an auto tranny, yes. I also recommend an inline filter...

 

I know the stock cooler is known to clog and cause problems but after seeing one out of the radiator I really don't see how it could clog, it's basically a straight tube, this is a picture someone found of one:

 

I believe this is from a Nissan rad and it's just sitting on a Toyota box:

 

ofuf43.jpg

I seem to remember the same picture myself. As for the straight tube part, well, it depends what is on the inside. Are there loops, rough joints or welds that material could build up against? :shrug:

We know it is a documented problem, just not exactly why...

 

B

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  • 2 months later...

Nice. I am gonna head to P&P and see what I can find. Just bought my Pathy and tranny seems fine but want to flush and replace filter. Might as well bypass cooler at the same time....

I love these forums!

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  • 2 years later...

A small update after re-mounting the cooler to my 93: 5/16" hose can be forced on if you have to, but it's really smaller than it needs to be. I plumbed in a magnefine on my latest install and didn't want to put too much force on its plastic hose barbs, so I used 3/8" hose, which worked fine but did seem slightly loose on the cooler in the rad until I got the clamps tightened down. The 11/32" line I've seen recommended wasn't available locally but might've fit better.

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