Automatic Transmission Coolers

[Vantropy]

Finally got the transmission cooler installed.

I was disappointed that the Small Car kit didn't come with a coolant hose-mending barb. When I buy a kit, it's because I don't want to go looking for parts, and this one is advertised as including "all the neccessary hardware." Is the mending barb necessary? EVERY other transmission kit supplier seems to think so. I do too. So, if you install this, you'll need a 5/8x5/8" mending barb and some good hose clamps (not cheap screw types). I got a brass one in the hardware store plumbing section. And some liquid thread sealant from an auto parts store: I used Loctite 592.

Instructions included with the Small Car kit leave much to be desired. pete000 had a good post about the install with some pictures:

https://www.thesamba.com/vw/forum/viewtopic.php?t=166327

And Van Cafe's install instructions are very useful (but don't follow their fluid refill instructions unless you're installing a kit with that much hose!):

https://www.vancafe.com/v/vspfiles/instructions/RMW%20Auto%20Trans%20Cooler.pdf

Overall, I'd say that kit is probably best for cooling efficacy as well if you've got the coin to spend. And, they've thoughtfully included a way to attach a temperature sender for a gauge.

But back to my install. As mentioned before, I went with the Small Car over FAS because I wanted to add a Bosch temp sender and Magnefine inline filter. Here is the sender assembly:

Note that sender needed a ground (usually this would be the transmission that it is screwed into, but in this case, I needed to supply one). I tightened the sender down until I thought it was snug and filled the remaining space with three washers, grounded to Transmission ground strap point. As you'll see later, I had to remove all three washers as the sender kept leaking (more on that later). Small Car recommends a liquid thread sealant throughout their install.

For this assembly, I used a Brass 3/8x3/8x3/8 Barstock Tee:
https://smile.amazon.com/gp/product/B000BODVGK/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1
and two 3/8x3/8" NPT Barb fittings:
https://smile.amazon.com/gp/product/B005DSTC6W/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1
The gauge I am installing is this Bosch SP0F000049:
https://smile.amazon.com/gp/product/B00UZ9H59A/ref=ppx_yo_dt_b_asin_title_o06_s01?ie=UTF8&psc=1
It came with the sender and adapter to screw into the barstock tee. The U-shaped bracket comes off if you want to add it to a gauge pod. It's pretty cheap, and I'm not expecting much out of it, so we'll see.
I'm not set on where I'm installing it, so for now, I stuck it by the fuse panel with magnets. It's wired to the fuse panel G terminals (power to G2 or G5, illumination to G8 ), grounded to the multi-point crown party ground:

Deinstalling the stock cooler into a concrete washout tub:

That thing is so tiny! About 3oz of ATF came out (mostly in cup) and only a few dribbles of coolant.

Connecting the two coolant hoses together with the 5/8"barb connector. I still have one of the two clamps on keeping the coolant from spilling out. Next time I do a coolant flush, I'm going to omit these hoses with the manual versions:

Install three metal straps. Two are sheetmetal screws into a hole drilled into the frame. The third was a bolt into a preexisting hole. You can see this is just below and behind the parking brake adjustment equalizer. There was enough hose in the kit to get to this location (even without the filter and sender). If I did it again, I would have used a longer sender wire that didn't get so close to the cooler. I also would have bent the straps the other direction so they weren't covering the cooler vents:

Cooler mounted on straps with included bolts:

Here's a closeup of the filter and sender tee grounded to trans ground:

And the finished install:

It seems like most people angle the cooler nose up to try to get airflow across the fins. I went with a parallel install for more airflow above the cooler. Nothing hangs down lower than the fuel tank.

Added a few oz. of ATF that were lost in the install, start and run for a minute, checking for leaks. I didn't see any at first, but after driving for a couple minutes:

Apparently, quarantine has made me weak. Tightened everything up. The AN fitting on the adapter into the transmission was now a bit hard to get to with an adjustable wrench, so I went out and got an 18mm wrench. I have a suspicion that it was actually 11/16", but got it done without having to remove the transmission mounting again. The sender unit continued to leak. I kept tightening, and testing, having to remove all the washers I added initially. Bosch says not to put thread sealant on because it interferes with the ground. I realized that my ground is happening at the cap, so the threads didn't matter, so on went the sealant and I went tighter than I had before. Waited 24 hours for it to cure. This finally stopped the leak.

It should be noted that the transmission takes far longer to warm up than the engine does. easily twice as long. I thought my gauge was broken, or the ground wasn't working. It just hadn't gotten over 100 degrees yet. Ten minutes of driving, and the gauge settled in at 150 degrees. IR gun at the trans pan showed 145 degrees, and the cooler itself read 158 degrees.
(Edit: after sustained driving of 20-30 minutes, the gauge settles at 180-185 degrees).

Once at temperature, keep engine running on level ground, fill with ATF at the dipstick a little at a time (an ounce), a short lap around the parking lot, recheck, fill again. I ended up using 8oz of my ATF container, but some of that was lost to leakage, so maybe 6-7oz was replaced.

Hope that helps. I'll see how things go when I go on a longer trip and up some steep hills, but regardless, I'm happy to have the ATF/Coolant intermix concern out of the way.
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1989 2.1L Vanagon Westy, Automatic, Titian Red

[?Waldo?]

As you posted previously, the manual trans hoses eliminate that coolant loop. IIRC connecting them together will just allow that coolant to bypass the radiator to no positive effect. It would be better to plug both hoses.

[Vantropy]

[flyboyaviator]

I'm also very interested in installing the auto-tranny cooling from FAS, are there any pictures/ video instructions that can be posted for us who are no that good of as a mechanic, in how to do this installation. Thanks for any help on this big job for me.

[?Waldo?]

I can't speak to why the producers of kits recommend connecting the loop together. Maybe because everyone else making a kit before them did it that way? I looked at the Bentley and in 19.10 and 19.11 you can see that any coolant flowing in that loop is just bypassing the radiator. Prior to removing the cooler, the cooler itself was a restriction to the flow on that circuit. Allowing unrestricted flow on that loop, bypassing the radiator for no purpose, doesn't make sense to me.

FWIW, I've seen people remove the rear heater and connect the two lines together with a similar fitting which is folly in that case as well.

Plugging them vs. connecting them would not make them more likely to leak.

[VicVan]

I agree with Waldo. It just reduces the efficiency of the cooling system.

[kamzcab86]

[Vantropy]

Finally got to go on a long trip with the new transmission cooler. Good news is that it does look to be a little bit cooler (maybe 5 degrees on average), according to IR gun temp readings at the transmission pan taken before and after install. After extended driving, the operating temperature of the transmission appears to settle at about 180 degrees F.

But now that I've got a gauge installed, I've got gauge-itis, the watching and worrying. On a couple long, steep hill climbs, the temperature got up to 210 degrees before I pulled over to cool down. I have to assume that if the ATF is 210 after leaving the trans, the internals have to be even hotter, and it's my understanding that 220 is when things start going bad (if not sooner). All of this is concerning, because if I hadn't installed a gauge, I probably would have kept driving to the point of possible damage. (After getting a reading of 210 on the gauge, the IR gun at the trans pan seam read 193).

But also, it makes me think that if I want to be able to keep driving up steep hills I'm going to have to either install a fan on the cooler or mount the cooler at the front of the van (as RMW/Van Cafe does)...Hmm...
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1989 2.1L Vanagon Westy, Automatic, Titian Red

[Mark Lewalski]

I'd have to say that neither the gauge nor the IR gun are calibrated and you will just get a temp reading that is in the ballpark of the actual temp.

And I agree... once you get access to information placed in front of you, you almost can't stop checking it. Kinda like FB or emails on your phone.

Mark
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'89 Vanagon GL Wolfsburg "Bluestar" (given to and owned by my son now)
'87 Vanagon Weekender
'74 Thing

[Vantropy]

Posting an update to my original installation.
After driving up some steep hills with the Small Car transmission cooler installed as in the previous post, I noticed high transmission temperatures (climbing up to 220F), whereupon I would pull over and let the transmission cool down for awhile. Changing the angle of the cooler had no appreciable impact.

I decided to reinstall the Small Car kit like the Rocky Mountain Westy kit, with the cooler installed in front of the radiator with some long pieces of hose and added a Derale thermostat.

For the sake of Vanagon science, I regret not first changing out my looped original hose, as per Waldo's advice, to see how this lowered temps (I am still waiting to do a full coolant hose changeover).

I remain uneasy about the idea of putting the cooler in front of the radiator, as this must have a negative impact on the radiator's cooling efficacy, but I can't say that I noticed appreciable difference in the radiator fan running time. I'm also assuming that VanCafe has spent more time thinking about this than I have, but I would love to see some before & after temperature information regarding this modification (I wish I had installed a trans temperature gauge on the original cooler!). In the end, I am choosing a lower temperature transmission over potentially increased radiator fan run time.

All this said, the new placement of the cooler has been a welcome improvement, even grinding up a steep hill last summer, the trans temp never got over 180 degrees, and usually settles in the 165-175F range.

Here's some photos of my install:

Thermostat with Magnafine filter and Brass "T" for temperature gauge sender:

Hose routing at front of vehicle:

Modified SmallCar brackets to screw up into sheetmetal (I'm _sure_ there's a more elegant solution than this!):

Final location of cooler:

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1989 2.1L Vanagon Westy, Automatic, Titian Red

[VicVan]

[blackglasspirate]

I also relocated my small car cooler to in front of the radiator a few years ago after my first transmission failure (of many...). In the end I still ended up burning through another trans but I likely had a different use case than you do. I was also slightly concerned about blocking the radiator (and also longer hoses and the potential for a drop in pressure) but the vans with stock A/C have the condenser in front of the radiator and that's a much bigger footprint than these small car coolers. If it was designed to have the condenser in front of it then I doubt having the trans cooler will have much impact.

In the end I ditched the small car cooler and am running one from GTA that has a temperature controlled fan and a thermostat. So far so good but time will tell.
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'87 Vanagon GL Westfalia
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