How to install automatic transmission cooler ?

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Andrew

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Dec 21, 2002
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I am looking at an automatic transmission cooler for my 2006 Corolla because sometimes when stuck in traffic for 5 - 10 mins, it loses its normal Toyota quality feel. Mainly, it gets jerky. I live in a warm climate and the coldest it EVER gets is approx 50 degress F (10 degrees C)in winter.

I understand that the cooler should be installed in series with the auxilliary cooler (most cooler manufacturers recommend this) but I have some other questions:

- should you fit a bigger cooler if it will fit
- would it be beneficial to fit a cooler with a 12V fan so that cooling will occur when the radiator fan is off and you are not moving
- should you install the cooler on the hot side of the radiator or the cold side of the radiator

Cheers
 
If you've got the room (which is hard to imagine that you have much) go big. I doubt you'll find a unit with a fan that's compact enough to fit anywhere in your Toyota.

In front of the rad is the preferred location. Consensus is that it should be after the in tank cooler on the rad. You may consider bypassing/eliminating it if you don't get the effect you desire leaving it part of the system.

Keep in mind that coolers come in several shapes. Wide and short tall) ..square ..etc. ..and what may require a small one in one configuration, due to limitations, may allow a larger one.
 
If you have room, use the biggest cooler possible. During the winter, you could always cardboard/tape it off. 50F isn't cold and you probably won't ever need to block it off.
Also, if ATF cooler is big, it will be hogging performance from the A/C condensor and engine radiator.

A fan is beneficial if you do a lot of city or traffic driving. IMO, I prefer fan on cooler only if placement isn't perfect. The fan allows you to place the cooler anyway/anywhere you want.

Frame rail coolers also are an option if front mount room is lacking space or airflow.

You should monitor ATF temp. This will help you decide on how big to go or whether you need the fan.

For your weather, install it after the OEM cooler.

Exercising the drainplug will do much to maintain fluid quality. A full synthetic is a worthy option. I would recommend Amsoil but your location might not have a price worthy supply. Penrite makes several T-IV equivalents, and I believe a couple are full synthetic.
 
Recently tranny performance people have been telling me they are concerned about pressure drop through coolers and are recommending a bypass kinda routing. You T into the "in" and "out" lines of the radiator cooler and plumb the cooler in that way, ratehr than having full flow through the aux cooler before or after the radiator cooler. They say the oil has more dwell time. Haven't though much about it, but can't see anything dangerously wrong with the idea. I'm not sure I understand how that would eliminate a pressure drop, though.
 
With a parallel cooler set up, differences in flow restriction may cause very little flow to one or the other. There is no way to predict this, so avoid it.
 
Not sure if they will ship to you, but I buy automatic transmission parts and coolers from bulkpart.com, and have good results with them.

Nope, I'm not affiliated with them either, just good service every time.
 
I'll agree with Gary that most people reccomend installing an oil-to-air cooler after the factory oil-to-water cooler. I've never heard any clear or consistent reasoning for this, though... and I'll dissent from the majority opinion.

In reality, you'll likely notice no difference at all whether the aftermarket cooler is plumbed in before or after the factory cooler... but it's still worth considering.

In my humble opinion, the ATF should be routed through the aftermarket cooler before the factory cooler. Here's why: The ATF will be at its hottest immediately after coming out of the transmission, and therefore the you'll have maximum temperature differential in the aftermarket cooler. This means that the aftermarket cooler will be dissipating more heat than it would with the more common [factory -> aftermarket] routing. Additionally (and more importantly?), the hottest fluid in the system (directly out of the transmission) will be dissipating heat directly into the air, rather than directly into the engine's cooling system.
 
I like the Onion's thinking here. The other advantage is that in cool or cold weather you have warm fluid going back to the tranny. In hot weather, the radiator heat load is reduced. Well said, Onion!
 
Thanks for the input guys.

UNDUMMY, thanks for the reminder regarding PENRITE. Completely forgot about them and have used their oils before. They make a mineral, semi-synth and syth ATF (group III) for T-IV uses. I am considering AMSOIL ATF as well since AMSOIL products are well priced here, costing around the same as Mobil synth products
 
use only a plate-fin type aux ATF cooler, much more efficient and far less pressure restriction drop

go with the PAO/ester syn ATF's for long life and low oxidation in hot climates especially with the small sump capacity high rpm japanese trannies
 
As long at the heat exchange is not upwind of the radiator, then I agree with onion. If it is upwind, then the transmission heat is still headed for the engine's cooling system.

I think that the reasoning for most on this subject is that if if the cooling system is downstream of the factory system, then the transmission fluid will be as cool as it can be. However, that reasoning does not consider the effects on the engines cooling system.
 
By brother and I have had extensive arguements on this subject. He brings up exactly the same reasoning as GMorg- and I agree that they're valid points... but here's why I still prefer my [aftermarket -> factory] cooler routing:

Aftermarket tranny coolers are almost always mounted in front of the radiator- often even in front of the a/c condensor... so the concern about heat moving downwind is legitimate- and I'm sure some heat will be transferred indirectly from the aftermarket cooler to the radiator this way. I think that the amount of heat transferred into the cooling system will be far less, though, with the ATF running through the aftermarket cooler first. In this scenario, the hottest oil dissipates heat into the air, then SOME of that heat may be absorbed back into the radiator. Contrast this with the more common [factory -> aftermarket] route, where the hottest oil will dissipate heat directly into the coolant... I think this oil-to-water heat transfer will be vastly more efficient (which is not a good thing, in this case) than an oil-to-air-to-water heat transfer. We're looking to get rid of heat, here.

I'll definitely agree that with the conventional [factory -> aftermarket] routing, the ATF will be as cool as possible... sometimes cooler than with my prefered setup (This is my brother's main arguement). I contend that this isn't neccesarily a good thing- for several reasons.

When it's cold outside, overcooling could be an issue with some transmissions. Lots of transmissions have thermostats that route oil differently according to temperature... and some vary shift points according to temperature. To the extent that overcooling is an issue (and it's debatable just HOW important it is), routing the ATF back through the radiator before entering the transmission will help avoid it. It might not help much as the factory cooler is on the 'cold' side of the radiator... but it'll definitely be better than exposing the ATF to a 10-degree/60 mph wind just before it goes back into the tranny.

When it's really hot out, I seriously doubt that any aftermarket cooler is efficient enough to cool the ATF so much that the factory cooler would actually heat it back up... but what if it did? Let's say your average cooling system is running at 200 degrees on a hot day. Now, the smallest specified temperature drop across a radiator that I've ever read about is a 10-degree drop... most radiators will drop more than that from the hot side to the cold side... but for the sake of discussion, we'll assume that the 'cold' side of the radiator is at 190 degrees (in a properly functioning cooling system, it'll probably be lower, though). This means that the maximum temp that it could heat the transmission oil to is 190 degrees. Is it worthwhile to get the ATF temperature lower than 190 degrees? I personally don't think so... in fact, I'd say that that's as close as you're going to get to an ideal operating temperature.
 
I don't see 190F as an ideal operating temp. I prefer it to be under 160. IMO, anything over 180 is stressful for the transmission.

Concerning location, it is user dependent. Thread starter does not have to worry about cold weather. The OEM cooling isn't sufficient. Adding an extra cooler after the OEM cooler can only help. Its so simple its not even worth debating simply because there are too many vehicle variables concerning ATF cooling location.

Even though plate fin coolers claim to be more efficient, I don't think that they are rugged enough. The tube/fin coolers are more reliable.
 
Well, given that I live in Texas, Auto-X, Drag Race and Night rallye my 4spd auto accord, I think I can give a little input from my POV.

My cooling/filtration setup consists of a remote hydraulic filter mount with a huge spin on transmission filter, a "24,000GVW" plate+fin cooler from B&M, and a derale 13011 180*F bypass valve. I also run amsoil ATF on my new transmission with a planned OCI (40% fluid change) every 10k miles, although I may bump it down to 5k miles depending on what my first UOA looks like. I'm currently about 7k miles on my new transmission with this setup that I first installed along with the Amsoil ATF when it had 1-1.5k miles on it. I did multiple drain+refills to get about 85% Amsoil ATF, wasted a lot of fresh Honda ATF doing so...

My fluid routing consists of the following:
transmission cooler output line -> remote filter mount with temp gauge sender -> factory radiator -> 180*F valve -> aux transmission cooler when hot -> back into the transmission.

When below 180*F or so, my aux transmission is bypassed. During the cold winters around here, I've had trouble getting the trans to go about 125-150*F. During the warm spring/summer it reaches 180ish with ease, but never much higher unless I'm romping on it. On night and day rallyes when I'm going WOT for extended periods of times, sometimes even limiting it to the first 3 gears to prevent constant up/down shifting into/from 4th, I've gotten it as hot as 215-250*F, without any adverse shifting affects (yes this is with 85% Amsoil ATF in my trans!). While it's been a long time since I last hit 215-250*F, I'd hope to install a thermostat-controlled fan on the cooler before putting it through such conditions again.

Anyways, I feel that during hot weather, the biggest cooling issue for the transmission isn't the transmission itself, or the size of cooling system, but rather the engine coolant temp. I haven't installed a second temp sender to back this up (to measure the radiator output temp), but I feel that when I do get my transmission hot with my current setup, it's because the engine coolant in the radiator is dumping a good amount of heat in the ATF, enough to possible heat soak the aux cooler downstream and limit its ability to cool down the fluid effectively before it goes back into the trans. On the plus side, even at 250*F output temp, I still had no adverse shifting affects.

My aux cooler is installed a full 3-4" in front of my a/c condensor, and is fully exposed to cool air flow when moving. At low speeds however, I doubt it is getting enough airflow to help cool off that really hot ATF. I definitely think installing a bigger/more efficient stacked plate cooler along with a high flow fan would really keep things cool and controlled. My current cooler seems too small to install a high flow fan.

My advise to you? If you're already experiencing adverse shifting issues with a stock, lightly driven setup in the hot Aussie weather, spend the extra money and get a GOOD, BIG stacked plate cooler, like the ones below, along with the highest flowing fan you can stick on it (activated by a thermostat).

I'm not sure how cold your trans fluid would get with a huge cooler in 50*F temp (different cars generate diffent amounts of heat). If you do end up having issues with overcooling, a Derale 13011 180*F bypass would be a great investment. If you can, install a trans temp gauge so you can actually see what is going on in your transmission and make adjustments accordingly.

Here's the bypass valve I use (IMO, same part sold under different brands, but this is the best price I've found so far):
http://www.transmissionpartsusa.com/Fluid_control_thermostat_kit_p/600-000013011.htm
http://derale.com/180-fluid-thermostat.html

I also use the following remote hydraulic filter mount and filter, both available for dirt cheap from site sponser, fleetfilter.com:
http://wixfilters.com/filterlookup/PartDetail.asp?Part=51622
http://wixfilters.com/filterlookup/PartDetail.asp?Part=24764

Finally, here are the setrab coolers I'm currently considering for the long term:
http://www.bakerprecision.com/setrab.htm

BTW, this is the cooler I currently have:
http://cgi.ebay.com/ebaymotors/New-B-M-2...emZ300081529566

I also use good quality 250PSI Goodyear transmission oil cooler hose available cut-to-length at the local parts store. Don't let them give you 50PSI fuel line hose, it may pop! Since I upped the number of hose clamps from the factory count of 4, to 12 with my current setup, I decided that it would be worthwhile to invest in better hose clamps and improve my chances against the laws of probability. I use ABA hose clamps with smooth bands that properly apply pressure around the entire hose, instead of digging/cutting into them like the cheap $0.50 clamps you can get anywhere:
http://truechoice.com/prodinfo.asp?number=ABA 19

I ordered 14 clamps, which came out to about $1 per clamp...
 
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I would consider the AM:OEM routing just for "buffering" of both cooling system and trans temp. The notion of "warming" with the OEM setup doesn't hold much weight if you consider the outlet temp of your rad at cold temps ..and how long it takes to get to temp. My lower hoses, at idle in freezing temps are stone cold. If I can't feel "warmth"..then it's no where near any temp anyone would consider viable for "warming". The trans is warming from the turn of the key ..the tank cooler isn't warming until the coolant thermostat opens ..except for sucking btu's from the trans fluid. I'm sure that this parasitic heat loss is for an extended amount of time if ambient temps are very low.


If you're not overheating in your worse case scenario, then the outlet temp of your rad is just fine for your trans. It's going to be below well below 195 at the outlet side of the rad where the tank is ..and as was mentioned, the liquid to liquid heat exchange is pretty efficient.

I like the thermostat method, but adds about $60+ to the install.

Now you can debate how to install the thermostat. Using it to include the auxiliary cooler, both coolers rigged in series,..or modulate between the in tank cooler and the auxiliary depending on temp (plugging the cooler return port and "T'ing" both returns to the trans. Effectively using it as a diverter.
grin.gif
 
I installed my stacked plate cooler before the rad cooler...I'm with onion on this one...get the heat out BEFORE it gets in the system.Plus I was always taught that oil to water is far more effcient than oil to air
grin.gif
 
This is the cooler I purchased.It's made by Dana in Canada.http://www.dana.com/Automotive_Systems/images/PDFs/TC_Brochure_2004_Website.pdf
 
A side note on oil thermostats. I've recently had cause to use one in a "non-conforming" usage as a coolant block. That is, I plugged both outlets and used the bypass path as a cooler block off after the coolant temp reached 180F+/-. Aside from Permacool's engineers (or whomever really makes this - it's marketed by many) not knowing the effects of long term usage in a coolant environment (assumed to be properly maintained) the device doesn't totally block flow. A fail safe feature of the thermostat is to allow 10% flow when the valve is fully closed.

Now I don't know how quite how they determine a percentage of flow ..they can only design a percentage of minimum port area. If you've ever looked at a Permacool sandwich adapter, you can see how the full flow of many (most in fact) engines passes through a very small port while creating only a 2 PSI differential pressure across it.

(edit: For those of you not making the connection - I'm comparing a minimum port opening of the oil thermostat -to a sandwich's relief valve in comparative "ease of flow")

Essentially, this means that you'll have variable flow across your cooler based on viscosity ..since it can never see anything more than 2 psi pressure alteration due to cooler/fluid resistance. Any of you wiz-bang fluid dynamic equation types (I'm surely not one) can factor your tube diameter alone over the length of them ..somehow come up with a flow rate (use hypotheticals) and see what you can expect across your cooler.

This would be different where you have no such pressure regulated diversion and merely rely on the restricted port/circuit method for flow divergence. Keep in mind the size of the relief port on a Permacool sandwich ..then imagine it with no spring/poppet to compel the fluid to take the long path to the cooler.

This doesn't seem to present too much of a problem in practice, but in regard to ATF @ op temps, you're dealing with a very thin fluid. This would/could seem that installing the thermostat as close to the auxiliary cooler as possible, reducing it's apparent resistance to the flow, would be a favorable thing to do.

Mocal oil thermostats don't sport the rhetoric that Perma-cool thermostats do in their literature. Theirs leaves full flow access to the coolers by default and just close off the short circuit/easy path as the oil heats. Permacool's appears to be a biasing diverter... with minimum openings at either end of the valve travel.

One alternative, for those who are installing auxiliary filtration at the same time, is a Hayden thermostatic sandwich. It has a flat bi-metal spring that closes off/over a bypass port. Although I have one, I haven't observed the performance of it on line. Conceptually, it appears to be pretty fool proof
dunno.gif


This may make installing the Permacool type of thermostat in a diverter type manner more sensible. Then the fluid would have a competitive choice of going to the in tank cooler or the auxiliary when the valve is fully biased in the hot position ..instead of giving it a clean shot back to the trans via the fail safe restricted port. There you would plug the normal cooler return to the thermostat, feed the in tank cooler with the normal return to the trans, feed the auxiliary cooler with the cooler (hot) feed, and Tee both returns to the transmission. Cold, it would go (mostly) to the in tank cooler. Hot, it would go (mostly) to the auxiliary cooler.

Just adding more complications to a relatively simple installation ..but that's why we're here
grin.gif
 
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