Using radiator tranny cooler as engine oil cooler

Heads, valves, pistons, rods, crankshaft, etc...

Moderators: Helpinators, Moderators

Post Reply
entirelyturbo
quasi-mod-o
quasi-mod-o
Posts: 6000
Joined: Thu Dec 05, 2002 7:06 pm
Location: Tampa, FL

Using radiator tranny cooler as engine oil cooler

Post by entirelyturbo »

I don't know that anyone has ever done this... probably for good reason :lol:

I have an AT radiator in my MT car right now, with the tranny cooler lines just blocked off.

I was wondering if this would be an improvement over the factory water-to-oil setup, as well as using an otherwise worthless component.

Not sure what oil filter adapter I'd use, as I'm reading a lot of negative reviews on Mishimoto and don't have the $ for Process West.

Thoughts?
"Der Wahnsinn ist nur eine schmale Brücke/die Ufer sind Vernunft und Trieb"

*Formerly DerFahrer*

@entirelyturbo on social media, including Facebook, Instagram, Twitter, and TikTok
evolutionmovement
Knowledgeable
Knowledgeable
Posts: 9809
Joined: Mon Jun 16, 2003 11:20 pm
Location: Beverly, MA

Post by evolutionmovement »

Do you plan on excess oil heat issues? You don't want to overcool it. You'd also need to account for the extra oil volume and I'm not sure what it would do as far as pressure goes.
Midnight in a Perfect World on Amazon or order anywhere. The first book in a quartet chronicling the rise of a man from angry criminal to philanthropist. Midnight... is a distopic noirish novel featuring 'Duchess', a modified 1990 Subaru Legacy wagon.
ericem
Fifth Gear
Posts: 3242
Joined: Mon Oct 16, 2006 9:44 pm
Location: Toronto,ON Canada

Post by ericem »

Probably not worth it. Probably more of a create a problem then prevent a problem kind of "thing". Best "thing" to do is not do this :)
1993 Subaru Legacy L AWD Wagon R.I.P
1994 Subaru Legacy SS R.I.P :(
2004 Nissan Titan LE 4X4
2007 Subaru Legacy GT :)
ciper
Knowledgeable
Knowledgeable
Posts: 4388
Joined: Tue Oct 15, 2002 8:16 pm
Location: SFCA

Post by ciper »

Ive broken apart a radiator before. The cooler is pretty small. I'd worry that it wouldn't flow enough for high RPMs
93forestpearl
Fifth Gear
Posts: 3043
Joined: Tue Jan 25, 2005 9:14 pm
Location: Twin Cities, MN

Post by 93forestpearl »

If using an auxiliary oil cooler, it is best to install it before the oil to water heat exchanger so it will get back to proper temp before the rest of the motor.


Or get the thermostatically controlled sandwich plate from Mocal. Those are nice.
→Dan

piddster34 at h0tma1l d0t c0m
206er
Fifth Gear
Posts: 2590
Joined: Wed Jun 04, 2003 4:24 pm

Post by 206er »

well where would you pull oil pressure from. oil coolers are cheap enough that it would be cool to run an oil-air if it was easily doable but i can't think of anyplace on an NA engine that would be easy to run oil lines off of without drilling and tapping. oil pressure sender with a T maybe for pressure side and drill/tap into valve cover? def. not worth it to run the radiator cooler imho.
1994 Touring Wagon: ruby mica, 5mt swapped
Legacy777
Site Admin
Site Admin
Posts: 27932
Joined: Tue Oct 15, 2002 11:37 am
Location: Houston, Tx
Contact:

Post by Legacy777 »

Most of the coolers are designed to pull oil from a sandwich type adapter between the block and oil filter.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
entirelyturbo
quasi-mod-o
quasi-mod-o
Posts: 6000
Joined: Thu Dec 05, 2002 7:06 pm
Location: Tampa, FL

Post by entirelyturbo »

Steve: I'm assuming the higher CR will generate more heat, and I'll assuredly have my foot in it more (maybe even some track time?). Do you think that would warrant extra cooling?

ciper: what pressure do you think the A/T cooler lines are under? I can't find A/T oil pump pressure output even in the FSMs. But I know A/Ts in general can see 70psi or more internally, so I would think it would be enough for the engine.

If this would reduce total oil pressure, would a turbo oil pump bring it back up sufficiently?

Yeah, I'd have to come up with a sandwich adapter somewhere.

If my understanding is correct, the oil never leaves the factory oil cooler adapter; the coolant comes to it. So that's no good for an external oil cooler.
"Der Wahnsinn ist nur eine schmale Brücke/die Ufer sind Vernunft und Trieb"

*Formerly DerFahrer*

@entirelyturbo on social media, including Facebook, Instagram, Twitter, and TikTok
ciper
Knowledgeable
Knowledgeable
Posts: 4388
Joined: Tue Oct 15, 2002 8:16 pm
Location: SFCA

Post by ciper »

I'm sure the unit could hold the pressure. I think you should visit the junk yard and break apart a radiator to see what this cooler looks like and then you might decide against using it. It is VERY small.
evolutionmovement
Knowledgeable
Knowledgeable
Posts: 9809
Joined: Mon Jun 16, 2003 11:20 pm
Location: Beverly, MA

Post by evolutionmovement »

I think you'd be fine with synthetic oil. What kind of CR are you talking about?
Midnight in a Perfect World on Amazon or order anywhere. The first book in a quartet chronicling the rise of a man from angry criminal to philanthropist. Midnight... is a distopic noirish novel featuring 'Duchess', a modified 1990 Subaru Legacy wagon.
vica153
First Gear
Posts: 172
Joined: Sun Mar 26, 2006 8:12 pm
Location: Seattle, WA

Post by vica153 »

I was thinking about this too, but the flared hose fittings had me worried. I may still try some really high quality hose and clamps.

I like the idea since it would still act as an oil warmer in the winter and I think it it would cool more, although maybe not by much, than the oem cooler.

The oem cooler is small too and only has the oil/water cooling. The trans cooler would have some oil/water and a decent amount of oil/air.

Yeah if you're going to spend money you might as well get an actual separate oil cooler, but if you already have the trans cooler and it might not be a bad idea.
ciper
Knowledgeable
Knowledgeable
Posts: 4388
Joined: Tue Oct 15, 2002 8:16 pm
Location: SFCA

Post by ciper »

The transmission cooler inside the radiator is much smaller than the OE oil cooler.
vica153
First Gear
Posts: 172
Joined: Sun Mar 26, 2006 8:12 pm
Location: Seattle, WA

Post by vica153 »

The stock one is just a 3" dia 3" tall cylinder right? I haven't seen the inside of one, but there isn't much volume there to design a whole lot of surface area for heat transfer. Even if the trans cooler only goes across and loops back once its still going to quickly be 3ft or so of tubing. It is pretty narrow tubing though......

I don't have the OEM cooler, so this was just one of those ideas where I thought i might use what I already had installed. I ever get an oil temp sensor setup I might try this trans cooler idea just for kicks.
Buffman
Second Gear
Posts: 501
Joined: Sat Sep 13, 2008 1:59 am
Location: MI

Post by Buffman »

most external trans oil cooler lines operate at less than 30psi. MY RMS was like 20psi, and from flushing the 4EAT, I'd say it's around there too. Internal Pressures on AT trans missions can exceed 250psi+.
1992 Legacy LS Special Wagon..
ciper
Knowledgeable
Knowledgeable
Posts: 4388
Joined: Tue Oct 15, 2002 8:16 pm
Location: SFCA

Post by ciper »

vica153 wrote:Even if the trans cooler only goes across and loops back once its still going to quickly be 3ft or so of tubing. It is pretty narrow tubing though......
The transmission cooler is probably 4 inches long at most. Measure the distance between the two hose fittings and thats how long it is.

Take a thin piece of copper pipe that is one inch diameter. Put another peice of pipe inside of it that is 15/16 diameter. Pinch the pipes to each other so there is a tiny air pocket inside and leave the center open. That is the design of the factory trans cooler.

All of you need to break a radiator open so you can see what it looks like and Im sure this idea will quickly die!
Post Reply