Installing an oil cooler on NA block?

douglas vincent · Post by **douglas vincent** » Thu Dec 16, 2004 7:18 am

Did all the turbo motors have an oil cooler, or just the 91?

And if they didnt, how did you install an oil cooler?

Since mine is an NA, and I dont have the exhaust problem, should I do the oil filter adapter thingy?

vrg3 · Post by **vrg3** » Thu Dec 16, 2004 3:11 pm

Only the 91 turbos had oil coolers.

I installed an oil cooler off a WRX on my car. Since I don't have the water pump meant for oil-cooler-equipped engines, I had to tee into the coolant hose coming from the turbo.

If you can score one, I'd recommend using an oil cooler kit from a Forester. Instead of using the water pump as the return they just have a nipple added to the thermostat housing. This is a really good writeup on ScoobyMods:

http://www.scoobymods.com/forums/showthread.php?t=170

Used ones occasionally go pretty cheap on NASIOC.

Post by **Legacy777** » Thu Mar 17, 2005 5:09 am

Anyone know if the forester oil cooler will fit on a turbo motor? I know the t-stat housing is different, but from what I can tell the 91 oil cooler has a line that runs over to it.....so it "should" be able to work.

Anyone have any ideas or a pic of the 91 oil cooler?

TIA

THAWA · Post by **THAWA** » Thu Mar 17, 2005 5:12 am

They're the same thing, and if not they're close enough for it not to matter. The setup is the same on a forester, legacy, outback, or impreza.

mikec · Post by **mikec** » Thu Mar 17, 2005 5:21 am

Sweet! A new thermostat housing is cheaper than buying a new water pump, seeing as I just changed mine 12000 kms ago.

And its got all the part numbers... Super sweet!

THAWA · Post by **THAWA** » Thu Mar 17, 2005 5:22 am

That thermo housing wont fit on your car.

mikec · Post by **mikec** » Thu Mar 17, 2005 5:31 am

Oh yeah... the turbo one is angled, right? Guess I'll go with Vikash's method of tapping a coolant hose then. Or maybe you could add a nipple to the thermostat housing....

THAWA · Post by **THAWA** » Thu Mar 17, 2005 5:41 am

No, it's because the bolt pattern is a mirror of yours. They're both angled.

mikec · Post by **mikec** » Thu Mar 17, 2005 5:51 am

Oh. Thanks!

vrg3 · Post by **vrg3** » Thu Mar 17, 2005 1:21 pm

The Forester oil cooler connects to the thermostat housing instead of the water pump. Like Hardy says, the Forester thermostat housing won't fit on the turbo water pump because Subaru mirrored the bolt pattern.

You should be able to make the Forester oil cooler fit right up but you'll just have to figure out how to connect that water line to the pump. You could tee into the turbo's water line or you could use a water pump with the fitting and maybe massage the hard line or use a hose with a curve. It's really no big deal. I didn't use a stock hard pipe anyway; I just cut/bent my own piece of 1/2" copper tubing.

I started to try to modify a stock turbo thermostat housing to add on a 1/2" nipple, but never finished. I cut a hole in the side of the housing and tapped it for 1/4" pipe threads. I was gonna try to somehow attach a brass 1/4"-pipe-to-1/2"-barb adapter, but I gave up trying to solder to aluminum.

It seems more sensible to put it on the pump side anyway, though, so you don't have to rely on flow through a closed thermosat when it's cold, right?

The 91 Legacy Turbo, the WRX, and the Forester actually all three use different oil coolers with slightly differently angled fittings.

mikec · Post by **mikec** » Thu Mar 17, 2005 1:56 pm

I wonder if there's a reason they changed from using the water pump to the thermostat housing? Is the Forester oil cooler on every Forester, or just the XT?

Because yeah, I can't see flow through a closed thermostat being very effective.

vrg3 · Post by **vrg3** » Thu Mar 17, 2005 4:48 pm

Well, their two options were to design a new water pump or to design a new thermostat housing. The thermostat housing is a lot cheaper and easier. Also, I think the oil cooler was supposed to be dealer-installed, so they wanted installation to be as simple as possible too.

I think the oil cooler was an option on Foresters. Maybe only 4EAT-equipped ones, or ones with towing packages, or something. I don't know.

mikec · Post by **mikec** » Thu Mar 17, 2005 9:59 pm

Good point on it being easier to redesign the housing over the pump.

Post by **Legacy777** » Thu Mar 17, 2005 10:17 pm

I think I should be able to rig something up.

However I'm still a little foggy. Where does the stock 91 oil cooler connect to? The water pump? Is there a special water pump for the 91 that has a line for the oil cooler?

vrg3 · Post by **vrg3** » Thu Mar 17, 2005 10:26 pm

Yes, the 91 oil cooler connects to the water pump. The 91 turbo uses a water pump like the new age WRX pump (in fact, the superceded 91 turbo water pump part number is the same as the WRX's).

Apparently at least some 92-94 water pumps actually have a 1/4" NPT (!) bung on the side for the water pump fitting; from the factory it's sealed with a plug.

THAWA · Post by **THAWA** » Fri Mar 18, 2005 2:28 am

I believe every year of the Forester had the option of an oil cooler. And I'm pretty sure I've seen a few manuals with one.

To elaborate a bit more, the coolant flows from the water galley in the bottom of the block, to the oil cooler, to the water pump, and back to the bottom water galley.

sammydafish · Post by **sammydafish** » Wed Apr 06, 2005 4:02 pm

why not just use an air oil cooler with a sandwich adapter or something of the like.

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Installing an oil cooler on NA block?

Installing an oil cooler on NA block?