Waterpump interchangeability b/t wrx and turbo legacy

boostjunkie · Post by **boostjunkie** » Fri Dec 19, 2003 11:28 pm

Hey guys,

The parts guy said that it might be till monday when they can source a new waterpump. Is there a difference in waterpumps (flow capacity, fitment, etc) between the wrx waterpump and the turbo legacy?

I'm sure they have the wrx pump in stock.

Thanks!

vrg3 · Post by **vrg3** » Fri Dec 19, 2003 11:37 pm

The water pump for 1991 Legacy Turbos is the same as the pump for 2002 WRX.

1992-1994 Legacy Turbos have different water pumps, since they don't have the oil/water heat exchanger.

boostjunkie · Post by **boostjunkie** » Fri Dec 19, 2003 11:41 pm

Hehe, as soon as I posted this I referenced the part number lookup in the "stuff you need to know" forum, and cross-referenced that with the subaruparts lookup for the wrx waterpump.

Wait a minute: you mean the 91s have an oil cooler? I thought all turbo legacies came without an oil cooler?

vrg3 · Post by **vrg3** » Sat Dec 20, 2003 12:18 am

1991 Legacy Turbos had oil coolers (more precisely: oil/water heat exchangers). They fit between the oil filter and the engine block. One coolant line goes to a fitting on the block (that's replaced by a plug on 92-94 models) and the other goes to a nipple on the water pump (that's missing on 92-94 models).

boostjunkie · Post by **boostjunkie** » Sat Dec 20, 2003 12:33 am

I'll have to take a look at that heat exchanger when I get the car back. Where's the second heat exchanger? In front of the radiator? Man, I never even noticed it before.

THAWA · Post by **THAWA** » Sat Dec 20, 2003 12:33 am

interesting, could you put a 91 pump on a 92-94 and use the tubing instead of that plug in the block? More importantly why does only the 91 turbo have this?

vrg3 · Post by **vrg3** » Sat Dec 20, 2003 12:42 am

boostjunkie - Second heat exchanger? There's only one. The unit mounted between the filter and block has coolant and oil running through it (they never touch, of course, but exchange heat through conductive fins).

People call this an "oil cooler" but it's really a two-way heat exchanger:

When the engine is just warming up, oil temperature tends to be higher than water temperature, so the exchanger allows the coolant to warm up more quickly. Then, once the engine's warm, the exchanger allows the coolant to keep the oil near its optimal operating temperature.

THAWA - The exchanger requires both the nipple on the water pump and the fitting on the block. After all, coolant has to flow in one side and flow out the other. 92-94 cars don't have the extra nipple on the pump and have a plug in the block instead of a nipple.

Subaru basically cheaped out a little for the 92-94 Legacy Turbos... they took out a few nice things like the LSD and oil/water heat exchanger.

New WRXs all have the exchanger. Some model years of Foresters also got the heat exchanger.

Maybe Subaru was trying to make the 1992 Legacy cost about the same as the 1991 to produce. The 92 has much more expensive headlamps and many had airbags, and then of course there was just the cost to redesign it...

boostjunkie · Post by **boostjunkie** » Sat Dec 20, 2003 12:48 am

My mistake. I was thinking the HE in the oil filter was routed to another exchanger in the bumper, similar to a transmission oil cooler.

Maybe Subaru was trying to make the 1992 Legacy cost about the same as the 1991 to produce. The 92 has much more expensive headlamps and many had airbags, and then of course there was just the cost to redesign it...

What is the difference in price between the 92-94 WP and the 91/wrx? I only see the part number for the 91/wrx WP listed.

ciper · Post by **ciper** » Sat Dec 20, 2003 1:24 am

Haha, you guys suck. Thats another reason to get the first generation legacy before the body style change. [dancing a jig]

Would you be surprised to know that I have two of the Oil/Coolant heat exchangers with bolt

evolutionmovement · Post by **evolutionmovement** » Sat Dec 20, 2003 1:37 am

"Get out of the MF' thread! I'm taking over, biatch!"

I had been meaning to post on this. My kitchen-turbo is a 1993 and I thought that maybe I could retrofit the oil cooler which I thought was an add-on. They wouldn't have changed the block itself, right? Is there a way to add this feature?

Steve

ciper · Post by **ciper** » Sat Dec 20, 2003 1:49 am

I can help you route it if you wish, I just got my 91 service manuals!!

One issue is that the 91/WRX water pump has two inlets. One for the oil cooler.

Also the 91 has a metal tube that runs along the timing cover, easily replaced with rubber though.

I suggest routing it in parralel to the heater core, it would be the easiest two pipes to get to. The heater is one of the recirculation paths so it would be similar to the stock setup (oil cooler is inline with the passenger bypass if I remember)

vrg3 · Post by **vrg3** » Sat Dec 20, 2003 2:50 am

boostjunkie - Yeah, it's purely an oil/water heat exchanger... there's no air-cooling involved. The 92-94 water pump is part number 21111AA065. It doesn't have the extra nipple for the oil cooler.

For future reference, I have a bunch of part numbers recorded at:
http://www.graphics.cornell.edu/~v/partnumbers.html

ciper - Wanna share the wealth? :)

Steve - You can retrofit the oil cooler. From what I can tell, here's what you need if you want to do it OEM-style:

- The oil/water heat exchanger itself.
- The longer threaded oil filter fitting to go with it.
- A water pump for a 91 Turbo Legacy or a new WRX.
- The threaded nipple fitting that goes into the block instead of the stock plug.
- The metal tube that ciper's talking about.
- Some heater hose to connect the cooler to the nipple on the block, to connect the cooler to the metal tube, and to connect the metal tube to the nipple on the water pump. 1/2" hose ought to be about right.
- Hose clamps.

If you don't mind doing it differently, you could tee into the stock heater circuit and/or use heater hose the whole way, as ciper describes. In my opinion, though, you might as well do it this way if you're building an engine in your kitchen anyway.

THAWA · Post by **THAWA** » Sat Dec 20, 2003 2:30 pm

Well I had meant to ask if you had all the parts for it from a 91 or wrx could you do this to a 92-94
but i see you can.

ciper · Post by **ciper** » Tue Dec 23, 2003 12:34 am

Someone want to host 3 black and white images?

They show the coolant flow maps, the cooler installed and a parts explosion.

THAWA · Post by **THAWA** » Tue Dec 23, 2003 3:05 am

email em

ciper · Post by **ciper** » Tue Dec 23, 2003 3:09 am

Sent. I made them smaller than original to save space and bandwidth.

If I remember right the outlet of the oil cooler goes into the plug opposite where the factory block heater is installed (those 14mm hex bolts).

Changed the oil and installed a Fumoto on my buds WRX this weekend and verified that the 91 turbo cooler and pump do look the same.

THAWA · Post by **THAWA** » Tue Dec 23, 2003 3:16 am

if these are too big ill make them links

ciper · Post by **ciper** » Tue Dec 23, 2003 3:17 am

Oops, that last one was for something else

Still cool none the less.

Dont think they are too big, all four combined are about 220k

biggreen96 · Post by **biggreen96** » Tue Mar 22, 2005 7:47 am

So if I pick up a WRX water pump and plug the hole that feeds the exchanger it might work for me? is this feasible?

vrg3 · Post by **vrg3** » Tue Mar 22, 2005 7:49 am

Yes. It will work if you use a 1/2" coolant bypass cap (and appropriate hose clamp) on the extra nipple.

biggreen96 · Post by **biggreen96** » Tue Mar 22, 2005 8:03 am

awesome

Post by **Legacy777** » Tue Mar 22, 2005 7:12 pm

Actually....this might work for me then. If I pickup a wrx water pump, I should be able to use that oil cooler from the forester.

THAWA · Post by **THAWA** » Tue Mar 22, 2005 9:36 pm

make sure to get the wrx coolant hard pipe. The forester one is shorter and not angled since it connects to the thermo housing, and not the water pump. I guess you could just use a longer hose between the water pump and the hard pipe instead but I personally like the idea of as little rubber as possible.

Post by **Legacy777** » Wed Mar 23, 2005 12:46 am

I'll take a look at it when I get it. The guy I bought it from noticed that the rubber line was sliced in one spot, and he said he'd reimburse me for the purchase of the new line. So we'll see.

vrg3 · Post by **vrg3** » Wed Mar 23, 2005 3:58 am

You can just make your own hard line out of 1/2" aluminum or copper pipe if you have to.

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Waterpump interchangeability b/t wrx and turbo legacy

Waterpump interchangeability b/t wrx and turbo legacy