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Old 05-02-2002, 12:13 PM   #1
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Question Coolant source for turbo

I was told that the coolant connection to the turbo is optional and that if I don't have coolant lines hooked up, just let the engine cool before shutting it down.

Anyway, I have decided that I want to have coolant running thru my turbo. I am thinking of putting the turbo in series with the heater core, at the outlet end.

The question is, is there a constant flow of coolant into the heater core at all times? even when not using the heater? I've heard that some cars have a valve that prevents hot coolant from flowing thru the heater core when the heat is not turned on, is the Subaru system similar? Thanks for any help.

Toon
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Old 05-02-2002, 12:58 PM   #2
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No, you'll want to run it parallel to the heater core instead of in series.

There is also a possible return on the backside of the passenger head. It's a fitting screwed into the back of the head... not sure of the thread, but it'll need to be replaced with some sort of hose nipple if you go that route. Then you'd just need to get coolant from the heater core line.
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Old 05-02-2002, 01:25 PM   #3
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8, why is it better to run in parallel with the heater core? Please correct me if I'm wrong. I thought that running in series would make sure that the coolant will have no choice but to flow through both the heater core and the turbo.
If in parallel, the flow will take the path of least resistance, therefore may bypass either the heater core or the turbo depending on which has more resistance to flow.
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Old 05-02-2002, 01:33 PM   #4
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Because I believe that the heater core switch shuts off a valve to let coolant through when it's set to fully cold. Means if you have the heater on the coolest setting, it'll shut off all travel of coolant through the turbo. When you run in parallel it'll always be flowing through, even moreso when it's fully closed, but even when it's fully open. Errrr, did that make sense?
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Old 05-02-2002, 09:22 PM   #5
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The fitting on the back of the head would be a source for cooling water, not a return - all water in the block is pressurized, and it returns to the waterpump.

I am not sure but I don't think that the heater core is ever switched out of the loop. Normally a heater core always gets water, and the temp switch determines how much air is passing over the core.

I think a parallel setup would sacrifice heating capacity.
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Old 05-02-2002, 10:19 PM   #6
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Could we just use the TB lines?? in series, simple, right?
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Old 05-03-2002, 12:33 AM   #7
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I belive the 2.5 RS pump has two holes in it whic are for input and output.. I was looking at a service manula a few months ago and I believe I remember soemthing to that effect. I believe there was two screws that can be undone on the bottom side of the pump that are pressurized.

can some one correct me if I'm wrong?

Brad
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Old 05-03-2002, 02:15 AM   #8
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I was looking at the pump and I did not see any of these screws; but I certified my theory...

from the pump it goes a hose barb, then to a black tube, it will go to heater, during its travels across the engines block, this black tube has an extra hose barb, wich goes to TB, once the heater has been filled with water from pump, it will return to the cast aluminum piece wich distributes the water from both open decks galleries in the block, the same happends with the tb return line, it line up with the cast piece.

I think you just could unplug the TB in line (left side, reffer yourself as your are driving the car) and then it will feed the turbo, then the water return just got to the other left line that you left unplugged in the TB, very very easy...


Anyone will have another opinion?

Thanks
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Old 05-03-2002, 07:42 AM   #9
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Quote:
Originally posted by STiTuner
I belive the 2.5 RS pump has two holes in it whic are for input and output.. I was looking at a service manula a few months ago and I believe I remember soemthing to that effect. I believe there was two screws that can be undone on the bottom side of the pump that are pressurized.

can some one correct me if I'm wrong?

Brad
Both fittings are returns.
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Old 05-03-2002, 08:05 AM   #10
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Quote:
Originally posted by DJIMPREZA
from the pump it goes a hose barb, then to a black tube, it will go to heater, during its travels across the engines block, this black tube has an extra hose barb, wich goes to TB, once the heater has been filled with water from pump, it will return to the cast aluminum piece wich distributes the water from both open decks galleries in the block, the same happends with the tb return line, it line up with the cast piece.
Thanks
DJIMPREZA, I went to have a look at the black tube you were talking about, I think that's the return from the heater core and the cast aluminum piece on top of the block supplies coolant to the heater core.

The hose barb coming out of the pump is (I think) on the suction side and also on the engine side of the thermostate. This just means that when the engine is warming up, the coolant circuit includes the heater core and only bypasses the radiator.
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Old 05-03-2002, 08:09 AM   #11
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Quote:
Originally posted by blaster88
I am not sure but I don't think that the heater core is ever switched out of the loop. Normally a heater core always gets water, and the temp switch determines how much air is passing over the core.
This is what I was hoping for. Since you are not sure, can anyboby confirm this? Is the heater core always in the loop regardless of HVAC temp setting? Thanks.
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Old 05-04-2002, 02:39 AM   #12
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mine is in parallel to the core, "t" off the line, and returns to the rear of the block on the passenger side.

See http://www.imprezars.com/images/turb...rboinstall.doc or http://www.imprezars.com/images/turb...rboinstall.pdf

I think the fitting is a 7/8" - GTB GUY will know.

Larry
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Old 05-05-2002, 12:22 AM   #13
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Default Larry I need clarification

I got that install manual, now that bronze adapter for turbo coolant that you place into the head, is it return or in?, sounds by your post it is return, are you sure? the banjo adater to passenger hed allen bolt, is just a copy of the wrx OEm system, a water gallery in the head
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Old 05-05-2002, 12:39 AM   #14
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here is a thought. has anyone thought of running a seperate system for turbo coolant. IE a seperate core and seperate pump? maybe if you use a seperate core if it is large enough you can lower the temps of the turbo enough to reduce teh intake charge temps?

Brad

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Old 05-05-2002, 09:54 PM   #15
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The adapter in the head is the return.
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Old 05-05-2002, 11:20 PM   #16
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Larry -

If you take the hose off of that fitting in the head, water will come out.

The block is pressurized.

So in your application, you are actually returning water to the heater core line.

I am guessing you are teed into the one that comes out of the firewall? That is returning to the waterpump.
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Old 05-06-2002, 12:09 AM   #17
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You may bloody well be right...
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Old 05-06-2002, 05:35 PM   #18
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Default Where to Tap

I was reading a Chilton manual on this, and I agree with Complex that the flow to the heater core is sometimes valved off if you have your A/C set at max. This would be bad. You could tee into the heater core return, as long as it is after the heater core. I would not to the bypass line. The cooling system bypass always flows, it just flows less when the thermostat is wide open, allowing flow from the radiator. This might be restrictive as well. The bypass temperature is what tells your thermostat to open when the coolant gets hot. I would tee the supply off of the heater core feed, then return to the main return line. Stay away from controled lines like the heater and return. I don't know where exactly you could tap or find plugs, but they are all over the place on the engine. Might take some research.
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Old 05-07-2002, 12:50 AM   #19
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I say just have a seperate pump and core for the water.. make things hella cool maybe drop the egts

Brad
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Old 05-09-2002, 08:22 AM   #20
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Can somebody help me please. Being the dump f%#@#ker that I am, I damaged the threads on the coolant plug that I had removed from the back of the cylinder head. Now I don't know what to do. Is that even a replaceable part that I can buy from the dealer? Does anyone have the part number handy?

Second solution would be to call JC Sports and buy what they used on page 16 in the link below. They said 7/8" flare adaptor but I'm pretty sure those threads are metric since this is a Jap car.

Please help

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Old 05-09-2002, 08:31 AM   #21
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Are the threads on the plug damaged but not in the fitting?

If so, I can send you a plug for the cost of shipping. PM me if you can wait a few days to get it.

Otherwise, call Pam at iSR, she can get you a fitting to go in there.

JC Sports, RIP, thank Heavens.
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Old 05-09-2002, 12:14 PM   #22
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Quote:
Originally posted by blaster88
Are the threads on the plug damaged but not in the fitting?
blaster88, I screwed up the threads on the plug/fitting itself only. The cylinder head internal thread are still good. If that's what you're asking?? The plug itself cannot be re-used.

I will let you know when I get back from the dealer if I need to get yours. Thanks a lot.
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Old 05-09-2002, 12:56 PM   #23
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Okay......just got back from the dealer, no luck there. The parts book shows many plugs in the block but none on the head. Are any of those other plugs interchangeable with the one I need? I'll call Pam ISR now.
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Old 05-09-2002, 02:52 PM   #24
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I am pretty sure block plugs are the same - for example, there is one at the bottom of the block, passenger side up front, that is where the coolant lines for the (stock) oil cooler go. That plug should be the same as the one in the back of the head.

That should be the same thread as a drain plug for the oil pan, but I doubt it would actually fit in the recessed well.
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Old 05-09-2002, 05:33 PM   #25
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blaster88!! You da man!! You saved the day!!!! Thank you so much! I just happened to have an extra oil drain plug laying around and I tried it on and it fits perfect! Even the aluminum crush washer fits perfect!

Now I wonder if I can buy that Forester oil cooler coolant supply fitting with hose barb end. Than I don't even have to modify any plugs.

Thanks man! I've been so pissed at myself for damaging the original plug...........well I still am, but now I feel much better.
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