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Water cooled turbo?

Discussion pertaining to positive pressure E28s.
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Jays535is
Posts: 1193
Joined: Mar 20, 2007 5:28 PM
Location: Spokane

Water cooled turbo?

Post by Jays535is »

So, my cars running find and all. But I can't help wondering if the cooling lines to my turbo produce the proper flow direction.

So the "in" line comes off the thermostat housing in to turbo then the "out" line goes from the turbo into the block drain. Is this hurting/fighting coolant flow?

The only reason I think about this is my upper rad. hose seems to get very pressurized.
turbodan
Posts: 9246
Joined: Jan 09, 2007 10:19 PM

Post by turbodan »

The water jacket in the engine block is under higher pressure than the rest of the system. The waterpump pumps directly into the block, then the water flows into the head and out through the thermostat housing. So if theres one point in the system the water will try to flow from, its going to be the engine block. I'm pretty sure that means it will try to flow from the block drain out to the thermostat housing, if it flowing at all.

When I was running a GT BB turbo I fed it from the old throttle body heater fitting on the block and returned it to the old throttle body heater port at the thermostat housing.

If you've got stiff hoses, you might have a blown HG. Good old combustion chamber pressure in the cooling system...
Jays535is
Posts: 1193
Joined: Mar 20, 2007 5:28 PM
Location: Spokane

Post by Jays535is »

I can't imagine the HG is blown. It's was running fine before turbo and only has maybe 5 miles since turbo. No water in oil or vise versa. What's normal coolant pressure supossed to be?

So in theory it should be flowing, just the opposite of what I thought. Which shouldn't matter for the turbo lines.
turbodan
Posts: 9246
Joined: Jan 09, 2007 10:19 PM

Post by turbodan »

The system should run at 12-14 psi when hot. If the hoses are rock hard, you've got a problem. It might be normal, it might not. I would have to give your hoses a squeeze to really help you out there.
cetanefreek
Posts: 66
Joined: Jan 23, 2008 6:58 PM
Location: north va/ southern ID

Post by cetanefreek »

two ways to check your headgasket, you can either get a cooling system pressure tester, pressurize the system and see if it leaks down, or with the engine cold, pull off the coolant resivor cap and see if it is blowing air out of the cap.
turbodan
Posts: 9246
Joined: Jan 09, 2007 10:19 PM

Post by turbodan »

In my case it became clear when it was over-pressurizing the cooling system with leakage from the combustion chambers. That can cause the system to purge past the radiator cap as if the motor were overheating. I also used a noticeable amount of coolant once it was really blown out.

M30's can mix coolant with the oil with just a blown head gasket. The oil passages on the M20 make this very unlikely. So if your small six is mixing the oil, you've very possibly got a cracked head.
Jays535is
Posts: 1193
Joined: Mar 20, 2007 5:28 PM
Location: Spokane

Post by Jays535is »

turbodan wrote:In my case it became clear when it was over-pressurizing the cooling system with leakage from the combustion chambers. That can cause the system to purge past the radiator cap as if the motor were overheating. I also used a noticeable amount of coolant once it was really blown out.

M30's can mix coolant with the oil with just a blown head gasket. The oil passages on the M20 make this very unlikely. So if your small six is mixing the oil, you've very possibly got a cracked head.
It pressurizes but doesn't purge any out the cap. It could be normal, I don't remeber how they felt pre-turbo. I think I'm just being alittle paranoid :nuts:

I'll find out when I can do some real road testing, roads need to clear up though.
Maddog
Posts: 191
Joined: Feb 12, 2006 12:00 PM
Location: Atlanta, GA

Post by Maddog »

Your cooling system should be pressurized to whatever coolant system pressure cap you have. I have a 20psi cap on mine to keep the coolant from boiling in the summertime here in Atlanta.
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