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Unread 07-27-2013, 11:59 AM   #1
Paradise XJ
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Cooling system testing??

OK fellas...I'm officially desperate.

Still struggling with cooling system FUBAR. When engine heats up and t-stat (new 195 stant) opens it starts blowing coolant out the overflow at idle OR at RPM's. ALL the cooling components are less than 3K miles or newer. 2 row CSF all metal radiator...1988 4.0L converted to open system...3K miles ago. I don't have a heater valve, I deleted it when I did the conversion. I know you've heard this all before, but I can't drive my truck anywhere without it getting HOT and blowing coolant. WTH??

I have tested:
◾New catalytic converter, new exhaust manifold, new gasket & flange donut.
◾compression - good (great actually) 119-124 within 5 psi across the board. No adjacent discrepancies.
◾No water in oil, no oil in water
◾NO driveability issues. Idles smooth at ~700-800
◾exhaust gases (block tester) - none - tested it 4 times, with different fluid each time
◾heater core - clear - no rust, crud, junk or small animals
◾radiator pressure - holds pressure at 20 psi overnight - good, no leaks.
◾cap - new 16 lb. - holds pressure @16 lbs for a couple of hours (the longest I've let it go)
◾all hoses - no leaks - spring in lower hose
◾coolant QUALTY...it's new, and it's fine. 50/50 Prestone Green (ethelyne glycol) and distilled water.
◾air bled from system...4 or 5 times and each time I have had to replace coolant.

How do I test for a.) a bad pump (it's not leaking, wobbling and the belt is good AND yes it's a reverse rotation with the belt routed properly) or b.) a blocked radiator before I drop the $$ on either. OR is there something else I am STILL overlooking???



Help me Obi-Wan Kenobi...you're my only hope.

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Unread 07-27-2013, 06:49 PM   #2
Paradise XJ
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Found a test for the WP...it's fine.
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Unread 07-27-2013, 10:35 PM   #3
wgirvine
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It's been my experience that coolant blowing out the cap is caused by a blown head gasket.
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Unread 07-27-2013, 11:44 PM   #4
mayeni
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Quote:
Originally Posted by wgirvine View Post
It's been my experience that coolant blowing out the cap is caused by a blown head gasket.
^^^X2. I totally agree, without actually seen the car myself. I dont know if you can test coolant for exhaust gases? Or try to smell if it smells of gas.
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Unread 07-28-2013, 06:27 AM   #5
cruiser54
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Quote:
Originally Posted by mayeni View Post
^^^X2. I totally agree, without actually seen the car myself. I dont know if you can test coolant for exhaust gases? Or try to smell if it smells of gas.
He did that 4 times.
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Unread 07-28-2013, 08:46 AM   #6
M35A2
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When it warms up and starts pushing coolant, is the lower radator hose cold?
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Unread 07-28-2013, 09:57 AM   #7
Paradise XJ
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No, all the hoses are hot. Now, the top rad hose is hard as a rock. The lower hose is hot, but has a spring in it, so I can't really tell if it's super hard or not.

Quote:
Originally Posted by wgirvine View Post
It's been my experience that coolant blowing out the cap is caused by a blown head gasket.
Me too. I had the same thing happen in my commuter car (a Nissan) and replacing the head gasket fixed it right away. But I needed that car to get to and from work and it cost me $1200 to get the job done...I can't afford that again so I'm being critical and don't want to do it myself if I don't have to.

Quote:
Originally Posted by cruiser54 View Post
He did that 4 times.
The reason I did the exhaust gases test (block test) 4 times is because I was very surprised that #1 came up negative. I fully expected it to show a leak from a cylinder into the coolant jacket at the filler neck (test #1). So I did a control test by sucking exhaust directly from the tailpipe which DID turn yellow. Then I tested the overflow bottle where the air from the radiator was going (test #2), that was negative, and another test (#3) at the filler neck, and yet another test (#4) at the overflow. I didn't even get a whisper of exhaust gas.
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Unread 07-28-2013, 02:31 PM   #8
mayeni
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The exhaust gas test is maybe not sensitive enough, because your symptoms fits with a blown gasket. What if you remove the t-stat, will it then start blowing out water immediately?
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Unread 07-28-2013, 10:29 PM   #9
M35A2
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Drain the coolant and then do the exhaust gas test. If the head gasket is blown, it will show up immediately with no coolant in it.
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