Are the Heads Leaking
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Instructor
Joined: Jul 2023
Posts: 172
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Are the Heads Leaking
Trying to get ac running, which lead to putting on new water pump, which lead to flushing the coolant system in preparation, which lead to burning coolant.
I replaced intake gasket and installed new water pump and all hoses. Pressurized system to 17lbs for 16 minutes with no loss of pressure. Fired it up amd started burning coolant once it was getting to operation temp. Re-presuurized system to 18lbs and it dropped 2 lbs in several minutes. No leaks anywhere I see and oil looks normal.
Sound like the heads?? Can I get to all the lower head bolts by moving exhaust manifold off to the side as opposed to removing completely? Of the Heads are cracked what year c4s fit an 1985? Any performanc pickup available by bolting on?
I replaced intake gasket and installed new water pump and all hoses. Pressurized system to 17lbs for 16 minutes with no loss of pressure. Fired it up amd started burning coolant once it was getting to operation temp. Re-presuurized system to 18lbs and it dropped 2 lbs in several minutes. No leaks anywhere I see and oil looks normal.
Sound like the heads?? Can I get to all the lower head bolts by moving exhaust manifold off to the side as opposed to removing completely? Of the Heads are cracked what year c4s fit an 1985? Any performanc pickup available by bolting on?
Drifting
Joined: Jan 2021
Posts: 1,312
Likes: 383
From: Northern California
I think it's more likely you are leaking coolant from the intake manifold gaskets internally into the motor and/or combustion chamber. If the heads were cracked they probably would have been burning coolant before the flush and water pump change.
Since you see no coolant leaks externally, and you know the coolant is going somewhere, it has to be internal or it's so slow that it's burning off / evaporating somewhere you can't find it. The internal leak is more likely, and since you mention replacing intake gasket that would be where I suspect. Did you use the correct torque and tightening sequence for the intake manifold bolts? Do you have a thin film of RTV or other sealant on the water jacket passages front and back of the intake manifold? What is your final torque on those bolts? etc....
Since you see no coolant leaks externally, and you know the coolant is going somewhere, it has to be internal or it's so slow that it's burning off / evaporating somewhere you can't find it. The internal leak is more likely, and since you mention replacing intake gasket that would be where I suspect. Did you use the correct torque and tightening sequence for the intake manifold bolts? Do you have a thin film of RTV or other sealant on the water jacket passages front and back of the intake manifold? What is your final torque on those bolts? etc....
Thread Starter
Instructor
Joined: Jul 2023
Posts: 172
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This is the second intake gasket changed. The first eas a year ago when I did the injectors. She leaked at the China walls and the intake was so Carbonell internally. That time I used 90 minute permatex black gasket sealer around the water ports and torqued to sequence to 35lbs. The past change hoping the burning coolant was an I take leak I used Grey ultra high torque (advised by Permatex tqch) and torqued to 40 lbs as my manual gave a range of 35 -45. Torqued in sequence.
again problem showed up only after I flushed the coolant system and motor warmed up. Car fired up and ran smooth, no smoke until it warmed up. I did see black coating inside water jackets of heads when intake was off. I'm thinking is was a bunch of fix a leak crap.
again problem showed up only after I flushed the coolant system and motor warmed up. Car fired up and ran smooth, no smoke until it warmed up. I did see black coating inside water jackets of heads when intake was off. I'm thinking is was a bunch of fix a leak crap.
