Bubbles in rad HELP!

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Billy Manness

Billy Manness

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Late 70s LA 360 in a 73 scamp. Only things I've done to the motor is aluminum intake, 4bbl, headers, and a top end gasket kit.

My coolant is super dirty and getting bubbles in it. I've flushed until clean multiple times and even used the chemical flush and it always comes back. Now that it is warming up outside, the car is warming up too (225-230) after 30-45 minute drive.

Water pump is new, thermostat is new, heater core is bypassed. What gives?!? I've heard about water jackets in exhaust bolt holes. Could this be my issue? I've always had an exhaust leak and put on the Mr gasket set and it isn't near as bad. Oil looks perfect and trans fluid looks great. Radiator looks like it has leaked in the past and could need replaced but would that fix the issue?

Any advice helps!
 
Billy Manness said:
Late 70s LA 360 in a 73 scamp. Only things I've done to the motor is aluminum intake, 4bbl, headers, and a top end gasket kit.

My coolant is super dirty and getting bubbles in it. I've flushed until clean multiple times and even used the chemical flush and it always comes back. Now that it is warming up outside, the car is warming up too (225-230) after 30-45 minute drive.

Water pump is new, thermostat is new, heater core is bypassed. What gives?!? I've heard about water jackets in exhaust bolt holes. Could this be my issue? I've always had an exhaust leak and put on the Mr gasket set and it isn't near as bad. Oil looks perfect and trans fluid looks great. Radiator looks like it has leaked in the past and could need replaced but would that fix the issue?

Any advice helps!
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Bubbles or foaming usually means it’s getting air somewhere. Make sure all your hoses are good and tight. Check very carefully around for any signs of a leak, especially around your manifolds. Could be burning off any leak but It’ll be obvious.

did you put any sealant on your exhaust studs? Or water pump bolts?
 
I didn't use anything on the bolts, wasn't sure that I needed to? Hoses are all good. I assume its exhaust getting in somewhere because it gets really nasty pretty quick. What kind of sealant should I use with the bolts?
 
Billy Manness said:
I didn't use anything on the bolts, wasn't sure that I needed to? Hoses are all good. I assume its exhaust getting in somewhere because it gets really nasty pretty quick. What kind of sealant should I use with the bolts?
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Any high temp RTV or thread sealant. You also need to have used it on your intake bolts and water pump bolts.
 
Also, did you torque down the head bolts in the right manner?
 
Hate to be the bearer of bad tidings, but if you're getting serious bubbling and coolant is all full of funk, you've probably got a blown head gasket. A compression check will most likely tell the tale.
 
Cracked head
Cracked cylinder wall
Leaking head gasket. Thats the options. Bubbles means combustion pressure is escaping into your coolant.

Pull plugs and inspect. Best case you will find one cleaner than the rest. Gives you an idea what cylinder is causing the issue.

no evidence, then leak down test with a twist,air pressure test with rad cap off. Same procedure when changing valve seals. Valves closed, and a spark plug air fitting.

still need to pull heads,but knowing where to look is a big help.
 
Tooljunkie said:
Cracked head
Cracked cylinder wall
Leaking head gasket. Thats the options. Bubbles means combustion pressure is escaping into your coolant.

Pull plugs and inspect. Best case you will find one cleaner than the rest. Gives you an idea what cylinder is causing the issue.

no evidence, then leak down test with a twist,air pressure test with rad cap off. Same procedure when changing valve seals. Valves closed, and a spark plug air fitting.

still need to pull heads,but knowing where to look is a big help.
Click to expand...
I had the heads off a month or 2 ago and everything looked great. Tops or pistons and chambers all looked really good. I've had this issue for a long time before I pulled the heads.
 
Can pull rocker shafts and hit each cylinder with air. Coolant should bubble or rise when you air up the bad cylinder. May take a couple minutes at 125 psi.
 
I have a chemical test, i use when i suspect a combustion chamber leak.
 
Head cracks arent always easy to spot, having them tested or swapping in a fresh pair are options.
 
Professor Fate said:
-- Hate to be the bearer of bad tidings, but if you're getting serious bubbling and coolant is all full of funk, you've probably got a blown head gasket. A compression check will most likely tell the tale. --
Click to expand...
-- Exhaust getting in -- Yep !!
 
Hate to say but if it was good before you took it apart then you f-ed up puting it back together. Check for Co in the cooling system if it is present take it apart and you will probably find it.
 
brian6pac said:
Hate to say but if it was good before you took it apart then you f-ed up puting it back together. Check for Co in the cooling system if it is present take it apart and you will probably find it.
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It was doing it before I took it apart. Everything went together like it should have. Only pulled the heads for new gaskets
 
Billy Manness said:
Late 70s LA 360 in a 73 scamp. Only things I've done to the motor is aluminum intake, 4bbl, headers, and a top end gasket kit.

My coolant is super dirty and getting bubbles in it. I've flushed until clean multiple times and even used the chemical flush and it always comes back. Now that it is warming up outside, the car is warming up too (225-230) after 30-45 minute drive.

Water pump is new, thermostat is new, heater core is bypassed. What gives?!? I've heard about water jackets in exhaust bolt holes. Could this be my issue? I've always had an exhaust leak and put on the Mr gasket set and it isn't near as bad. Oil looks perfect and trans fluid looks great. Radiator looks like it has leaked in the past and could need replaced but would that fix the issue?

Any advice helps!
Click to expand...
1st. and easy thing 1st. Top off radiator plum full. Disable ignition by pulling coil wire, whatever. Have a helper crank engine over while you watch radiator filler neck with cap off. If it raises up and runs out you have compression leaking into cooling system, this will show anything MAJOR wrong 1st. Hope it helps.
 
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