What’s my coolant trying to tell me ?

[Purepony]

So I have a 360 small block la engine. I added a four speed and ever since I did that when I turn the car off I can hear the coolant boiling or the pressure of the coolant. I’ve checked a few times for air pockets and I don’t see any.
I haven’t checked the oil but car runs good and nice just when I turn it off I can hear the coolant and I can hear it venting out.
I’ll slowly turn the cap counter clockwise and I can hear the steam pushing out fast

so it started spilling coolant which I think was an air bubble because after I ran it without a cap and filled it it stopped but now I have a hissing sound when ever I turn the car off

Water pumps new
Belts are new
Radiator was working great before it’s al older unit but no leaks
Timing cover gasket new with seal no leaks there that I can see
coolants also new
Hoses are new
Thermostats new
What am I missing ?
I don’t have a shroud but it was running great before the swap no shroud back then either
Not sure about my gauge because it only goes up a quarter so it works but not sure it’s accurate (wired to the intake on the pass side

any ideas ? Or is this normal ? no spills what to check or what to do ?

 

[steve340]

Have you raised the angle of the engine transmission too much.
From the front of the car the engine /trans should have around 2 degrees downward slope.
Is the actual radiator cap working correctly?
Sometimes it is a simple fix overlooked.

 

[diesel_lv]

1st thing is go to local parts store and rent/borrow pressure tester. Test cap to 16psi. If bad, replace. Then test system to 16psi. Next, make sure that radiator is only filled to 1" below filler neck, no higher. Next, cheap Harbor Freight temp gun to verify engine temps.

 

[R413]

If you loosen any rad cap on a hot engine it will dump fluid and make noise. That is normal.

Sounds like a bad radiator cap or radiator neck isn’t sealing to the cap.

 

[Purepony]

Have you raised the angle of the engine transmission too much.
From the front of the car the engine /trans should have around 2 degrees downward slope.
Is the actual radiator cap working correctly?
Sometimes it is a simple fix overlooked.

Thanks Steve I put a new cap, but you make a good point I will be replacing the cap I mean it’s like 5 bucks for a new one

two I didn’t raise the trans, it’s a stock mopar trans a833 everything fit

hmm I did add a small spacer so it would bind against the body but your talking half a center meter if that

 

[Purepony]

If you loosen any rad cap on a hot engine it will dump fluid and make noise. That is normal.

Sounds like a bad radiator cap or radiator neck isn’t sealing to the cap.

Hmm the radiator neck os a suspicion there was a leak there but it stopped after the air pocket

I’ll replace the cap and then recheck all the hose clamps.
Thanks r m413

I did drive my satellite and that doesn’t make any coolant noises whatsoever when I shut the car off hmm

 

[440 Charger]

So I have a 360 small block la engine. I added a four speed and ever since I did that when I turn the car off I can hear the coolant boiling or the pressure of the coolant. I’ve checked a few times for air pockets and I don’t see any.
I haven’t checked the oil but car runs good and nice just when I turn it off I can hear the coolant and I can hear it venting out.
I’ll slowly turn the cap counter clockwise and I can hear the steam pushing out fast

so it started spilling coolant which I think was an air bubble because after I ran it without a cap and filled it it stopped but now I have a hissing sound when ever I turn the car off

Water pumps new
Belts are new
Radiator was working great before it’s al older unit but no leaks
Timing cover gasket new with seal no leaks there that I can see
coolants also new
Hoses are new
Thermostats new
What am I missing ?
I don’t have a shroud but it was running great before the swap no shroud back then either
Not sure about my gauge because it only goes up a quarter so it works but not sure it’s accurate (wired to the intake on the pass side

any ideas ? Or is this normal ? no spills what to check or what to do ?

The passages in the heads are clogged.

 

[Purepony]

The passages in the heads are clogged.

Hmm I could see that... what could I do to help or make it better ?

 

[diesel_lv]

Purepony, if the engine is not running hot, the heads are not clogged. Please start w the basics. And please read the service manual, do "NOT" fill radiator all the way to top. It should be 1" below bottom of filler, this leaves room for expansion. When a radiator is filled completely, the coolant has to go somewhere as it expands. When you turn off the engine, the temp rises and the coolant will expand more. When this happens, it will push past the cap. If you leave the 1" expansion room in the radiator, it may purge once or twice but will balance out. Do not refill, run it a few more times and see where it's at.

 

[steve340]

Just a thought - there are two types of cap - recovery and non-recovery.
If you have no recovery bottle use the non-recovery that eliminates the little valve.
They are designed to allow air and fluid out of the radiator.

 

[diesel_lv]

Just a thought - there are two types of cap - recovery and non-recovery.
If you have no recovery bottle use the non-recovery that eliminates the little valve.
They are designed to allow air and fluid out of the radiator.

A recovery type cap can be used on any type system, the non recovery can only be used on non recovery systems.

https://www.allpar.com/threads/cooling-systems-the-surprisingly-wide-range-of-radiator-caps.229050/

 

[Purepony]

A recovery type cap can be used on any type system, the non recovery can only be used on non recovery systems.

https://www.allpar.com/threads/cooling-systems-the-surprisingly-wide-range-of-radiator-caps.229050/

Ok I don’t want to mess up something so simple

I don’t have a recovery tank (tank on side for coolant overflow) my hose goes to the floor

does anyone have a pic or a part number of the cap I need

I currently have this

 

[Cranky]

Do you have a 'recovery' bottle on it? Even if it didn't come with one, it's a good idea to run one and use the right cap for that system. Me, I like them but also like lower psi caps. Been doing that for 30+ years.

 

[diesel_lv]

Ok I don’t want to mess up something so simple

I don’t have a recovery tank (tank on side for coolant overflow) my hose goes to the floor

does anyone have a pic or a part number of the cap I need

I currently have this

View attachment 1135706

That is just fine as long as it has been tested to hold 16psi. Then make sure radiator is not filled all the way. Then drive n see what happens.

 

[toolmanmike]

So I have a 360 small block la engine. I added a four speed and ever since I did that when I turn the car off I can hear the coolant boiling or the pressure of the coolant. I’ve checked a few times for air pockets and I don’t see any.
I haven’t checked the oil but car runs good and nice just when I turn it off I can hear the coolant and I can hear it venting out.
I’ll slowly turn the cap counter clockwise and I can hear the steam pushing out fast

so it started spilling coolant which I think was an air bubble because after I ran it without a cap and filled it it stopped but now I have a hissing sound when ever I turn the car off

Water pumps new
Belts are new
Radiator was working great before it’s al older unit but no leaks
Timing cover gasket new with seal no leaks there that I can see
coolants also new
Hoses are new
Thermostats new
What am I missing ?
I don’t have a shroud but it was running great before the swap no shroud back then either
Not sure about my gauge because it only goes up a quarter so it works but not sure it’s accurate (wired to the intake on the pass side

any ideas ? Or is this normal ? no spills what to check or what to do ?

Are you just wigged out about the hissing noise? First thing I thought about is the cap or a small leak above the coolant level (which should be a inch or so below the top of the filler neck) A 15# pressure cap will raise the boiling point from around 212° to about 257°. If you have a bad cap or a leak the pressure will bleed off and boiling comes back to around 212°. With a well sealed system it will have pressure for many hours after the engine is shut off. Like Diesel_lv said, get a pressure tester and test the cap and system. That's the first thing to do.

 

[440 Charger]

Do you have a 'recovery' bottle on it? Even if it didn't come with one, it's a good idea to run one and use the right cap for that system. Me, I like them but also like lower psi caps. Been doing that for 30+ years.

Very smart.

 

[440 Charger]

Are you just wigged out about the hissing noise? First thing I thought about is the cap or a small leak above the coolant level (which should be a inch or so below the top of the filler neck) A 15# pressure cap will raise the boiling point from around 212° to about 257°. If you have a bad cap or a leak the pressure will bleed off and boiling comes back to around 212°. With a well sealed system it will have pressure for many hours after the engine is shut off. Like Diesel_lv said, get a pressure tester and test the cap and system. That's the first thing to do.

You know the old mopars dont like above 170.

 

[440 Charger]

Purepony, if the engine is not running hot, the heads are not clogged. Please start w the basics. And please read the service manual, do "NOT" fill radiator all the way to top. It should be 1" below bottom of filler, this leaves room for expansion. When a radiator is filled completely, the coolant has to go somewhere as it expands. When you turn off the engine, the temp rises and the coolant will expand more. When this happens, it will push past the cap. If you leave the 1" expansion room in the radiator, it may purge once or twice but will balance out. Do not refill, run it a few more times and see where it's at.

That is what the puke bottel is for.

 

[Ranger16]

when I turn the car off I can hear the coolant boiling or the pressure of the coolant. I’ve checked a few times for air pockets and I don’t see any.
I haven’t checked the oil but car runs good and nice just when I turn it off I can hear the coolant and I can hear it venting out.
I’ll slowly turn the cap counter clockwise and I can hear the steam pushing out fast

If it is not a bad cap (not holding pressure), or overfilled as Diesel lv suggested, then you might be pressurizing the cooling system via a bad HG.

 

[440 Charger]

If it is not a bad cap (not holding pressure), or overfilled as Diesel lv suggested, then you might be pressurizing the cooling system via a bad HG.

A bad HG interesting?