Pressure build up in radiator

[65Yorker]

Hello everyone, here with another issue I'm hoping to get some insight on.
1965 Chrysler New Yorker, 413 wedge big block.
Everytime I drive it, no more than 5-10 minutes, it gets really hot or should I say really steamy! I haven't been able to drive it more than 10 minutes without having to pull off the road and let it sit an hour to cool down, I've gone through 3 lower radiator hoses in the last month. Crazy pressure building up in the radiator. I've pulled the stat to run without it, I've replaced the radiator with shroud and electric fan, I bypassed the heater core - still doing the same!
I'm thinking head gaskets, piston rings... Can someone point me in the right direction?

 

[Badvert65]

Sounds likely that it is a blown head gasket. Check the oil and plugs for signs of water. A compression test should narrow down where the problem is.

 

[65Yorker]

Maybe intake manifold leak? Vacuum leak somewhere?
What could be the most common reason for the radiator to build up that much pressure in minutes? Just really not wanting to pull the motor to rebuild it if it's something more simple. Engine runs great other than that. No ticks, no knocks, no grinds. No abnormal smoke out the tailpipe, no oil in coolant - vise versa!

 

[Boydsdodge]

Are you saying the engine is over heating, or that you are building pressure? Do you have a correct pressure release rad cap on the rad?
16 lbs on the 440 sitting next to me

 

[65Yorker]

Yes, 16lb cap, and honestly I'd just have to say building pressure more than the engine actually over heating. The rad will have so much pressure that the cap dances as if it's half off, steaming like crazy, with little to no coolant coming out the overflow hose, just steam

 

[65Yorker]

I definitely wouldn't mind pulling the heads to have all that done, I'd actually enjoy it if I knew that was going to do the trick.

 

[Badvert65]

Head Gasket
jus' sayin'.........

 

[Boydsdodge]

Is the coolant clear? I thinking head gasket. How long since rad has been rebuilt?

 

[65Yorker]

Man, that sounds good to me too! Honestly am looking forward to tackling that. Because in doing so, it can take of other possibilities as well. Intake gaskets, exhaust gaskets, etc. etc. I'm just praying it isn't rings, because there is also a lot of blow-by ( I forgot to mention ). Could the excessive blow-by also be from bad head gaskets?

 

[65Yorker]

Is the coolant clear? I thinking head gasket. How long since rad has been rebuilt?

It has been clear since the rad replacement, about a week now. Previous rad was not circulating as it should have. I felt that was my whole problem, replaced it with new fan and if anything, it got worse!

 

[Badvert65]

Head Gasket....Head Gasket....Head Gasket....Head Gasket....Head Gasket....Head Gasket....Head Gasket....Head Gasket....Head Gasket....
Jus' sayin'..........

 

[65Yorker]

Lol, thank you my friend, I seriously appreciate it. Will be ordering the set and will update. Thank you Thank you

 

[68PK21 440.6bbl]

Lol, thank you my friend, I seriously appreciate it. Will be ordering the set and will update. Thank you Thank you

A proper compression test should tell you is the head gasket is gone (hot & cold crank)
With a old car/engine like that it could be the block water passages are filled with crude.
Have you had the core/freeze plugs out ever?

.

 

[volksworld]

they make head gasket testers that are way more accurate than a compression test (which should be done with a cooling system pressure tester on the radiator at the same time)...its a squeeze bulb device that you put on the radiator cap hole and as you squeeze the bulb it sucks the air out of the radiator tank and bubbles it through a special fluid...if the fluid changes color you know combustion gases have found their way into the coolant...these will find leaks that are much smaller than the pressure testers

 

[Darby]

I have a vacuum for different radiator cap sizes. It uses air hose pressure to produce vacuum in the cooling system. It'll pull all the air out of the system and will allow coolant back into the system when the air pressure is turned off. A lot of shops have these and I recommend having that done. That will rule out air in the system and completely fill the system with coolant. Put the thermostat back in it first, go with the hottest one you're comfortable with. I went with a 195 in my 440. The coolant needs to stay in the radiator, cooling down while the coolant in the engine is absorbing heat, when the thermostat opens it changes places with the cooler coolant. Without a thermostat the coolant in the radiator doesn't have enough time to cool down when the engine starts making more heat. As far as pressure, for every pound of pressure it raises the boiling point by 3 degrees, a 16lb. cap equals a 48 degree rise in boiling point. 50/50% mix is near 223 degree bp and a 70/30% has a bp of around 234 degrees. Add the 48 degrees to that and you're looking at 271 or 282 degree bp. Even straight water goes from 212 to 260 degrees. If it seems to be oferheating under these temps, it's going to be compression/cumbustion getting into the cooling system.
If a compression test is good, your radiator flows well (use an inferred temperature gun looking for cold spots), use an inferred gun to find hot spots on the engine (may have something in there stopping flow), correct water pump (?), and if you're using a clutch fan, I'd probably replace it. After all that, if you still have an overheating problem, I'd say there's a buildup of calcium (tap water etc.) or other crap/rust in the block/heads/radiator. A 1/16" buildup can be equal to heat transfer going through a 1" piece of casting.
It sounds like a bad head gasket or a cracked block/head, but there should be some cross contamination of liquids. With the cap off do you smell exhaust coming out of the radiator when it's running (cold of corse)? An engine should never be hot enough to boil coolant within 10 minutes!!
Just my 2 cents............... Good luck!!! Post you findings. Education happens with some strugles, none of know everything!!!

 

[65Yorker]

I have a vacuum for different radiator cap sizes. It uses air hose pressure to produce vacuum in the cooling system. It'll pull all the air out of the system and will allow coolant back into the system when the air pressure is turned off. A lot of shops have these and I recommend having that done. That will rule out air in the system and completely fill the system with coolant. Put the thermostat back in it first, go with the hottest one you're comfortable with. I went with a 195 in my 440. The coolant needs to stay in the radiator, cooling down while the coolant in the engine is absorbing heat, when the thermostat opens it changes places with the cooler coolant. Without a thermostat the coolant in the radiator doesn't have enough time to cool down when the engine starts making more heat. As far as pressure, for every pound of pressure it raises the boiling point by 3 degrees, a 16lb. cap equals a 48 degree rise in boiling point. 50/50% mix is near 223 degree bp and a 70/30% has a bp of around 234 degrees. Add the 48 degrees to that and you're looking at 271 or 282 degree bp. Even straight water goes from 212 to 260 degrees. If it seems to be oferheating under these temps, it's going to be compression/cumbustion getting into the cooling system.
If a compression test is good, your radiator flows well (use an inferred temperature gun looking for cold spots), use an inferred gun to find hot spots on the engine (may have something in there stopping flow), correct water pump (?), and if you're using a clutch fan, I'd probably replace it. After all that, if you still have an overheating problem, I'd say there's a buildup of calcium (tap water etc.) or other crap/rust in the block/heads/radiator. A 1/16" buildup can be equal to heat transfer going through a 1" piece of casting.
It sounds like a bad head gasket or a cracked block/head, but there should be some cross contamination of liquids. With the cap off do you smell exhaust coming out of the radiator when it's running (cold of corse)? An engine should never be hot enough to boil coolant within 10 minutes!!
Just my 2 cents............... Good luck!!! Post you findings. Education happens with some strugles, none of know everything!!!

Wonderful read! Thank you for taking the time to share that information. I'm definitely going to look into all of that. Although I did just start to pull the intake off, just bolts by the time I got to reading this.

 

[70bigblockdodge]

You can rent a cooling system pressure tester from the crappy chain auto parts. You put it on and if it turns colors you have combustion gasses in cooling system, which..................
Wait for it.........................
Leads to...........................




Head gasket!

Or cracked block.
Most likely head gasket from cylinder past bolt to cooling passage restrictor in head gasket.

 

[65Yorker]

You can rent a cooling system pressure tester from the crappy chain auto parts. You put it on and if it turns colors you have combustion gasses in cooling system, which..................
Wait for it.........................
Leads to...........................




Head gasket!

Or cracked block.
Most likely head gasket from cylinder past bolt to cooling passage restrictor in head gasket.

I agree , I'm going to go ahead and just pull it all apart for head gaskets. I don't believe I have any other major issues going on. Possibly a cracked head, Bad gaskets or both! Won't know for sure til I get them off. I'm sure it's going to be something noticable. I mean the only other thing I was worrying about is the bad blow-by. Would bad heads or even just bad gaskets cause the blow-by? Or is that a for sure piston rings kinda thing?

 

[70bigblockdodge]

I agree , I'm going to go ahead and just pull it all apart for head gaskets. I don't believe I have any other major issues going on. Possibly a cracked head, Bad gaskets or both! Won't know for sure til I get them off. I'm sure it's going to be something noticable. I mean the only other thing I was worrying about is the bad blow-by. Would bad heads or even just bad gaskets cause the blow-by? Or is that a for sure piston rings kinda thing?

If you're getting huffing out of the breather or oil cap and a pressured cooling system, you have a really blown head gasket. Getting white foamy crap on the inside of the oil cap?
Cracked head on a big block rarely goes to water. The cracks will be from exhaust valves to head surface around the Siamese exhaust ports. 516 castings usually do not crack.

 

[jmustian]

Wonderful read! Thank you for taking the time to share that information. I'm definitely going to look into all of that. Although I did just start to pull the intake off, just bolts by the time I got to reading this.

I've also found a water pump with no fins due to poor maintenance.