The Stovebolt Site Forums The Shop Area Engine Shop I boil over

Now that I have my truck on the road I can have fun with it and DRIVE!...BUT, I have some issues that I'm working out. What would be wrong with putting a pressurized radiator cap on my original 216? I have a BRAND NEW 3 row core on my radiator and a 160 degree thermostat. I have a non pressure radiator cap and it always boils over when I shut off the motor. Other than that, it runs real nice. :confused:

John, unless you have someother problem, I think a pressure cap would be needed. For every pound pressure you put on your system, you raise the boiling point by two and a half degrees and especially if you are in a high elevation, the water will boil at a lower temp also. If you are running a fan clutch, that could be a problem or if your fan is too far from the radiator or if the fan shroud has been removed could cause over-heating.
Truck Tinker

I'd try a 7 pound cap first ... you don't want to put too much pressure on an older system; it could cause bigger problems.

My truck was boiling over when I first got it ... I found out it had NO thermostat in it! I put a 180 thermostat in (I have a 350 sbc) and all was well.

Thanks for the info. My motor is in it's original configeration, no shroud, no fan clutch. I don't know, maybe it wasn't boiling over. At the very top of my radiator there's an overflow tube that goes from the middle of the top all the way down the side. It's not connected to the radiator cap opening. The coolant is coming out of the bottom of that tube. So even if I use a pressurized cap the same thing would happen. Maybe I have too much coolant that is being expelled? :confused:

There is supposed to be some air space in the top tank of the stock radiator, unlike in modern ones. The overflow should puke a little coolant until it stabilizes. If it keeps doing it and the level drops below the top of the fins then you have a problem, otherwise just let it puke and leave it alone.

Or you could install an overflow tank, like I did:
See Here

Yea, I was thinking of adding an overflow tank but it's gotta look old. Call me anal, but I don't want anything modern looking on my truck. I'm gonna check around and see what I can come up with. john.

Cool idea, John.

I sure don't like the LOOKS of mine at all ... it'd be much cooler to find some old antique jug of some kind to use! Only, it needs to be something that's easy enough to add the hoses to.

Any bright ideas? This puts a whole new light on garage sales and flea markets!

hmm... old jugs with hoses connecting to it ...

just make sure someone doesn't mistake it for a home brewery and try drinking it

oh wait, these are "post"-prohibition trucks, right?

lol lol

Husker

Several of the vendors have a reproduction overflow tank. There are expensive though. Try Chevs of the 40s or Filling Station.

not meaning to hi jack the thread but horvath what about useing an old Glass Washer jar from a car of the 50's? I had a 1955 olds 88 tha thad a glass window washer jar (I may still have the jar/no top) but the bracket and hoses you would have to fabricate. I think that would look more vintage.

Most folks just add the plastic tank like you did but you needn't cut the original overflow tube , as long as the puke tank is higher than the top tank it'll siphon back in just fine .

No more than a 4 # cap unless you want to test your radiator and heater core for leaks .

The repop puke tanks are very nice but overly costly IMO .

If the overflow tank needs to be higher then the top tank of the radiator then I guess it won't work on my truck. 'Cause the top of my radiator is allmost a foot higher the the fenders. I would've liked to mount an overflow tank on the inner fender. If I mount way over on the firewall it would look kinda corny.

Hey, Brian -- cool idea!


Steppinwood -- I agree; it looks horrible, but the firewall works for me ... I'm more into function than show. But, again, something vintage - especially in such an obvious-looking spot - would be awesome! Even an old mason jar would look pretty cool ... question is how to get the hoses happening.

216’s are not my area of expertise. Please, educate me as to why the coolant bottle has to be higher than top of the radiator. I installed a coolant jug on my 56 a few years ago. It is a 235 with a 7 lb cap. The jug is lower than the top of the radiator and it works fine. When the engine cools down, it draws the coolant back into the system. What is different with a 216 cooling system? It seems to me with a 3 to 7 lb cap, it would work the same. Or do the 216 Chevy trucks have a similar set up to the old GMCs?

I installed my coolant jug because of my employer. They freak out when they see coolant in the parking lot. They have emergency response teams to clean up leaks. My understanding is that Cal EPA can fine them for spillage, but that another topic

My 216 has a pressure cap and never runs hot or "pukes" when I shut it off.

The puke tank will work at any level, as long as the line going into it is below the level of the coolant in the tank. I've used a 1-quart paint thinner can with a piece of copper tubing soldered into the screw-on cap, and a small vent hole drilled into the top of the can. Run a rubber hose from the end of the puke tube to the tubing in the can. Fill the can about 1/3 with coolant, and make the copper tube go to within about 1/2" of the bottom of the can. When the radiator pukes a little fluid, the can catches it, and it siphons back into the radiator when the engine cools down and creates a vacuum in the cooling system. I mounted the can to the core support with a piece of sheet metal soldered to the can, and a couple of sheet metal screws into the core support. Paint everything flat black, and it looks original. Be sure the cap you install has a spring-loaded vent valve that will allow vacuum to refill the radiator. A 7# cap should be plenty of pressure without damaging the radiator or heater.
Jerry

John, I got the "generic" coolant overflow tank from the Filling Station a couple of years back. Here's a pic (it's the stainless steel cylinder on the firewall)

Coolant recovery tank

It works good but if I were doing it again, I would look for one of the original optional "Radiator Overflow Condensers" that looked a bit like a coffee can and mounted in the same location on the Advance Design series trucks.