The Stovebolt Site Forums The Shop Area Engine Shop Bleeding the cooling system

Anyone have any tips for bleeding air out of the cooling system on my '64 w/ a 350 small block?

I just replaced the radiator, did a reverse flush and replaced the thermostat with a 195 degree. Seems to be running hot (about 210 - or maybe the old thermo was just a lower temp and I'm not used to it). Got a feeling I didn't get all the air out. I let it sit overnight and the temp gauge was still at 150 the next morning.

Maybe a lower temp thermostat? I live in a mid-sized city in Oregon and it never really gets that hot, but most of my trips are just around town driving.

I've read to remove the heater hose that connects to the manifold when refilling with coolant (but I've already filled it); running the engine with the truck front end raised up (I don't have the tools to do this as yet), drilling a small hole in the wide metal part of the thermostat to let air out, etc.

If I need to drain again and do it right, the cost of new fluid is nothing compared to the cost of fixing potential damage from overheating.

Thanks in advance.

I've parked mine on a severe incline pointing nose up of coarse, and let it idle until the stat opens and coolant flows continuously. Some put a 3/16" hole in the t-stat flange to let air escape. Either way, get a laser thermometer to verify the actual coolant temps in several different locations. Don't trust a factory gauge to be accurate,
Scott

Thanks Scott ... a buddy of mine lives on a really steep hill. Sounds like the perfect spot.

Hopefully Scotts idea will work....but if it sit overnight and the temp guage was 150 then I'd suspect the guage.

Since you have an actual guage you may want to try one of those "stick thermometer's",if no one has a lazer, and stick it down in the radiator as it heats up to compare it to the guage.

Yep ... the gauge was sticky. Still running hot at around town driving (about 210). Thinking of putting a 180 thermo in there.

If it's not boiling, it's not hot. With a 14 Lb. radiator cap, the coolant can get to 250 degrees + without a boil-over. Use at least a 180 thermostat, and 195 is better. A 350 is designed to run betweeen 200 and 220 degrees in everyday use. Anything above 220 might be a concern, but below that, just drive on!
Jerry

Thanks Jerry ... I'm pretty new at all things auto mechanical and am learning as I go. Good to know what the running water temp range is.

I left out one factor in my original post ... when removing the old radiator I broke off a 4x6 inch piece of the fan shroud near the top. Man that thing is brittle! Until I can find a local guy with a shroud he's willing to sell off a parts truck (those things are $110 new), I'll patch it up with duct tape to get good air flow through the radiator.

I'll be taking the truck to Salem, OR from Eugene, which is about 60 miles each way ... it will be the first chance I've gotten to really get it on the highway and see how it does.

Here's a little more effective fix than duct tape- - - -cut a piece of thin aluminum sheet metal a little larger than the broken-off piece and use it to back up the area where the piece broke away. Then attach it with "pop" rivets and fit the broken-off section back in like a jigsaw puzzle piece. More pop rivets, and you're good to go. It's a permanent fix, and it looks a lot less "shade tree" than duct tape!
Jerry

..and just to add to Jerry's comments you can find small pieces of aluminum at Ace Hardware or Lowes/NothernTool/Home Depot ect.

and aluminum doesn't get sucked into the fan blade when it starts to fray.....

IT is best, especially for short trips around town, to keep the temp hot, 195 or higher 'stat, get better fuel mileage, stop sludge from forming.

Interesting. So many contradictory things online.

Here's what my hotrodder, 60's drag racing pops had to say: "That truck is older than you. Don't worry about breaking it. That truck is tough. Just learn as much as you can, keep it simple, and learn from your mistakes."