I just flushed my radiator to add coolants and I changed my thermostat as well since my last one was stuck open. It's supposed to freeze tonight and I have to get my boat to a garage 3 hrs away and now my truck keeps over heating. The top radiator hose will not fill up with water for some reason and I cannot figure it out. This has never been a problem before. Please help!!
CK5
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Can't get air out of cooling system need help ASAP!!!
- Thread starter Jorwood
- Start date
Truck? Engine?
Joe In Montana
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Sounds like a stuck thermostat to me. This is assuming a GM any-V8.
I'm in Ravalli County, Montana and it's already +2F outside. It's gonna get colder by morning though.
I'm in Ravalli County, Montana and it's already +2F outside. It's gonna get colder by morning though.
All I can think of is that I had the rear wheels up on a ramp when I drained the radiator and changed the thermostat. I wonder if that created an air bubble in the engine.... I'm gonna remove the thermostat and see if that releases the bubble in the process.
I switched back to my thermostat that stuck open at 110 and sure enough everything works great. Then I switched back to my new one thinking the air pocket must have escaped but it's the same thing again... I got a heat lamp with the engine for now...
Joe In Montana
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If you have the vehicle at 45 degrees, it won't matter if the thermostat opens. The flow from the pump will purge the system with a couple of blips of the throttle.
GM small blocks just don't hide air in the system like you're thinking.
The only place air might hide is in the heater fore --- more so if you also have rear heat.
Since the old bad 'stat doesn't surge and the new one does, it's pretty obvious what the problem is.
In a shop, you don't have time to hand purge a vehicle, so I took an old radiator cap and ripped the smaller rubber seal off it.
That way you won't build pressure, but the cap will allow coolant to go back and forth from radiator to recovery bottle until the system is pure coolant with no air.
........ and since it can't build pressure while the engine's running or gets shut down with the dummy cap in place.... you can just take the cap off once you've had full circulation, and calmly put the new pressure cap on it with no blowing coolant, no scalded mechanic and no expensive coolant lost.
If you make one of these caps, you'll find it helpful one the really tougher cooling systems when it just won't purge.
Again though ....... GM small blocks just don't have the problem you're having unless the thermostat is goofy.
THe way to purge air out of engines that are notorious for air lock is to take the thermostat OUT of the engine and fill the radiator until you can see water right below the rim of the t stat housing. Half the time air lock is from thermostats that are air tight.
Joe In Montana
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True, the thermostats being pretty air tight!
I used to keep some macaroni in my tool box for that problem. If you ask - I'll tell you why.
If anyone remembers the Toyota and maybe a few Datsuns (that's Nissan to you younger guys) used to have a small hole drilled into the thermostat to let the air bleed out. I've drilled quite a few thermostats and it doesn't change the dynamics of them one bit either - other than allowing the air to bleed out.
Again I say: GM's small blocks don't really have much trouble purging - even the dual-type thermostats purge pretty easily.
This OP's problem may just be a bad/new thermostat. "New" is an untested part.
rampage
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Put the t-stat in a pan of boiling water and see if it operates.
I've had a couple t-stats bad out of the box.....
Joe In Montana
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So-o-o-o Nobody wants to ask about the macaroni, huh?
Jam a piece of uncooked in the thermostat it lets the coolant and air go past it...When it heats up the macaroni gets soft, gets cut in two and the thermostat works as normal?
Joe In Montana
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So then you have a chunk of macaroni floating around in your cooling system?
After the macaroni gets chopped into dust by the water pump impeller--it might become an effective stop leak too ?...
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Wise beyond my years....Actually many years of doing meatball mechanic work taught me some tricks on getting things back to work after the parts stores are all closed and the crews are coming in at 5:00am to go to work.
And yes I'm old too...If you consider 53 old.
Stomis
Professional Amateur
I mean, or just drill an 1/8 bleed hole in the thermostat like the rest of the civilized world.
Joe In Montana
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I like drilling the holes too - but 1/8" is a teensy bit large I feel. I go for 3/32" or smaller.
Ever see the thermostats with the bleeder "toggle" in them?
Ever see the thermostats with the bleeder "toggle" in them?
Stomis
Professional Amateur
You realize that in a 1-1/2in hose the difference between drilling an 1/8in hole and a 3/32 hole is less than 1%?
