Air in the cooling system?

[mudpie]

'96 C2500HD, 5.7, runs awesome except the radiator was leaking, so I put a radiator in it. I refilled it with water, had to wait for the level in the radiator to gurgle and bubble a bit, then top it off. Did this a few times until it stopped bubbling, then drove a couple miles. The temp gauge started climbing and didn't stop. It shot way up to about 220+, but I was at a spot where I had to go a couple hundred yards to pull over and stop. Just as I was pulling over, the temp dropped to normal. I got home, let it cool, opened it up and it was low. I topped it off and haven't had an issue since. But it's just got water in it, with some Prestone radiator flush stuff, so I have to drain it a couple more times to get all that out, then put coolant in. I'm worried about overheating it.

My assumption is that water can't fill the engine from the top hose because the thermostat is blocking it, and water doesn't fill the block from the bottom hose because there's air trapped in the block. It gets super hot, the thermostat eventually opens, trapped air escapes, coolant circulates, and the temp drops. Is that a fair assumption, or is there something else I'm missing? Is there a bleeder valve somewhere on the block? Or is there some procedure I'm not doing correctly? I tried searching with multiple phrases and found nothing.

Any thoughts on what I'm doing wrong would be appreciated. I don't want to blow my engine up, obviously.
Thanks

 

[Donald Mitchell]

Drill a small hole in the thermostat to let it bleed the air out. Years ago they used to come with a hole in them.

 

[SAATR]

Expounding on Donald Mitchell's post:

Some thermostats have a built in air bleed hole, as pictured here:

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Notice the brass colored tab on the front side. It lets air bypass the thermostat and prevent air lock.

Some, on the other hand, do not:

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Either drill a 1/8" hole in the rim of your existing thermostat if it doesn't have one, or buy one that does.

 

[1998_K1500_Sub]

Did this a few times until it stopped bubbling...

Taking it from your (quoted) comment...

At this point in the process I usually start the engine and let it idle until I start feeling warmth in the heater hoses and heat in the blower air (which should happen in short order), adding coolant as necessary at the filler neck. I continue to monitor for oddities in coolant level, the hoses' temp, and engine temp gauge with the engine idling all the while, until I start to feel heat in the upper radiator hose and see the temp gauge at its typical reading. If / when that all goes well, I feel comfortable about driving it; until then... nah.

If anything odd happens, then (a) engine off and (b) start checking for trapped air. Pulling the heater hose at the intake, for instance, isn't a bad place to bleed. Others will do too (thermostat housing).

I'm not a fan of leaving just water in an engine for long, things can get rusty fast. I'm also cautious about water pump lubrication; I don't believe water, itself, does it well.

 

[herkyhawki]

Lisle 24680 Lisle Spill-Free Coolant Funnels | Summit Racing

Free Shipping - Lisle Spill-Free Coolant Funnels with qualifying orders of $109. Shop Funnels at Summit Racing.

www.summitracing.com

use this. worth every penny.

 

[454cid]

Only 220? Run it and top it off when it cools.

 

[1952Chevy]

Lisle 24680 Lisle Spill-Free Coolant Funnels | Summit Racing

Free Shipping - Lisle Spill-Free Coolant Funnels with qualifying orders of $109. Shop Funnels at Summit Racing.

www.summitracing.com

use this. worth every penny.

I was going to recommend this as well. I came across one somehow(literally have no idea how I got it). I have used it quite a few times, no mess, haven't had any air issues since I started using this.

When you think you're done, make sure to pinch the rad hose while to put the stopper in the funnel(learned this the hard way). Dump excess in the overflow and you're good to go.

 

[eran tomer]

Lisle 24680 Lisle Spill-Free Coolant Funnels | Summit Racing

Free Shipping - Lisle Spill-Free Coolant Funnels with qualifying orders of $109. Shop Funnels at Summit Racing.

www.summitracing.com

use this. worth every penny.

i got one of those kit that doesn't have an adaptor for our radiators.

 

[mudpie]

Yep, turned out to be missing the hole in the thermostat. I got a new one that isn't a custom brown color. Thanks for all the input.

Only 220? Run it and top it off when it cools.

This is where my gauge runs almost all the time. When it gets up almost to the 3/4 line, I'm getting a bit concerned.

 

[SAATR]

Yep, turned out to be missing the hole in the thermostat. I got a new one that isn't a custom brown color. Thanks for all the input.


This is where my gauge runs almost all the time. When it gets up almost to the 3/4 line, I'm getting a bit concerned.

Glad your sorted it out. Always nice to hear the resolution to these things.