Overheating coolant

[SlinktRR]

Had a strange thing happen today with my 383 with stock 26" radiator. My coolant system has been rock solid all summer with daily driving in 90+ degree heat. I have some sort of blockage, thermostat issue or gas bubble I cant get rid of now. From dead cold start I can drive until about when the thermostat would normally open, like 5 minutes. Then the temp gauge goes straight to 230-240 and I have to shut down. The first time it happened it puked coolant into the catch bottle and overflowed.

So I let it cool down, took the radiator cap off and refilled what was lost, leaving it about 4 inches down from the lip of the radiator. I left it open to see if I could burp the system. I watched the coolant as the motor ran. I never got any signs of coolant flow inside the radiator. Then the coolant level suddenly rose and boiled over violently. temperature gets to about 230F using infrared.

I'm going to get the system pressure tested in the morning, test the thermostat. Engine runs fine and no signs of any other issues. Any ideas on things to try, how do I get air pockets out?

 

[gtxno1]

Replace the thermostat and watch for flow like you did before the true way of checking a thermostat is to remove and place it in a pot of boiling water to see if it opens but in all my years as a tech I have never done it nor has any other tech I have known on the old school cars like ours we just watched them open slowly you can watch iy flow like you were doinig

 

[Badvert65]

I agree, replace the thermostat.
I have done the 'boiling trick'. All is does is let you know if the thing actually works (it isn't like you can adjust anything on them). Thermostats have a 'begins to open point', a 'fully open point', and a 'begins to close' point. For all the effort, it is sooo much simpler to just replace the thermostat. Boiling is a big waste of time IMHO.

 

[Dennis H]

Keep us posted. I just got lucky with a burping issue. The 180 stant superstat in mine seems to be reliable. The onset for me was a radiator leak. Yours came out of nowhere?

 

[BLK 68 R/T]

Also check your bottom radiator hose to make sure it is not collapsing shut. It should have a spring inside of it to keep that from happening, but the majority of todays hoses do not have the spring in them like they should.

 

[gtxno1]

The bottom hose will not collapse if the cap is off and checking for the stat to open

 

[1967coronet]

like posted above change out the T stat, as far as the air in the system once you have a working thermostat the engine and rad will self burp once up to operating temp and you get flow.
as long as the rad cap / fill point is higher than the intake manifold the air will work its way out.
You can run it with the cap on the 1st notch for a short time at temp to help get any air out.

 

[SlinktRR]

Fortunately it was the thermostat. I installed the thermostat on the left 4 years ago, I think it was a mr gasket 180 degree I think it was the one for 25 bucks. I boiled them up on the stove and the left one stayed closed while the right one (new stant 180F) opened. Not sure if it just failed or got plugged up with rust but it is not usable. I like the stant design, simple is good. So the boilovers were coming from the block getting superheated with no coolant flow.

I popped off thermostat housing expecting to have coolant fall out but it was bone dry from boiling with signs of corrosion. I took the thermostat out and bolted back up without a t-stat, ran about 20 miles on the highway and around town. Took a long time for the engine to get to operating temp as expected but once it did it stayed at 180F and didnt move. Heads, water pump, radiator, all 180F. With the old thermostat the water temp would bounce between 180-220. I'm tempted to run without a thermostat because it runs so cool, it doesnt run quite as well that cold probably will need to retune. For now I'm going to get the system flushed out and install the stant.

 

[Dennis H]

Congrats man, good news.

 

[gtxno1]

Believe it or not the only thing in there are wax pellets once over heated they are not the same need to be replaced but some of the material could have migrated out causing your issue glad to see your back in business see you at etown

 

[69a100]

$25 for a T-stat, geeeeeeeeez, glad your made of money. Guess you get what you pay for for 4 years!

 

[gtxno1]

Lol

 

[SlinktRR]

$25 for a T-stat, geeeeeeeeez, glad your made of money. Guess you get what you pay for for 4 years!

Yeah it said "race" and "high flow" on it so I got it. My memory is bad or it used to be more expensive, this is the unit now for 15 bucks at Summit:

http://www.summitracing.com/parts/mrg-4367

The reviews are not great.

 

[gtxno1]

Advance sells the super stat 180 cheap

 

[Dennis H]

Race and hi-po marked I Usually avoid. Same with water pumps.

 

[Buckeye Charger]

Crazy timing on this topic, because I just installed the same Mr. Gasket T-stat on my 426 hemi and took it out for a test drive today. I'm 99% sure it never opened! Both hoses were HOT and rock hard with pressure. Good thing it was a short drive, because the engine was HOT. Going to take it out and do the boil test just to see if it opens at all. Just read the reviews on Summit and this thing is a piece of junk! SlinktRR, where did you get your Stant?

 

[Dennis H]

Crazy timing on this topic, because I just installed the same Mr. Gasket T-stat on my 426 hemi and took it out for a test drive today. I'm 99% sure it never opened! Both hoses were HOT and rock hard with pressure. Good thing it was a short drive, because the engine was HOT. Going to take it out and do the boil test just to see if it opens at all. Just read the reviews on Summit and this thing is a piece of junk! SlinktRR, where did you get your Stant?

Napa carries the Stant Super-Stat 180. Reliable.

 

[Buckeye Charger]

Napa carries the Stant Super-Stat 180. Reliable.

Thanks Dennis! I'm heading there tomorrow!

 

[Dennis H]

Thanks Dennis! I'm heading there tomorrow!

Advance has them too. Better check first. Mines been in for at least 10 years since the motor was done. Only $10.09 in my over-priced neck of the woods.

 

[Bigal75]

I don't use a thermostat. All they're for is to get the engine up to temp faster.