Engine Overheating very quickly

[crossram 426]

Hi, any thoughts on why my 440 would go to 200F in 5 mins of starting, checked the coolant and it was hot too. Was just turning it over and noticed the flange gasket starting to smoke on the drivers side so I checked the temp gauge and it was up over 200...seems very strange as it's not even a hot day here. TIA

 

[Dennis H]

How much over? Thermal laser temp gun? How long since it was started. I have on occasion seen a start-up spike similar to yours. It flirted with 205 once, the settled down. Very short time after start up.

 

[crossram 426]

has only been 2 weeks since the last good run...and start it weekly. Might go start it again and see if it calms down.

 

[Dreamcatcher]

It has been my experience that a leaking head gasket will spike the temp almost immediately. I had one that would boil in about 4 minutes.

 

[crossram 426]

nothing in the oil...yet

 

[Dreamcatcher]

nothing in the oil...yet

When I had the bad head gasket I never got anything in the oil or on the ground. It just simply over heated. I let it cool down and fired it up with no radiator cap. With in a few minutes it pushed a large amount of antifreeze out and was hot. I changed both head gaskets and now it runs 190 all the time and takes 12 to 15 minutes to reach that temp. Just a thought.

 

[crossram 426]

just checked the radiator number and it's from
#2898038 1968 B 22" 273 318 motor
ran the car again and it seems to be sitting on 190ish then I shut it down turn ignition back on to start and the temp is then at 220+ so I start it and it drops back down to 190ish. Is that radiator from the smaller engine size enough? are they the same?

 

[terzmo]

see if stat opened...start car and leave rad cap cap off...watch gauge as climbs and then should drop quick because the stat opened...if stat doesn't open..there is the issue..if it opened..rev the engine and see if there is coolant flow...if no coolant flow...the pump is not doing it's job

 

[Dennis H]

Stat, the obvious. Have had good luck with a Stant Super-Stat 180.

 

[oldbee]

I go with Dennis- t-stat is stuck shut.

 

[crossram 426]

just tested the stat in hot water and opened and closed well, did it a couple of times. will now check pump condition. numbers on stat are 700/800-180?

 

[Ranger16]

How are you measuring the temperature? Factory gauge, mechanical aftermarket, electrical aftermarket, IR temp gun?

 

[SlinktRR]

Probably an air pocket or stuck thermostat. Take the thermostat out and leave the cap off to clear out any air while it runs. Check for coolant flow.

 

[crossram 426]

filled with water to top where stat sits and spun fan around a few times and no movement in the water is visible. Should movement be visible?

 

[Mike67]

If you have concerns about a head gasket you can buy a radiator pressure tester or even get a loaner from a local parts house...

 

[oldbee]

You can't spin the impeller in water pump fast enuf by hand. New t-stat and leave the rad. cap off and watch the water in radiator. Hope this helps; when t-stat opens you should see a rush of water flow in radiator at the beginning and then a normal flow going by. If water blows up thru rad. neck with new t-stat then you may have a blown head gasket. It's hard to describe but soon you'll know the difference.

 

[Fran Blacker]

Impeller slipping on shaft? Seen that before. As old bee said do you see water moving in radiator, thermo or impeller if not. Collapsed lower hose?

 

[oldbee]

Dennis H and others-- This stuff is hard to talk/teach about. A lot of us have years of experiences with all this stuff and a lot of it comes naturally w/o really thinking about it. Just kind of a "oh yeah" memory, while the younger guys haven't seen it before. Always have to kinda think back to the younger years. I have grandsons of 7&10 yrs. old and what can I school them on when I'm no longer here. Carb tuning, measuring in the .001" ? The daughter-in-law wants them to drive my '68. So far it has been 'back-seat' with alot of smiles!

 

[SlinktRR]

Unless you are having boilovers I wouldnt be too worried about a blown head gasket. 200F is no big deal. 230F is more serious. I boiled my big block one day last summer dealing with an air pocket problem, IR gun would show 230F in the block and 80F in the radiator, then 240 and a boilover. Take the thermostat out, run it for a while. Then put a new one in. I like the 180F, with running temp around 205F on hot days.

 

[miller]

Fran mentioned collapsed lower radiator hose. Next time it heats up...might look down.