O/T TECH. ? '67 COMET OVERHEATING...

[nor cal nic]

i changed the thermostat in the 289, it is opening and closing, did stove top test, no noise from waterpump or signs of leaking. flushed radiator looked good, water flowing from top and out bottom good with hoses off...no water in oil or oil in water, took sample from inside water inlet. filled radiator with mix of h20 and coolant, it moves around looking in and gets hot like it's going through the block ok. but, it still is boiling over when driven. what next do i do? i'm stumped...
thanks
nic

[Unkl Ian]

Have you changed anything with the vacuum advance lately ? Checked the ignition timing ? What do the plugs look like ?

[Lionheart]

Nic, when my 65 Mustang was NEW, it didn't cool worth a shit. I put a bigger rad (3 core) and that helped alot. NOW 35 years later, i have installed an alum rad in it and now it runs cooler than a 'blue moose'.

[Deyomatic]

Is this a car that you've been driving around for awhile and has been fine, but all of a sudden started overheating after doing the thermostat?
Did you by chance remove a spring thing from your lower radiator hose? If so, that is to prevent the hose from collapsing.
I had a similar thing happen in my late model recently, where it would run really hot on the highway. I flushed the radiator, changed hoses, changed t-stat, etc. I changed all kinds of stuff until finally I bought a new radiator and it fixed all of the problems. Sometimes the grime can't be flushed out.

Good Luck.

[prime mover]

is it boiling over because its getting hot or because the cap wont hold the pressure in? pressure test the radiator cap.

[Flat Ernie]

When you say:
[ QUOTE ]
took sample from inside water inlet

[/ QUOTE ]
Do you mean you did a test for CO in the water? ie - blown headgasket? Check for white "smoke" out the exhaust. Otherwise, I'd check/replace lower hose w/spring - easily collapsing when warm/hot w/o spring. Good luck!
http://www.jalopyjournal.com/ubbthreads/images/graemlins/cool.gif

[Paul2748]

Take the radiator to a radiator shop and have it boiled out

[jonizzle]

these cars don't cool worth shit. the stock radiator is too narrow and is only a 2 core. i took a radiator out of a 67 galaxie with a 289 and put it in my 67 Fairlane. it is about an inch to an inch and a half wider on each side and bolts right in. that seemed to do the trick. but after building up my 289 it was getting hot again. the stock mechanical fan was pretty much worthless in my application so i switched to an electric unit by Flex-a-lite. but it still really isn't all that great, but it does stay cool. when building up my car i replaced a the lower radiator hose with one without a spring, so maybe i will try one with a spring. only problem was the Schuck's didn't sell them like that. but i think in the long run i am going to get my radiator recored to a 3 or 4 core. also like others posted check the radiator cap, and get radiator cleaned. hope you get this figured out.

[nor cal nic]

thanx jonizzle and all...it was running nice and cool, then started getting hot. i figured i'd just change the thermostat but, that didn't do it. when i said i checked the water for oil i stuck my finger in the inlet at the top of block and water was clean. also, no white "smoke" from exhaust. the water was blowing out the overflow not the cap, i didn't monkey with the advance and i'll check the plugs now. thanks for ALL!
nic

[jonizzle]

yea no problem. what i meant by the cap is that the spring is fatigued so it can't hold any pressure and the water comes out of the overflow when the engine starts to get up to operating temp. you probably know that water expands when it gets hotter. this is just an idea but if you do suspect the cap take it to an autoparts store if they have a pressure tester and see if they can pressure test the cap. by the way what is the pressure rating is on your cap?