200 Overheated

Got a new 3 row aluminum earlier this year after my original radiator bit the dust. Noticed it seemed to run hotter after installing this bad boy, but it is also getting hotter out here in southern Louisiana. Well today, I overheated BAD on the way home. Heat gauge was off the charts. I am not sure if somehow this radiator is of inferior quality, or if maybe I just need to get an electric puller fan on it. It is about 1/2" thicker than the original, maybe that is hindering airflow with my flexfan? Thoughts?

Might it have had some air in it that needed to be purged?

Possibly, but I have been running this new radiator for several months now. Matter of fact I just took a 300 mile road trip the other day, and it did fine on the highway... Although of course there is more airflow at 60+ mph.

But it didn't boil over did it?
What thermostat are you running?
What temp did the guage read?
Thermostats can get stuck.
You could pull that off and drop it in some hot water to see it's functioning ok.

It did. I didn't notice until I got to the house, but it WAS steaming and I had lost a good bit of fluid.
As far as temperature, I don't know - I just have the dummy gauge that goes from C to H, and I don't have a thermo.
The thermometer is the stock one - 182?
I will check to see if it is sticking.

You might run it until the water gets to running temp with the radiator cap off. You can observe if the water in the radiator is flowing from the hose. If it is not flowing, the impeller on the water pump might be slipping. Or you might have a big bubble passing through the water jacket and the pump can't get any pull. Typically, I fill the radiator and watch the water. At some point there is usually a big bubble and the water level sinks below the blades of the radiator. I top it off with my favored fluid, water, AF or 50/50. If the bubble moves through after you close the radiator cap, you get no movement of water.

And BTW, run it until it gets hot with the cap off, otherwise, when/if you get a bubble, it won't blow scalding water all over you when you go to open the cap.

You might have a collapsing lower hose too. The spring in there gets awful weak after 40 years or so. Even after 20, and the hose collapses when the pump pulls water up. Then you get severely reduced flow too.

I actually just replaced the rubber hose. I will definitely fire it up and let it get to operating temp and see what happens though...

did you put a new rad cap on? if you used the old one, it may be weak and ready for the trash heap. when you installed the new rad, did you also install a fan shroud? if not that will also prevent proper cooling at low speeds.

Ok... I fired it up this morning with the radiator cap off. Let it idle for a little bit, then Old Faithful happened and fluid shot out of the open top of the radiator. So I guess that means my water pump is working. I topped it off with distilled water... and it is still overheating badly. Not sure what I am missing... This is 730am, it's only around 80 degrees out.

I'm thinking you have a bubble in the block. That is the only reason I can think of that would blow water out with the cap off shortly after startup because the pump doesn't blast water; it just moves it. I can see the water drift past at the top of the radiator. It doesn't shoot past.

Of course the overheating may be somewhere else too. Timing too far advanced with cause it to run hot, and too lean mix will do that too.

Methinks you burped the baby.

JackFish":37uxyq4b said:

Methinks you burped the baby.

Click to expand...

If you got kids, you know the first belch isn't the final belch. Keep patting until it all comes up. Ditto for Ford.

:rolflmao: haha nailed it, no kids here.

If you have a heater you need to turn the temp control on too so that the trapped air comes out of it also. Good luck

Take the cap off **first** and start it up. Throw a cloth (aka: burp rag) over the filler first if you fear another geyser.

Without water, the block heats up REALLY FAST. If you have air in the cooling jacket in the block, it gets hot super fast and creates extraordinary pressure, far above what you would get with just water. Tthat would cause the pressure to blow the first water out. I don't think you are done yet. Guaranteed, it will bubble again.

The other thing is that you could simply remove the t-stat and let the water run through from the get go instead of building pressure like you had. Of course the engine won't reach the target temp, 170* or 180*, without the t-stat. But this is one of the things you can do to start. If the engine does not get all the way warm, it would have been the t-stat not opening.

Just a little hint here.When filling your radiator,have the vehicle nose high,that will help to get the air out.Air WILL look for the highest point.Nose down to drain.
Good luck.Have fun.Be safe.
Leo

If all the air burping doesn't help, I'd suspect a problem with water flow through the radiator. Here's my thinking: you started it up with the cap off, engine runs for a short while with little/no flow through the radiator because the thermostat is closed, when engine heats up and thermostat opens pumping a rush of hot water through the upper radiator hose into the upper tank faster than the flow through the tubes (reason unknown but top tank quickly overflows out the open cap). I don't know why a new radiator would have a flow problem like that but I have seen old radiators that have had Stop Leak used on them plug up the cores and cause the same problem you are having. Just a thought if nothing else works out, maybe swap for another radiator to test.

Scott

I'm still leaning towards thermostat. Did you try feeling the two hoses running into the firewall that feed the heater core? Do they both feel equally warm/hot after running? If only one side is I suspect a clog or blockage somewhere or thermo. Also Napa Sells a 165" thermo for this motor! cost me 5.99

I'm a doofus... My GF, who knew I'd just replaced the radiator hoses, asked me if it was one of them. I said no, but then I started thinking, what about the heater hoses? Sure enough.. One of them was coming apart where it runs through the carb base and leaking coolant all over my intake. Replaced that (as well as the thermostat) and it's running like a boss.

Glad you got it!