Hot Rods Over heating.

Just put a stock/mild 350sbc in my 51 F1. 180⁰ thermostat. Timing is set at 10⁰ advanced. Everything is good but it is climbing up to 250⁰ or higher(gauge only goes to 250. And this is only after driving for 15 minutes on a 70⁰ day. The radiator is a 4 row. Seems like it would be enough. I can't fit a manual fan because the engine sits too low and the smallest fan I could put on hits the lower hose. So, I got a 16" electric 2660cfm. As you can see from the pics there is a lot of area on the radiator not having air pulled through. My guess is to make a shroud and hope it is all that is needed. I would like to hear some of your thoughts on the matter.

 

First I’d question the gauge, 2nd the thermostat. Assuming correct water pump is being used.

 

I believe the gauge and thermostat are working. The fan has a sensor to kick on at 180⁰. As the gauge gets to 180⁰ the fan kicks on. Also, when watching the gauge, it gets a little warmer than 180⁰ then I see the gauge dip back down about 5⁰. Then from there, the temp just climbs.

 

Does the fan spin the right way?

 

yes

 

I've tried both. It acts the same.

 

I don’t think 2660cfm is enough airflow through the radiator to keep the engine cool. I think you need closer to 5,000cfm from my personal experience.

 

The slight dip in temp at just over 180* would seem to indicate that the thermostat is opening. If it continues to heat up after that, it might be a flow problem. As @Moriarity says, it should not need the fan at highway speeds, so blocked radiator or water pump problems ???

 

If the engine sat for any time the water jackets may have built up crud in them. You need to confirm water flow. A good flush with commercial product may help if theres a buildup. The other observation is your timing. I would try bumpimg up the initial to perhaps 16 deg. I would check for the advance coming in corrctly for the engine.

 

What is a stock-mild 350.You need way more timing, what dist is in it,is it curved,does it have a vacuum advance?

 

Does a flathead radiator have a baffle in the top tank? If so you could be using only half the radiator with one hose opening plugged.

 

Did you buy the water pump for the year of the engine or for V Belts?
Simply meaning that serpentine belt engines have reverse rotation water pumps. They turn counterclockwise when viewed from the front of the engine. Water pumps intended for V belts turn clockwise.
I saw the reverse of it years ago when they brought an 91 Camaro to the shop that was doing exactly what you are saying this one does, Gets hot at all speeds. On that one they had replaced the stock engine with an older 350 with V belts and then the guy who bought the car put a water pump for an 81 on it. Not long after that either Car Craft or Hot Rod or PHR came out with a short OBTW article. that said if you swapped V belts on to a Serpertine belt engine you had to swap pumps.

 

Not to argue with the above, but a fairly cheap infrared thermometer from Amazon really helps diagnose the problem. First thing is to check the temp at the top hose, and then the bottom. If it’s not cooler going back to the engine it’s in the radiator or the fan. If it is, then look further.

If you’re right about the fan sensor/temp gauge, it will also match the infrared and you’ll know all that’s good. Let’s you set the griddle for pancakes, too.

 

For the price an infrared thermometer is all too handy to have.

I'd be seriously checking that water pump being as it is a fresh engine.

 

I've never run a shroud with an electric fan, I would verify top dead center because of the harmonic balancer being 2 pcs and they are known to slip, also pull the plugs and make sure it isn't running lean.

 

From the looks of the photos, it looks like to me that the crank pulley diameter is too small and the water pump pulley diameter too big. Maybe the water pump is turning too slow?

Bill

 

Is that the OG radiator, what is the condition of it? I'm not huge on eliminating a mechanical fan either. The electric as your only line of defense is sketchy to me. Plus they make too much noise when running constantly for my ears.

 

If it is getting hot driving down the road,,,,,,and it sounds like it is getting really hot,,,,,,it’s the radiator,,or pump .
I’m betting the old core is stopped up .

Rule of thumb :
1. If it is getting hot sitting still,,,,usually insufficient air flow .
2. If it’s getting hot at highway speeds,,,,usually insufficient water flow .
3. If it blows the water out of the radiator,,or recovery jug,,,,,and then gets hot,,,,,,it’s usually a badly leaking head gasket.

I have found these to be right,,,every time at least so far for me .
Of course that takes into account,,that the water pump is correct,,,,and the thermostat is working correctly.
But,,,those things should be checked first anyway.

Tommy

 

Tell us about the radiator, please. What it is from. What has been done to it. Surface area.

Ben

 

Get an Infared thermometer and check if there are cold spots in the radiator. If the block is a vortec you will need a bypass hose. Bump the timing 10 degrees you may have a miss matched balancer and pointer.

 

I'm with all those who question the radiator, and suggest a infrared thermometer to spot check it. They're so cheap these days at Amazon, Harbor Freight, etc. that it's a tool every car guy should have in the toolbox.
My '39 has the engine sitting low, so mechanical fan only covers the bottom 2/3 of the core. That's not an issue on the highway, but sitting at traffic lights it got hot even in cooler temps. I added an electric pusher fan mounted to the top half of the radiator, and set the electric stat at 180 degrees. It keeps the engine temps at 180 degrees even on days over 100 degrees, but I don't have to listen to it all the time. Actually even when it comes on I barely notice as my exhaust is loud enough not to hear it.

 

I'm thinking the rad is set up for the flathead as 2 baffled halves. Your connected to the top half on one side, and the bottom half of the other side.

 

That one I have never heard or seen on any flathead V8 radiator. Think about it, that would call for two filler necks and radiator camps to work as you describe.

 

I might have sufferred a brain cramp or fart or somethin'..still sitting on the john afterall.

 

The radiator just came back from the shop having a small hole being sealed. I would hope the shop checked it out thoroughly. But who knows. When I got the truck it had this radiator with a sbf 302. It ran cool with a clutch fan.
I am going over all your suggestions one at a time. I made a shroud and will be putting it on some time tomorrow. I don't expect it to solve the problem.
Next I want the flush the block to check for build up. After that I will attack the pump. How can I tell if the pump is bad?
Thank you to all that have made suggestions. I will report back when I find the culprit.

 

Go Back to my post 14. I didn't say anything about the pump being bad, What I said is that it may be the wrong pump for your belt setup.
Meaning if the engine was new enough to have come with a Serpentine and who ever you got the engine from bought the pump for the year and model it came out of it would be running in reverse with V belts.

Do you know what year the engine is supposed to be and what it came out of? Suffix number should give a good indication.
If the radiator setup worked for you before with a different engine it should work now.

If you bought the pump new what did you buy it for model and year wise?

 

Mr48, I appreciate you hanging with me on this. The engine is a 1988. The heads have the 4 canted intake bolt holes.
The water pump has 306 on the front which I believed to be a regular rotation pump. I have the V-belt set up.
I made the shroud and reinstalled the radiator tonight. Tomorrow I will fill and test. Here is two more pictures if they can provide any info. BTW. I ran the fan and I got a small piece of paper to stick to the front of the radiator where ever I placed it. So, at the very least I had have air going through the whole radiator

 

It's an HEI with vacuum advance.