Engine overheat during break in

[japrine]

Hey guys I need some help, my new 302 won't run longer than five mins before overheating. When I shut the car off the lower hose was gurgling. The top of the radiator is hot and the bottom is completely cold. I tried with thermostat in and out with same result. It is a brand new radiator and water pump. Suggestions????

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[rvrtrash]

Never had this happen to me, so am only guessing. If the radiator drains normally (doesn't appear plugged), I'd check to see if the water pump is the correct one. The 80's 5.0's rotated the opposite direction of the older 302's. Might even have the wrong impeller installed from the rebuild.

Steve

 

[Mikes73]

If the cooling system checks out and it is a new combo you might check your timing and carb jetting as a to lean carb jetting or incorrect ignition tiiming could cause over heating. Good luck.

 

[rocket366]

Check water pump action

When engine gets to temp you will see action in

radiator with cap off when thermostat opens

Paul

 

[72HCODE]

thinking out loud

* monster air bubble trapped in system and the pump won't prime?

run with coolant cap off and keep filling with water. disconnect heater hoses,

fill rad until it pours out of water pump housing, reconnect the hoses.

* water pump wrong direction, wrong pump for engine.

you took the thermo out and had the same problem, yet everything is new.

* timing is too far ********.

* head gasket on backwards:

"Small-block Ford cylinder-head gaskets can be installed backwards, which is an automatic overheat because head gaskets installed backwards cut off coolant flow to the back of the block and heads. Install one head gasket backwards and you have a hidden overheat issue. Hidden because the engine runs a pinch hotter but doesn't boil over. But because coolant flow isn't reaching the back of the block and head on one side, damage is being done you're unaware of until an exhaust valve fails or pistons crack on that bank."

 

[japrine]

Thanks everyone, I'm hoping it is air, I will try your suggestion tomorrow. When I took out the thermostat today,nothing leaked out of the housing and when I restarted the engine with cap off the fluid level dropped a lot, it didn't do that with the stat in.I filled while running and put cap on after fluid level was rising in the radiator. It then started overheating shortly after.

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[barnett468]

well what is your timing at idle and almost 1/2 throttle with the distributor vacuum hose connected?

what is it with it disconnected and plugged?

you should not have an air bubble with the t stat out.

your water should be around 1" below the filler neck with the engine off.

start the car and rev the engine t 1/4 throttle and look in the rad to see if it looks like it is flowing. . it should look like someone turned on a garden hose.

 

[Don C]

Because the bottom half of your radiator doesn't get hot you have no circulation. Because you already tried it without the thermostat I'm guessing it's the water pump, either the wrong rotation or the impeller is incorrect or fell off. The are a few different water pump and timing cover configurations for 302s, and they need to match.

 

[japrine]

Timing was at 12 BTDC at idle and water pump rotation correct. I'm going to have to pull the heads as I see moisture on dipstick now

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[Jeff73Mach1]

Pull the heads. Coolant is hell on bearings

 

[japrine]

So far I've pulled the intake, I haven't pulled the heads yet,I can see coolant in both the front and rear passages in the Head of the drivers side and also coolant at the back of the Head on the passengers side but the front port looks bone dry as if nothing has run through it. Thoughts before I go further?

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[InjectedMach]

One head gasket on backwards is my guess. On one bank the gasket will lay face down and face up on the opposite side but no matter how they lay, they say "front" and that means no matter how it has to be flipped( as odd as it may look) both words imprinted into the gaskets go to the front of the block.

Also make sure the impeller is not spinning or slipping on the water pump shaft, its rare but happens too. Best of luck I know how bad this sucks. Take lots of pics during tear down for your refernce.

 

[72HCODE]

could also be a huge piece of junk inside the water jacket in that area something broke loose when the engine was cleaned during rebuild.

I've seen that happen before on a chevy. they dipped the engine and they cleaned it out, but up inside the water jacket was a chunk of sludge that didn't come out and when the engine was put together and put in the car the problem revealed itself.

if you can pull the gaskets in one piece then see if something was installed backwards.

 

[japrine]

The heads are off and both gaskets look intact and installed correctly with water jackets open at the rear. I'm going to take the heads to the shop to make sure they aren't warped

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[Manu Mach1]

Is it possible that your problem comes from a failed or leaking timing chain cover?

I think about that as I'm working in this area of the car.

 

[midlife]

While a head gasket can create over-heating problems, the fact that the radiator is hot up top but cold on the bottom tells me there's no circulation: bad water pump, clogged radiator, or bottom hose is collapsing.

 

[japrine]

Is it possible that your problem comes from a failed or leaking timing chain cover?

I think about that as I'm working in this area of the car.

It's definetly on my mind, the timing cover and water pump are both brand new though

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[MotoArts]

...the timing cover and water pump are both brand new though

Doesn't mean much, especially in today's absolutely dismal company quality control.

Question EVERYTHING. At least twice.

Although I don't feel it is the problem, quadruple check the impeller with a known correct 289-302 unit to make sure there is not a 5.0 reverse rotation impeller on it.

Do the same with the head gaskets and compare.

SBF's are self purging. I've never seen one trap an air bubble. There has to be something more obvious.

My 351C had the right head gasket installed backwards by its previous owner. Luckily it popped the power valve and fouled the plugs before causing any warping or damage. I could hear the water boiling on the right side compared to the left, which was quiet.

Good luck.

 

[barnett468]

Hey guys I need some help, my new 302 won't run longer than five mins before overheating. When I shut the car off the lower hose was gurgling. The top of the radiator is hot and the bottom is completely cold. I tried with thermostat in and out with same result. It is a brand new radiator and water pump. Suggestions????

how far over is it bored?

what is your ignition timing at 2000 rpm?

what is the number on your spark plugs?

Thanks everyone, I'm hoping it is air, I will try your suggestion tomorrow. When I took out the thermostat today,nothing leaked out of the housing and when I restarted the engine with cap off the fluid level dropped a lot, it didn't do that with the stat in.I filled while running and put cap on after fluid level was rising in the radiator. It then started overheating shortly after.

ok, this makes no sense.

could you see water in the radiator before you removed the thermostat?

did you remove the thermostat without draining water from the rad?

if your rad was full and you removed the thermostat and there was no water, you have a major blockage in your system because NO water is entering your engine which is basically impossible.

was the

Timing was at 12 BTDC at idle and water pump rotation correct. I'm going to have to pull the heads as I see moisture on dipstick now

drain some oil into a clear glass like a 1 qt measuring glass . . if it looks cloudy, it has water or if you see two separate layers of liquid it has water.

you need to check the surface of the block also and should have the heads magged for cracks too.