Car running hot

[mercuryzephyrz7]

I have a new thermostat, good radiator, new water pump, new hoses, new heater core, etc in my 302 Zephyr but it started running hot not too long ago. It takes almost no time for the gauge to rise up and just about peg on the "H" side. It will hold steady just at the very tip of the "normal" range and won't overheat...any ideas?

[86asccoupe20]

Did this happen before you changed the thermostat? If everything else is new you may have a defective thermostat. Also, did you burp it at any point.

[83t-topp]

are you still running you stock gauge ? Iv'e heard they can be not so accurate some times . you might want to try an after market gauge .
then you would know for sure.


just a thought.

[peppahillcustom]

are you losing coolant?

[Greywolf]

make sure it's the correct rotation water pump!

[mercuryzephyrz7]

It was after I replaced the thermostat....however it's been about 3 months since I did the thermostat. The gauge is a possibility as well...however I found a leak due to a slightly loose hose clamp, which helped it quite a bit actually.

The main thing is that my top radiator hose is hot when the engine is warm, but the bottom is just warm. Also, my radiator cap isn't getting very hot at all. I put my hand on the radiator itself in different spots and noticed it was burning my skin in some spots, and cold in others. I think I have a clog...

There is a cobra radiator from a '98 on c/l i'm curious if it will fit?

[83t-topp]

definately sounds like a blockage some where .

[86asccoupe20]

Might want to try an acid coolant flush through the radiaator first. Cheapest way out.

[mercuryzephyrz7]

What do I use to do an acid coolant flush?

[Maindrian Pace]

I'd do a Prestone coolant flush with the radiator as is, flush it out real good with the flush and fill kit that puts a T in a heater hose and uses a garden hose, then remove the radiator and take it to a radiator shop for a rod job. You're getting all the junk and scale out of the engine block before it clogs up a fresh/rodded radiator. I also would make sure that the t-stat is opening all the way - remove it and put it in a pan of boiling water and check to see that the spring is relaxing all the way leaving it wide open. Some new t-stats only open a crack.

-MP

[mercuryzephyrz7]

I did a flush on the radiator with Prestone stuff. I didn't use the T-handle thing, though. I ran it with the flush chemical in for about 15 minutes after the car was already warm, then drained it out. I then ran garden hose water in through the top of the radiator and left the drain petcock open and just ran water straight through until it ran freely and clear, which it did. However, it didn't fix the problem. I'm doing a 160 degree thermostat today and hopefully that works. If not, i'm doing a compression test

[NAVYCAT]

did you ...... by chance install the thermstat upside down? that would cause a blockage causing overheating

[mercuryzephyrz7]

I just installed the thermostat and the spring is facing the inside of the block. HOWEVER...I do have a very very important question.

I bought the water pump new for a '79 Zephyr 302, but last minute I decided to use an '84 Mustang H.O. engine but just used the water pump for my '79 non-H.O. motor. I looked up water pumps for both cars on autozone and got two different part numbers.

What exactly would my car do with the wrong water pump installed on this engine??? Do 302 H.O. engines have the different water pumps, just like it has the different firing order??

[83GTRAG]

could be directional fins in pump! Some pumps are set for rotation ,if not does the overflow tank bubble after car is off for 5 minutes?

[mercuryzephyrz7]

Hmm i'm not really sure...I haven't just watched it after I shut it off. I can tell you that with the cap off and the radiator full while running, when I rev the engine the coolant will go down until I let off the throttle then it will return to the top. I figured that was normal....

[83GTRAG]

bubbling indicates head gasket problem, very minor bubbles. I am putting in an engine as we speak so I am positive.

[mercuryzephyrz7]

Okay follow this if you can: I took the '84 H.O. motor, swapped the water pumps and put on my old V-belt system. The stock serpentine water pump is reverse from the V-belt one, correct?

If so, is the water pump specific to the ENGINE, or to the BELT SYSTEM?

In other words: If I'm using a '79 water pump with a '79 belt system, will the coolant flow through fine? OR...is the block conditioned to have the reverse flow and ONLY the reverse flow? ....Hope that makes sense :/

[Greywolf]

Water pump is specific to the BELT SYSTEM. V-belts turn the pump the SAME DIRECTION as the crank pulley. Serpentine belts turn the pump in the REVERSE DIRECTION.

If you put the wrong pump in place, it will turn in the wrong direction. It will flow less than half of the water through the system, allowing it to run hot.

Once the water leaves the water pump, it flows the same in new or old engines, so if the water pump and belt system match, the engine should be happy. It sounds like your setup is good, if I followed it right.

I would suspect the radiator still. The coolant flush helps wash out loose crud, but if it's really plugged you won't get that stuff out. If it's in good condition otherwise, find a radiator shop that can pop the end caps off, flush the core clean, and put it back together. Last time I had it done it was under $50 and they made it look like new. But there should be a steady drop in temperature from one end cap to the other; if there are local hot/cold spots then it is probably plugged up.