My 1967 mustang 289 three speed keeps pushing water out the overflow pipe. I’ve tried a new cap with a higher rating and I’ve replaced the fan clutch that seemed to be worn. It still does it. Any suggestions on what else to look for?
Sounds like it’s overheating - are you using 50:50 mix of water and antifreeze? Common problems would either be a bad water pump (but that would likely be leaking) or a plugged radiator. Can you see into the radiator looking through where the cap goes? Look at the tops of the tubes, you may see that some are blocked off. Remove the radiator, take it to a radiator shop and have it rodded out.
edit-good point 59tbird, and that would be cheaper. Feral, can you check your thermostat? You’ll want to be able to do these things with a '67.
Have you checked the thermostat ? Does it overheat only during idle ? highway speeds ? or all the time ?
Need more info.
I hate to say it, but possible head gasket.
It’s a longshot, but I’ve seen it! If everything else checks out first, and it’s still a mystery, remove the water pump and check the impeller. It may be eroded beyond effectiveness, or – get this – may have fallen off!
If the car doesn’t have a coolant recovery tank, it seems to me that cars used to require that the coolant level should be about an inch below the top of the radiator to allow the coolant to expand. You probably know your car well enough not to overflow the radiator, but I thought I should bring it to your attention.
An easy way to check for a bad head gasket is to slip the belt off and start the engine. Look down the radiator and see if you see bubbles forming in the coolant (don’t run the engine very long). If it bubbles, you have a head gasket issue or worse.
Is the car overheating or is it just forcing coolant out the overfolw pipe?