Water pump question

Guys- I need any help possible. My 65 Merc has a 390 that was supposedly rebuilt about 6 years ago before it went into hibernation until I bought the car a year ago. I have an overheating problem when the car runs at idle but it runs cool down the road when air is flowing through the rad. I have tried everything I can think of(new hoses, thermo etc...) with exception of replacing the water pump. This was supposedly new 6-7 years ago but I can see rust build up on the snout for the lower rad hose. Water flows as the car runs and I have checked the front of the water pump for play but everything seems tight as it should be. Can a water pump be malfunctioning internally without notice? I have no problem replacing the pump if a lot of you motor heads suggest, I just don't want to waste my time and money if I don't have too. Thanks

 

If you run cool going down the road that tells you that you have enough cooling system. If it overheats setting still or at low speeds that tells you that you have an airflow problem. The impellers on the water pump Ralely wear out especially if they are cast iron. I have seen instances where stmped steel ones have worn out, but is rare. Since the car has been setting for a few years the radiator core may be clogged with dirt and dust. Take an air hose or high pressure water hose and blow it out and see if that helps. Good luck.

 

What type of fan? Does it have a shroud?

 

Since you can see water circulating, I think you either have a lot of blockage/corrosion in the radiator, or a fan/shroud problem. I start by flushing the system, maybe having a radiator shop do it. If that doesn't cure it, what is the fan and shroud situation?

 

Since it cools going down the road, that shows an airflow issue,,,, I'm betting fan is a weak link.

 

Don't know if you have checked the belts ,water pump belt may be slipping at idle,this could reduce water flow. I've been caught by some really ,stupid simple stuff in the past.

Good luck. ..........Jack

 

If your idle is too lean it can also make it overheat when idling, or improper base timing.

 

I'd check any air flow at idle problems. Did they leave off any fan shroud when they put it back together? Is the fan close enough to the radiator to ensure the air is pulled through the core? (it won't be if it came with a shroud) Is the fan a factory fan? Is it a worn out clutch fan?

A partially clogged radiator will usually over heat at speed (under load) and cool well enough at idle.

 

Buy an electric fan......14" is only about $85.00.........Problem solved!!!!!!!!

 

Thanks for all the suggestions, this thing has really got me puzzled. I'm going to look for a shroud even though I do not know if this car came with one. Last resort but probably the best idea is an electric fan. The car isn't stock so I don't have to worry about that, I just never hooked one of these up so I might as well start learning. Thanks

 

When it sat, did it have water in the rad, or was it drained? FE's are notorious for rusting the metal head gaskets out so that the coolant flows through the front of the heads without circulating to the back. A common mistake when assembling these engines is to put the gaskets in backwards, causing extreme overheating. I doubt this last is your problem because the heating isn't bad enough, but if the water blocks are rusting through, it will act as you describe. The cure is to pull the heads and replace the gaskets.

 

did the 65 come with a 390? does it have a small block radiator in it?
If yes get a radiator for a 1970 f250 with the 390, they are cheap and should fit with minimal cutting, that with a shroud and good fan, should keep you cool, I would run the biggest flex-a-lite fan you can get in there, also remember its only march, think ahead to august, dont spend money twice. good luck.

a 390 is a cool running motor so it sounds to me like a volume issue

 

The car is a bit of a mystery as I bought it from a guy on e-bay. I am sure he was legit but he bought it from the guy who stored it for 6 years or so. I never had a Merc or a 390 before so I am plodding through this right now. The car has the original 390 and the rad looks like it could be the original with a re-core. No clue if these things came with a shroud or a fan clutch drive for that matter but I'm ordering a Merc/Ford catalog from MAC that appears to carry a shroud for this car. Good news is I bought this car in particular to be a bit of a mule and teach myself a few things about bodywork and engine performance upgrades so whatever I do I can only learn from. I definately like the sound of the f250 swap for more volume though, who knows how long this thing really sat. I'll tell you one thing, this cars got an awesone 60's street look with the ass jacked and fats in the rear with skinnies up front.

 

65 Mercury had a big old shroud, Stuck up above the radiator if i remember correctly. It also had a fan clutch and that expansion tank in the upper hose that you fill the radiator through.