While checking under the hood of my 93 aerostar 3.0 I found that the upper radiotor hose had been sucked flat. I recently replaced the water pump and thermostat. Can anyone provide a possible cause or at least a direction I should be looking... the aerostar hasn't over heated yet.

Thanks

 

Off hand I'd say it is either of two things. First the hose is shot and needs replaced. Second is the radiator cap.

The cap allows coolant to pass out into the overflow when the coolant expands due to heat. It also is supposed to allow it to siphon back in as it cools and creates a vacuum. If the cap will not let the fluid back in then the vacuum is causing the hose to get sucked flat.

Better yet, replace both. They are pretty cheap.

 

I don't want to cause any alarm (or more than needed) but usually, it's the bottom hose that gets sucked flat. If the problem is not the radiator cap, it could be the pump. The bottom hose is usually on the inlet (low pressure) side of the water pump and that's why there's a spring in the hose so it keeps its shape. The top hose is under pressure and retains its shape. That's the way it usually is (from my experience).

Anyway, it appears as though your top hose is now on the low pressure side, which might suggest that you have a reverse rotation water pump installed. My understanding is that there are two types of water pumps for the 3.0 motor, standard and reverse rotation (although I have to admit I could be getting it confused with another motor). I know of other people who have gotten the wrong rotation pump from the parts store. If you have a reverse rotation pump installed, then the top hose would be colder than the bottom hose. If the top hose is really supposed to be the one on the low pressure side, it should have a spring in it to keep it from collapsing. If the hose is old, the spring could have corroded away.

 

That reverse rotation pump thing almost happened to me once. Fortunately, I had the old pump with me to check against. It was an easy mistake to make; the parts list chart indicated a particular pump, and it looked identical to mine from the outside. But looking from the back sides where I could see the internals, it was obvious that they were intended to turn in opposite directions. The parts man found the right one pretty quickly.

 

i think it means that the hose is old and needs replacement , but check your radiator cap firstmake sure it is on right and working . note :if it is easy to squish top hose together when you pinch it , it is bad and needs replacement .

 

the top hose will go flat,had it happen.
Or heat and just being old,try one with inner spring or
as I have done as a quick finot a cure)wrap some bailing wire around
the hose.(old school)






















9

 

Since you started having this problem after you replaced the pump, I'd have to follow Mikeman's suggestion. A hose on the high side of the system should not go flat.
Why Ford would be stupid enough to produce similar pumps with opposite rotation is beyond me!!

 

Earlier 3.0L engines like my '93 have two sepentine belts, and the pump rotates clockwise. Later 3.0L engines have one single serpentine belt and the water pump rotates counter-clockwise, hence two different water pumps. This has been mentioned countless times on this forum, but people's first impulse has always been to blame an old hose

 

hose collapse is a function of radiator cap. Period. wrong rotation of pump will be caught by not being able to screw fan clutch onto w/p

Good news. It also means that all gaskets are in good shape.

Ken

 

who wants to ruin a vacation just for a $5 radiator cap that causes overheating with blown head gaskets and cracked heads....
and check the outflow line to overflow tank....
Murphy's First Dictum of Hot/Cold....what flows out when hot must be able to flow back when cooling...

little goober ball in bottom of overflow tank can plug up the works.