What are the chances - cooling system issues

[whtbronco]

This past weekend I popped the hood for my weekly inspection and noticed the 2004 Expedition was low on coolant. Look around some more and I find the heater valve leaking. It had cracked where the hose fitting meets the valve body after 5yrs and was spraying coolant and left the telltale white chalk like lines. So I replaced it that evening.

Next day coolant is leaking from the front of the engine. At home I found it was leaking out the bottom of the water pump. It only leaked at operating temperature. No worries, 2 days later I replaced the water pump gasket with a Fel-Pro gasket. I coated it with a thin layer of silicone grease and that did make it a bit easier to slip the o-ring style gasket on and install the unit. That almost sealed it, instead of a puddle(1/2" in the reservoir after 30-35 miles) it's just three 1" diameter spots. I found nothing that seemed messed up, scratched or even corroded on the water pump or block. Maybe at operating temp the water pump is warping a bit and then contracts again as it cools down. Current water pump is a Motorcraft and has about 35k miles on it. It seems fine, it is not leaking from the weep hole or the pulley shaft bushing. The only thing I can think of is to replace the water pump. Any other thoughts I may be overlooking?

I gotta look through my maintenance book to see if I have replaced the water pump 3 or 4 times now. I know I installed 2 Gates water pumps before going back to Motorcraft 2 years ago.

What are the chances of 2 coolant related issues in a week. Coolant is the fluid I least like dealing with in a vehicle. It just seems to never end.

 

[whtbronco]

New Motorcraft water pump enroute. I'm not gonna try a new gasket again. I'm just gonna replace the water pump and gasket of course. I'm half tempted to lay a thin bead of Permatex The Right Stuff on the mounting flange of the pump where it mates with the block as a second seal. It will make it more difficult to remove as this stuff holds rather tenaciously compared to most RTV products, but it doesn't leak.

 

[AWAR]

I always wet the o-ring with good quality rtv when installing a water pump. I would also rather work on anything other than cooling systems.

 

[whtbronco]

I always wet the o-ring with good quality rtv when installing a water pump. I would also rather work on anything other than cooling systems.

Heck, a thin coat of RTV on the o-ring style gasket would probably seal it up. The new gasket dang near sealed it by itself. I probably never would have considered this. I'll put a little RTV on the o-ring next time. Thank you for sharing your years of experience @AWAR .

Why is it that coolant is so nasty, sticky and it seems never ending. You think you have it all and then all of a sudden there's more.

 

[AWAR]

You can flip one of these engines on an engine stand and get coolant for the first three times. It hides everywhere, in Oregon it is embittered to keep small animals from drinking the sweet kind. It is miserable to get doused with it when the car is up on the hoist.

 

[whtbronco]

The new Motorcraft water pump and gasket resolved the leak. I also did use a bit of RTV for the o-ring style gasket as suggested by @AWAR , thank you sir.

As I was cleaning up I noticed 2-3 drops of coolant coming out of a small weep hole that sits on the bottom of the old water pump. I thought the weep hole was the ~5/16" hole on the top when installed. Maybe this lower hole is where all the coolant was coming from after the first gasket replacement. I'm not certain, but I did notice that some of the replacement water pumps have this hole and some don't. The MC water pump does have it.