Water pump...replace?


#1

1994 F150, 164k mi. 4.9L I-6.

I’m in the middle of a head gasket job. While wait for the machine shop, I figured it’d be worth inspecting the water pump while it’s accessible.

But what constitutes a “bad” water pump? Impeller erosion, obviously, but what else? Bearing play?

Thsnks for input…including whether I should replace, inspect, or fuggetaboudit!


#2

If the pump has never been replaced then I would do it if the truck were mine. The seals would be 20 years old and prone to failure at any time. My opinion is to be a bit pro-active with some things.
A new thermostat is a must with every head gasket job.


#3

The three big water pump killers. 1) seal leak, 2) bearing play/noise, and 3) impeller erosion. Also, like @ok4450 said, if this is the original pump, or it is more than 7 years old, I’d replace it just because. It could save you the hassle of replacing it later due to reasons 1 or 2.


#4

Thanks…I’ll replace it. I bought it with 124k on it, and I don’t know the history.

I’ll pass on the thermostat right now, because it didn’t overheat, the coolant temp is observed behaving normally, I’ll be driving it/monitoring it, and the thermostat is easily accessible even after full assembly.

One question, though: is it advisable (or even possible) to run “old-school” coolant? I read somewhere that OAT coolant really isn’t for cars with non-pressurized overflows, because it doesn’t play well with even traces of dissolved oxygen in the coolant system.


#5

Personally, I run old school green in every car our entire family has simply because it’s always been problem free.

One of my son’s car uses Dex-Cool and that car went through 3 water pumps in the first roughly 80k miles. It kept sludging up through repeated flushes and there were zero leaks and loss of coolant. After the 3rd pump I flushed it again, filled it with green, and it’s never had an issue with leaks, pump failures or sludging since and up to the current mileage of around 250k.


#6

While you’re in there, might as well do the timing chain.

It’s probably stretched.

Tester


#7

You’ve got the cooling system empty, the thermostat and housing are off, you’re proactively replacing the water pump, a new t-stat gasket will come with the head gasket set, you don’t know the service history of the car, why wouldn’t you replace the thermostat?

That truck originally came with old-school green coolant, that’s what I’d put in it.

Why does it need a head gasket?


#8

No chain, just bakelite gears. It’s not an interference engine, so I’ll probably wait for issues, then upgrade to metal at that time.

I thought even “green stuff” was partially organic these days, unless you sought out “original formula” coolant.

I think the gasket was partially breached when I bought it and got worse. Ran fine, but a sound at WOT between knock and "pfft."
Gradually got worse until it happened at half throttle or more…a precautionary compression test showed 150-170 on all cylinders except 95 on #3. Looked to be leaking toward the head bolt outward on the “non-intake/exhaust” side of the block.