Water Pump - Preventive Maintenance Item, or no?

[maxm50]

Hi all,

I'm planning to replace my original thermostat sometime this year, because the car takes a bit too long to warm up. The thermostat is original and it never COMPLETELY blocks flow to the radiator, just chokes it down when cold (not sure if that was the original design intent, or if that's what 40 years does to an original thermostat that never seems to have had any rubber sealing surfaces to begin with)... but I digress.

My question is: While I'm replacing the thermostat and have the system drained of coolant, should I go ahead and replace the water pump while I'm at it? I have no reason to suspect the water pump is bad. It doesn't make any bad noises. I've owned some cars where the internet wisdom is to replace the water pump at religious intervals, and other cars where we all said "if it's working, for the love of god don't touch it because you'll play Russian Roulette with the new one". I'm wondering where these Spiders are in that spectrum. The part is pretty cheap. I have 45k miles on the odometer, which I'm reasonably sure is 45k and not 145k.

Water pump replacement looks VERY simple on this engine, correct?

And finally, I might loosen the belt and spin it by hand - how much resistance / noise would be "normal" to feel when spinning it by hand on a cold engine?

Thanks all!
Max

[SteinOnkel]

Hi all,

I'm planning to replace my original thermostat sometime this year, because the car takes a bit too long to warm up. The thermostat is original and it never COMPLETELY blocks flow to the radiator, just chokes it down when cold (not sure if that was the original design intent, or if that's what 40 years does to an original thermostat that never seems to have had any rubber sealing surfaces to begin with)... but I digress.

My question is: While I'm replacing the thermostat and have the system drained of coolant, should I go ahead and replace the water pump while I'm at it? I have no reason to suspect the water pump is bad. It doesn't make any bad noises. I've owned some cars where the internet wisdom is to replace the water pump at religious intervals, and other cars where we all said "if it's working, for the love of god don't touch it because you'll play Russian Roulette with the new one". I'm wondering where these Spiders are in that spectrum. The part is pretty cheap. I have 45k miles on the odometer, which I'm reasonably sure is 45k and not 145k.

Water pump replacement looks VERY simple on this engine, correct?

And finally, I might loosen the belt and spin it by hand - how much resistance / noise would be "normal" to feel when spinning it by hand on a cold engine?

Thanks all!
Max

Bahahah have you worked on these cars!?

Have you done the timing belt on your car or do you know for a fact that it has been done recently? If not, I would do one big ol' laundry list of belt (s),thermostat, waterpump, heater hose pipe tiny gasket etc etc.

Also, most people seem to have a bear of a time bleeding these coolant systems. Here's what I would do: mark your existing thermostat before you remove it. Hold it next to the new one and mark that the exact same way. Then drill a small hole into the new thermostat. It's a bitch to get a drill bit in there, but trust me you want to do this. Lastly, when you go to fill it go to Autozone and borrow their radiator test kit. Fill the system, pressurize it with the tool, bleed the pressure, rinse and repeat until your radiator is full. For me, that has been the only sure-fire way of getting all the air out of this. If that still doesn't do it and the engine won't open the thermostat, boil a big ol' pot of water, run the engine for 15 minutes and slowly pour the water over the thermostat. All three hoses should be warm.

^Because of b.s. like that, these cars are no fun to work on.

[SteinOnkel]

I realize exactly none of that answers your actual question

The short answer is yes, I would replace it. I've got a different philosophy than most though and have a quick trigger parts cannon. I.e. When I get a new car, I replace the alternator, battery and starter immediately. Just my way of doing it, haven't been on a flatbed in years...

[18Fiatsandcounting]

And finally, I might loosen the belt and spin it by hand - how much resistance / noise would be "normal" to feel when spinning it by hand on a cold engine?

There should be no noise when spinning by hand, and the resistance should be minimal. The pulley shouldn't continue to spin if you give it a good twist and release, but it should take hardly any effort to get it to spin.

As for replacing the water pump in the first place... I'm split on this. If the coolant was rarely ever replaced, the water pump could be pretty gunked up and starting to corrode. On the other hand, if the coolant was drained and refilled on a regular schedule, then with 45K miles, the water pump is probably fine.

The one issue that I always fear with replacing a water pump is to have one (or more) of the 4 bolts break off when unscrewing. If they do, you have a real mess.

One other thought: Your thermostat could be fine but simply installed incorrectly, and that could cause long warm-up times. I'm assuming you have the 3-neck thermostat, and it is pretty confusing which neck goes to which hose, and people often get it wrong.

-Bryan

[RRoller123]

Orientation: The little short side stub goes over to the water pump. These pumps are ridiculously inexpensive. Good idea in my opinion to change it.

[18Fiatsandcounting]

Thanks for that picture, Roller. Another way to look at it: The thermostat neck that is connected to the inlet of the water pump (the short 4" hose) is open to either of the two other necks, or a mixture. The coolant temperature in the thermostat determines which of these it is. When the coolant (engine) is cold, the neck to the water pump inlet is connected to the neck that goes to the hose that goes upward to the T-connection. As the coolant warms up, the thermostat gradually opens to allow coolant to enter the thermostat from the hose going to the bottom of the radiator as well, and when the coolant is really hot, the internal thermostat "passageway" from the water pump inlet to the top hose should be closed.

I replaced the water pump on my '71 about nine months ago, and of course one of the 4 bolts had "welded" itself to the bolt hole in the water pump. I had to use a Dremel cutoff wheel to cut apart the water pump (to be discarded anyway), and fortunately the bolt threads into the block were fine. Just a heads-up.

-Bryan

[Odoyle]

I can say enough good things about using GMB water pumps compared to any other. They redesigned the impeller to flow better than the stock and it has solved my cooling troubles time and time again.

[maxm50]

Thanks ODoyle - looks like the GMB pump is a whopping $20 on Rockauto. I'll give it a try!

https://www.rockauto.com/en/moreinfo.ph ... 4512&jsn=2