Can the impeller on a water pump go bad?

[custom10nut]

I had a recent thread about having a “Temp Gauge Issue”.
After a process of elimination, I’ve Figured out that the coolant is not circulating.
The water pump is probably 25 years old.
In the the past Five years the truck has sat ALOT. I’d start it up and toy with it, but in those 5 years I’d say I put less that 500 miles on her.
A mechanic friend of mine said it’s possible that the impellers went bad.
After thinking about it, the temp gauge started showing in the “High Normal” range, then Went to showing hot all the time.
I went the rout of “it must be the t-stat”, then “It must be the Sender”, then “it must be the gauge”, never even considering the water pump.
As I’ve said in my other Thread, the engine runs like a top.

[jabborabbo]

Originally Posted by custom10nut

I had a recent thread about having a “Temp Gauge Issue”.
After a process of elimination, I’ve Figured out that the coolant is not circulating.
The water pump is probably 25 years old.
In the the past Five years the truck has sat ALOT. I’d start it up and toy with it, but in those 5 years I’d say I put less that 500 miles on her.
A mechanic friend of mine said it’s possible that the impellers went bad.
After thinking about it, the temp gauge started showing in the “High Normal” range, then Went to showing hot all the time.
I went the rout of “it must be the t-stat”, then “It must be the Sender”, then “it must be the gauge”, never even considering the water pump.
As I’ve said in my other Thread, the engine runs like a top.

Have you checked the water temp with an ether-driven (purely mechanical fluid) gauge? I had a temp problem with a Volvo 240 years ago and the ether-driven gauge showed that the temp was indeed red-lining. I read a thread about the possibility of pump impellers cavitating...I didn’t put much stock in that, but went ahead and replaced the water pump. Didn’t have any problems after that.... And yes, I realize that it sounds like a bunch of crap, but there it is....

[Steeveedee]

Lots of things it could be, in order of my experience:

1. Radiator clogged
2. Stuck thermostat
3. Collapsing lower radiator hose
4. Blown head gasket

Does it do it at idle? Bad fan clutch, or insufficient air flow.
Does it do it at speed? Clogged radiator.

It is entirely possible that the gauge or sender (or the wiring/circuit board) have gone bad.

If the truck has sat a lot, it is entirely possible that the impeller is rusted away enough for this problem. I chased my tail on my truck for awhile and discovered that it liked a high-flow thermostat...after replacing the fan clutch and making a fan shroud to fit the larger fan that I had installed.

I'd recommend cleaning the cooling system with some common product and then taking the radiator to a shop if the flow still looks low. Maybe take the t-stat out first as an easy check, though.

If you're handy, you can just throw a water pump at it for grins. They aren't that expensive. I personally like to make certain that I locate the true problem. When I worked as a mechanic, I wanted to be proud of the correct diagnosis, instead of throwing the customer's money at it. They don't like people guessing with their money. I know I sure don't.

[custom10nut]

Originally Posted by Steeveedee

Lots of things it could be, in order of my experience:

1. Radiator clogged
2. Stuck thermostat
3. Collapsing lower radiator hose
4. Blown head gasket

Does it do it at idle? Bad fan clutch, or insufficient air flow.
Does it do it at speed? Clogged radiator.


It is entirely possible that the gauge or sender (or the wiring/circuit board) have gone bad.

If the truck has sat a lot, it is entirely possible that the impeller is rusted away enough for this problem. I chased my tail on my truck for awhile and discovered that it liked a high-flow thermostat...after replacing the fan clutch and making a fan shroud to fit the larger fan that I had installed.

I'd recommend cleaning the cooling system with some common product and then taking the radiator to a shop if the flow still looks low. Maybe take the t-stat out first as an easy check, though.

If you're handy, you can just throw a water pump at it for grins. They aren't that expensive. I personally like to make certain that I locate the true problem. When I worked as a mechanic, I wanted to be proud of the correct diagnosis, instead of throwing the customer's money at it. They don't like people guessing with their money. I know I sure don't.

Yeah, the thing that has me boggled is
, it’s got a fairly new radiator, new T-stat, New sending unit, the system was flushed about 5 years ago, but as I said before has had very little use.
It starts up fine then the gauge just climbs.

As my friend said, it’s not circulating. I’m going to put the new water pump in and hope for the best.

In the mean time any insight is encouraged.

[kwmech]

I have seen them completely rusted through after sitting for quite a few years. Fill it up and pull the heater hose that feeds the core and see if there is any flow

[72c20customcamper]

YES the impeller can rot away if it's a stamped steel unit. I had a jeep that was overheating. Checked everything when I pulled the water pump there was bits left of the impeller. Changed it out truck ran like normal again

[custom10nut]

I have another water pump that I’m going to change out in the morning. I really hope this is the end of the saga.

[HO455]

It is pretty easy to tell if you have a bad impeller. Drain the coolant until it is 6 to 8 inches down in the radiator. Then start the engine and let it get hot. When it warm enough the thermostat will open. The coolant level will drop and you will see water flow from the tubes in the radiato. The water should be flowing strongly from the tubes not just dribbling out. . It should get stronger when you rev the engine.

A simple check before you pull the pump.

[custom10nut]

Originally Posted by HO455

It is pretty easy to tell if you have a bad impeller. Drain the coolant until it is 6 to 8 inches down in the radiator. Then start the engine and let it get hot. When it warm enough the thermostat will open. The coolant level will drop and you will see water flow from the tubes in the radiato. The water should be flowing strongly from the tubes not just dribbling out. . It should get stronger when you rev the engine.

A simple check before you pull the pump.

Thanks. I’m going to do that this morning. I’m pretty sure it not circulating, but this will be confirmation

[custom10nut]

So I went and drained some coolant and started it up. The gauge did the same, and I could feel the upper hose get hot when the T-stat opened. Looking down in the Radiator there was no coolant moving. So I’m going to say it is a bad water pump. I got it ordered, and just have to wait for it to come in.
I’ll either be up and running this afternoon or tomorrow morning

[custom10nut]

So I put the new pump in, and everything works, except my gauge, still.
I think I have to go with the Auto Wire sending unit, because the pegged out gauge drives me crazy, especially when I know everything is working correctly.
Next, I have to figure out the Vapor Lock issue I’ve developed