Water pump failing ?

[Drillman]

Hi guys,
Just bouncing ideas at the moment as I'm having temp issues. 1997 Sierra 2500 6.5ltr, replaced radiator and fan hub. Temp still sitting around 195 to 200 without towing. Tows fine on flat but under load on a hill pulling 9000lb trailer and it's "Huston we have a problem".
Did notice though that new fan hub is now not kicking in.
Please correct me if I'm wrong as just trying some lateral thinking.
Water pump failing and not moving water fast enough causing engine to get hot under load while water in radiator is cooler and air temp through radiator not enough to cause fan to engage.
Does this sound logical ?

[Dvldog8793]

Howdy
Did you clean out the AC core in front of the radiator?
If you don't get air flow through the AC core then it cant go through the radiator to get the fan clutch to kick in.
You should be able to hear the fan kick in.
If you have a temp gun you can run it up to hot and then stop and check to where the hear is. If it stops at the stats, then you have a flow problem if it is hot all over then then the fan is not kicking in and you either have a clutch issue or a air flow problem.
Hope this help!

[Drillman]

Yes cleaned everything to ensure air flow when changing the radiator. Fan clutch is new from Kennedy Diesel so shouldn't be the issue.

[Robyn]

How old is the radiator ???

[trbankii]

“Water pump failing” usually shows up as leaking coolant out the weep hole.

[Robyn]

I agree 100% on the leak indicating a bad pump.

This rig should have dual T stats.

Make sure these are the correct ones that have the flow control plate on the bottom to shut off the bypass port once the flow to the radiator starts.

If the radiator is not new (As in still the factory unit) this is likely the issue.

[Drillman]

Radiator is new. About to replace both thermostats and water pump just to cover all bases. Cheaper than a blown motor in the long run. Doesn't the weep hole indicate shaft seal ? Is it possible for impeller to be shot without fluid from telltale?

[Dvldog8793]

Howdy
Personally I have never seen a water pump impeller fail. That's just my experience. I have seen shaft bearing failures with the weep hole NOT dripping.
I would expect it is either the thermostats or the fan not kicking in.
Make sure to replace the stats with the RIGHT ones.
IMHO, I would replace those before the water pump and see what happens.
Can you verify by sound that the fan is engaging?
Can trace the heat buildup with a temp gun? That should tell you if it is the stats. You can also hit the fan clutch with a temp gun and see if it is engaged.

[Drillman]

When the fan kicks in you get the audible howl that's hard to miss. I have had a pump go on a petrol Ford and it's not that it stopped but wasn't moving enough fluid. As I said I've ordered pump and stats just to be safe so will fit the lot. No fluid loss so would think heads are all good. Just don't need issues as moving horses in the 5th wheeler. Don't have a temp gun but should probably invest in one by the sounds of it.

[Drillman]

Well finally we have a result.
After new radiator, fan hub, thermostats and water pump still we had high temps.
I was at the point of increasing the temp myself with and can of fuel and a match and I decided to try one last thing. I replaced the temp guage with a Saas electric system.
Problem solved. Running 85 to 90 c (185 to 195 f ) so basically I was being lied to by the stock guage. Still yet to see how it goes with 9000lb horse trailer but at least now I'm fairly confident of a trouble free run. Up side is that with 334,000 kms on the truck she was probably due for some new ear and now the cooling system is new.
😁😁😁😁😂

[Robyn]

Good deal.

Glad to hear all is better.

The electrical systems on the gauges are just too flaky to be trusted.

A bit of a bad ground here and there and all bets are off as to what you are seeing on the dash gauge.