Water pump lubricant additives, any benefit?

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I need to replace the coolant in two of the family fleet, firstly my wife's 2005 Chrysler Pacifica. I'll use Zerex G-05.

The last two times one of my vehicles needed a coolant replacement I took it to a local independent father and son shop. I used them quite a bit for about 10 years but they closed last year. I was looking through my maintenance records and I noticed that both times that shop did a cooling system service they flushed the system, replaced the coolant, and automatically added what they called "sealant," which they told me was a "water pump lubricant." I remember my dad using something like this in the 1970's, and I still see various versions of it on auto parts store shelves.

So the question is: is there any need for this nowadays?

My gut reaction is no, as I suspect cooling system material improvements and coolant chemistry advances obviate the need for aftermarket additives. But would it hurt?

I can find generic "cooling system conditioners," plus another class of products that reduce surface tension to improve heat transfer like Amsoil Dominator Coolant Boost and Redline Water Wetter. Amsoil's product sheet specifically says it contains corrosion inhibitors. But is inhibiting corrosion the same as lubricating the water pump? Any idea what chemical constituents make up the conditioner products, and are they of any benefit?
 
If you have the correct 50/50 mixture, that's plenty enough to lube up the water pump.

Some people say the separate water pump lube can clog up your radiator core.
 
Originally Posted By: Merkava_4
If you have the correct 50/50 mixture, that's plenty enough to lube up the water pump.

Some people say the separate water pump lube can clog up your radiator core.


Doesn't the water pump have a sealed bearing?

I don't think thick water has ever served the purpose of a lubricant in vehicles.
 
As others have stated, the bearings are sealed, and lubricated for life.

water_pump_cross_section.jpg


The water seal arrangement is known as a mechanical seal. The two faces (Primary and Mating) ring are extremely hard surfaces (carbides and the like) with incredibly fine finishes.

They rub against each other, and are lubricated by a tiny film of water/coolant between the faces...that's all they need. (At the power stations, these seal are holding back 1,500psi water, 400F, 6" diameter at 7,000RPM, and have nothing but water in them).

Run them dry, and they fail in seconds, if the water flashes to steam in the faces, they fail in minutes. Get debris under them and they will score, leak and run for a long time in that condition.

Additive manufacturers who suggest that they require anything extra are lying through their teeth, or living 60+ years ago.
 
What about the bearing on a 1970 Ford 351C water pump ? Sealed ?

That's the whole reason I got into turning wrenches right there. I used to burn one up every 3 months.
 
Sealed, you have to back a lot longer than that to find them with packing, grease cups or fittings.
The main cause of failure in the earlier cars was incorrect belt tension and old school seal materials.
 
I believe the lube is for old water pumps that used packing,not rubber seals.They used to have grease fittings to lube the bearing inside but the lube was to keep the packing pliable on the outside (water side).
 
Originally Posted By: Merkava_4
If all the bearings are sealed, then why do they purposely make coolant slippery ?



They don't...the chemicals that they use for antifreeze ARE slippery, between your fingers and on the road....they don't add chemicals to make them slippery...only the likes of water wetter and that RP stuff, and soluble oils additive manufacturers claim that coolant is made to be slippery.

But the additive manufacturers claim that they are needed to "lubricate" water pumps, while being non slippery on the track.

How does that work ?
 
In the days we used alcohol anti freeze for winter and water in the summer it was common to use a lube or conditioner in the radiator.
With the advancements in coolant and modern pumps it is unnecessary.
 
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Originally Posted By: Merkava_4
If all the bearings are sealed, then why do they purposely make coolant slippery ?


So its slips around inside your engine better.
lol.gif
 
Originally Posted By: Merkava_4
If all the bearings are sealed, then why do they purposely make coolant slippery ?


Who are "they" and how do "they" "purposely" make coolant slippery?
 
Great information, thanks gents.

Shannow: many thanks for the diagram and explanation! It's exactly what I was looking for, and completely refutes the need for any aftermarket lubricant.

Your explanation of steam causing failure in minutes also clarifies why the shop I was mentioning replaced the water pump immediately after an episode where my wife drove the car till the ECM shut it off, after popping a rad hose and losing all the coolant. I thought it was due to potential warpage from overheating, but now I see it's also likely that the seal would have been permanently damaged.

I much appreciate the detailed explanations, as knowing why is far better than just knowing.
 
Originally Posted By: MolaKule
Doesn't the water pump have a sealed bearing?

Lubricating the seal is the issue - not the bearing.
Originally Posted By: Shannow
They rub against each other, and are lubricated by a tiny film of water/coolant between the faces...that's all they need.

Therefore, it's logical to conclude that anything improving the lubricity of that "tiny film" will contribute to longer seal life.
 
You should witness the spectacular show when the water pump seal on a Cummins 5.9 fails suddenly and catastrophically. I like stuff that might prevent or delay this type thing, even if the only real benefit is just making me feel better about it:

CTD_239.jpg

There is a real potential for radiator damage and other nasties when this happens.
 
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The water pump has nothing that an added lube can do. I have rebuilt a couple water pumps and they are a sealed bearing with a shaft pressed into the center and the shaft and bearing then pressed into the water pump housing. Once the seal on the bearing wears out the coolant washes the lube from the sealed bearing the end comes soon.
 
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