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OK

Before TS gets in here. I found several sources of information. This one looks the most useful

COMMON WATER PUMP FAILURES & THEIR CAUSES | FlowKooler Water Pumps - Chevy, Dodge, Jeep, Ford, & more

Exerpt here for your consideration:
1. LEAKING FROM THE WEEP HOLE: To understand leaking from a weep hole let's begin with some common questions and answers.
• What is the purpose of a weep hole?
The two holes you see in the water pump casting are called weep holes. The upper weep hole acts as an air vent. It allows air to evacuate the casting system and prevents the build up of humidity around the bearing. Also the vent allows atmospheric pressure into the pump and the seal remains seated.
The lower weep hole exists to allow fluid to collect or drain out of the water pump to protect the bearing integrity. In a horizontal centrifugal pump there is little space between the bearing and the seal so fluid build-up could potentially threaten the bearing. Weep holes permit this coolant to evacuate the system and protect the bearing. Weep holes also allow atmospheric pressure into the pumps and help the seals to remain seated.
• Does a drip from the weep hole mean seal or pump failure?
Perhaps. Seals will drip as the seal lap in but to understand a more prolonged or intermittent “drip” you have to understand a seal’s design. Seals purposefully drip because capillary action draws fluid from the seal face. As the seal drips, it helps wash loose debris out and reduce the heat load. Most drips evaporate or fall on the road and are not noticed.
Naturally, a more pronounced drip indicates a compromised seal and impending bearing failure.
• What causes a seal to prematurely fail?
High Temperatures:
Mechanical seal have spring-loaded assemblies to keep the carbon seals intact and rubber parts that may disintegrate if the engine runs hot or overheats. If a system overheats to the point of boiling out and the system is permitted to run dry, the polished sealing faces can wear and warp. A worn seal face allows fluids to escape and leak out the weep hole. Most pumps will leak catastrophically shortly after a boil-over.
Electrolysis:
Electrolysis may cause filming and/or crystallization on the seal face and cause the seals to permit fluid into the weep chamber. High mileage vehicle tend to have a greater incidence of seal failure due to pH imbalance that compromises the seal face causing fluids to leak out the weep hole.
Corrosive inhibitors are made up of silicates which plate metal surfaces. The degree of plating that actually occurs varies but as it does, the silicate levels deteriorate over time and the coolant becomes more corrosive. As the corrosion inhibitors deteriorate and the pH of the coolant drops to 7 or below, the result is electrolysis and plating. For this reason most mechanics and recommend a flush & fill at 24 months/30,000 miles. Unfortunately, few car owners flush and fill and radiators and water pump seals become compromised.
Additive Gels:
It seems every few months a new chemical additive for the cooling system comes on the market. Seal manufacturers find concentrations of gel from these additives and/or filming deposits build on the seal face or they find carbon rip out on the ring. These all contribute to premature seal failure.
Abrasive particles
If there are abrasive particles present in the cooling fluid can affect the wear resistance of the seal. Sand is the most common.
2. BROKEN WATER PUMP HOUSINGS AND SHAFTS COMMONLY CAUSED BY: Broken shafts are result of excessive vibration & unbalance and principally due to:
• Bent, cracked, or broken fans
• Fan not squarely mounted on the shafts
• Cracked or bent pulleys due to improper handling or installation
• Overtightened belts cause overload on the bearing and impose a powerful bending force on the shaft causing it to deflect substantially from true center rotation resulting in imbalance and early shaft fracture
 

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Having read this, I suspect that some of the early failures are due to heat. A bubble of air gets into the system, that results in cavitation of the pump, the lack of coolant flow allows localized overheating, that overheated coolant begins to move again, travels to the pump area and transfers the heat to the seal area . .. failed seal.

If you have the PH checked, you can tell if you are subject to electrolysis. This is basically the test that my GM tech has been running to identify when the fluid needs to be flushed.
 

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I have to say it's poor design....the undue stress that is put on a direct drive pulley. Has anyone looked at the '02 Vette (I think). They had a direct drive alternator and A/C compressor. Wondering if their failures are as numerous.
 

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Or it could just be GM sourced their pumps from the lowest competitive bidder?

Just saying.................

:lol:
That is of course always a consideration, but I have to believe that GM provided the mechanical design and the design paramaters. And I would be surprised if the manufacturer built things that are likely to fail like the seal. The seals and many (most?) of the parts making up the pump come from second and third tier suppliers.

Also, since the pump is used in all ecotec motors, I wonder what the failure rate is in other cars with a similar motor. Are Cobalts having similar failure rates? I have not read that they have the same challenges with their cooling systems injesting air for instance.:thumbs:
 

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I have to say it's poor design....the undue stress that is put on a direct drive pulley. Has anyone looked at the '02 Vette (I think). They had a direct drive alternator and A/C compressor. Wondering if their failures are as numerous.
While I am sympathetic with your statement, I have no evidence other than the current failure rates that its a good design or a bad design. The water pump loading is not a particularly challenging environment, nor are the loads all that high. I guess I would like to understand better what is the basis for your statement.

Maybe the shock loads are higher? But it does not appear that the failures are due to purely mechanical failures but instead the seals are going bad and puking out the coolant in many (most?) of the cases we have seen documented.
 

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Hmmm: I just hit the Cobalt Forum and did a quick search. Seems like a lot of familiar territory with over temp/coolant issues. :lol:

But there does seem to be a higher number of PYTs frequenting that particular forum. Perhaps I need to hang out there. :rofl:
 

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I have to say it's poor design....the undue stress that is put on a direct drive pulley. Has anyone looked at the '02 Vette (I think). They had a direct drive alternator and A/C compressor. Wondering if their failures are as numerous.
BINGO!!! digalingaling!! and the winner is Da Ghost...:thumbs: Whatcha want fer ur prize buddy..:willy:

runner up prize goes to GS1 for post #4..:D
 

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Rob,
Do you know the PH?
LLLFLY
 

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I'm not a fan of sprocket driven water pumps off the timing chain. Look at the bearing and seal diameters of the other chain driven components. Serp belt components have similar shaft diameters as a water pump because less lateral load on the bearing.
 

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So after it was brought up about the number of other LNF motors in other models with WP issues, I posted on several other boards. Very FEW in the HHR or Cobalt have had failiures....many of them being over 120k before they had an issue at all. So, what makes the Solstice and Sky so vulnerable to WP failure? Is it the rear wheel drive? hmmmmm.....this is an interesting question. I will do research on the Corvette that had a majority of the accessories driven internally. And repost here in a day or so....
 

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If I had to guess I would say its heat. The kappas are more susceptible to overheating.

I would like to see a correlation between over heating and pump failures.
 

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Off to CVS.
LLLFLY
 

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In response to GS' comment re: "lowest bidder" - it is incredibly rare that a domestic car maker does anything BUT grant the work to the lowest bidder. It's been a while since I've supplied anything direct to an OEM but a few years back it was common for them to select the lowest price, require annual price reductions, AND have the supplier commit to covering warranty costs. In many cases the supplier will also design the component or system.

The theory is that the supplier knows his business so he's going to design something that is cost effective to build and if he's responsible for the warranty cost, he's not going to produce something that is prone to failure. The problems start when the supplier has to reduce his price every year for 3 to 5 years. That requires greater efficiencies in his process and/or reduced material costs. Remember the Ford/Firestone tire failures? Nobody will admit it, but Firestone left out a wind of wire in order to get their costs down.

I think the thread is headed in the right direction though. There must be an environmental or mechanical reason the Kappa goes through water pumps more than other vehicles. I'd be shocked if the seals and many of the components are not common across many different water pumps and vehicles - possibly even non-GM vehicles.

Shock loads, heat, etc as many of you have brought up would be suspicious. It would be interesting to see a breakdown of GXP versus N/A, auto versus manual, etc.
 

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I agree with Rob. Practically all the Ecotec engines including the 2.2 in my 2004 Cavalier use the same water pump as in the LNF and water pumps aren't an issue there. I suspect it's heat and perhaps cavitation from air in the system that makes the pumps fail prematurely.
 

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In response to GS' comment re: "lowest bidder" - it is incredibly rare that a domestic car maker does anything BUT grant the work to the lowest bidder. It's been a while since I've supplied anything direct to an OEM but a few years back it was common for them to select the lowest price, require annual price reductions, AND have the supplier commit to covering warranty costs. In many cases the supplier will also design the component or system.

The theory is that the supplier knows his business so he's going to design something that is cost effective to build and if he's responsible for the warranty cost, he's not going to produce something that is prone to failure. The problems start when the supplier has to reduce his price every year for 3 to 5 years. That requires greater efficiencies in his process and/or reduced material costs. Remember the Ford/Firestone tire failures? Nobody will admit it, but Firestone left out a wind of wire in order to get their costs down.

I think the thread is headed in the right direction though. There must be an environmental or mechanical reason the Kappa goes through water pumps more than other vehicles. I'd be shocked if the seals and many of the components are not common across many different water pumps and vehicles - possibly even non-GM vehicles.

Shock loads, heat, etc as many of you have brought up would be suspicious. It would be interesting to see a breakdown of GXP versus N/A, auto versus manual, etc.
Good points.

In every production program that I have been involved with, there is a lot of discussion about the shape of the manufacturing learning curve. There are a lot of assumptions made on how quickly performing repetitive processes over time will yield lower costs due to efficiencies. Many manufacturers get in trouble by over estimating the cost savings down the line when setting their starting price structure.

Experience curve effects - Wikipedia, the free encyclopedia
 

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I am continuing my research. Found this

Gates offers the tool to address the need for a more thorough way to flush radiators, engine blocks and, most importantly, heater cores. Extensive chemical laboratory testing of coolants and their behavior on water pumps showed that improper cooling maintenance adversely impacts the water pump. Cross contamination of coolant and mixing of coolant chemistry can lead to premature and catastrophic water pump failures.
Field testing also showed that conventional flushing methods do not remove enough solid contaminants, which are held in suspension or have fallen out of suspension and remain in the system. These solids damage the water pump seal, the most critical component.

Tests by the American Society for Testing Materials (ASTM) as well as Gates research show that water pump surface material loss does take place in the system and is not limited to the water pump. This material loss is harmful to water pump seals and results in compromised mating seal surfaces. Over time, all metal components in the cooling system can succumb to premature failure.


And


An auto's water pump failure is usually caused by a bearing failure on the pump shaft accompanied by a water leak. The water leak is generally witnessed coming out of the weep hole at the bottom of the pump. There can also be a leak around the gasket located behind the pump. At times, water pumps have be seen to leak at a certain spot on the bearing surface. A water pump definitely does not leak when the engine is shut off, so it must be pressure tested when the engine is running.

Use a radiator pressure tester for this test. Remove the radiator cap when the engine is cold. Fill the radiator as necessary to bring it to the normal level. Pump the pressure tester up to 15 pounds and look closely to the water pump for leaks. If any leaks are present, the pump needs to be replaced. While the pressure tester is pumped up, check for leaks in the radiator, hoses, the top of the engine for intake manifold leaks, the side of the engine for freeze plug leaks and at the heater core.
 
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