350 Water Pump Woes

[racerboy9]

I am on my third low mileage NAPA water pump on my 1984 K10 4x4. The pump doesn't wear out but the back plate erodes to the point it leaks. Always has 50/50 antifreeze. It doesn't leak from corrosion but seems to erode from the water action against the back plate. If the back plate was hardened I don't think I would be having this problem. Any tips for a solution is appreciated.

 

[75gmck25]

I used the cheapest Stewart high flow water pump and it’s been in my truck for at least 15 years. Keeps the truck cool without any problem. I also use a Stewart high flow 195 degree thermostat.

My pump is the small block Stage One, and Summit has them for about $110. More expensive than a NAPA pump, but still reasonable.

 

[Bextreme04]

I've had a NAPA water pump on my 350 for at least 4 years now on two different motors and zero leaks. I also have one on my L29 454 that is getting ready to go in. I think you have another problem TBH.

 

[SirRobyn0]

I am on my third low mileage NAPA water pump on my 1984 K10 4x4. The pump doesn't wear out but the back plate erodes to the point it leaks. Always has 50/50 antifreeze. It doesn't leak from corrosion but seems to erode from the water action against the back plate. If the back plate was hardened I don't think I would be having this problem. Any tips for a solution is appreciated.

Are you purchasing remanufactured Napa pumps or new? If they are remanufactured they might have all ready had pin holes in it, that they patched up during the remanufacturing process and didn't do a very good job. It look like Gates make the new water pumps for Napa and rayloc the reman'ed units. My vote I think you've gotten a run of pumps with flaws in the, purchase a new pump instead of remanufactured. Or change brands, get one from another supplier if necessary. Make sure you use good quality anti-freeze you can always put an additive in the coolant with a good anti-corrosion package such as Kool-it or Mac's radiator anti-rust if that is still available, but I think if it was something wrong with the truck or the anti-freeze you'd be having other issues as well.

 

[fast 99]

Make sure all grounds are intact. Block to body, body to battery, battery to block. Have seen corrosion issues caused by missing or poor grounds. Usually, the heater core is the first thing that goes but grounds are cheap and adding extras won't hurt anything.

 

[SquareRoot]

Check the hardness of your water...lol, just kidding. Napa now sells mostly cheap Chinese junk. I just bought and installed a Tuff Stuff pump. It was so purty and well built I almost just put it on the shelf.

 

[SirRobyn0]

Check the hardness of your water...lol, just kidding. Napa now sells mostly cheap Chinese junk. I just bought and installed a Tuff Stuff pump. It was so purty and well built I almost just put it on the shelf.

Don't forget to tell him to add chorine and shock it once a week. (kidding of course).

 

[Bextreme04]

In all fairness... sometimes we think it doesn't need to be said, but it does. Use concentrate antifreeze and mix 50/50 with distilled water or use the pre-diluted. Never use tap water to dilute your coolant.

The grounding and corrosion issue will show itself more if you are using tap water instead of distilled.

 

[SirRobyn0]

In all fairness... sometimes we think it doesn't need to be said, but it does. Use concentrate antifreeze and mix 50/50 with distilled water or use the pre-diluted. Never use tap water to dilute your coolant.

The grounding and corrosion issue will show itself more if you are using tap water instead of distilled.

Eric is absolutely right about this, I still think that if it was a coolant issue or ground / electrolysis issue that it would be showing up in other places besides the back of his water pumps, but you never know. Seriously, though Mike and I just made a pool joke out of coolant your tap water does matter, if your using city water there are all kinds of additives in the water from chlorine to fluoride, and if your on a well if your water is hard or has a lot of iron in it that's definitely bad, hard water will leave deposits in your cooling system, and acidic water can do damage, but it's usually done over time. The shop I work at is on city water so we buy only pre-mixed, on the farm the water is hard, but I prefer to buy concentrate and use distilled water.

I think the take away is to get another water pump, try to make sure it is of good quality (you can run brand names past us your looking at) and make sure you do everything correctly with the coolant and you should be good to go.

 

[waterpirate]

Ask anybody that has run a boat in salt water, and you will quickly learn about electrolysis. I would drain the entire cooling system, flush with clean water, and then go back in with a water that has a neutral ph, no hardness.
Eric

 

[fast 99]

PH test strips are available.
We use them when hooked up to the flush machine.

 

[racerboy9]

I will be pulling the pump today to have a look and will post up a few pics.

 

[Ricko1966]

Is everything stock on your cooling system, especially the engine pulleys? What ratio of antifreeze mix are you running? I'm suspicious of cavitation damage, especially if you don't have the correct pulleys on your engine.

 

[racerboy9]

I use Zerex G05 50/50 mix. My truck originally had a 305 with a ton of miles and wiped the cam so I put a new GM 350 crate motor in and swapped the pulleys from the 305.

 

[racerboy9]

Pulled the pump and same back plate problem as my last one. Erosion, corrosion and pinholes. Always had anti-freeze mix. I could just put a new back plate on but given the work involved it seems better to get a new pump with a more heavy duty back plate. Most of the new pumps tout being "high flow" but I don't really need more flow.