Water pump differences question

[Buick35]

My original 35 40 series water pump which has the flange nut and oil caps looks like it had a different impeller( more fins) than a replacement one I got that has the self lubricating bearings without the 1 1/8" nut. Both will fit. My question is will the earlier pump water better than the other later one or are they the same? Like you might know from my other blog my replacement newer style pump came with an aluminum cover plate which was corroding.

Edited August 6, 2022 by Buick35
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[Jim Nelson]

The 37 / 38 water pumps have a 1-1/2" inlet  piping.   Does your 35-40 series engine Water Pump (pump inlet  - radiator outlet ) have the same size ?      My 35-50 series has a 1-3/8"  radiator outlet  and the  37-40 and the  38 -40  (248)  has the 1-1/2".    I had to make up a transition hose to get from the 1-3/8" radiator outlet  to the 1-1/2" water pump.      Is your radiator (35-40) a two core or three core radiator.    Mine is a three core and is 20" wide and max 21-1/2"  high.       

[Bloo]

I have a thread going about a bunch of Pontiac water pumps, I think you saw it. Pontiac, and I would bet Buick too, made "modern" replacement water pumps with modern bearings and seals later on for their earlier cars. The modern setup is better in all respects except one thing. If it starts leaking on a tour, you can't just tighten the nut. The pump has to be pressed apart and rebuilt, and there would probably be lead time for that. They won't have a pump at the parts store.

 

Apart from that, with the new bearing you don't have to be quite so careful about belt tension, you don't have to remember to oil the pump, it's less messy because the modern one does not have to leak a tiny bit of coolant to lubricate the shaft and packing, it can far better deal with a pressure cap (4 lbs) if you convert the radiator to take one, maybe even 16 lbs if a more modern seal is used in the pump rebuild. Also, oil from the bushings won't be slowly leeching into your cooling system.

 

On the other hand, with the old style packing nut pump if you maintain it properly there isn't much to go wrong once it has been rebuilt. If it starts leaking, tighten the nut a little to slow the leak. If the nut bottoms out, stuff more packing in.

 

I'm rebuilding both. I am planning to use the packing nut pump and keep the modern one around for a spare. I don't expect to need it.

 

 

[Buick35]

2 hours ago, Bloo said:

I have a thread going about a bunch of Pontiac water pumps, I think you saw it. Pontiac, and I would bet Buick too, made "modern" replacement water pumps with modern bearings and seals later on for their earlier cars. The modern setup is better in all respects except one thing. If it starts leaking on a tour, you can't just tighten the nut. The pump has to be pressed apart and rebuilt, and there would probably be lead time for that. They won't have a pump at the parts store.

 

Apart from that, with the new bearing you don't have to be quite so careful about belt tension, you don't have to remember to oil the pump, it's less messy because the modern one does not have to leak a tiny bit of coolant to lubricate the shaft and packing, it can far better deal with a pressure cap (4 lbs) if you convert the radiator to take one, maybe even 16 lbs if a more modern seal is used in the pump rebuild. Also, oil from the bushings won't be slowly leeching into your cooling system.

 

On the other hand, with the old style packing nut pump if you maintain it properly there isn't much to go wrong once it has been rebuilt. If it starts leaking, tighten the nut a little to slow the leak. If the nut bottoms out, stuff more packing in.

 

I'm rebuilding both. I am planning to use the packing nut pump and keep the modern one around for a spare. I don't expect to need it.

 

 

That's what I plan on too. I hope when I get my back cover I ordered it will be steel. Though the old style pump I sent back has a steel cover it also has a pin hole that's leaking water through.

[Buick35]

On 8/6/2022 at 6:42 PM, Bloo said:

I have a thread going about a bunch of Pontiac water pumps, I think you saw it. Pontiac, and I would bet Buick too, made "modern" replacement water pumps with modern bearings and seals later on for their earlier cars. The modern setup is better in all respects except one thing. If it starts leaking on a tour, you can't just tighten the nut. The pump has to be pressed apart and rebuilt, and there would probably be lead time for that. They won't have a pump at the parts store.

 

Apart from that, with the new bearing you don't have to be quite so careful about belt tension, you don't have to remember to oil the pump, it's less messy because the modern one does not have to leak a tiny bit of coolant to lubricate the shaft and packing, it can far better deal with a pressure cap (4 lbs) if you convert the radiator to take one, maybe even 16 lbs if a more modern seal is used in the pump rebuild. Also, oil from the bushings won't be slowly leeching into your cooling system.

 

On the other hand, with the old style packing nut pump if you maintain it properly there isn't much to go wrong once it has been rebuilt. If it starts leaking, tighten the nut a little to slow the leak. If the nut bottoms out, stuff more packing in.

 

I'm rebuilding both. I am planning to use the packing nut pump and keep the modern one around for a spare. I don't expect to need it.

 

 

I installed the newer style pump back on today after I put a new steel backing plate on it.It's a universal fitting hub in that it has eight bolt holes for the pulley/fan and I only use four.The hub also didn't have a raised shoulder for the pulley to fit on.I finally got it to all line up in this 100percent humidity. What a pain! My older style pump is on its way back from the rebuilders.I think I'll just leave it for a spare. Greg.

[Buick35]

On 8/6/2022 at 6:42 PM, Bloo said:

I have a thread going about a bunch of Pontiac water pumps, I think you saw it. Pontiac, and I would bet Buick too, made "modern" replacement water pumps with modern bearings and seals later on for their earlier cars. The modern setup is better in all respects except one thing. If it starts leaking on a tour, you can't just tighten the nut. The pump has to be pressed apart and rebuilt, and there would probably be lead time for that. They won't have a pump at the parts store.

 

Apart from that, with the new bearing you don't have to be quite so careful about belt tension, you don't have to remember to oil the pump, it's less messy because the modern one does not have to leak a tiny bit of coolant to lubricate the shaft and packing, it can far better deal with a pressure cap (4 lbs) if you convert the radiator to take one, maybe even 16 lbs if a more modern seal is used in the pump rebuild. Also, oil from the bushings won't be slowly leeching into your cooling system.

 

On the other hand, with the old style packing nut pump if you maintain it properly there isn't much to go wrong once it has been rebuilt. If it starts leaking, tighten the nut a little to slow the leak. If the nut bottoms out, stuff more packing in.

 

I'm rebuilding both. I am planning to use the packing nut pump and keep the modern one around for a spare. I don't expect to need it.

 

 

I got the packing nut one back from the rebuilders yesterday but I'm going to keep it for a spare.Greg