1951 Water Pump

[dirty dan]

I have a P-23 Engine in my 1946 2 Door Sedan. (Lucky me)

Can anyone confirm if an A1 Cardone #58-459 Water Pump is correct for this engine?

The Cardone website shows R/R only for a water pump for a '51 Cambridge, but my local parts store says the 58-459 is correct.

[55 Fargo]

The waterpump you need for the P 23 engine is the internal by-pass type, if you use the non by-pass type you will have problems, as your engine is designed to use the internal by-pass waterpump.

I am not sure if the water pumps for the 23.5 inch block is different than the pump for the 25 inch block, but I doubt it.

[dirty dan]

The waterpump you need for the P 23 engine is the internal by-pass type, if you use the non by-pass type you will have problems, as your engine is designed to use the internal by-pass waterpump.

I am not sure if the water pumps for the 23.5 inch block is different than the pump for the 25 inch block, but I doubt it.

I can't find a picture that shows the rear of that water pump. Are you saying that it's an external bypass style pump? The parts store doesn't have that information.

[Don Coatney]

The waterpump you need for the P 23 engine is the internal by-pass type, if you use the non by-pass type you will have problems, as your engine is designed to use the internal by-pass waterpump.

I am not sure if the water pumps for the 23.5 inch block is different than the pump for the 25 inch block, but I doubt it.

Water pumps do not care if the system is internal or external by-pass. The difference is in the backing plate for the water pump not the pump itself. Long block and short block water pumps are the same.

[55 Fargo]

This is true, but should you not use the pump that has the backing pplate for internal by-pass, for an internal by-pass engine?

I read somewhere on our website, that you can use the waterpump designed for internal bypass on a non- bypass engine, because the by-pass is in the t/stat housing, with the short hose, correct?

But you should not use the waterpump designed for an external by-pass engine on the internal by-pass engine (1950 and beyond), as the coolant would not by-pass, with this type of waterpump, is that correct?

If I am wrong, I would like to know what is need, just in case I need to change my water pump.......Fred

[greg g]

The pump is the pump is the pump. When you remove the old one, check the rear of the unit, if it is different from the one you just bought, swap the rear plates. If your thrmostat housing is a big hunk of cast iron with a short hose attached to the water pump it external. If there is no hose, and the stat housing is a small steel stamping, it is an internal bypass. The application and reason you have one or the other is one of historoes mysteries, my 45 engine was internal, and so was the 56 I picked up. I have seen both in many different applications.

[Young Ed]

I have to disagree a little on the pumps being all the same. I have seen newer pump that only have a pipe thread for the heater outlet and no bolt holes for the bolt on piece that goes back towards the thermostat outlet on the older style ones.

[55 Fargo]

Greg has one solution. Buy the new pump. If the new one doesn't have the correct backing plate you have two choices. One........do what Greg said and switch backing plates. Two........if you don't want to use the old backing plate' date=' take both pumps back to the store, show them the difference and either get a refund or exchange on the new one.

FYI, when I bought my new pump from JC Whitney back in the late 90's it came so I could use it either way.[/quote']

Thanx Norm, as you have said, you can use the internal by-pass waterpump on the external by-pass engine, as the external design contiues to work as normal.

It's the reverse, where you need to either have the correct waterpump or switch the backplate, to use on the internal by-pass engine.

I would opt for the compare the pumps at the parts store and get the correct pump.

[dirty dan]

OK...

I ordered it.$49.99 + $15.00 Core.

I'll let y'all (it a southern thing) know how it turns out.

[55 Fargo]

Did y'all order from Rock Auto, they have real fine prices for a lot of parts for our cars, all the best..............Fred

[Don Coatney]

This is true, but should you not use the pump that has the backing pplate for internal by-pass, for an internal by-pass engine?

I read somewhere on our website, that you can use the waterpump designed for internal bypass on a non- bypass engine, because the by-pass is in the t/stat housing, with the short hose, correct?

But you should not use the waterpump designed for an external by-pass engine on the internal by-pass engine (1950 and beyond), as the coolant would not by-pass, with this type of waterpump, is that correct?

If I am wrong, I would like to know what is need, just in case I need to change my water pump.......Fred

Fred;

Thought I answered that. Water pumps do not care if the system is internal or external by-pass. The difference is in the backing plate for the water pump not the pump itself.

OK...

I ordered it.$49.99 + $15.00 Core.

I'll let y'all (it a southern thing) know how it turns out.

dirty dan;

If the pump was new why do you have to pay a core charge?

[55 Fargo]

Fred;

Thought I answered that. Water pumps do not care if the system is internal or external by-pass. The difference is in the backing plate for the water pump not the pump itself.

dirty dan;

If the pump was new why do you have to pay a core charge?

Okay, I now realize it's the backing plate, and not the pump itself...........Thanx Fred

[dirty dan]

Did y'all order from Rock Auto, they have real fine prices for a lot of parts for our cars, all the best..............Fred

Ordered from O'Reilly Auto Parts. It will be there in the morning at 07:30.

Don,

It's a reman.

[dirty dan]

OK. Got the pump. The A1 Cardone #58-459 is the correct pump and has the built in bypass. It is a reman and has the zerk fitting (I like that). $49.99 (+ $15.00 core) from O'Reilly Auto Parts.

[55 Fargo]

Glad to hear you were able to get the right pump, price sounds good too........Fred

[Don Coatney]

OK. Got the pump. The A1 Cardone #58-459 is the correct pump and has the built in bypass. It is a reman and has the zerk fitting (I like that). $49.99 (+ $15.00 core) from O'Reilly Auto Parts.

Make sure you use the correct grease for your water pump. The grease used to lubricate boat trailer wheel bearings will work. Standard chassie grease will not work. Also do not over grease the water pump or wou will blow the seal.

[dodgebomb]

what identifies the bypass (internal) on the backing plate for the pump? Is it just a small hole (besides the water jacket hole that is)on the face of it? Asking cause I have a couple different units, trying to make one and want to go internal. Also i noticed there to be two different types of impellor blades. Is one more efficient than the other? New here, thanks.

[martybose]

The only difference in the backing plate is one additional small hole, which mates up to a hole on the front of the block, which has a right angle passage to the front edge of the head surface, where it mates up with a passage in the head. In the small block motors (23" 218 and 230) only the later blocks are set up for internal bypass, so make sure that you have both the block and head for an internal bypass!

Marty

[dirty dan]

what identifies the bypass (internal) on the backing plate for the pump? Is it just a small hole (besides the water jacket hole that is)on the face of it? Asking cause I have a couple different units, trying to make one and want to go internal. Also i noticed there to be two different types of impellor blades. Is one more efficient than the other? New here, thanks.

There is a @ 1/4" hole on the plate behind the impellar for the internal bypass.

[Don Coatney]

The only difference in the backing plate is one additional small hole, which mates up to a hole on the front of the block, which has a right angle passage to the front edge of the head surface, where it mates up with a passage in the head. In the small block motors (23" 218 and 230) only the later blocks are set up for internal bypass, so make sure that you have both the block and head for an internal bypass!

Marty

Marty;

Are you sure all internal by-pass engines have the bump on the front of the head and block?

[martybose]

Marty;

Are you sure all internal by-pass engines have the bump on the front of the head and block?

I'm not SURE, but there isn't any way an internal bypass would even work without the extra machining in the block and a connection from the thermostat area to use it! There might be bumpless heads that do this for all I know.

Marty