Let's beat this water pump dead horse one more time

[Jim Yergin]

I am planning on using an external bypass water pump on a later block that has an internal bypass passage. Is the external bypass water pump gasket and the solid water pump rear plate sufficient to close off the internal bypass opening in the block or do I need to something more to prevent any coolant leakage behind the water pump?

Jim Yergin

[Merle Coggins]

Why not just get a water pump for the internal bypass system? If you go with the external bypass water pump you will also need the external bypass thermostat system to go with it. Then as long as the small hole, in the block, behind the water pump is sealed off by the pump gasket, it should work.

Merle

[Jim Yergin]

Merle,

I have the external thermostat system and a new external bypass water pump from my old engine and want to use them on the new block. My concern was whether the gasket blocking the internal bypass opening is sufficient to stop any leakage. Thanks for letting me know that you think it is.

Jim Yergin

[55 Fargo]

Jim, you are basically using the t/stat housing, and external by-pass pump on the internal by pass block.

1st question, have you tried this before, 2nd question, could you go strictly internal bypass, you would need the t/stat housing, the waterpump, thats it.

From your question, I see you want to use the new waterpump you already have, I would want to also if in your position.

Here is the scoop, you can use an internal by-pass wter pump on an external by pass system, but not the reverse. The internal system, normally has the t/stat housing which houses only a t/stat, no by-pass hose to direct water thorugh the waterpump into the block, etc. But since you have the external t/stat housing and the waterpump, you may be able to make this work, as you said, you need to seal off the internal by pass system from water pump to block, a good gasket and sealant should take care of this.

Your coolant system is not under pressure, so you do not risk anything because of a pressurized system. Not sure if that helped.........Fred

[Jim Yergin]

Fred,

I think you confirmed what I thought. Since I am not relying upon the internal bypass but rather the external bypass with the proper fittings on the top of the pump and the cylinder head, I can use the external bypass water pump. Your point about there not being any pressure is a good one and one I had not considered. I will use some sealant on the internal bypass opening and rely upon the new gasket and the solid backing plate on the pump to seal that opening.

Thanks.

Jim Yergin

[55 Fargo]

Jim double verify this, so there are no hidden surprises later, as long as the coolant can circulate, before the t/stat opens is critical.............Fred PS Tim Adams or Greybeard might know the answer to this

[james curl]

If you are using a head without the bump out for the water passage then you will have to plug the hole in the block to prevent the water from running out the uncovered hole in the block. When using old alum heads on late model blocks you have to use the t/stat housing with the external by pass and block the hole in the block that is not covered by the head.

[Jim Yergin]

James,

The head I am using has the "bump" that covers the internal bypass opening in the top of the block. My question is about the internal bypass opening in the end of the block behind the water pump. Does that need to be blocked by something more than the water pump gasket and the external bypass water pump?

Thanks.

Jim Yergin

[james curl]

I would think not, as there is no pressure on the system. I brought up the issue of the head with no bump out because a friend has a 52 Plymouth and has an old original P-15 Fenton alum. head which does not have the bump and he will have to seal the hole at the top of the block to prevent the water from coming out.