Water Pump Heater Line Questions

Attached is a photo showing old and new water pumps. New one is Airtex AW52. Also shown is the fitting I ordered for the heater outlet. Old and new are also shown. Clearly there is a difference in the openings. (I always get confused by the naming of pipe fittings, but I believe the new pump has a 3/8 npt opening and the old one has 1/2 npt.) The new fitting matches the old one in the threaded part. My questions:
1. Assuming I can find fittings, will this pose any problems? (I can't imagine anything other than reduced volume through the heater and head? But maybe that is a problem?)
2. Can I use brass fittings?
3. Is there a better thread compound to use for automobiles rather than standard plumbing thread compound?
4. I have not replaced a water pump in many years. What is a good gasket compound to use?

Thanks, all.

 

Year, model, equipment? You need to put that in every post. Put it in your signature file and it will always be there.

I'd assume it's a F134? You can buy an automotive-type fitting to go in the 3/8" NPT hole. Look on the Dorman Products website. Any parts tore can get Dorman stuff. Brass parts will work too, but more expensive than the plated steel automotive grade parts.

Your new part looks right for the 1/2" NPT hole. The question is - which size hole is correct for this application? I would guess that Airtex is being cheap and putting a convenient (for them) sized hole in the part they sell. Or they are stretching the compatibility to include water pump years that have both sizes of hole. It's to connect the heater hose - it'll work fine with 3/8" NPT, but I expect your old part is the right spec. Maybe somebody here will know, or you could ask an expert like Carl Walcks whether the 1/2" NPT is right. They sell a replacement, but it's hard to tell whether their part is the same as what you have.
https://walcks4wd.com/Water-Pump-L-F-Head-4-Cylinder_p_322.html

I would use teflon tape. Permatex #2 would probably be ok, if you have that. Plumbers pipe dope would probably work, but how it reacts to coolant I don't know. Don't use anything that will harden.

 

Thank you. Yes, the F134, 1962. I am not sure how to put that into a signature file, but I will look into it. And thanks for the other tips.

 

Or get your original pump rebuilt. Takes more time but less issues.

 

That thought has crossed my mind. I have found kits for sale. Is that something a shade tree mechanic can do? I have access to a press.

Thanks.

 

The smaller fitting may just be a benefit. The fitting at the pump should be the return from the heater, slowing the flow out of the heater core may allow you to get a bit more heat from it. Jeep must of thought so at some point, the heater core in my ‘69 has the outlet tube crimped down to restrict flow. When I took it to an old school radiator shop to have checked out, I asked them about opening up the crimping figuring it was something a PO had done. They said that was most likely the way it was supposed to be, had seen it a great deal over the years on lots of different heater cores for the above reason. I can’t say it’s for sure true, but seemed to make sense.
Tim

 

You could always drill out the smaller hole and tap the larger pipe thread to match the original.
-Donny

 

I found this and it looks straight forward enough.