Adding a bypass

[hanvyj]

Okay, my 1275 head doesn't have any bypass. After a bunch of overheating problems, the pump is all messed up and needs replacing.

Seems the head (from a metro) originally had a sandwich plate that bypassed the thermostat. I know this is a touch topic, reading through the historic threads, but I have a few questions if anyone knows.

If I were to put a sandwich plate back, where would it plumb into the system? Would I need to get a bypass water pump, or does it connect somewhere else?

[bmcecosse]

A bypass water pump is for use with a bypass head.......it's nothing to do with the 'sandwich plate' which is merely an alternative supply point for the heater . Why would the water pump be 'messed up' ?

[hanvyj]

One of the veins has a hole in it. I thought the sandwich plate was to keep circulation around the cylinder head?

[bmcecosse]

It is - but the heater circuit does that too - if you keep the valve open of course. Usual thing is to drill a couple of 1/8" holes in the rim of the thermostat, or leave the heater valve open all year round - which makes for MUCH faster heater warm up in cool weather! I assume you mean 'vane' - in the water pump? Is it a pressed steel impeller ?

[hanvyj]

Yes, vane. It's the large cast type impeller, new a few hundred miles ago. Thermostat had a single 1/8" hole.

[bmcecosse]

I would send the pump back!