[allenga]

Hi Guys, I want to bypass the heater core to lower the temp on the interior, help my AC.

I read about two methods. 1. one shut off valve on one heater hose. I am fine with this. I would shut off in summer, on in winter. Will this stop flow of water through intake. Is that bad?

2. By pass valve. I read some think this is bad and hot water is coming back to water pump. I don't want to mess with vacuum lines. Would look for pull cable or electronic.

Thoughts?

Thanks!

[Goatracer1]

The factory used a valve in the heater hose.

[allenga]

Originally Posted by Goatracer1

The factory used a valve in the heater hose.

Thanks. Do you know which way the water flows. Which line would I plug. What are the downsides of block vs by pass.

[Squidward]

On my 72 Lemans I use a quarter turn ball valve plumbed in-line from the outlet at the passenger side head to the timing cover heater hose inlet. I have it partially open to allow circulation at all time, yet provide some resistance to flow so that the coolant moves more through the radiator.

Some people run a straight hose from the head nipple to the timing cover inlet with no restriction. I try to simulate the flow resistance that I am guessing would be provided by the heater core, if I had one.

[Vid]

Big bump from 2018, but why start another thread with the same topic.

Maybe some kind Pontiyakker can clarify something for me. This is regarding my ‘69 LeMans 455 build.


I discovered that my heater core has a minor leak. I don’t use the heat or defrost at all, so looking to bypass before the floor rusts. I blew it out with compressed air and will cap off the inlets at the firewall until the day comes when I am motivated to repair it properly.

So here’s my question. To maintain proper cooling and flow is it necessary to run a hose from rear of the passenger side head to the timing cover/water pump? Or can both just be capped off as well?

And just to stir the pot, any benefit to adding a nipple to the driver’s side head and connecting the two heads, or maybe even add a “T” between the two heads that connects to the timing cover/water pump? Just kicking ideas around and looking to keep it cool.

Thanks, ‘Vid Sutton


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[nytrainer]

Check out these 2 YouTube episodes. Maybe help you decide what works best. Also addresses teeing head coolant ports.
https://youtu.be/DWvVkrGQDsw
https://youtu.be/9ou2GKZFf3Q

[Vid]

Originally Posted by nytrainer

Check out these 2 YouTube episodes. Maybe help you decide what works best. Also addresses teeing head coolant ports.
https://youtu.be/DWvVkrGQDsw
https://youtu.be/9ou2GKZFf3Q

Thanks for these!


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[Mister Pontiac]

The simple solution is just cap both the head and the timing cover. It will be perfectly fine. Bonus is that it's super easy to pull caps and hook everything back up again once you get the heater core replaced.

I wouldn't recommend another nipple in the left head either and running a crossover. Not needed, and won't aid cooling in any way. Adds complexity to things. The hose gets in the way of the distributor and firewall wiring. Looks wrong. Just can't see any benefit to a crossover between the heads. That's what the intake crossover up front is designed to do.

Hope that helps.