heater core bypass

[georgeramos]

I just watched the IAP video and i see it looks fairly simple but there is no mention of the inlet/outlet of the heater. Do i just leave them open or is it better to plug them and if so what have you done?

Thanks

[bradbig]

My 73 has the heater core bypassed. A previous owner must have just removed the clamps and hoses from the fittings that protrude from the firewall, and connected a length of heater hose from the "hot" supply pipe, to the return line to create a loop.

I don't know, yet, whether it was the core or the valve that was leaking, but one of them must have developed a leak. I'm thinking it was the core, as the valve isn't that big of a deal to change, unless it was winter perhaps. Anyway, my firewall has two fittings just sticking out.

If you were planning to one day have the core redone, you'd think it'd be better to put plugs or covers over those fittings to prevent dust and crud from entering. One day, I'll remove the centre/radio console, drop the bottom half of the heater core box, and connect a garden hose to one of the core fittings to determine where the leak is.

Good luck!

[kmead]

The nice thing about having a working heater core that works, above and beyond its base function offering warmth on a cool evening ride (or back when we were willing to sacrifice them to the almighty tin worm, heat us up in winter), is it can give you an additional way of dissipating heat when the car is starting to overheat. Of course this isn't a great experience for the occupants but I have seen it be that little bit extra that keeps you from being another old car steaming by the side of the road

[Ellie]

Hi, I reckon putting a rubber stopper on the in an out pipes sticking out through the firewall is a good idea.

I am about to remove my heater core to give it a clean out (and replace the valve that exploded pouring coolant all over the floor). Because I don't know how long I am going to take to get the heater system fully functional, I am going to put a bypass hose in so I can keep driving. What diameter size hose is it that is used for the bypass?

[Ellie]

Ok, so I have connected the bypass hose. As the hose comes up, it runs right next to the distributor cap, is this ok? If the hose is getting hot (or at least warm) is this going to pose any issues for the distributor?

Cheers

[georgeramos]

It shouldn't as the rubber doesnt get super hot but theres no need to have it that close. Did you add a coolant fill "t"? if not that will add a couple of inches to the hose which might get it a bit further out.

[bradbig]

My bypass hose is quite close the the block, and it seems fine. I think proper automotive heating/cooling hose stands up fine to relatively high temps, anything but direct contact to something really hot, like the exhaust manifold.

[Ellie]

Thanks for the input, I just took the car for a run and it all worked fine. Although the system is still full of air so the engine got hot real quick. I didn't put a coolant T in the bypass hose but wishing I had as I'm going through the burping process now, which is fun. I don't if i'll ever be really sure all the air is out.

[georgeramos]

The coolant T is cheap and easy to install. Makes the burping process a breeze.

[RRoller123]

If you want to get the rest of the air out before you go buy the coolant T, just jack up the front end really high and fill the system through the coolant T fitting at the front of the engine. If you have a throttle plate heater, you can disconnect a hose and fill both sides of it too. Make sure he heater is on.

Agreed that adding the coolant T is the best solution, makes it automatically the highest point and very easy to bleed!

[Ellie]

In the end I jacked the car up and it's all good. I took her for good drive and I reckon the temp stayed down the best it's ever done!

Now for the heater core. I have the bottom of the heater box out, should the core just drop out? It looks like it should with a bit of coaxing, but I have a habit of breaking things when I coax them. Just want to make sure there aren't any more hidden screws, clips etc before I pull the sucker out.

[bradbig]

Unless you're worried about leaks, I wouldn't pull the heater core. You can clean it out by draining some of the coolant from the system/engine/rad, and disconnect the hoses at the firewall, and hook up moderately high pressure water line to the outlet, the one towards the driver. Running the water backwards through the core will flush out a fair amount of crud, which will come pouring out of the inlet. I think I've read, perhaps on this website, some people suggesting using a pressure washer for this process. I'm not sure about that. The water might hit with enough force/pressure that it might cause a leak. Anyone done this?

[redcars]

Don't use a pressure washer your cooling system only has 16 PSI, the garden hose between 50-60 and the pressure washer 1.500 to 4,000 PSI. You are pushing it with a garden hose. If you use a pressure washer the Lord only knows how much damage you will do under the dash.