Heater either hot or cold

[hrforever]

In the process of getting the car ready for winter use and after a couple of years of putting up with this issue I think its time to sort it out once and for all.

The vehicle is a 1979 Volvo which originally had some sort of thermostaticly controlled heater valve. This failed years ago and so I put a straight on/off cable operated tap in its place. With the original 4 cyl motor this worked fine.

With the conversion to the 1UZ, I again plumbed the tap again into the water feed hose but I found that regulating the temp of the heater was impossible. It was either hot or cold. So last year I put another tap in the return hose but the problem remained.

Now, an on/off tap cannot be that hard to get right. So I've been wondering if there's something I'm missing. Does the amount of water the 1UZ pushes around the system need to be restricted for the heater? Is some sort of bypass needed to easy water passage?

I'd like to go for a drive without having to alternating between freezing and sweating.

 

[hrforever]

Please ignore this post. Some more internet searching today turned up a little known fact (to me at least). The heater core is not a simple water in, water out arrangement. Volvo made their heater cores to split the hot water to the outsides of the core with the return (cold) back up thru the middle.

Nothing like Volvo ingenuity/complexity.

So, turns out I've always had the plumbing backwards so this weekend I'm back under the dash.