Howdy guys:

Got my freshly .030-bored B18 all put together and in the engine bay...all that is left is hooking up the cooling system before the big day of breaking in!

I do however, have a question about the hook up of the lines running to the heater core and heat control valve. See the picture below:



What bothered me about the original set up is that the hot coolant goes directly into the heater core from the engine. Even if the valve shuts off the circulation, would the existing coolant in the core still eventually become hot from heat diffusion from the heated coolant running from the engine?

If I change the hoses around as shown in the modified diagram, the only way the hot coolant could reach the heater core is through the opening of the valve.

If my thinking is flawed with this modification, please advise. Any caution appreciated!

Thanks,

-DS

Thanks Patrick and Derek:

Patrick: I live in Florida, so I definitely welcome any plumbing setup that would exclude heat from existing in the core when the valve is shut off!

That is a good point to consider that if the flow goes into the valve directly from the engine that the heat might shorten the valve's life. Hmmm...

Derek: I did consider that alternate setup you had suggested...but from what I understand, the flow is supposed to go into the curved valve pipe, going out of the straight one. But I will definitely avoid causing any hose stress with bending, twisting, etc.

Worse comes to worse, I'll just follow the original setup if all else fails. Maybe I would just add extra firewall padding around the heater housing under the dash!

-DS

DS (I'm DS too) I stand corrected. A look at the parts book does confirm your standard routing of the pipes. I thought the side pipe just came up at right angles at the end and that's what it looks like in a picture I found of my engine. Not an area you photograph very often! The side pipe does dog leg round so it's the other side of the brass connector.

I went ahead and followed the modified set up as I had shown in the diagram. Drove a bit (the power band of the rebuild was awesome! More about it later in a new posting). Absolutely ZERO heat around my legs. Groovy!

-DS

In the standard install illustration you have the black and blue transposed at one end i.e. the side pipe should connect to the lower matrix connection and the straight heater valve connection should go to the brass connection on the back of the head.
It's worthwhile having the proper preformed pipe on the upper matrix connection as a bent round piece of pipe either kinks or puts a lot of strain on the matrix connection which can cause it to fracture.

I agree that for no heat required best heat exclusion your mod works best, I think for best heating volvo's design works best. When I drove a 120 in the winter, it was very nice and toasty, warmest car I have had. In your mod the longer distance and restriction of the hot liquid could possibly slow down initial heating; and response time in coolant driven heating systems is always an issue....as hardly anyone drives 120s in -30 anymore, probably not such an issue for you. Also the control valve in old 120s is quite frail, I doubt higher operating temps will help it.
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Patrick, '68 220 , '53 GMC 4104, '97 VW Transporter.