I've seen it both ways but would like to hear what the factory configuration is for a 1972 240.  

The inlet hose coming of the head to the heater valve goes through the bottom hole in the firewall?

The outlet comes out the top hole on the firewall?  

That's what I've been able to find so far.  Also I think it'll work either way but if someone could be so kind as to confirm this I would appreciate it. 

Thanks!

Cliff

RED=inlet

BLUE=outlet

 

 

Edited June 4, 20177 yr by siteunseen

i put the hose off the top of the core through the top hole just so the air could bleed out better, but my control valve is in the engine bay. i have no idea if it made any difference at all

That's a head scratcher right there!  Great idea too.  I'm guessing a longer cable through the firewall to the valve?

yes. i made the cables with piano wire and used that stuff for bicycle control cables for the outer part. my thinking was:

cheap, easy to find and replace valve

no leaks inside, easy access

see #1 above   cheap

Similar - 

 

Always thought these were nice diagrams. 

 

 

 

Edited June 5, 20177 yr by JSM

23 hours ago, Zed Head said:

Similar - 

 

the only problem i see in the captains post is the valve should (in my opinion) be before the heater core.

I have pondered the same but realized that at 10-13 psi system pressure the coolant's coming out no matter which side the valve is on.

The 240's valve shuts off the flow through the core.  I was worried that coolant would be coming inside the cabin all the time but it won't be until the valve is opened.  So plugging the elbow on the head is the same as closing the valve.

Don't know about the 280's, they are different

 

Holy crap!  Give me a motor rebuild any day over interior work.

Putting the OE radio in last month used up my months supply of heroin now the new heater valve and hoses finds my bag empty again.

Flushed it out with a hose pipe then stuck my finger in the out flow hose to check for leaks. It leaked around my finger only, thank goodness.  I can't take anymore today but tomorrow the inlet hose and valve go on then I'm checking myself into rehab. 

SUCCESS!!!

Blazing hot defrost/heat that I won't use one month a year.

Now to celebrate with nurse Ratched's little paper cup full of jelly beans.

Edited June 10, 20177 yr by siteunseen

I've been out of town off-line and am coming late to the party, but glad to hear that the project is complete. Working under that dash is a royal PITA. In fact, I've done it both ways and have actually found it to be worth the time to just pull the entire dash out to work on the heater system.

As for which side of the heater core the valve is on, I don't think it really matters, especially if you use one of the newer style ball valves that Sweaty and I used. The original style valve is more affected by flow direction than a ball valve since it could theoretically be forced open by pressure of the water pump, but I wouldn't worry about any of the direction stuff at all with a ball valve.