1986F150Six Posted August 7, 2019 Share Posted August 7, 2019 And, the Ranger 4-port is a good mod. I just have a cable-operated valve with no cable in Big Blue's supply-side heater hose and I turn it on in the winter and off in the spring. But I really want to try my vacuum-operated mod, so...... If you "T" off the vacuum hose going to the servo-motor for operating the fresh air vent door [passenger side, under hood], the heater still works but the hot coolant is cut off when MAX COOL is selected. Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 7, 2019 Share Posted August 7, 2019 And, the Ranger 4-port is a good mod. I just have a cable-operated valve with no cable in Big Blue's supply-side heater hose and I turn it on in the winter and off in the spring. But I really want to try my vacuum-operated mod, so...... If you "T" off the vacuum hose going to the servo-motor for operating the fresh air vent door [passenger side, under hood], the heater still works but the hot coolant is cut off when MAX COOL is selected. Very true. But, you still have heat in the Vent position. And there are many times I'd like to have outside air temp coming through via Vent. Link to comment Share on other sites More sharing options...
Dk46 Posted August 7, 2019 Author Share Posted August 7, 2019 Does it matter which heater hose i put the valve on?Functionally, no. Stopping the coolant in one place within that circuit stops it everywhere in that circuit. But it's better to block the hose coming from the intake - the hot/supply/PRESSURE side. Blocking the cold side puts the heater core under slightly more pressure, which makes it more prone to leak or rupture. The best way to do it is to use a 4-port valve, so coolant still flows. https://supermotors.net/getfile/992200/thumbnail/38htrvlv.jpg I already have the single port valve but can get the 4 port. Would the coolant not flow through the engine with the 2 port? Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 7, 2019 Share Posted August 7, 2019 I already have the single port valve but can get the 4 port. Would the coolant not flow through the engine with the 2 port? I think all of the engines but the 4.9L/300 six have a bypass where coolant will flow w/o the heater. Certainly the Windsors do. So there's no problem blocking off the heater, meaning the valve you have (2-port?) will work. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted August 7, 2019 Share Posted August 7, 2019 I think all of the engines but the 4.9L/300 six have a bypass where coolant will flow w/o the heater. Certainly the Windsors do. So there's no problem blocking off the heater, meaning the valve you have (2-port?) will work. But in my 460 the bypass only goes from intake to water pump. Whereas the heater loop picks up at the head side of the thermostat housing. I don't really know about the I-6 Link to comment Share on other sites More sharing options...
1986F150Six Posted August 7, 2019 Share Posted August 7, 2019 But in my 460 the bypass only goes from intake to water pump. Whereas the heater loop picks up at the head side of the thermostat housing. I don't really know about the I-6 I know of one 4.9L engine which has fine temperature control with one heater hose blocked during the warm months. Link to comment Share on other sites More sharing options...
Steve83 Posted August 8, 2019 Share Posted August 8, 2019 Would the coolant not flow through the engine with the 2 port?The engine isn't the issue; it's the heater core (and any sensors in the heater core loop, like EFIs have). Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted August 8, 2019 Share Posted August 8, 2019 I know of one 4.9L engine which has fine temperature control with one heater hose blocked during the warm months. In my onboard bag of tricks I carry a 1/2" copper freeze coupling, to bypass the heater core if it pops like it used to with a cracked head. You can always take the heater out of the loop. Link to comment Share on other sites More sharing options...
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