Full of Hot Air
#11
08-16-2012, 08:27 AM
Rover used to cut off flow to heater core, the current system is a way to please folks that want a little heat, etc. If bypassing the heater core, keep the coolant flow going as a loop, don't stub it off. On a D2 you don't need to decrease the coolant flow entering the top of the thermostat. That small flow mixes with coolant from the radiator, and warms up the stat to open. You certainly don't want the stat opening later.
The problem of fresh air ventilation and heater cores has been around a long time, back in the 60's Chevy owners who did not have AC would install a plumbing valve at the firewall to kill the hot flow to the heater core. And plenty of Rovers in warm climates have the heater core bypassed.
Two potential problems come to mind. First, the diagnostic for air in coolant or exhaust gas in coolant is removed (bubbles thru pipes under dash). Second, when servicing cooling system, will need to remember to flush out the heater core. Heater core needs antifreeze. Replacing a heater core introduces the technician to the concept that the truck is built around the heater core.
I think the vac operated valve is an elegant solution. There will even be some flow from time to time under wide open throttle, which might be a plus.
Plumbing flow diagram attached.
The problem of fresh air ventilation and heater cores has been around a long time, back in the 60's Chevy owners who did not have AC would install a plumbing valve at the firewall to kill the hot flow to the heater core. And plenty of Rovers in warm climates have the heater core bypassed.
Two potential problems come to mind. First, the diagnostic for air in coolant or exhaust gas in coolant is removed (bubbles thru pipes under dash). Second, when servicing cooling system, will need to remember to flush out the heater core. Heater core needs antifreeze. Replacing a heater core introduces the technician to the concept that the truck is built around the heater core.
I think the vac operated valve is an elegant solution. There will even be some flow from time to time under wide open throttle, which might be a plus.
Plumbing flow diagram attached.
As you mentioned, the "sensing holes" on the tstat are very important! Modifying the system makes me a bit nervous, but I guess as long as the heater grid is bypassed and not blocked off (as something will probably go "pop" since at idle with bypass spring shut, a cold engine will send 100% of coolant through the header grid loop.
I know the other cars you mentioned didn't use the bypass system - perhaps it has something to do with that, maybe engine temps could rise so quickly when cold/bypassed at idle without a heater grid that the tstat sensing holes would fail to register the increase and open as accurately (since we all know they hardly work as it is).
I noticed that my new tstat (motorrad or whatever) has two large sensing holes instead of 4 smaller ones! This rocks because most OEM ones I've inspected had 1 of the 4 holes BLOCKED with crap, ie. lose 25% of sensing ability and open later.
#12
08-16-2012, 12:05 PM
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By the way, it is spelled out in the Rave about the design of our t/stat and how it works with the heater core.
#13
08-16-2012, 01:35 PM
Recovery Vehicle
Maybe OK for the rest of the vehicles but the heater core is part of the cooling system only on our D2's, because of the design of our t/stat and as such you can not by-pass the heater core without setting yourself up for an over heat issue.
By the way, it is spelled out in the Rave about the design of our t/stat and how it works with the heater core.
By the way, it is spelled out in the Rave about the design of our t/stat and how it works with the heater core.
#14
08-16-2012, 05:19 PM
OK so, Because the rover has dual thermostat controls - your wife may be cold (or feel cold). (that is why one should always marry a hot woman. But, I digress). So, she turns UP the heat. You keep the A/C on low. So, Rover has chosen to have HEAT flow thru the core. Savannah and Master Rover Tech are correct. Put in this valve. And be done with it. Or, don't be cheap and run your A/C I would just run the A/C.
#15
08-17-2012, 07:37 PM
As annoying as it is I've found that turning off the heat/ac system doesn't actually change the flap configuration. The vent flaps stay in the same orientation as they were when you turned them off. That being said I've found a pretty easy (and annoying) way to deal with this by putting the defroster on before shutting it off. This makes all air come out only the defrost vents near the window and keeps you from getting (much) hot air blowing at you and none at your feet. Its not an end all but it makes it very manageable.
#16
08-20-2012, 10:19 AM
Same thing happened to me, air is warm out the vents.
Checking the service manual, the heater core and the evaporator are one on front of the other in the same housing, and there is no flow shut-off valve. I do not like the AC fighting with the heater.
I solved it my way:
http://i588.photobucket.com/albums/s...t/P1000960.jpg
Open in winter, shut in summer.
Checking the service manual, the heater core and the evaporator are one on front of the other in the same housing, and there is no flow shut-off valve. I do not like the AC fighting with the heater.
I solved it my way:
http://i588.photobucket.com/albums/s...t/P1000960.jpg
Open in winter, shut in summer.
#17
08-20-2012, 11:24 AM
Same thing happened to me, air is warm out the vents.
Checking the service manual, the heater core and the evaporator are one on front of the other in the same housing, and there is no flow shut-off valve. I do not like the AC fighting with the heater.
I solved it my way:
http://i588.photobucket.com/albums/s...t/P1000960.jpg
Open in winter, shut in summer.
Checking the service manual, the heater core and the evaporator are one on front of the other in the same housing, and there is no flow shut-off valve. I do not like the AC fighting with the heater.
I solved it my way:
http://i588.photobucket.com/albums/s...t/P1000960.jpg
Open in winter, shut in summer.
Will that allow the coolant to circulate? Looks like you just cut-off the flow to the core, not by-passed it. Won't that just pressurize the system and go POP!
#18
09-17-2012, 03:32 PM
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Same thing happened to me, air is warm out the vents.
Checking the service manual, the heater core and the evaporator are one on front of the other in the same housing, and there is no flow shut-off valve. I do not like the AC fighting with the heater.
I solved it my way:
http://i588.photobucket.com/albums/s...t/P1000960.jpg
Open in winter, shut in summer.
Checking the service manual, the heater core and the evaporator are one on front of the other in the same housing, and there is no flow shut-off valve. I do not like the AC fighting with the heater.
I solved it my way:
http://i588.photobucket.com/albums/s...t/P1000960.jpg
Open in winter, shut in summer.
I guess I can just bypass it with a bit of hose.
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