flyingbrick Posted October 22, 2014 Share Posted October 22, 2014 Hi all. As a general rule of thumb does the radiator cap have to be higher than all parts of the cooling system? Its a draft question but where I want to mount my heater is about 6" higher than where the old core sat... I'm getting paranoid that it might not be strong enough to push water up to it or airlock (never understood the concept to be honest) or something. Anyone keen to lend helpful/unhelpful advice Go Quote Link to comment Share on other sites More sharing options...
Beaver Posted October 22, 2014 Share Posted October 22, 2014 Any point of the system higher than the rad cap becomes a likely spot for air to form/get trapped (basic physics). If you lift your heater core just smash a remote filler next to it. 3 Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted October 22, 2014 Author Share Posted October 22, 2014 What if I had my inlet and outlet at the top of the core so air would be pushed into the out hose? I guess I don't understand how much pressure the water pump has to force water uphill I could throw a metal shroder (whatever) valve into top of core.. Push pin to evacuate air while motors running? Quote Link to comment Share on other sites More sharing options...
ta63-1uzze Posted October 22, 2014 Share Posted October 22, 2014 if you pressure/vacuum fill the cooling system then its not normally an issue, an air lock is when you cant get the air out of the cooling system, it gets trapped at the highest point. air is compressible so even when the cooling system gets hot and expands the air stays where it is. this is an issue as it interrupts the flow of coolant. making hot spots in the system where coolant doesn't flow so it sits in the same spot and boils = very bad in every kind of way.  you can get bleeding systems that either pressurize the system or vacuums the system and you fill it using the suction created by the vacuum these work very well , you do need a compressor to use such tools and a little bit of know how.  bnt sell vacuum bleeders as does most auto parts places. I personally have one cause I have a heater tap that is higher than my radiator. I would recommend them they save a lot of time but you do need a compressor to use it    1 Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted October 22, 2014 Author Share Posted October 22, 2014 Sounds rediculious but I do have an oil extraction unit (vessel with pump that pulls vacuum on it) I wonder if that would work.. I'll try it and report back Quote Link to comment Share on other sites More sharing options...
Bling Posted October 22, 2014 Share Posted October 22, 2014 Just park on a hill. May or may not work.* Â I guess the inlet an outlet pipes will be higher than the cap though so it might be another physics fail. 2 Quote Link to comment Share on other sites More sharing options...
CaMpylobacter Posted October 22, 2014 Share Posted October 22, 2014 big fan of vac bleeders. only prob i can see is if you don't have  your filler at the highest point is every time you check your water it'll chooch the 'head' out of there? 1 Quote Link to comment Share on other sites More sharing options...
CaMpylobacter Posted October 22, 2014 Share Posted October 22, 2014 Just park on a hill. May or may not work.* Â to bleed cooling system on a pajero with rear heater you park on the steepest hill you can 1 Quote Link to comment Share on other sites More sharing options...
Beaver Posted October 22, 2014 Share Posted October 22, 2014 big fan of vac bleeders. only prob i can see is if you don't have  your filler at the highest point is every time you check your water it'll chooch the 'head' out of there? also this. TBH i would just relocate the filler to the highest point. Then you dont have to fuck around with everything else. 1 Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted October 22, 2014 Author Share Posted October 22, 2014 That's not a bad idea. Would mean my filler ends up being on the firewall though. I guess I could even T it into my heater hose... Not a bad idea at all. Edit. Nah fuck that.. Too much work. I'll put my heater core where its ment to be. I just wanted it up high hidden. . 1 Quote Link to comment Share on other sites More sharing options...
V8Pete Posted October 22, 2014 Share Posted October 22, 2014 Doesn't the dashboard normally hide the heater core? What on earth are you making? 1 Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted October 22, 2014 Author Share Posted October 22, 2014 Hahaha. I'll post a pic in my thread sometime soon. You do raise a valid question as I don't think I have shown this. Quote Link to comment Share on other sites More sharing options...
Mof Posted October 22, 2014 Share Posted October 22, 2014 Just fill coolant, then pull one hose from core a little bit to let the air out, refit hose and job is done. I have to do this to my samurai coz the auto choke works on coolant and the carb is higher than the rad cap 1 Quote Link to comment Share on other sites More sharing options...
Yowzer Posted October 22, 2014 Share Posted October 22, 2014 Didn't read the thread, slap a bleed valve at the highest point in your cooling system. Shove a hose in the rad, open bleed valve, close when water falls out. Â Jhea. 1 Quote Link to comment Share on other sites More sharing options...
Roman Posted October 22, 2014 Share Posted October 22, 2014 Use one of the taps that are in the front of an MR2 that you normally use to bleed the heater circuit with... Can run them inline with rubber hoses about the same diameter as most heater pipes. Â I used to have airlocks at the back of my engine but fitted one of these into the highest rear pipe and now it's fine. 2 Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted October 23, 2014 Author Share Posted October 23, 2014 Wow.. Brilliant thinking. I can have the hose go from my high spot (in the cabin) and have the valve on firewall in engine bay... Quote Link to comment Share on other sites More sharing options...
Roman Posted October 23, 2014 Share Posted October 23, 2014 Theres a bunch of mr2s in auckland pickaparts / zebra at the moment so shouldnt be hard to find one. Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted October 23, 2014 Share Posted October 23, 2014 Stock factory viva heater core position is well above factory radiator filler with no bleed point. But it's a small core so maybe enough flow to push air through and out? Quote Link to comment Share on other sites More sharing options...
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