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JONORacing 5th May 2014 22:41

K20A2 Coolant System
Hi All,

I've been trying to find some pictures to see how the coolant system is done on a K20 exi as I am having problems with air locks but with no luck. I have no heater so a loop pipe has been fitted with an outlet to return fluid back to the bottle so it can circulate. However I have a feeling this maybe the main problem as at idle it works fine however as soon as the rpm increases the the flow stops and then it starts sucking coolant. I only found out it was actually sucking the fluid back after changing the bottle to different one, thinking the Rover unit was causing the issue. I can take the loop off and cap the heater feed but I'm just wondering how the road ones are done with regards the return to the bottle and circulation as may give that a go whilst making a mess draining the system.

Cheers Jono

Ric H 11th May 2014 16:09

I had a similar problem getting mine to work. I had taken a breather vent from the outlet casting on the cylinder head (connection that used to go to the injector heater - which I can do without) to the bottle. Like you , I found at idle it worked fine and squirted coolant into the bottle. Revs up, it sucked air back, which then collected in the radiator and airlocked it. I fixed it by putting a dip pipe into the breather connection on the bottle, so when it sucks back it sucks coolant instead of air. A bit of a hack, but it's worked fine ever since.


EDIT - here's a link to the thread at the time when I was trying to fix mine:

JONORacing 13th May 2014 09:17

Thanks for the reply. When I changed the bottle, thinking this was the issue, I used a round one from an Audi A3 which has some fancy return system inside the bottle, like a dip pipe & this is when I found out it was still sucking. My return was on the heater side so I have blanked that off and have now removed the breather vent and done like you have which now works fine. Mine doesn't even suck, and took a long time before it started to circulate but once it built pressure it worked fine. The real test will be on Thursday when I do a shakedown.


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