Coolant Pressure Cap Question

[mshaw1980]

Hello

I have an oe pressure cap (checked on brickwerks website regarding rubbish aftermarket ones) and wanted to know whether it is knackered. When I blow through the hose connector on it there is no 'quack' noise made although I can hear air coming through the valve. When I suck then nothing happens. If the cap doesnt 'quack' does that mean its knackered?

Reason I ask is because last week instead of parking the van nose down I left the van parked nose up in front of my garage on a gradient (van front at the highest point). I then took it for a drive and after 5 miles it started overheating, fan came on so I stopped for an hour then drove it home. I noticed that the coolant header tank was full with the engine running (tiny leak where the coolant level sensor is on top of the tank) and the coolant appeared to be at or close to boiling point. Expansion tank was full and the heater control was set to cold. When I took the coolant cap off my kids said it smelt like fish?

I have a subaru ej20 engine with all rjes coolant hoses, bypass etc fitted. It has been running fine, temp guage right in the middle until this particular problem. I am wondering if I have an airlock as I did notice a few tiny drops of coolant over the past few months but have had no coolant issues. To narrow the issue down I took the oe thermostat out and heated it in a pan of water. Opens as it should.

So I am hoping it is something as simple as an airlock, pressure cap and not headgaskets as I can be doing without a nice job like that at the moment. Any help appreciated though

[mshaw1980]

[jrt]

My favourite youtube video https://youtu.be/RT8Ew43mNg4" onclick="window.open(this.href);return false;
David.

[mshaw1980]

My favourite youtube video https://youtu.be/RT8Ew43mNg4" onclick="window.open(this.href);return false;
David.

I did see that. Its pretty funny. Any other suggestions around the strange overheating?

[jrt]

Dunno. I'd change the cap and bleed the radiator on the drive and see if it behaves.
David.

[Mocki]

I know nothing about Rice Burners , BUT , you say you had a small leak from the header tank level sender and the parked with the front uphill ?
Says to me that it has a airlock .
When the coolant gets hot it expands , and leaks out , but more importantly, when it cools it contracts and the vacuum caused by it contracting would suck air in from that small leak you had , and as we all know , air always goes to the highest point when left to settle in liquids, which if you parked nose uphill will be the radiator .

Try fixing the leak and bleeding the system thoroughly.

[mshaw1980]

Hi guys

Spent a while tonight bleeding the system and it appears you were right about an airlock. Used simon's bleed method and temp is now just over mid point. Will take it out again tomorrow and top it up again. May also siphon some more coolant in the top of the road using rjes method just to make sure it is full of fluid. Thanks all.

Removing engine to do head gaskets would not have made me very happy

[adie89]

If it’s an air lock on a Subaru lump I had to crack the bolts on the thermostat housing while it warmed up to bleed it, exciting and hot times! It was fine after that.