Hey, does anyone know for sure what the OEM radiator cap should be on the TW radiator.

Just doing some routine checking and the bottom button has broken off? Fatigue i guess, the 2 seals appear to be ok and the car is not overheating but best I replace it, 8 years old.

The issue i'm having though is everwhere i look in the aftermarket references, they're saying 13psi/90Kpa.
Well the cap i have which to my knowledge is the original, it's certainly an OEM nippondenso Cap and it's 1.1 bar or 110 kpa which I think makes it 16psi!

We've had the car since 2007 / ex gov fleet vehicle so second owner. I doubt the cap would have been replaced within the first 38 000k.

I'm in the NT so ambient temps are always pretty high

I have been using a 13psi/90 kPa cap in mine for the last 45,000km - which is what CPC suggests in their catalogue (part number CPC 580-90) - and it works fine. I've not lost any coolant, temperature has always stayed constant.

I still have the original on my TJ at 11 yrs old. Why is broken, has you coolent not been changed regulary? Maybe try asking Mitsubishi for a price or looking at the wreckers for a good 2nd hand one.

Bottom/central button on the rad cap is for sucking coolant back from the overflow tank when the engine cools down. If it is missing, the cooling system is not pressurising when hot.

Try a 13 psi cap, if it is not enough you will know about it. Usually a couple of minutes after switching off a hot engine, as the higher temp of the oil and engine feeds into the cooling system. You will hear a steam hiss and coolant will flow out of the car in front of the passenger tyre. If it doesn't, the cap is ok.

Cap on my TJ is the original Nippon-Denso, 0.9 bar.

I got the 0.9 580-90 cap. Funny, maybe it was a NT pack (LOL) . The portion where the button was was composite materiel so maybe age and heat made it brittle, floating inside the tank i guess. My V6 Galant has 0.9 bar, same style of cap and USA export Diamante had the same cap 0.9. WHo knows, strange how it ended up with a 1.1.

meant to mention I went into the factory manual, says 75–105kpa so 90 would be the mid point, 110kpa is beyond, 65 is limit

Confirmed the OEM cap number with the VIN, radiator cap MB660667 replacement No. MR481216 0.9 bar 13 psi . $43

TW2005 that NT comment may not be so wrong there could be a tropical version available, I remember years ago there were on Sigmas and very early Magnas tropicalized parts to stop overheating. Such things were also common on Fords and Mazdas with different fans with more blades on both fords and mazdas!

1.1 Bar is possibly an upgrade part on a factory installed heavy duty towbar pack?

Donno, my TJ has 0.9 and no towbar, my TL has a factory towbar but still the 0.9 cap, so I don't know.

Higher pressure cap will raise the boiling temp of the coolant.
So could be a mod for topical areas.

The vehicle was ordered, sold and delivered here in Darwin and it has a factory towbar. You'd think though if it was part of modified build the VIN would be the key to what was fitted as it left the factory?

Anyway I guess we'll never know.