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Okay, so I've had a Mishimoto radiator for about a year now. And I've noticed the coolant temperature on my cluster never ever fully reaches the middle (AP2 dash) no matter how hard I drive it. It's perpetually one bar away from the center. Extremely stable, but never gets to the middle. With the older OEM radiator the gauge when warmed up would sit right in the dead center. This change happened with the new radiator.
Does it have to do with the Mishi/Koyo being much larger than the OEM in terms of liquid capacity and therefore cooling? I will add I do have a 1.35 bar spoon cap on my radiator. Would that higher pressure and increased boiling point have anything to do with it? I know the stock Mishi is 1.3 bar and the OEM Honda is 1.1
Here is a visual representation of how my coolant temp gauge looks even when fully warmed up.
MY06 sits at 8 bars and the fans will start if needed. Eyes are not what they used to be, so I placed a piece of bright yellow tape on the instrument cluster to not go pasted that mark.
Happy trails!
Last edited by stock06; Sep 7, 2022 at 07:32 AM.
Reason: duplicate smile
This is the oft-pictured AP2 temperature display (below). The one on the Left is the OEM version.
I don't recall my '06 ever getting "straight up" ever and always looks like your post (commonly referred to as 8 bars) which according to the diagram below is 225°F. 50-50 antifreeze at no pressure (1 Bar) boils at 253°F -- and higher under pressure -- so no concern over the temperature or chance of boiling. All the higher pressure 1.3 Bar radiator cap does is increase the boiling point of the antifreeze even higher than normal, it doesn't keep the engine any cooler so I don't know any reason for using it unless you're running very high engine temperatures. 1.1 Bar should be good enough.
This is the oft-pictured AP2 temperature display (below). The one on the Left is the OEM version.
I don't recall my '06 ever getting "straight up" ever and always looks like your post (commonly referred to as 8 bars) which according to the diagram below is 225°F. 50-50 antifreeze at no pressure (1 Bar) boils at 253°F -- and higher under pressure -- so no concern over the temperature or chance of boiling. All the higher pressure 1.3 Bar radiator cap does is increase the boiling point of the antifreeze even higher than normal, it doesn't keep the engine any cooler so I don't know any reason for using it unless you're running very high engine temperatures. 1.1 Bar should be good enough.
-- Chuck
Aftermarket performance radiators come with high pressure caps. The stock cap won't fit.
The temp gauge in your photo is at the normal position.
Not sure why it was sitting hotter with your factory radiator. Maybe the fins were clogged or something was wrong.
the coolant thermostat controls the final temperature of the coolant. The radiator maintains it.
This. My '06 has never moved past the one less than center. Either before with stock radiator, or after with koyo after stock leaked. My stock rads fins were indeed clogged with debris. I bet if I did a track day or drove it hard long enough on street, temp would have crept up. Very common for fins to get clogged.
Sounds like your car is fine, but when re-filling the cooling system, always double check that heat coming out the vents is HOT when the car is warmed up. If it's not burning hot (full hot/full fan), you could have air in the system.
Aftermarket performance radiators come with high pressure caps. The stock cap won't fit.
Yeah, F series caps (type 1) fit the Koyo and Mishimotos. The OEM cap does not fit. And the radiator came with a 1.3 bar cap. But Mishimoto's track record with caps is pretty shoddy so I got a different one to prevent future leaks.
Does anyone here have a Koyo or Mishimoto? What pressure cap do you run? Can I just go back to 1.1 even though it came with a 1.3?
This. My '06 has never moved past the one less than center. Either before with stock radiator, or after with koyo after stock leaked. My stock rads fins were indeed clogged with debris. I bet if I did a track day or drove it hard long enough on street, temp would have crept up. Very common for fins to get clogged.
Thanks thats a bit relieving. It's just odd since I had the car since 30k miles back in 2008 and I didnt replacing the radiator until 100k+ later when it started leaking. And it's ALWAYS been direct center with OEM radiator. (which looks like 232 degrees F)
temp gauge never hits middle (ap2)
