I popped the trunk earlier this afternoon just to check out everything before I did the engine/differential/transmission oil change this weekend and I noticed some coolant leaking from around the radiator cap. I'm not sure if it's just a faulty cap that needs to be replaced or could the hose be cracking?
Also, does anyone have the part number for the coolant reservoir cap? The plastic cap is cracked so it's not sealing properly.

 

Do you see any cracks underneath the cap? On the neck?

Did you tighten the cap all the way down?

As for the coolant reservoir, i just bought this. Its cheap and it works just as well.

 

That looks like its leaking at the hose joint, not the cap. Check the hose. Try and and wiggle it, pull it off with light pressure. It should feel almost glued to the post, due to habit bond.

Hopefully its just an old, cracked hose, not a crack in rad. Might even be able to temporarily just cut hose like an inch shorter and reattach, until you can replace it.

 

Easy to find the part number yourself.

(That's a link...)

-- Chuck

 

If it's the plastic housing of the radiator, it's done. The OEM radiator is very good but you can get an all aluminum Mishimoto replacement for a little less.

 

clean it all up good, start the car and let it get to operating temp and look to see where the leak is coming from.

 

the hose looks tight and at it's proper location, I'd say you have a crack on the filler neck and it looks pretty significant. The leak looks to be lower than the radiator cap unless it is coming from the backside of that picture which we can't see.

 

You don't even need to spray hot coolant anywhere, just pressurize the radiator to 16-18 psi(no more than 18 psi) with a cheap harbor freight tester, the leak will be clear as day.

 

So I did some further testing and it looks like a slow leak right below the fill cap which means I'm looking to replace the radiator soon . As it's a DD, I should probably get it done ASAP yeah?

From what I've read on here, most of the (cheaper) aftermarket radiators for our car are visually identical to one another as they're direct fit. Aside from the Mishimoto radiator cap possibly being leaky, has anyone had any issues with Koyo or Megan radiators?

 

Lol why spend money? Coolant pressure doesn't go from zero to full pressure in a blink of an eye. Start the car and let it idle. Pressure will slowly build as the car warms up. Look for leaks. Shut car down after leak is found. It won't start shooting out like a geyser the moment the car is started lol. Pretty simple.