I have a coolant leak from the o-ring closest to the water pump/thermostat assembly (front of vehicle). When I try to pressurize the system with a test kit/pump it dribbles out really fast.

These rings are sold at parts stores as:

felpro, p/n 35959, black, $3.99.
Mahle, p/n- b45797, red. $2.99.

I can't seem to find what Mitsubishi part numbers are. Anyone used these aftermarket o-rings and verify they work?

Where leak from coolant pipe is happening when pressurized.

Also, can I just remove the thermostat assembly manifold at the front and get the L-shaped coolant pipe out of the two sections it pops into? I'm hoping it can be because I hate removing the manifold plenum and all that!

 

Found part number. It is MD030764 $8 each on eBay, etc.

But I still want to know if that L-shaped cooling pipe can be removed (to access the o-rings on both ends) without removing the intake manifold. Anyone have experience? I can't find info in manual but I'm looking in ones and not sure if right one.