Delica Canada | Mitsubishi Van Club

Hey all,

Having some issues with our L300 at the moment, hoping for some advice on whether its the head or maybe just a cooling system issue. We recently replaced the radiator cap with a new one on the advice of a mechanic since our old one wasn't pressurising the system. Since getting the new rad cap, we have been experiencing a couple of suspect issues (we don't know if this is coincidental or not).

Here are some symptoms we are having:
-Intermittent bubbling of the overflow reservoir even only after driving small distances
-Black then greyish then white smoke on startup (we also have a turbo leak which contributes to smoke)
-Doesn't appear as if pressurisation is working correctly - rad dumps into overflow when running but a lot of the time it isn't sucked back in when cooled down leaving the rad appearing bone dry, in fact it's as if the coolant disappears (has been burnt ??) as we top it up quite often only to find the next day its gone as mentioned above. We don't see it spilling onto the ground at all.

Here are some things that lead us to hope (!!!!) its just a cooling system issue:
-We have no milky residue on the oil cap or dipstick
-We never had this issue before the new rad cap
-The issue is intermittent, it doesn't bubble every time we drive it, nor does it always lose coolant from the rad/overflow
-We did the 'sizzle test' of our oil, didn't sizzle so no coolant/oil mixing (or not enough to show up in this way)
-Van does not overheat, never goes over half way even on some of those crazy mountain passes. Got up to the 3/4 mark 4WDing once. Driving around town/highway driving the guage barely moves.

Any advice much appreciated.

The A-Team

Hello sir,

-First of all, before replacing your rad cad, were you loosing coolant other than going into the surge tank?
-Have your local tech do a pressure test and combustion leak test done then you'll know for sure if you're head is capout!

Pour a bottle of head gasket sealer in to the radiator and assess.

Agreed- it might be a cracked head. 4D56 head gasket/cracked head failures don't always allow the oil and water to mix. The best check would be for combustion gases in the coolant: a tester like this https://amzn.com/B0007ZDRUI would do the trick, but a decent garage might be able to do the test for less.

A leaky radiator cap might have allowed combustion gas to exit the radiator at the cap without pushing much coolant out. The new cap might be forcing gas to exit through the overflow tank, taking coolant with it.