Delica Canada | Mitsubishi Van Club

So after rebuilding the front calipers, flushing and cleaning the radiator, playing with the wastegate, and adding a thermostat, I finally had a chance to take her for a good drive. Results were interesting.

The good news is I am no longer losing coolant. I drove about 100km, with lots of hills, and normally would have expected to add a bit of coolant but I didn't need to add a drop! I think it must have been the seal around the thermostat.

The bad news is I am still pulling high EGTs, so I guess the brake calipers weren't the problem after all. I'm going to mess around with the wastegate more to try to get more boost, and see if that does anything. If that doesn't work I think I might try adjusting the timing. Has anyone here ever retarded their timing before? What kind of results did you get?

The other interesting thing is that with the thermostat installed, it always runs kind of hot. The temperature gauge won't go below 1/4 which I guess is the temperature at which the thermostat allows water into the radiator. It's an 86 degree thermostat which seems unnecessarily high to me, so I think I will either try to find a lower thermostat or take it's guts out so that it's always open. Or just pull it entirely, like the previous owner did.

Looking back at your original post, and with the benefit of a new, better quality EGT gauge in my own van, I don't think your EGTs are particularly high. I run (pre-turbo) 800-1000F at 100kph, 1000-1200F when towing, and up to 1400F when towing up hill. Our turbos are fine up to 1700F, but the cylinder heads don't cope with sudden changes of temperature.

In general, retarding the timing gives higher EGTs and advancing the timing leads to higher coolant temperatures. Factory timing is ideal for a factory-fresh engine, but might not be best for a tired engine as reduced compression, tired injectors, or a worn pump all act to retard timing. I'd set my timing to factory and go from there. Old 4D56s go better with a bit more advance (to the point where the idle is a bit more clattery than usual) but too much advance is dangerous. The line between "a bit more" and "too much" is very fine, and can be very expensive.

The normal range for our temperature gauges seems to be variable. On mine, it'll quickly warm up to about 1/4 and sits there around town, and slightly higher at 100kph. It'll rise to about 1/2 on a long, hard uphill stretch when I'm keeping up with traffic or if I'm towing on the flat, and approaches 3/4 when towing up a steep hill. I've got an 86C thermostat and new radiator.

86C is high for a gas engine, but about right for a diesel engine- a good hot engine block helps diesel efficiency and timing stability. You're right about it sitting at 1/4- that's where the thermostat starts to open, and it shouldn't really drop below that.

It kind of sounds like your engine's temperatures are in the acceptable range. I'd focus on finding the cause of the low boost.

Could you try something? Disconnect and plug (fold over and cable tie) the wastegate hose, then go for a drive around the block.

You should get one of three results:
-Boost insane (20-30psi. Don't let boost that high for long, obviously)= everything is good, you just need to shorten your wastegate actuator rod/add washers to increase your boost to the normal range.
-Boost higher than usual, but only a little (12-15psi) = wastegate actuator spring isn't strong enough to hold the waste gate valve closed against exhaust pressure. Not good. Shortening the rod/adding washers will help, but you probably need a new actuator.
-Boost unchanged, still low (5-10psi, I recall?) = boost leak somewhere. Probably the blowoff/relief valve or the rubber hose between turbo and inlet manifold.

Let me know if you try that and what happens.

Just wanted to post an update on the issues. Turns out the head gasket was blown. It started losing water again and it then started to build up crazy pressure in the rad at which point it got pretty obvious.

Fortunately I'm in a place where labour is cheap, so I got the head gasket changed and the head machined flat for about $180. Runs perfectly now, and the EGTs are back to normal.

As for the turbo issues, it was definitely the actuator. Now that the EGTs are back to normal, I think I'm just going to keep it as is. It maxes out at 9psi, if it drops below that I'll get a new one, but I haven't noticed a change in fuel mileage so I don't see the point right now.

Thanks for all the advice, I'm sure I'll need more soon!