2004 Mitsubishi Lancer Pricing and Specs

The first sign of a blocked drainage system in a car is usually wet carpets. This, however, is not necessarily the result of a blocked plenum drain, as there are other causes including a blocked air-conditioning drain, a poor door or window seal and even a hole in the firewall between the engine bay and the passenger compartment.

In the case of a simple hole in the firewall, the solution is usually a rubber grommet which will cost a few cents and will sort things. For other leaks, however, you need to take the time to learn where the drain tubes live and ensure that they’re clear and free of mud or dust that could be blocking them, causing them to overflow into the cabin.

The other possibility is that the leak into the car is being caused by a faulty heater core which is allowing the engine’s coolant to escape. That’s a bigger fix as it usually involves removing the dashboard to access the heater core which then needs to be replaced. But if you’re lucky and it’s a simple blocked drain pipe, the drain holes for both the plenum and the air-conditioning drain should be visible on the firewall, below the windscreen. Undoing them and clearing them would be the first step to curing the problem.

Your Lancer uses a timing belt which is made from a rubber compound and drives the camshaft. This makes for a cheaper engine to build and potentially quieter running, but it also means that the belt has to be changed periodically to prevent it snapping in service.

Mitsubishi recommends a belt-change interval of 100,000km. The advice of most mechanics it to replace the water pump at the same time since this part of the engine will be apart to change the belt anyway. It’s a lot cheaper to do both things at once, rather than open the engine a second time to change a water pump at a later date.

It sounds like a nice car. The trade values it at $2500-$3900, but that’s with an odometer reading of 200,000-300,000 km. With such a low odometer reading yours should be worth more. I would suggest $4000-$5000 as a private sale.