Jeep Compass Coolant Reservoirs

The coolant level should sit between the MIN and MAX marks on the side of the translucent reservoir tank when the engine is cold. On Wrangler JL and Grand Cherokee WK2 models, this is typically visible near the firewall on the passenger side—if it's below the MIN line, top up with the correct Mopar OAT coolant mixture (50/50 with distilled water). Never check or open the reservoir when the engine is hot, as the system is pressurized and can cause serious burns.

A genuine Mopar coolant reservoir for a Wrangler JK or Grand Cherokee WK2 typically costs R800-R1,800, while aftermarket options range from R450-R1,200. Installation is straightforward and takes about 30-45 minutes, so labour at a Joburg or Cape Town workshop should add R300-R600 to the total cost.

Common causes include a cracked reservoir tank (common on older Cherokee XJ and KL models due to heat cycling), a faulty pressure cap that won't hold system pressure, or an internal leak like a blown head gasket on the 2.4L Tigershark engine. If you're constantly topping up coolant but see no external puddles, have a pressure test done immediately—internal leaks can cause catastrophic engine damage on the 3.6L Pentastar V6.

Jeep vehicles require Mopar OAT (Organic Additive Technology) coolant, which is typically orange or pink—never mix it with green conventional coolant as this causes sludge and corrosion. Wrangler JL, Grand Cherokee WK2, and Cherokee KL models specifically need OAT coolant (MS-12106 specification), available at Jeep dealers or auto parts stores in SA for R180-R350 per 5-litre bottle.

On Wrangler JL (2018+) and JK (2007-2018) models, the coolant reservoir is located on the passenger side of the engine bay, near the firewall and mounted to the inner fender. It's a translucent white or light-coloured plastic tank with MIN/MAX markings—on the JL, it sits just behind the air intake assembly and is easily visible when you open the bonnet.