Land Rover Repair: 01 Disco Cooling System overheating, land rover discovery, land rover discovery ii

Question
I own a 2001 Land Rover Discovery II SE with 68,000 miles. Recently, I have had an odd development where at "lower" speeds - under 40 mph - my temperature gauge has gone up and into the red zone accompanied by a burning smell but when I get to highway speed thwe temperature gauge goes back to normal range and the smell goes away. This morning once I got off the highway and drove into the parking garage, the temperature climbed again and the smell came back and when I turned off the engine, smoke was coming out of the engine. The coolant seems to be at a normal range and the last time this happened I put in a couple liters of water and the problem seemed to go away. I cannot figure out why this doing this at lower speeds but goes to normal at higher speeds.

Answer
Hi Joe,

one of two common problems could be involved here.  It could be a failing thermostat and the fix is simply replacing it.  Most local garage mechanics can do this - provided they have the replacement thermostat.

The other common problem is more serious and requires a LR mechanic or someone with LR experience.  A blown headgasket could cause this kind of problem and it could cost upwards of $2000 to remedy.

It would appear that your coolant is boiling over within the engine.  Do not allow this to happen for much longer - the cylinder sleeves have been known to loosen and when this happens, the engine is ruined.  The overheating engine can cause the welds on the sleeves to break and then you have a $6000 to $8000 repair.

Have the cooling system pressure tested and the thermostat replaced.  You could bench test the thermostat BUT its cost is small and since you have to remove it anyway....why not just replace it and be done?

As for the headgasket, not always do you see this signs in frothy oil in the sump.  If the leak is small, the leaking coolant can burn off BUT you smell the odour and may even see smoke.  Continual loss of coolant is usually a key sign of this.

Best of luck with this,

JohnMc