230E losing water slowly

[simmo300e]

Our 230E is using water at the rate of around 500ml every week or so. There are no apparent leaks and the hoses look Ok. The coolant tank cap has been replaced. The water pump doesn't appear to be leaking. Also the car runs hot sometimes, up to 100 on the meter when in traffic but drops to 85 when running on an open road.

Any thoughts/suggestions on where it might be losing water?

Also, as we are in the tropics, the cars are running with plain water in the system, which is not something that's been commented on or changed when they go to the dealer for a checkup/oil change. Is this Ok or should I be using a coolant mixture anyway?

Your help, as always, would be greatly appreciated.

[sixto]

You should be using a coolant mix for lubricants and corrosion inhibitors.

Sixto
95 S420
87 300SDL

[nachi11744]

Hello,
You should run at least 30% coolant OR a corrosion inhibitor, check with the local Land Rover agent for the stuff they use in the all alloy V-8 cooling system. The slow leak is probably a failing radiator, a hose would have blown by now in the tropics. Do not discount the heater matrix, if still plumbed into the system. You do not specify chassis type(W123 or 124?)
Hope that helps.

[Greg in Oz]

Here in Sydney we don't have much need for the "anti-freeze" properties of coolant either, but I would not consider running our cars without it. The anti-corrosion properties are still very much needed and I always use genuine MB coolant (we get the blue German stuff here) at a concentration of 50%. If you have been running without the correct coolant then your leak may be the head gasket. On these engines the head gasket appears to behave like a sacrificial anode. Whenever I have had to replace a head gasket they appear badly corroded, possibly due to poor coolant maintenance at some time during the life of the engine.

[simmo300e]

Nachi, its a 124 chassis, the heater matrix - by this I understand you to mean the heater valve near the brake booster - has been blocked off due to malfunction.

noted comments re coolant requirements. will do that asap.

[psfred]

Possible leaks are heater core (unless blocked on BOTH sides of the heater core), head gasket, heater hose clamps (this was the leak on the TE that drove me nuts), heater core (if connected), radiator.

Sadly, "mysterious" coolant loss is often a head gasket.

Do not run plain water, the engine will corrode terribly, and you will also end up with a ruilned radiator and heater core. You need the boilover protection in the tropics as much as we need the freeze protection in this part of the world, plus the protection from corrosion.

A leaking head gasket will usually pressurise the cooling system cold -- is the upper radiator hose hard with a cold engine? If so, head gasket time (or head if you've let it go with plain water some years).

Peter

[autozen]

You need to go to a shop or get your hands on a cooling system pressure tester. You connect the tester to where the radiator cap goes. Be carefull not to go higher than the kpa of your particular system or you run the risk of rupturing the heater core. This test must be performed with the engine COLD. You can not do this on a hot engine. What you are looking for is a weeping hose connection or possibly water pump. Here is the reasoning. When you bring the car to operating temp, you presureize the system to the value of the cap. All hose connections and pump sealls, etc. are swollen and won't leak. As the engine cools, the connections relax and allow a slight coolant leak at any connection that is not properly tight. Coolant is forced out by the system pressure until pressure goes to zero. Now the system tries to go to a vacuum, so the connection has lost maybe 100ml of coolant and now stops leaking. This whole process starts over again next time you use the car. In a weeks time you have lost 500mls. Soon the car runs hot because it is low on water. Check this first, and then look at a head gasket. You may also have a restricted radiator and you are boiling off water since you are running straight water.

Good luck,
Peter