1998 Range Rover 4.0 overheating the other day, all steam came from the inside of the truck nothing under the hood was disturbed. Im thinking its a hose going to the heating core or the heating core itself. my problem is the issue is behind the dashboard, wonder how much trouble that would be. Im sure the labor cost for removing a dashboard is very expensive. What should i do?

 

To get back in operation - could you not take apart the two hose lines that feed the heater core, and use some pipe and clamps to make them up as a loop under the hood? This would allow operation of the vehicle without the sauna, and confirm the source of the leak.

 

Heater cores are a typical problem for P38s. Savannah has mentioned an effective temporary fix for it by connecting the two heater core pipes. Ultimately, replacing the heater core is the only true fix. Here is a DIY guide for replacing it: Heater Core Replacement (Range Rover 4.0/4.6/P48)

 

I bypassed the heater core. It still overheated but no steam this time. Could it be the thermostat now? Not I don't know much about rangerovers

 

Well, you have come to the right place - the tuition is cheap. First thing is search the forum for a download of the RAVE, which is the set of shop manuals on Rovers. Were I to look at overheating, here are some things to check, in order of cost:

1. Coolant level - about midway in the coolant tank, not oily. If you don't know if coolant was changed in last 2 - 3 years, flush and change it. If coolant has little sparkly metal flakes in it, or other floating dirt like clay stuff, the previous owner may have used one of the many head gasket / radiator repair products.

2. Cap on tank should be on tight. Sometimes we open these and point the wheels uphill at a steep angle, and run engine for 20 minutes or so to get bubbles to rise out of the cooling system. At normal temp. pressure can be 15 PSI or more, so cap has to work. It will vent at higher pressure.

3. Start at the grille and work back - no trash, leaves, etc. blocking the grille, the AC condenser radiator, the hidden space between the AC condenser and the water radiator (a favorite place for gunk), and no dried mud clogging the fins of the radiator. Blow out with compressed air or wash out if in doubt.

4. With engine cold turn fan by hand. Should turn, but stiff, that's the visocus fan clutch at rest. Try to spin it - should not spin even 1 revolution. Mine only goes about 1/10 revolution. Crank engine. Fan should make a "roaring" noise at first, then drop off in volume in a minute or two. That is the fluid in the fan clutch being circulated and warming up, It changes the coupling from 75% or so to about 20% at normal temp. That saves gas and water pump bearings. Once truck is warmed up, turn off. Then spin fan. Should not be as stiff as before, but should not free wheel or spin even a whole revolution. Ones that do usually have lost some of their fluid. Fan clutches do have to be replaced from time to time. Now drive the truck to get to that almost overheated stage.

4. If truck gets hot while driving at 45 mph or more, problem could be radiator clogged (outside or inside). It is just not able to do the job. If a flush does not do it, radiator shop can acid flush and take it apart and rod out the calcium deposits (cuased by failing to sue distilled water). Much cheaper than new radiator.

5. If truck overheats at idle or in slow traffic, could be that fan clutch. Stop engine in this condition, and spin fan, it should be stiffer. As the face plate of the fan heats up above 170 degrees it starts re-coupling, it is gradual, like a variable speed drill, not on/off.

6. Of course there is the thermostat. The job of that part is to control how cold the engine gets. Thermostats can stick, in either direction, but usually don't care how fast you are driving. So if only in slow traffic, might not be the stat. I would go with a 180 degree replacement. 160 is too low.

7. Water pump is always waiting to die. But usually shows up at all speeds, not just one.

8. Radiator may have oil cooler and tranny cooler lines, and we certainly don't want those fluids mixing with coolant. Coolant should not have oil in it.

9. Head gaskets are a serious possibility, can be diagnosed by a pressure test, usually will show up some change in color of spark plugs from one or two cylinder, oil in coolant, coolant in oil, etc. There is a simple chemical test you can buy from auto parts store to test for combustion gas in coolant.

10. Cracked block. Game over.