Disco Overheat AGAIN!!!

Hi All,

I am new to the site and am in The bahamas, thought it would be a good idea to have a bit of UK with me so brought a Land Rover? Anyway my problem is it always over heats after about 10 mins of running, I have tried all the usual stuff remove thermostat, turn hot air on, no luck and it is not a gauge as she is very hot!!! Any ideas. 1998 3.9 V8 Petrol

Pop

Bring her back cos its too hot there Nah maybe give the fermostat a smack wi' a universal adjustment tool. It could be sticking shut, so that you're only using a tiny bit of coolant! Or the coolant pump might be on the faff, I dont know if its electric or driven, check that too praps.

Hi,
Thanks, I took the stat out, just flushed the matrix and rad through again added fresh coolant still after a 5 min run up to the red again? water pumps are fine lots of water flow when i remove hoses etc. I am totally confused?

Just notice when she get hot that i get a hissing sound from behind or under manifold, losing a little coolant, do you think the head gasket has gone as well. This was not the problem to start with as she was and still is running perfect.

pop

bahamapop said:

Hi,
Thanks, I took the stat out, just flushed the matrix and rad through again added fresh coolant still after a 5 min run up to the red again? water pumps are fine lots of water flow when i remove hoses etc. I am totally confused?

Just notice when she get hot that i get a hissing sound from behind or under manifold, losing a little coolant, do you think the head gasket has gone as well. This was not the problem to start with as she was and still is running perfect.

pop

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It's heating up very quick, particularilly so with the thermostat out, I think the water pump is fooked, even if you think the flow is ok. Take it off and check the impeller.

I doubt all that heat can come from the head gasket, lots of gas and pressure yes, but removing the thermostat usually releves that

When you run it up with the cap off, to get the air out, bleed it, does it chuck all it's water out with loads of bubbling and gas.

Might even be the temp transmittors died.

Well I'm stumped then, if it's making all that heat with a full rad flow I've no idea what's wrong! Will keep an eye in here though, as I'm interested now! Sorry I can't be more help bahamapop

Hi David,

No with the cap off to bleed system all i get is a steedy stream of air but only enough just to trickle over the top of the exspan tank. I have looked closer at the water pump and can hear a knocking from the bearing I think?

If it was a bad temp transmitter would this just give a bad reading.as the engine is getting very hot.

pop

bahamapop said:

Hi David,

No with the cap off to bleed system all i get is a steedy stream of air but only enough just to trickle over the top of the exspan tank. I have looked closer at the water pump and can hear a knocking from the bearing I think?

If it was a bad temp transmitter would this just give a bad reading.as the engine is getting very hot.

pop

Click to expand...

You need to fill it from the thermostat plug, sounds like it's full of air, make sure yer heaters are set to hot to allow the water and air out

If the temp transmittor got cooked then it could be irratic, and giving wrong reading.

Take the fan belt off and turn the pump by hand and see what it feels like that way.

Hi David,

Should the water pump have a lot of resistance when turning it by hand? and do you mean the plug with the wires on the side of the stat housing? or the plug on the top of the rad?

Many thanks

Pop

Hi mate,

To help you tell if it's full of air my Landrover manual tells me that your cooling system should take 11.30 litres of coolant so make sure that it takes near enough this amount

Regarding the "hissing" sound from the manifold ...... get a good strong torch and check to see if any coolant is weeping out from the same area your getting the hiss from.

The knock may or may not be nothing serious ...... if the engines running very hot the oil will be very hot too and when oil gets very hot it thins down so might just be the oil struggling to cope with the high temperature

Also check all the coolant hoses for blockages ....... especially the small ones ...... this can cause problems with bleeding the air out

Also you say the waterpump feels tight ....... how tight? ....... there should be some resistance if you try to turn it but not loads ...... if the pump bearings are gone they will heat up and in turn transfer heat to the coolant etc etc

Hope this helps a little mate

bahamapop said:

Hi All,

I am new to the site and am in The bahamas, thought it would be a good idea to have a bit of UK with me so brought a Land Rover? Anyway my problem is it always over heats after about 10 mins of running, I have tried all the usual stuff remove thermostat, turn hot air on, no luck and it is not a gauge as she is very hot!!! Any ideas. 1998 3.9 V8 Petrol

Pop

Click to expand...

I am not suggesting that the cause cannot be exotic..but so often it is the simple things.

I am assuming, of course, that your rad fan is working well. That being the case I would do two things first;

1. Examine your fan belt. They should be changed regularly..and one should even carry a spare, but few do. The fan belts stretch (needing retensioning) and then develop minute cracks. These bad belts will turn the pumps but insufficenyl, or not at all at certain speeds.

2. If all is well with the fan belt, then flsuh the rad an engine. This is costless if you know how to remove a thermostat. Take the thermostat out, opne the engine watercocks or remove them completely and pull the lower rad hose off the rad. Then run a hose through the rad from the top until the water runs clear . Then do the same with the hose inserting it the engine. (20 minures)

Then reassemble everything and see what you have.