Heater Not Reaching Hot

mentokk · Nov 14, 2009

Hi,

I have a problem with my 96 300TDI Disco. A week ago I noticed that the engine temp wasn't getting as hot as normal - guage goes to 1/3 and used tho be 1/2 also the heater only blows out warm air not hot.

I assumed it was a stuck thermostat so replaced it today but the problem isn't cured. All the pipes from the thermostat housing seem to be getting warm - any ideas.

Also I have another minor problem - my front fogs have stopped working -the switch illuminates when pressed but no fogs. I replaced the bulb in the clock recently and the switch for the fogs is just below it and I had to remove it - I may have disturbed a wire - is there any way to test?

thanks

Ben

discool · Nov 14, 2009

Fog lamps thats easy if they are factory fit, just go to the white plugs behind the headlamps and disconnect the plug and test there for voltage and an earth with the dash switch and ignition on. If it's ok there then it's the lamps or no then switch/fuse.

Sorry I cant help with the over cooling but have u tried blanking off the lower part of the rad, you should not have to, but it's a test.

david451 · Nov 14, 2009

discool said:
Fog lamps thats easy if they are factory fit, just go to the white plugs behind the headlamps and disconnect the plug and test there for voltage and an earth with the dash switch and ignition on. If it's ok there then it's the lamps or no then switch/fuse.

Sorry I cant help with the over cooling but have u tried blanking off the lower part of the rad, you should not have to, but it's a test.

Probably the bastid fan stuck on all the time, I took mine off and fitted a kenlowe

david451 · Nov 14, 2009

discool said:
Fog lamps thats easy if they are factory fit, just go to the white plugs behind the headlamps and disconnect the plug and test there for voltage and an earth with the dash switch and ignition on. If it's ok there then it's the lamps or no then switch/fuse.

Sorry I cant help with the over cooling but have u tried blanking off the lower part of the rad, you should not have to, but it's a test.

Oh and a tip when doing electrics, specially behind a dash, open the bonnet and slacken the battery terminal off. You cause a short and the whole vehicle will go up in seconds before you find a spanner to get the battery disconnected.

mentokk · Nov 14, 2009

david451 said:
Probably the bastid fan stuck on all the time, I took mine off and fitted a kenlowe

Thanks for the info - no you come to mention it the fan was on when I was looking under the bonnet. I will test in the morning when engine cold and see if it comes on right away - if it does how do I cure it?

mentokk · Nov 14, 2009

discool said:
Fog lamps thats easy if they are factory fit, just go to the white plugs behind the headlamps and disconnect the plug and test there for voltage and an earth with the dash switch and ignition on. If it's ok there then it's the lamps or no then switch/fuse.

Sorry I cant help with the over cooling but have u tried blanking off the lower part of the rad, you should not have to, but it's a test.

They are factory fit - I'll give it a try on the morning

nicedayforit · Nov 14, 2009

mentokk said:
Thanks for the info - no you come to mention it the fan was on when I was looking under the bonnet. I will test in the morning when engine cold and see if it comes on right away - if it does how do I cure it?

Take the fan off and run the car without it, I run my 300 most of the time without it. Only put it back on in very hot weather.
If the engine heats better that could be your problem.
Two other things to check, the wire connection to the temperature sender in the front of the head, below the thermostat housing. Check to see if it's clean and tight. Secondly check that the coolant system is full by filling at the bung in the top of the thermostat housing. You will have let a bit of air into the system changing the thermostat, it'll take a few days of running to clear.

david451 · Nov 14, 2009

nicedayforit said:
Take the fan off and run the car without it, I run my 300 most of the time without it. Only put it back on in very hot weather.
If the engine heats better that could be your problem.
Two other things to check, the wire connection to the temperature sender in the front of the head, below the thermostat housing. Check to see if it's clean and tight. Secondly check that the coolant system is full by filling at the bung in the top of the thermostat housing. You will have let a bit of air into the system changing the thermostat, it'll take a few days of running to clear.

If you take that bung out toss it and fit a plumbing fitting, the plastic fokirs break off and you wont get any overheating indications because it drains the water from the sender first, ie a dead engine.

lerk · Nov 14, 2009

The fan will turn all the time by design, but it isn't just ON - with the engine off, try moving it... you should be able to turn it without the belt moving, if not you viscous coupling is knackered!

The plugs in the thermostat housing and radiator are 1/2" BSP blank plugs (1.67 each from B&Q) wrap a layer of PerfectTapeForEverything to seal and stop them seizing!

mentokk · Nov 15, 2009

lerk said:
The fan will turn all the time by design, but it isn't just ON - with the engine off, try moving it... you should be able to turn it without the belt moving, if not you viscous coupling is knackered!

The plugs in the thermostat housing and radiator are 1/2" BSP blank plugs (1.67 each from B&Q) wrap a layer of PerfectTapeForEverything to seal and stop them seizing!

The fan turns on it's own without moving the fan belt so I gues the viscous coupling is OK.

mentokk · Nov 15, 2009

Still got the heater problem - any more suggestions?

Heater Not Reaching Hot

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