getting warm

Evening gents and ladies

Having a problem with my diesel range rover, few months ago in the very warm uk weather whilst travelling up a steep hill in slow moving traffic 10 to 15mph the temp guage jumped to around 80% of the temp guage just as I hit the top of the hill on the flat and travelling at the same speed it dropped to the normal 12 o'clock position.

It has jumped to 80% on the guage twice more but this has been under heavy acceleration for prolonged period ie off a roundabout on the dual carriageway to the national speedlimit and inexcess on a private road. Now when backed off the throttle and reapplying it even when maintaining the same speed the temp guage returns to the normal position instantly.

The guage doesnt build up gradually it sit at 12 and jumps up and down to 80% and normal temp.

Any other type of driving it is fine have towed a trailer and car and it was fine sitting idle it is fine 90% of the time it is fine just these three occasion s are starting to worry me.

I have replace the stat and water pump as it was leaking, flushed rad and it was fine, filled with new coolant and was done with a vacuum filling system so no air locks, got no leaks and doesnt use water, have checked viscous and it is locking up when hot have check rad for cold spots and all is well.

The only things I can think of is that the baffle in the rad has possibly given way but seens as the rad is hot all over kind of disproves this and possible the rad could have a partial block. Or maybe a duff sensor the guage shows a warm engine within 3 minutes of driving.

Any body have any suggestions

Many thanks

Matt

Trying to flush the Diesel Range Rover will be fruitless, they are top flow and almost impossible to clear out.

They silt up at the bottom, so I would check to see if it is warm all round or in patches...also make sure the baffle at the top of the rad hasn't broken away - this directs the coolant round the rad rather than straight across the top...

Hi saint v8 I flushed the rad whilst I had it out of the car filled it via top hoses gave it a whirl and tipped it upside down but I understand what your saying about the top hose system and I should have checked the baffle when it was out but totally forgot about it.

Have checked rad all over and couldnt detect any cold spots il see if I can get a laser temp guage and check it that way also.

Also check the Viscous Fan when it is warm too...it could be slipping to much and not having any cooling effect.

To check viscous should it has a bit of resistance when turning

Yep when it gets hot, the coupling should start locking up to turn the fan faster...usually test is with a rolled up newspaper...if you can slow or worse, stop, the fan - its fecked.

It will not be the baffle in the RAD if it gets hot at the bottom. Most likely it's the viscous fan. A candidate for my aircon fans cooling mod

I shall do the newspaper test this weekend and will report the finding. Many thanks guys

matt1987 said:

I shall do the newspaper test this weekend and will report the finding. Many thanks guys

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Also look at Wammers How to for less hazardous method, in the how to section

If I park the old girl up once warm and go back in 15 to 20 mins the viscous fan roars when you start her up and drive off im assuming this is normal and the fan is working correctly.

If this is correct then maybe a header cap and new sensor could solve my problem

Its so intermittent it unreal the guage can shoot up and I can back off reapply throttle and it back at 12 o'clock slow down and open her up and she wont do it again there is no steady increase in the guage movement it jumps up and down

Im puzzled to what is going on with the old girl

matt1987 said:

If I park the old girl up once warm and go back in 15 to 20 mins the viscous fan roars when you start her up and drive off im assuming this is normal and the fan is working correctly.

If this is correct then maybe a header cap and new sensor could solve my problem

Its so intermittent it unreal the guage can shoot up and I can back off reapply throttle and it back at 12 o'clock slow down and open her up and she wont do it again there is no steady increase in the guage movement it jumps up and down

Im puzzled to what is going on with the old girl

Click to expand...

Could just be an electrical problem.

Datatek said:

Could just be an electrical problem.

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.

Agree especially if its a 95 or 96 MY.

Was reading this and sound like could be an earth problem

She is a 97my

Unless the temp gauge circuit uses a seperate earth then a earth fault could be possible but knowing landrover it will most likely share the same earth point so a problem with the shared earth point would show a fault with another component

The becm uses a 5V signal to the temp sender and the 95 & 96 MY temp senders relied upon the engine earth, so with a 5V signal to the sender, a small earth shift on the engine causes the needle on the temp gauge to rise. The fix at 97 was to provide the sensor with its own ground wire which is earthed to the body. However if this is a 97MY then and earth shift on the engine should not cause the temp gauge to rise.
If this was my car, I would try and work out if this was an electrical problem or a genuine overheating problem. The best way to do this is to measure the top hose temperature with a thermocouple. The thermocouple needs to be the thin wire size (about 0.2 mm thick). Remove top hose retaining clip, partially remove the top hose from the radiator and feed the thermocouple into the coolant. Then carefully refit hose and clip. To stop any leaks apply grease to the thermouple. . Then with an inexpensive volt meter that can measure temperature you can work out whether the engine is overheating or its an electrical issue.

So when they added the temp sender own ground wire is it visable when they did the mod I suppose mine could have been built in 96 and registered 97 il use all this info on the weekend and see how I get on

davidg said:

The becm uses a 5V signal to the temp sender and the 95 & 96 MY temp senders relied upon the engine earth, so with a 5V signal to the sender, a small earth shift on the engine causes the needle on the temp gauge to rise. The fix at 97 was to provide the sensor with its own ground wire which is earthed to the body. However if this is a 97MY then and earth shift on the engine should not cause the temp gauge to rise.
If this was my car, I would try and work out if this was an electrical problem or a genuine overheating problem. The best way to do this is to measure the top hose temperature with a thermocouple. The thermocouple needs to be the thin wire size (about 0.2 mm thick). Remove top hose retaining clip, partially remove the top hose from the radiator and feed the thermocouple into the coolant. Then carefully refit hose and clip. To stop any leaks apply grease to the thermouple. . Then with an inexpensive volt meter that can measure temperature you can work out whether the engine is overheating or its an electrical issue.

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No need to put the thermocouple into the coolant, just cable tie it to the top surface of the top hose and put foam pipe lagging over it, reading will be within a couple of degrees of water temperature and no risk of air locks due to coolant loss.

Datatek said:

No need to put the thermocouple into the coolant, just cable tie it to the top surface of the top hose and put foam pipe lagging over it, reading will be within a couple of degrees of water temperature and no risk of air locks due to coolant loss.

Click to expand...

Good idea!

Ok sorry for the late reply ive finally got round to testing the temp and the readings I got was the ns top rad hose was reading 67°c and the os top rad hose was reading 57°c this reading was taken after a 10mile journey. It hasnt jumped from the normal 12 o'clock position to near the upper limit of the temp guage like it had done before. The viscous is working and no water loss is present.

Thats all I have to report at the minute I may put it on diagnostics and check the temp that way at idle and at 2k rpm and see what that reports