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Sudden overheating problem


IanT90
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Been a while since I was last on, had the old girl resprayed all new doors fitted etc that took up Oct and Nov.

So decided to have a break from jobs till the new year and just enjoy driving around for a while.

That was until yesterday when I set off for work on my customary 9 mile journey, majority of which is motorway. I was about 1 mile from work just about to leave the slip road when something made me glance at the temp gauge.

To my surprise it was at maximum ! I turned on the heater to get an idea how hot it was feeling in the system (after slowing down to 30 mph) the air was stone cold coming through the vents.

The temp gauge dropped slightly for the last bit of my journey, but remained high. Glanced under the bonnet when I arrived at work hoses where warm/hot but not scalding hot, no steam etc escaping ?

I went out again at lunch time in the daylight to have a better look, only recently checked water in the top up reservoir that had been okay. I rechecked and it was low this time so topped it up with about a litre of water.

I noticed a slight brown discolouration around the plastic vent nut on top of the thermostat housing looked like some radiator coloured water had been leaking out ?

Drove home that night after work temp gauge rose to just above half way but didn't go higher. I had fan heater on all the way home but it was cold for 80% of the journey only just warm in later stages.

When I got home checked saw no leaks all hoses where warm/hot even the heater matrix pipes. The water pump pulley was turning so assume that is okay.

So this is my situation does anyone have a clue what it might be ?

Thermostat fault ? only replaced it less than a year ago.

Water pump problem ? Pulley still rotating, although I can not tell if internal parts okay without removing

Viscous motor for fan faulty ? Fan was turning when I checked

Blockage or restriction in cooling pipes ? wont know without strip down.

Something more serious and worrying ie engine problem :unsure:

Any help advice or comments would be helpful

Thanks Ian

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Been out again in it today,no overheating but took ages for any warmth to get through from the heater matrix, that was intermittent sometimes warm then cold again.

At least the temp gauge never rose above half way.

Thermostat was my first thought apart from its age not driven excessive miles this year and think it was only February when I fitted it ?

Got time off around Christmas I will check out the stat then

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Its a 300TDI and exactly my thoughts on the matter. Don't know if anyone remembers my cylinder head rebuild earlier in the year when I lost a piece locating dowel for cylinder head in to the block ? wondering if it finally made its way into the pump and has caused some damage. This could be my problem although the air lock also sounds more feasable as the matrix runs hot and cold. As in earlier post I noticed a light brown leak around the plastic vent bolt above the thermostat housing.

Could be a combination of the broken section of metal dowel and an air lock.

Had plans to replace the timing belt in the new year along with the water pump and change all the hoses for new silicon ones. Hopefully this will solve the problem or highlight something.

Must admit engine has not been running all that well lately, plenty of torque and pulls okay just a bit noisey when it starts up suspect tappit's, as noise seems to disapear after about a mile as the oil starts circulating. Also been wondered if it's worth investing in a recon engine before they start becoming scarce and too expensive. What sort of price should I be looking at realistically ? Anyone got a good reliable garage in the North West area who could give me a quote. Think nearest one to me is Land Ranger services at Atherton Nr Manchester.

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I had an over reading 300tdi temp gauge earlier this year, turned out to be a loose connection to the sender stud combined with a failing battery to engine/chassis earth. Those non-contact infra red temp guns are worth a bit of cash to check coolant hoses and block temps without burning yourself.

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I will look at that as battery was removed recently to recharge it, maybe I dislodged the chassis terminal ? would explain the one off high reading but not the fluctuating temp of the matrix.

Gives me plenty to think about and look at anyway.

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A cold heater is the first sign of coolant loss; the heater will go cold before the gauge notices a problem, as the heater is pretty much the highest point. You need to bleed the system thoroughly, then keep a close watch on coolant levels, you probably have a small leak and over time the level drops. At least your gauge showed hot. The next stage is it would show cold and that is bad news.

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A second/alternative way to measure the actual temperature is handy during this type of problem... try and identify if its a mechanical problem or an electrical glitch... I bought a cheap infrared point and shoot thermometer for doing this when I had problems a few years ago.

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Fairly certain its an air lock now, heater fluctuating hot and cold links in with temp gauge fluctuation. Off work over Christmas so will look for leak first then bleed the system of possible airlocks thanks for the tips.

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so a mate of mine had some problem with his 110 that he decided to fix (can't remember exactly what it was) and while he was at it thought he would replace some other bits and bobs, new radiator hoses, new shocks all round, new thermostat, new water pump, give the old girl a bit of a new life, he put it all back together, all worked really well, till suddenly a few months later when the engine suddenly started overheating......and he battled ......he tried air lock, thermostat, water pump, all the tricks, till one day he stripped the whole thing and while he was putting the radiator hose on the workbench a shock absorber bush fell out of the pipe!!!! the very same one he had missed and cursed about when he assembled his fancy new colourful shocks..... it had obviously been in a position that allowed enough water through till a day when it turned and blocked the system just that little bit more and suddenly it all didn't work anymore....

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  • 6 years later...

I have an overheating issue on my 1984/ 110. It has a 2.25L petrol engine. The truck has aftermarket Revtec dual cooling fans for the radiator. I noticed they were not working recently. I first replaced the t-stat, new coolant, and then the fan relay. The temp gauge has been a bit erratic, pinning the needle in the hot area, then dropping to normal randomly, then moving to hot again. To get the fan running, I took the dust cap off the sensor, turned the adjustment screw 1/4 turn and the fan kicked-on! I am still getting a hot gauge though, with the engine wanting to stall when I come to a stop. Is this the sensor or maybe a water pump? Is there possibly an air bubble and how would I bleed? 

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I had inconsistent hot running with a. 2.5 diesel.  It’d get hot on long hills in 4th, and would then stay hot on the descent in 4th with overdrive but dropping down a gear would quickly sort it as the water pump spun faster.  It transpired to be the exhaust being restrictive.

I think you would do yourself a great service by refitting the standard fan and rad cowl.  As long as the rad is clean inside and out, that set up is good enough for tropical climates as well as more moderate temperatures.

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