tpk241 Posted August 4, 2009 Share Posted August 4, 2009 Hi All, My 96' P reg 300tdi disco started to overheat the other day (15mile regular journey which usually causes no problems) .. The temp gauge flew up to the red then rapidly drop back down again, it did this a couple of times before i made it back home. I haven't driven it since this happened so thought i would pick your brains as to the problem. There is a chirping / squealing which i suspected to be the tensioner bearing, but now i am starting to think the waterpump has failed ? Is this a possibility or does anyone have any other ideas ? Thanks in advance Stu Quote Link to comment Share on other sites More sharing options...
BogMonster Posted August 4, 2009 Share Posted August 4, 2009 Yes it could be that, take the belt off and see if there is any play in the bearings Quote Link to comment Share on other sites More sharing options...
jimmy_neutron Posted August 5, 2009 Share Posted August 5, 2009 Yes it could be that, take the belt off and see if there is any play in the bearings maybe .. or there was no longer any coolant at the sensor which causes the gauge to read low and then something died. Quote Link to comment Share on other sites More sharing options...
tpk241 Posted August 5, 2009 Author Share Posted August 5, 2009 Thanks .... Jimmy can you elaborate at all what could have died ? I am not sure on this cos the temp gauge always reaches half way at the same point on my journey (i use the truck to commute everyday) and this is the first time i have noticed the high temp gauge in usual usage situation. This coupled with the squealing noise i thought it may be the water pump failing. No flow through the rad = overheating. What I am not sure about is whether the pump is a simple case of 'its works or it doesnt' or whether it can be working intermittently causing the temp gauge to rise until the pump starts pumping again .... Maybe someone can help enlighten me on this ? Thanks Bogmonster i will check the bearings over the weekend at some point. Is there anything else i should check as well ? Cheers Stu Quote Link to comment Share on other sites More sharing options...
jimmy_neutron Posted August 6, 2009 Share Posted August 6, 2009 Its hard to diagnose without seeing but if it was me i'd drop the water pump belt off and start her up just for a second or two to see if you still get the chirping noise. At a guess you won't which will lead you to the water pump. When the bearings fail in the water pump they can chirp a bit. The other thing that happens is that they can sometimes dump coolant very slowly when running and dump a load just after switching off the engine. This can cause an air lock and even cause the water pump to cavitate. As the coolant sensor is close to the water pump, the sensor can end up reading the trapped air temperature rather than the coolant temperature, this explaining the needle jumping around. The worry of this is what other damage may of been done whilst overheating Quote Link to comment Share on other sites More sharing options...
tpk241 Posted August 6, 2009 Author Share Posted August 6, 2009 Thanks Jimmy .. good advice .. i will give this a go over the weekend ... Thanks again Stu Quote Link to comment Share on other sites More sharing options...
StevenA Posted August 6, 2009 Share Posted August 6, 2009 I had this a couple of years ago driving down through France in the summer - turned out it was the radiator (corroded fins + blockages). After changing the radiator, runs like a dream at just below mid point regardless of weather, load etc Quote Link to comment Share on other sites More sharing options...
kitters Posted August 7, 2009 Share Posted August 7, 2009 In my (previous) Discop 1 Tdi I had similar fun with the temerature guage, for no readily apparent reason it would suddenly go right up, then drop and then keep fluctuating - but with NO water problems. We eventually traced the problem to a broken Earth Strap which was somehow making the temerature guage act like a volt meter! Have no idea why but new earth strap fixed the problem. Quote Link to comment Share on other sites More sharing options...
tpk241 Posted September 29, 2009 Author Share Posted September 29, 2009 Hi all .. An update to this situation .. . I have changed the thermo (for gen LR one). Also changed the waterpump for a known good replacement, same with radiator (flushed through for about an hour in all directions with a hose). Changed thermo housing plug to a x-Eng one. Whilst doing this i noticed the alternator bearing had failed badly causing severe slack in the tension of the belt. This i thought could have been responsible for the dodgy temps as the belt would have been slipping on the pump pulley. So i changed the alternator to a known good one too .. Now ... I am still overheating, not quite as much as before but i am still getting the sudden rise and fall of the gauge. When the temp gauge is up the heater blows cold, and when in mornal half way point the heater is blowing hot ? Is this the sign of a head gasket problem or a coolant airlock ? I am a bit baffled and cheesed off to say the least ? Any pointers would be great ! Thanks Stu Quote Link to comment Share on other sites More sharing options...
Dagsey Posted September 30, 2009 Share Posted September 30, 2009 Hi Stu IMHO I think your problem now is an airlock in the metal heater pipe that runs across the top of the inlet manifold which you'll need to bleed. Also, make sure there are no leaks in the system (suspect top hose to aforementioned heater pipe and, since you have replaced the water pump, possibly the P gasket may be leaking). Sorry, in a hurry but search here on the site for correct refilling/bleeding proceedure and how to check/replace the P gasket if necessary. Finally, if your rad was full of ****e when you flushed it then suggest you flush the heater matrix through similiarly as blockages/restrictions here can cause what you're experiencing. Don't dismiss the previously discussed earth problems, these are common and if the gauge is jumping violently I would suspect that rather than actual overheating! Good luck, Dags. Quote Link to comment Share on other sites More sharing options...
pw8757 Posted September 30, 2009 Share Posted September 30, 2009 Sequentially, you should be able to check for a coolant airlock quicker....................must say it sounds that way, or perhaps electrical problem still...................... Quote Link to comment Share on other sites More sharing options...
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