jackmac Posted July 1, 2014 Share Posted July 1, 2014 Hi all, Had some problems the other week with my 300TDi on a long drive, thought I would ask about them as I have the same journey in reverse coming up on Friday. Ever since I've owned the car (300TDi conversion 90) it's run quite warm when worked on the motorway. I've always put it down to the full frontal intercooler, very high winch bumper and 8274 winch combining to deny the radiator much air flow. At the moment there is a lot of rust and particles in the coolant as well which is no doubt not helping, and I've just replaced viscous fan with a much more viscous unit after finding no resistance at all on the one I had fitted. On the last trip (160 miles mostly motorway) it got hotter than ever before and I had to pull over. The needle was right on the edge of the red, I've done miles since and am confident it didn't cause any damage. Before it got really hot, the temp gauge was playing up. It went from 2/3 of the way up, then over the course of a few seconds went deep into the red, then 30 seconds later it took about 2 seconds for the temp to suddenly drop back to 2/3. The gauge was moving way too quick for it to actually be reflecting the water temp, so what might have been causing it? Checked water level, losing a very small amount from thermostat gasket but level is fine as I fill it high before each journey. Connection for temp sender is nice and clean. Tomorrow I will check the connections on the gauge. Is there anything else I should be looking at ( temp sender on its way out?)? Also, is the coolant having a lot of rust in likely to not help matters? I was hesitant changing it in case of introducing an airlock Apologies for the essay! Quote Link to comment Share on other sites More sharing options...
jbs Posted July 1, 2014 Share Posted July 1, 2014 Cooling system need flushing out by any chance?, If I hammer mine on the motorway and I have a similar situation as you-big intercooler in front of the rad, I normally turn the electric fan on as I keep an eye on my temperature gauge and that normally sorts it out John Quote Link to comment Share on other sites More sharing options...
western Posted July 1, 2014 Share Posted July 1, 2014 what state is the radiator in ? if most of the fins are missing the rad won't be able to disapate the heat & it'll tell you it's getting too hot Quote Link to comment Share on other sites More sharing options...
jackmac Posted July 1, 2014 Author Share Posted July 1, 2014 Coolant could definitely do with flushing. Rad is good condition, not perfectly clean but definitely not blocked. But neither of those would explain the sudden rise and decrease on the gauge would they? I'll go buy 5L of anti-freeze tomorrow and flush the system in the meantime Quote Link to comment Share on other sites More sharing options...
mmgemini Posted July 2, 2014 Share Posted July 2, 2014 Coolant could definitely do with flushing. Rad is good condition, not perfectly clean but definitely not blocked. But neither of those would explain the sudden rise and decrease on the gauge would they? I'll go buy 5L of anti-freeze tomorrow and flush the system in the meantime How do you know the rad is in good condition ? How old is the rad ? If older than five years the bottom of the matrix could be silted up. 1 Quote Link to comment Share on other sites More sharing options...
jbs Posted July 2, 2014 Share Posted July 2, 2014 Coolant could definitely do with flushing. Rad is good condition, not perfectly clean but definitely not blocked. But neither of those would explain the sudden rise and decrease on the gauge would they? I'll go buy 5L of anti-freeze tomorrow and flush the system in the meantime Jack, surely if the rads semi blocked(with the rust particles that you mentioned in your first post-why does it have rust in it and not just coolant?) then it'd cause a decrease/increase of flow when the blockages are moving around when the pump is working-hence why the gauge fluctuates? John Quote Link to comment Share on other sites More sharing options...
jackmac Posted July 2, 2014 Author Share Posted July 2, 2014 How do you know the rad is in good condition ? How old is the rad ? If older than five years the bottom of the matrix could be silted up. Visibly it's in good condition. I have never flushed it out before though which is today's job. Don't know the age, I would guess older than 5 years though. Jack, surely if the rads semi blocked(with the rust particles that you mentioned in your first post-why does it have rust in it and not just coolant?) then it'd cause a decrease/increase of flow when the blockages are moving around when the pump is working-hence why the gauge fluctuates? John It has rust in because I think the previous owner of the engine block I built up and fitted a few months ago must have used very little anti freeze, and also did not fully drain the block before leaving it to sit for a while after removal. I would definitely expect that to cause some fluctuation, but almost 1/3 of the gauge in 2 seconds? Quote Link to comment Share on other sites More sharing options...
jbs Posted July 2, 2014 Share Posted July 2, 2014 What about then the thermostat sticking? John Quote Link to comment Share on other sites More sharing options...
jackmac Posted July 2, 2014 Author Share Posted July 2, 2014 How would I diagnose a stick thermostat John? It definitely opens etc as the rad is getting warm, no cold patches on rad either so that's not blocked. Flushed and changed coolant today, cost an arm and a leg as halfrauds didn't have any 5L containers so had to buy 2 x 2L Anyway, it definitely seems to run a touch cooler now after that and replacing the viscous fan, gauge needle now seems to sit just before vertical on normal driving which is an improvement. Can't seem to repeat the gauge fluctuation though. I'll keep an eye out for it on Friday, taking plenty of water and a spare viscous in case this one goes as well! Quote Link to comment Share on other sites More sharing options...
Tanuki Posted July 2, 2014 Share Posted July 2, 2014 Job One should be to replace the radiator. If it's full-of-carp or the fins have got the usual crumbliness due to 50,000 miles of exposure to road-crud and salt then however much water you manage to get circulating through it, it won't dissipate the heat. Treat Land-Rover radiators as service-items, like Diesel heater-plugs, brake-discs, water-pumps and batteries. Quote Link to comment Share on other sites More sharing options...
jbs Posted July 2, 2014 Share Posted July 2, 2014 Jack, there is several threads regarding stuck thermostats Google is what I used , http://www.landyzone.co.uk/lz/f49/how-can-i-test-my-300-tdi-thermostat-241158.html John Quote Link to comment Share on other sites More sharing options...
jackmac Posted July 2, 2014 Author Share Posted July 2, 2014 Ah OK, I see what you meant now. Stat is definitely opening, I suppose I could whip it out and check it opens fully though 1 Quote Link to comment Share on other sites More sharing options...
Maverik Posted July 3, 2014 Share Posted July 3, 2014 Be wary of taking thermostats out to "test" I had two in a source pan and visually they acted the same, putting them in the engine I got very different gauge readings/behaviour... Wax thermostats, certainly ones for land Rovers seem to be really hit or miss... Quote Link to comment Share on other sites More sharing options...
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