Souster Posted December 2, 2014 Share Posted December 2, 2014 Hi all I have a 1995 defender 300tdi. Excuse the long thread. Approximately a month ago, it did a 250 mile round trip, not really with any load, country roads and on the return home in the dark, the temperature gauge was reading towards the red. It normally sits half way, however it was sitting at 2/3rds to 3/4. So i pulled over, all seemed well under the bonnet, no issues at all. Coolant hose felt hot, but not alarmingly hot. Not much warmer than a friends 300tdi that was doing the same journey. Ever since then ive been trying to find the issue. The following week i replaced the thermostat, which was already a new genuine lr stat approx 6 months ago. The rad and all pipes were flushed 6 months ago (not due to any issues), water pump feels fine externally along with a new stat as i mention above. The system doesnt seem to be over pressurising either. Nor does it use water. Last week, i took the vehicle on a 25 mile round trip, with the viscous fan removed, with absolutley no issues what so ever. Temp gauge stuck bang on half way, all journey regardless. Tonight i drove approx 15 miles round trip, and on the return after 20 mins in traffic, the gauge seemed to creep up to 3/4's. I got home during the gauge at this level, and used as infa red temp gun (cheap £15 off amazon). Pointed it at the cylinder head near the glow plugs, and it was showing 85 degrees Celsius, the thermostat housing about the same. The top and bottom hose was approx 65. The rad seems to get fairly hot all over, the right hand side nearest the hoses are hotter than the opposing side near the oil cooler pipes. Can anyone help me out here, i cant see whats left really. Could it be a faulty sender? I know the gauges arent that accurate, but i certainly dont like it reaching any higher than half way. Many thanks in advance Quote Link to comment Share on other sites More sharing options...
Retroanaconda Posted December 2, 2014 Share Posted December 2, 2014 Does it only happen in traffic? Quote Link to comment Share on other sites More sharing options...
Souster Posted December 2, 2014 Author Share Posted December 2, 2014 Does it only happen in traffic?Thanks for reply It didnt really happen it traffic, it happened 10 mins after really in a 50mph zone. But to answer your question, no it doesnt. Its happened on country roads in the past. Quote Link to comment Share on other sites More sharing options...
pete3000 Posted December 2, 2014 Share Posted December 2, 2014 mine did this last weekend, check the push on bullet connector is clean (uncorroded) and is tight fit on the sender, next check the gauge earth or the earth on the engine bulkhead/engine earth strap. Gave mine a squish and tighten up and the gauge is back to just off to the right of middle. Quote Link to comment Share on other sites More sharing options...
Souster Posted December 2, 2014 Author Share Posted December 2, 2014 mine did this last weekend, check the push on bullet connector is clean (uncorroded) and is tight fit on the sender, next check the gauge earth or the earth on the engine bulkhead/engine earth strap. Gave mine a squish and tighten up and the gauge is back to just off to the right of middle. Thanks Pete. I'll check the sender connection, any ideas where the engine/bulkhead earth strap is? And the gauge really, i know theres a black wire but not sure where it earths? Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted December 2, 2014 Share Posted December 2, 2014 Refit the cooling fan souster, if it does overheat how will it cool otherwise. Mo Quote Link to comment Share on other sites More sharing options...
Souster Posted December 2, 2014 Author Share Posted December 2, 2014 Refit the cooling fan souster, if it does overheat how will it cool otherwise. Mo Cheers Mo, i will do mate. I took it off temporarily as i was advised to take it off, and cooling issues will be shown up clearer without it fitted. Its only a viscous unit. Ive got a long journey ahead of me on sunday. And im abit apprehensive of the temperature situation. Concerned it may overheat! Would it be worth sticking a new sender on it? Quote Link to comment Share on other sites More sharing options...
qwakers Posted December 2, 2014 Share Posted December 2, 2014 it would be worth sticking the fan back on it. that is its job, afterall. Quote Link to comment Share on other sites More sharing options...
Souster Posted December 2, 2014 Author Share Posted December 2, 2014 The fan was removed perposely to highlight the cooling problem and allow me to feel the whole of the radiator to see if it was doing its job. The gauge would creep up regardless of viscous fan fitted Quote Link to comment Share on other sites More sharing options...
qwakers Posted December 2, 2014 Share Posted December 2, 2014 then you have a problem. most likely cause is a knackered radiator.(if the temp is actually creeping up and the gauge isnt simply misreading...) Quote Link to comment Share on other sites More sharing options...
Souster Posted December 3, 2014 Author Share Posted December 3, 2014 then you have a problem. most likely cause is a knackered radiator.(if the temp is actually creeping up and the gauge isnt simply misreading...) Ive pointed the IR gun (£15 one) at the engine near the glow plugs, immediatley after the gauge reading 3/4 and that was reading 85 Celsius - And so was the thermostat housing. Top and bottom hose was around 65 though. Radiator was flushed thoroughly approx 4 months ago. Allthough it does feel hotter towards to inlet and outlet hoses, its still getting warm/hot on the left side. Odd one really Quote Link to comment Share on other sites More sharing options...
mmgemini Posted December 3, 2014 Share Posted December 3, 2014 then you have a problem. most likely cause is a knackered radiator.(if the temp is actually creeping up and the gauge isnt simply misreading...) I'll second that. THEN fit a proper coolant gauge. Quote Link to comment Share on other sites More sharing options...
Souster Posted December 3, 2014 Author Share Posted December 3, 2014 Thanks guys, not what i wanted to hear. How come its so intermittent though, i can do a 25/30 mile journey with no issues, and then last night it reached 3/4s. When i first noticed the gauge reading higher, i had about 40 miles of the journey home remaining, and it never got any higher than 2/3rds up the gauge. Do you guys not trust the infra red temp gun pointed at the engine then? Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted December 3, 2014 Share Posted December 3, 2014 85 degrees C is 3 degrees below the temp that the thermostat opens at. Seems to me that your gauge is misreading. Do as suggested and clean the connectors. Mo Quote Link to comment Share on other sites More sharing options...
Daan Posted December 3, 2014 Share Posted December 3, 2014 Has the viscous fan enough resistance? it could be the viscous unit gone bad. I think you can lock it by unscrewing 1 m8 bolt from the pouley and one from the fan and put a tyrap in between them. Daan Quote Link to comment Share on other sites More sharing options...
Souster Posted December 3, 2014 Author Share Posted December 3, 2014 Thanks guys. I was under the impression the vehicle didnt need the viscous unit especially in the winter? Maybe im wrong? I keep checking the stat housing bleed plug, and everytime i check the coolant inside, it only ever seems half full. Never full or over flowing. However ive repeatedly tried to bleed the system. Even starting the engine... And loosening the bung to evacuate the air Quote Link to comment Share on other sites More sharing options...
mmgemini Posted December 3, 2014 Share Posted December 3, 2014 I don't normally run a fan summer or winter. No problems towing either. The 300Tdi rad is good at silting up at the base. This causes all sorts of funny readings and temperature variations. NO you can't back flush them. Quote Link to comment Share on other sites More sharing options...
Souster Posted December 3, 2014 Author Share Posted December 3, 2014 I don't normally run a fan summer or winter. No problems towing either. The 300Tdi rad is good at silting up at the base. This causes all sorts of funny readings and temperature variations. NO you can't back flush them. Yeah i didnt think it needed one either. Is it time for a new Rad then do you think? The only thing i did before the temp gauge issue was the valve clearances, i couldnt have got these wrong could i? Quote Link to comment Share on other sites More sharing options...
mmgemini Posted December 3, 2014 Share Posted December 3, 2014 Yeah i didnt think it needed one either. Is it time for a new Rad then do you think? The only thing i did before the temp gauge issue was the valve clearances, i couldnt have got these wrong could i? I was in southern Africa with the simptions you deascribe Imentioned this to Steve Graham when he was running his LR workshop. He told me that the 300Tdi rads silt up after about five years. I took his advic and had a new core fitted. No more overheating Quote Link to comment Share on other sites More sharing options...
Souster Posted December 3, 2014 Author Share Posted December 3, 2014 Took the vehicle on a 30 mile round trip tonight, temp gauge stood at half way on country roads with a fairly low average speed. Once that average speed was increased, the temp gauge rose to 3/4. Once it got to 3/4 it didnt increased any further for the remaining 15 miles. On the return i used my infa red temp gun on several points as follows:Header tank 66Stat housing 733 positions between glow plugs 75-803 core plugs under turbo 85-90Both heater pipes 60ish including rail across rocker coverBack of water pump 78Seems fine to me. Must be a faulty gauge or sender. Do you guys agree? Quote Link to comment Share on other sites More sharing options...
pete3000 Posted December 4, 2014 Share Posted December 4, 2014 I'd go with the cheapest to start with, re-fit the fan, and check the sender is making a good connection to the loom and the engine has an earth return of some sort. There should ideally be a stranded pvc or braided strap near an engine mount to chassis rail. This is the return path for the starter/alternator/glowplugs etc etc. Likewise there should be a matching one from the battery box to the chassis rail. Quote Link to comment Share on other sites More sharing options...
Souster Posted December 4, 2014 Author Share Posted December 4, 2014 I'd go with the cheapest to start with, re-fit the fan, and check the sender is making a good connection to the loom and the engine has an earth return of some sort. There should ideally be a stranded pvc or braided strap near an engine mount to chassis rail. This is the return path for the starter/alternator/glowplugs etc etc. Likewise there should be a matching one from the battery box to the chassis rail. Thanks Pete. Ive cleaned up the main battery earth which is to the g/box or t/box. And ideas where i should start looking for the engine earth strap? Where is it normally positioned? I cleaned up the contact for the sender, and also ordered a new one Quote Link to comment Share on other sites More sharing options...
pete3000 Posted December 4, 2014 Share Posted December 4, 2014 If you have one on the gearbox, that should be fine. Quote Link to comment Share on other sites More sharing options...
Tanuki Posted December 4, 2014 Share Posted December 4, 2014 I don't normally run a fan summer or winter. No problems towing either. The 300Tdi rad is good at silting up at the base. This causes all sorts of funny readings and temperature variations. NO you can't back flush them. It's not just silting up internally: road-salt corrosion rots away the fins on the cooling-tubes and cause a dramatic reduction in the thing's ability to get rid of the heat. Same goes for intercoolers! A classic-car variety of my acquaintance is renowned for overheating and subsequent cylinder-head-gasket issues. People do all sorts of expensively-creative-things to try and "improve" the cooling. The issue is that the radiator is very low-mounted so picks up all the salt-spray and the fins rot out. From experience, I treat the radiators as 50,000-mile/5-year service-items. I don't have overheating issues. Quote Link to comment Share on other sites More sharing options...
Souster Posted December 4, 2014 Author Share Posted December 4, 2014 The rad is fine. As is the temperature. I havent got a gearbox temp sensor, thats unrelated anyway. Thats for the gearbox Quote Link to comment Share on other sites More sharing options...
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