Question-----------------Follow up To
Question -
Thanks John this is a great service you provide, further to the recent problem, I now have a red light on with hte thermometer picture, I tried the quick check to earth the temp sender, all is well.
However when I removed the rubber mat on top of the engine there was another switch or sender unit on the head in the middle of the exaust side. No mention of this in the Haynes repair mnual! anyhow it is broke.
When I run the engine the hoses and rad get hot, pressure is in all hoses and I have flushed everything backwards. The temp still goes to norm range reasonably quickly (expected I am in BORNEO.) After a little while the temp rises in 3 secs to reach max, then switch off and it reads low cool only ignition on, start engine and we have high normal range, run for 3-4 mins and red again.
What do you think - Temp sender having a bad day?
Also the engine runs cleaner now since the temp reads higher, is there a temp input to diesel injector pump (ie overfuelling?)
Thanks again -Mark
Dear John,
I need some backup here, my TDi300 has run great, previously all core plugs changed then the other day after 3 days standing I went out and the temperature needle went through red in 6mins. As it fluctuated at different engine speed whilst returning home 2miles, I knew it was air.
Now after much hard work I found a small leak, cut the hose and re-joined. Still the problem occured. The temp seems to climb and remain at half, then all of a sudden in 10secs climbs to red whilst driving.
Back I came, removed the expansion pipe that connects to bottom hose, reverse flushed with hose and pressure washer until clean water came out top and bottom.
Slowly filled the system with hose at the same pipe. The plastic top up plugs were out, when full I replaced them, then run engine and kept squeezing the hoses and letting air out of system. This seems endless, I am sure the system is full and reasonably well bled, I know the expansion tank cap is leeking slightly, but where is the air coming from, I cannnot be sure if it is steam bubbles or head gasket that is fairly new? When I returned from a drive the needle was in the red, but I switch off engine then on the ignition and it shows low end of normal?
Help?
Kind regrds
Mark
Answer -
Hi Mark,
Could you pressure test the rad? If all the hoses check out ok, the rad is holding up under pressure, it could be the headgasket.
Just in case, check the thermostat and see if it is stuck half open. Test it out by removing and placing it in a pan of water on your stove. Measure the temperature of the water when the thermostat opens fully. Normally, it should be at 185F.
You may have to pressure test the entire system to find the leak. I hope its not the headgasket.
Best of luck,
JohnMc
AnswerHi Mark,
seems your TDi is running cleaner with an overheated engine. The burn is hotter, that's for sure.
There has to be a problem within the cooling system for the temp icon to appear.
Here's what LR has to say...
ENGINE OVERHEATING
Before conducting any cooling system diagnosis: See Description and operation, Engine Cooling
1. Is coolant level correct?
NO - Allow engine to cool, top up level to expansion tank seam.
YES - Continue.
2. Is drive belt tension correct?
NO - See ENGINE, Repair, Compressor Drive Belt
YES - Continue.
3. Is coolant in radiator frozen?
YES - Slowly thaw and drain system. See Adjustment, Coolant
NO - Continue.
4. Is air flow through radiator restricted or blocked?
YES - Apply air pressure from engine side of radiator to clear obstruction.
NO - Continue.
5. Are there any external leaks, from water pump, engine gaskets, fast idle thermostat or the heater unit?
YES - Investigate and rectify. See Adjustment, Coolant
NO - Continue.
6. Are fan blades fitted correct way round, concave side towards engine?
NO - Rectify.
YES - Continue
7. Is viscous unit operating correctly? See Description and operation, Viscous Fan
NO - Renew. See Repair, Viscous Coupling, Fan Blades, Pulley and Fan Cowl
YES - Carry out a pressure test on radiator cap and system. Check thermostat type, operation and correct fitting. See Repair, Thermostat
If pressure test leads you to suspect coolant leakage across gaskets, go to check 10, otherwise: Continue.
8. Are the air conditioning fans operating correctly?
See Electrical Trouble Shooting Manual.
NO - Rectify.
YES - Continue.
9. Is temperature sender and gauge giving accurate readings?
NO - Sustitute parts and compare readings.
YES - Continue.
10. Carry out cylinder pressure test to determine if pressure is leaking into cooling system causing over pressurising and loss of coolant.
If problem is not diagnosed, check the coolant system for engine oil contamination and engine lubrication system for coolant contamination.
If only the coolant system is contaminated suspect a cylinder head gasket.
If both systems are contaminated, suspect the radiator.
If only the lubrication system is contaminated with coolant, suspect leakage past cylinder liner seals or cylinder head gasket.
end.
Hope this helps,
JohnMc
