Hello,
got an intermittant overheating issues I want to put to the masses.
L200 mk5, 2009, 2.5 diesel. Just hit 100k.
So about 2 months ago I was driving in. There is a point about 5 minutes from my house where the truck reaches normal temperature- I know this exactly as this is where I switch on the heater in the winter. I glanced down at my temp guage and it was stone cold. Bit odd so I watched it for another 20 seconds and all of a sudden it jumped from cold to normal. Not gradual, just nothing to middle in a blink. Stopped and check it all over, levels seems fine etc. Carried on, nothing different for another week and few hundred miles.
Week later I was on the motorway and the temp started to rise. Got towards the red so I stopped. Check it all over, left it 5 minutes and restarted. All fine again for a week and few hundred more miles.
I was due a bit of maintenance so did the timing belt and tensioners, new water pump, new thermostat and coolant. I thought the temp issue might be a sticky thermostat.
A week after it got hot again. I stopped and this time the expand tank was bubbling over and steaming out the over flow. I let it cool down and found the coolant had dropped loads. Lost about a litre. Refilled with 50/50 mix and carried on. Fine again for 2 week or so. I thought i'd give it a test so when I had my multione trailered behind and a reasonable steep uphill on the M40 - dropped it down to 4th gear and really pushed it. Within 10 seconds tue temperature rocketed and when I stopped it was bubbling over from the expansion tank. Let it cool and topped up.
I am thinking it's the head gasket but I'm not seeing anything else Is associate with it - the oil seems clean, no milky aspect. Same with the coolant, no oily residue. No smoke from the exhaust etc.
I have not seen any drops or obvious leaks under the truck so I don't think it's a spilt hose split.
The thermostat seems to be working fine. cold one side of the unit the. once the engone has been on for 5 minutes the other side heats up.
Radiator fins seem clear and nothing that would hinder it.
I'm going to run it into the local place and get them to test the head gasket.
Any other thoughts?