So I got my Inline thermostat mode done the Disco is running well, now the temps are below 100 I run maybe 186 at 3000 rpm 60 miles an hour at around 70F ambient. testing 3rd gear for the rpm

But as while doing the mod I had a very high temp issue 235-240 for about minute, stuck thermostat shut down and let everything cool off - note no rad cap on at that point so no pressure

Now I seem to be using a bit of coolant, and have a possible over pressure issue very very tiny, I would say not even measureable like a thimble full in my expansion capture bottle

And yes my 1st thought is head gasket, but :

• so far no white smoke from the tailpipe
• a bit of 1st thing start water, after sitting overnight pretty much normal for short drives and it is water
• no milkshake on oil filler cap - need to check the intake and PCV valve
• no hard hoses
• no major pressure into the next day.
• oil is normal as is the level
• no bubbling in the tank

Started simple replaced the rad cap to confirm it is not an issue I will not know on this for a bit
Did the test drive as noted above to see if my temps spikes nope.
Expansion tank as expected is high post drive with pressure in the system
I have not pulled spark plugs yet - but there are no running issues she runs smooth and solid

Any comment or thoughts, I am on holidays in week I do not really want to strip it down to find the issue is something stupid

Now this could just be residual air, a small external leak under pressure or bad rad cap, most of my driving has been short distances a 50 mph.

 

How many miles on the HG?

 

@Extinct Maybe 10000 the Disco is not a daily driver

 

Ok, with that few miles on it I don't think you have hurt the gaskets. I have had a few that went hotter than I wanted before i learned to change everything. You probably won't get 90k out of them, but maybe 40-50k. My daughter overheated hers several times after I changed the HG the first time, they didn't finally let go till 30k later and I considered them abused.

 

@Extinct It is my nature to figure stuff out, or as my wife say obsess about my truck. But thanks for the feedback.

I did notice after the test run with the new cap my expansion tank was much fuller, maybe an 3/4 to inch higher and slowly dropped back to level after an 2 hours. For new guys reading this it should do that, then drop down as the engine cools and pressure normalizes.
Cracking the cap let off the pressure and the tank stayed to where I topped it off.

I figure 10 minute at 3000 RPM and 50-60 mph with a brief drop to 30 mph not causing any overheat or massive over pressure is pretty good sign, and engine temps were excellent at 186 dropped to 183 at the traffic light at the end of the run.

I will update this in few days as I test a little more

 

Richard, all the best on figuring out the temp issue. I was hoping to catch up with you this weekend on our Roverlanders run. Talk soon.

 

Maybe still a bit of air in the system from stat change?

Was into the cooling system on my wife's 03 a while ago, doing something, don't remember, but, it was like a total month, checking every three or four days, and adding a bit, before it finally found it's correct level. Been spot on for probably three months now.

 

@The Deputy That is is my suspicion just trapped air, or like last time I had this stupid pin hole leak on the underside of the upper rad hose that only opened hot and under pressure.

But asking questions for me is like a checklist have I missed anything simple

 

have you thought about trying some UV dye to pinpoint if there is a leak? If it's a small enough leak, it could be evaporating before you see it but altering things enough to notice the tank level. that combined with a pressure test would probably pinpoint any leaks for you

 

@tnrangerover that is on my list for holidays if I do not find something else.