L 3 2008 4.4 V8 HSE
Recent History:

• Oil was in the coolant a month ago
• Replaced the head gaskets,
• The heads were skimmed,
• New valve guides inserted
• and thermostat
• Oil cooler replaced
• All done by a pro mechanic not me.

Today:

• Temp raised to three quarters after 10 mins driving so I parked and left to cool for a few hours
• Toped the coolant
• Started engine and left to idle for 35 mins
• Fan goes into overdrive and coolant blows out the expansion bottle lid

Suggestions please?
Is this a blown head gasket, faulty thermostat, faulty temp sensor?

 

Start with the easy stuff. Verify coolant level is full. Find the "Doug from Atlantic British tech support" video on how to burp the cooling system and follow his procedure. If you've been driving for a month since the rebuild that's probably not going to change anything but it's easy to check. You can pull the thermostat and test it in boiling water; they are inexpensive so you may want to just swap it out. For now I would ignore the coolant temp sensor, I don't think that's your issue, the fact that coolant is blowing out shows that things are too hot.

As for a gasket issue, you can get a exhaust gas detection kit for the coolant, they are easy to use and not expensive.

 

Do you get hot air when the heater is turned on? If so, that is a quick way to verify that your cooling system has been purged of air.

 

The T,s at the fire wall for the heater broke a few days ago so looped the supply and return lines with a pipe so would be unable to test.
Any way sent Disco Dave off on the back of a recovery truck this morning.

 

have you returned to your pro mechanic?

 

Yes the mechanic that did the top cylinder work etc. let's see what happens.
Given that the average country temp is 38 degrees c even at night with highs of 55 c in summer would there be an issue removing the thermostat once faults are repaired?

 

Update:
Head gasket blown, must have happened when the heater connection broke at the fire wall though it didn't boil that high.
Anyway will change the gaskets but will also remove the thermostat.
Not chuffed as the engine was only done a month ago. Land Rovers by buy them with your heart not your head.

 

Tells me the head gaskets were not replaced or someone messed up. Overheating does not automatically cause head gasket failure unless it was a pretty big overheat.

 

The system was positive and negative pressure tested with no drop or rise.
Idled the vehicle for 30 mins with the temp running normal then all of a sudden the fan goes to full power and a few seconds later the temp goes to 3/4 and starts to boil.
So definitely removing the thermostat, and may adjust the fan to run at full also need to confirm the water pump. But this is all dependent on the heads being usable.

 

Well got Disco Dave back from the mechanic, head polished and pressure tested, a couple of bolt holes on the block drilled out and retreaded and new bolts used. Fresh oil service.
Just drove 50 km and all good.
Plan on an oil change this weekend to remove the possibility of machine metal bur in the oil.
Next week draining the weak coolant and replace with good stuff.
Hopefully that will be all for a while.