Fuel gauge is fine, it's the temp gauge. From threads elsewhere I'm thinking someone has put some Barrs leak stop in it, and it's clogged the thermostat. Or maybe the stat is just knackered. I'll either do it myself or get it flushed and changed when it gets serviced.

Doubt it's anything to do with the stat, you certainly couldn't block one with bars leaks or similar, what that will do is sludge up the bottom of the rad even more, and it's that bit that cools the gearbox, if you start getting Trans Overheat messages bonging up get a new rad asap...

The temp gauge is not directly connected to a sender, it is controlled by an ecu and it reads what you expect to see... i.e., it gets to normal at around 75deg then stays there until the temp gets to over 110deg, then moves up to tell you it's hot...

You really need an IID tool or something similar to get in and read the live values and see what's going on, there are two places the water temp is measured, one coming out the engine, and one on the bottom hose connection which measures the temp coming out the rad, these can tell you a lot...

If you plan on keeping it then you will need a diagnostic tool of some kind, IMHO the IID is the best in terms of value, features and backup, they are a bit expensive but you will always get a good price for it second hand when you sell so it's sort of an investment (man maths)....

If you want to change the stat then I highly recommend one of these kits, they made the engine run so hot when new to help with part throttle emissions, the engine was never designed to run at Land Rovers 110deg... change the stat for an 80deg one and it helps all sorts of things... cooler is better...

http://www.ebay.co.uk/itm/80-C-Thermostat-...xyUrZSwcNg Pete
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I called Aylmer and had a good chat with Neil about the cooling issues.He booked me in for a couple of weeks' time, but said I could pop down today and he'd read/clear codes. All down the A1 it was fine, then as we went onto smaller A roads she started to heat up, cool down, heat up - then I got "TRANSFER BOX NEUTRAL" messages (I think so, pixels dead makes for guesswork on that one). She still drove fine.

At the garage it was clear that the system was pressurised a LOT. No leaks though. They read the codes, seemed like there were some older low battery-type ones which they cleared. We then had a discussion starting with HGF, then rad blockage, then thermostat... I was feeling sick by then, fearing the worst.

I set off home, gingerly, with the temp gauge in the middle, and thought I'd run home on petrol instead of LPG and see what happened. No problem at all, the gauge stayed in the middle all the way home. Hmm.

Then I had a call back from my local BRC place, to book an LPG service. I explained the cooling issue, since I wasn't sure whether to have the LPG serviced before or after the rest of the work. Apparently it might be the LPG regulator. Over time they can leak gas into the coolant, which pressurises it and the temp rises. The leak is small (probably) so can take a few miles to have an effect, which is of course masked at higher speeds as the air cools the engine more effectively.

The plan is, then, to run around on petrol for a few days and see if it's OK. If it is, he'll change the regulator. If not, I'm back to square 1.

Sounds like a plan... that should be an easy fix...  Pete
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2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
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My fingers are firmly crossed! Makes it hard to type though. I don't have much luck though. Just ordered a new key fob case, at least something will work better.

I was just going to ask if it overheats on petrol as well as LPG and you answered it in your last post

So far, inconclusive. Went to the village (a couple of miles) and it was fine all the way. Then on the way back the temp rose quickly, but then it switched to LPG, so it must have been warming up before that. Back to petrol for the last half mile and it stabilised and dropped a little.

I'll have to try again with the LPG properly disabled, it's supposed to remember its setting.

Well, I don't feel this is good. A drive on petrol showed that although the temp is more under control, it's still pressurising the system. The gauge would move a mm or two, come back down, up, down etc. Then up to the right "normal" range mark, down, then up to a mm past the normal upper range. It didn't actually overheat. It doesn't seem to be rev related, or throttle opening. I'm now thinking it's not the thermostat, as that may cause temp fluctuations but not pressure, same with the rad.

So I am expecting the worst. Not happy today, especially since I need a car quite a lot at the moment.

Reading some more (googling BMW M62 coolant pressurizing) i find that it can be a blocked rad, rad cap or just lots of air.

Is a hard top hose (oo er) really a problem? from here:

http://forum.bmw5.co.uk/topic/76262-535i-s...em/?page=2

these engines run at 2 Bar which is pretty high pressure anyway, so at 110 degrees under pressure the water stays liquid, when the cap is removed it WILL boil over.

Aargh.

This is becoming an obsession! This is a GREAT page about the M62 engine:

http://www.meeknet.co.uk/e31/BMW_M60_M62_M...System.htm

Quote:

At slow road speed or at idle, if the temperature gauge is seen to leave the centre position and head to the red, and then return to the centre in regular cycles - this often indicates failure of the viscous coupled fan. The reason for this is that the viscous coupled fan is not providing sufficient airflow through the radiator, the coolant temperature increases and the temperature gauge starts climbing. At a radiator outlet temperature of 99C the auxiliary fan cuts in at high speed, reduces the coolant temperature and the temperature gauge returns to the centre.

If the stat was shut, it would boil over in about 5mins...

I expect you will end up doing what I did to sort out the system

New rad
New hoses
New gearbox oil cooler manifold and thermostat
Thermostat mod with 80deg one
New expansion bottle cap, check with the dealer which one yours needs mine had a later one on it...

Plenty of info in my build thread....

First job, get an IID tool and check the two temps, into rad and out of rad, should be at least 20deg drop....

Actually, first job is to pull the fuse on the LPG and run it around on petrol for a few days... Pete
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2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
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I think (hope) we have a winner! The viscous fan clutch seems to have failed. It should lock up when hot, and in the first 30 seconds after start up. In both cases I can stop it with a newspaper. The rad is hot all the way to the bottom, and there's the sound of pressure escaping the expansion bottle at the cap.

So, I think I'll replace the clutch and the cap, and see how we go.

Does this all make sense? Did I miss anything?

Haylands wrote:

If the stat was shut, it would boil over in about 5mins...

I expect you will end up doing what I did to sort out the system

New rad
New hoses
New gearbox oil cooler manifold and thermostat
Thermostat mod with 80deg one
New expansion bottle cap, check with the dealer which one yours needs mine had a later one on it...

Plenty of info in my build thread....

First job, get an IID tool and check the two temps, into rad and out of rad, should be at least 20deg drop....

Actually, first job is to pull the fuse on the LPG and run it around on petrol for a few days...

If it's not working then that could be it... Although the aircon fan should come on if the viscous can't cope to prevent overheating so maybe that ones defective as well....

Sit down when you ask for a price of the viscous, I seem to remember they are rather expensive.... Pete
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2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
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-Click for Project Fatty off roader-

i bought a new viscous fan for mine, online, it was around £70 this was aftter i was quoted £150 for a secondhand one, ('with some chisel marks on the nut...') from some idiotic dismantler, i said i didnt need the rest of the engine, that was no doubt screwed to it still, and told him where to go. new one cured my slow spinning fan. as said, they are very 'windy' at 1st start, and then they sort of ease off as the engine comes down, then they are very quiet. i cant remember the make i got, but it was a think from an ebay seller. -has been good for three years now.

p.s i run lpg all the time.. and no probs, but im going for the lower temp 'stat too.

edit.. part number pgb000040 comes up as £340 inc vat genuine. when quick checked online.