* Mr Spock

Of course it's possible they're right. But...

The system is supposed to be pressurised. That's why normal operating temp is over 100 degrees, and the pressure cap is 2 bar from the factory (although some may be fitted with 1.4 or 1.8 bar caps). If there's air in, the top hose will be very very hard as the air heats and expands. If there's no air, it's firm but still squishy.

The point I'm making, badly, is that you can't bleed these engines like an old Cortina. Running it up to temp with the cap off will just boil fluid out since it's at atmospheric pressure. Opening the cap when it's hot (apart from being dangerous) will make the fluid boil as the pressure drops (Boyle's law) so, guess what, the mechanic goes "oh look, it's boiling up and there's air in" - yes, you just made it boil up and let air in!

There are lots more places than the head gasket to let air in. Coolant hoses at the back of the engine - which will have been modified for your LPG system to get hot coolant to the vaporiser - the vaporiser, valley pan gasket, radiator, expansion tank (although you've eliminated 2 of those).

There are lots of reasons why it isn't cooling properly which will overheat coolant and push it out of any leaky place including the rad cap - fan clutch, aux fan (less likely), water pump (not an uncommon issue), thermostat stuck closed (not likely, but ..) .. and a badly bled system.

Did you read the link I posted describing the system? It's REALLY useful to get your head around this thing. Good guide to bleeding: http://www.meeknet.co.uk/e31/E31_Cooling_S...eeding.htm

Until they do the hydrocarbon test I'd go with the more likely scenarios. Get that done and tell us. DO NOT OPEN THE ENGINE until that's done. A number of people have told me of these BMW engines that have had expensive work done which was not required.

I've always been a fan of Mr Spock

Your logic makes total sense, I did actually find the Meeknet post before, but after returning to read it for the third time I do get it now.

I think they generally work on Discos and defenders - I'm guessing there is no similar cooling system in those?

I'll try and get it home then attempt to bleed it fully myself before getting it to the guys to be reconditioned.

P38/Defender are more simple than the BMW engine. I've not done much on the Rover V8, but I have done plenty on American engines and they're really simple. I have a Series, which is also very basic, and i can't imagine the Defender is much more complex.

However, in the end you have a pump (2 in the FF with the aux motor), thermostat (a couple of those, I think one for the transmission), radiator made of tin foil, viscous AND electric fans, thermostat pre-heater - and then you've got LPG which messes with it a little!

Look, it may still be a head gasket. I'd get them to do the HC test, or get one yourself from your local motor factor.

If you do get it home, PM me and I'm happy to help you over the phone, or FaceTime/Skype etc. When my local specialist told me it was probably a head gasket, I had that horrible sinking feeling which was completely unnecessary. If I can help you avoid it, it would be my pleasure. I'm no expert by any means, but I like to do my research, test carefully and follow a logical (!) troubleshooting path.

Ian

Bit of a resurrection this but wondering how the Op got on.

I had weird overheating issues after fitting the 80 degree mod and put it down to the system not bleeding properly and I then tried driving the front up onto ramps after reading the meeknet info and i got a load more air out of the system and the radiator return pipe is now warm rather than cold indicating i had an air lock by the stat.

However I was also getting a low oil pressure light when it was getting hot although the temp gauge never went past the middle and my heater was working but i thought i would do an oil change even though the oil was only a few months old and the oil had light brown swirls running through it which didn't concern me to start with but have since learned this could indicate that the oil has water mixed into it....

Now i only use the FF once a week for a 3 mile round trip to the chippy and every other week for a 30 mile round trip so i am hoping it is condensation not burning off in the oil......

My compression tester, leak down tester and coolant hydrocarbon thingy tester are in the post to me as i type ....

Fingers crossed for you buddy..worse case scenario it is the head gasket does a repair guarantee a fix? I presume you will do it yourself self as you seem pretty clued up..really hope it's not..keep us posted

one thing maybe to check easily, i did it on mine and it was faulty, the auxilliary water pump. yes, there is (on my 2002 v and electric pump, right down low, on the inner wing on the passenger (uk) inner wing... I think it tried it by running a couple of wires direct to it from the battery, and then removed it to proper test it, is was dead. so i got hold of a secondhand one, i think they fit many different BMW's, and fitted it easily. it felt like it was humming when i rechecked it. ive not had any bleeding problems.. (well, not any venting problems... im always getting poxy 'bleedin' problems...!) i just remember having to top up the bottle a few times, in the first few journeys, as it settled into the crooks and crannies etc.

alistairh wrote:

Fingers crossed for you buddy..worse case scenario it is the head gasket does a repair guarantee a fix? I presume you will do it yourself self as you seem pretty clued up..really hope it's not..keep us posted

johnboyairey wrote:

one thing maybe to check easily, i did it on mine and it was faulty, the auxilliary water pump. yes, there is (on my 2002 v and electric pump, right down low, on the inner wing on the passenger (uk) inner wing... I think it tried it by running a couple of wires direct to it from the battery, and then removed it to proper test it, is was dead. so i got hold of a secondhand one, i think they fit many different BMW's, and fitted it easily. it felt like it was humming when i rechecked it. ive not had any bleeding problems.. (well, not any venting problems... im always getting poxy 'bleedin' problems...!) i just remember having to top up the bottle a few times, in the first few journeys, as it settled into the crooks and crannies etc.

Ignition on, fan on 1, heat fully up - you should head the heater pump running. You won't see water circulation anywhere, but it helps to push the air out. A slight backward incline might help. I haven't re-read the thread, but I recall you have LPG - is the vaporiser below the expansion tank?

i am not the OP and no LPG to worry about thankfully and i did bleed the system successfully once i put the front up on ramps. the meeknet site said you should see coolant coming through the little squirty bit just inside the cap which i do get but only when i squeeze the pipes and cant hear any pump running...
Would the pump not running cause any major issues ?

My main worry is my oil is a mix of dark brown and light brown and has only been in the car a few months with very little driving

HC, my old gas p38 used to collect loads of condensation in the oil. Same story, loads of short journeys.

I'm not Convinced about this talk of an auxiliary pump on the BMW v8. I've never heard of one being fitted nor never found one in my exploration of the cooling system on two bm v8 powered cars. Are we sure we are not getting confused with the heater valves ? These are why it's important at to set the heating to on when bleeding. These valves close off the water flow to the heater matrix,so need to be open when bleeding. What I have experienced is two faulty thermostats failing in the closed position and a cheap water pump not being up to the job, sedimented rads and failed viscous drives. Head gasket ? I would be surprised.

Remember,from the factory these run at 110 / 115 deg c which is very high. No7 - 2003 V8 Vogue

Thanks for the heads up, I am waiting on the leak down tester to arrive and i have ordered some enthusiasm which will hopefully get here by the weekend and weather permitting i will give it the full going over.
I don't have LPG and the oil was relatively new as is the PCV valve but I am hoping that it may survive. it was also the first oil change since i rebuilt the vanos and chains so maybe there was some flush left in the followers, but i doubt it.

I found mention of the pump on meeknet site but i have never seen a pump but i do know the valves you are talking about. i am wondering if the pump is to do with the fuel burning heater as i read the pump is designed to move coolant around the heater while the engine is off to still give out some heat but apart from potentially helping with bleeding I dont think it would be detrimental to not have one working.

If the head gaskets are gone then i can only put it down to the top hose blowing off and the coolant level not dropping straight away in the header tank but we'll see..
Thanks for support, this is playing on my mind but still, worse things happened in 2016 !!

Errrrr so out head gasket went so got it repaired with a rebuild specialist.

They went again and it was repaired again under warranty- they realised that the stat loom was plugged in with the wrong plug.

Revisited we now have a faulty stat sensor. Want to do the 80 deg mod now.

I know what plug you mean, there is a spare plug that sits under the top cover on mine that does nothing but i am not entirely sure the 80 degree mod wasn't my downfall as i had an airlock around the stat that i only discovered after having issues of low engine oil pressure. i raised the front of the RR up on a ramp and got loads more air out of the system and the bottom rad hose was then warm rather than cold as before but the engine was in trouble by then.

Either the top hose blowing off caused my overheat and potential head gasket as i put in the 80 degree mod when i replaced the top hose or my not bleeding the system correctly after putting in the 80 degree stat caused the overheat.

It is hard to know, I am not 100 % sure I have lost my head gasket but will find out soon.

The plug on the stat you refer to only heats up the stat to make it open earlier than 105 degrees under high load, without it connected or the wrong one connected wouldn't stop the stat opening unless the stat itself was faulty. Without the plug it is just s standard 105 degree stat.

How long is it since your second rebuild?

Without me raising the front of the vehicle and following the instructions on meeknet site and i would still have the airlock around the stat which prevents the coolant flowing around the engine.
Sorry for hijacking your thread, i thought you had gone away

No worries buddy.

about a month but not many drives since the last rebuild!