excessive coolant pressure - help!

Hi and welcome to the forum.

I think, (I am no expert on the E34 nor on the cooling system on V8s) you have simply got an air lock in your cooling system.

As you had to hastily refil it from the pub (are you sure it wasn't beer and the car just has a hangover) you probably just managed to get air in the cooling system.  These systems need to be filled very slowly and bled to get the air out, the 6 pot E39 is a real pig for air locks but with patience it can be done.

There should be little plastic bleed screws mounted on top of the radiator, expansion tank, thermostat housing etc which can be un done and air can be bled out.  Failing that remove the hoses at one end and pour coolant into the hoses then couple them back up.

Although I'm struggling to see how an air lock would prevent the car from starting unless the coolant level is too low for the coolant sensor(i.e. the air lock is in the position of the coolant sensor) to pick up the temp of the water so the ECU then has to guess what temperature the engine is at which will make starting the engine difficult.

Have you got any warning lights on the dash? 

It doesn't sound like to me that you have got a blown cylinder head gasket(s).

Keep us posted on how you get on and hopefull someone with better knowledge of the E34 V8 cooling system will be along.

Andrew

Thanks for replies.  Re bleeding the system, couldnt seem to find any bleed screws anywhere but when browsing the web noticed that this system is supposed to be self bleeding? Dont know if this is true or not, but therefore I havent bled the system.

With regards to smell of petrol from header tank, I could be wrong but it appears to be coming from there although I can still smell it when cap is on so perhaps its coming from engine? cant be sure.

Is a compression test something I could do myself? , or would I need to use a specialist garage. As said money for me tight at the moment so Im not afraid to get my hands dirty and Im eager to learn, but this car is far more complex than the vw polo I owned previous to this car, and indeed more so than the porsche 924s which I have done some work to myself successfully.

One of my friends has been telling me im paranoid to think head gasket, but thats whats been going through my mind (a lot!)

Just would seem so unfair as car runs so well otherwise and oil is perfectly normal, and car is not loosing any coolant.

I really appreciate everyones input, thanks.

540 V8 wrote: We all know what you mean when you say you cannot describe how much you love the car, it does get you like that for sure!

Oh yeah, the car's the baby.  Got it bad.second to the wife...

You should be o.k. going to the local garage for a diagnostic check on a car of that age.  The newer the car the more problems the smaller local garages appear to have with interogating the diagnostics

villman540 wrote: I think the problem is that every time I have a problem with this car it carries an emotional attachment that didnt exist with my previous cars, so much so that it can tend to distract me from concentrating on other things in life, and even result in lack of sleep in my case. Its as if some kind of disease came inherently with the car which is gradually taking me over! lol. Clean, polish and wax it every week, and to be honest would happily do it every day if the need facilitated it, or I had an excuse to.

You are sooo right, except I have formed an emotional attachment with every car I have owned.  I shed a tear or two when I traded in my old Senator for my E39, I shed even more when I was deprived of my first E60.  Cars are not just lumps of metal, oil and rubber.  It's just a pitty women will never understand that.

Hello again everybody. Tried removing top hose and filling that way as suggested.  Unfortunately coolant is under even more pressure now, and cap blew off into the air with the car having been running less than a minute, like a big fountain. Also checked oil filler cap again(which seemed ok when I checked yesterday), and timing chain is coated in a reasonable amount of milky emulsified scum. It certainly doesnt look good for me does it. 

The saddest thing is that it still sounds so sweet when it does start up, which just rubs it in all the more.

Spoke to a local garage today as well, and guy tells me that he feels certain that its definitely a blown head gasket/damaged cylinder head, and that it would be beyond economical repair in his opinion -he reckons it would be easier to lift the whole engine and replace it.

Dont think I will be able to afford these sort of bills now or in the forseeable future (because my business of 8 years has recently gone down), and therefore might be forced to sell it for somebody else to repair, although guess it will probably be more likely broken for spares.

So so so so so sad....

May I thanks everybody once again for their kind efforts to assist me. I will keep a check on the forum in case anybody has any other ideas, but think I would need nothing short of a miracle to help me here. Not feeling good at all right now...

Well, after gradually calming down, have decided not to give up just yet. There may still be hope..  or I could just be building myself up for yet another fall...

Could I take the head off myself? Have only ever really changed/removed things like water pumps, alternators,rads, and most other servicable parts, so if its not tremendously difficult would consider doing it myself.

Part of me thinks Im being ridiculous by even suggesting this, but the other half of me is thinking that if I dont tackle jobs like this then Ill never learn....

Ok thanks for the reassurance Andrew , will begin searching for info as you have suggested.

 If anybody else  can shed any light on where to find torque settings/procedure info for e34 540i (m60) then that would be great, otherwise I'll post again when I have made any more progress.

Will probably have compression test done first anyway.