740i 1998 blown head gasket???

I have a 1998 740i, recently the "check coolant" light was coming on, i topped it up every now and then (about once a month) and thought nothing of it, i took it to BMW for a MOT and they said there was a split in the expansion tank, so i paid to get this replaced, when i picked it up they said it was mis-firing and the head gasket could be on its way out, since then it is loosing water even faster (need topping up every day) and there is a smell of burning "something" not sure what it is, i have checked the oil and it doesnt seem watery, so im not sure what to do, shall i ring BMW and have a go at them saying now its loosing water faster since i took it to them, if so wont they just say its the headgasket, could it be something else? also any ideas what this will cost and a reccomended place to take it in south east london?

oil filler cap "looks" Ok, and so does the oil on the dipstick, thing is i took it to BMW and they would have pointed out any leaks surely?? not sure what to do, not very technical. dont want to sepnd another few hundred quid for BMW to tell me its not the headgasket..... i have noticed twice the car "judders" once when i thrashed it on the M25 and then came of the motorway and stopped at lights and it was juddering, another time was when i thrashed it of the lights then stopped to turn right and it started juddering again as if it was going to stall, turned engine off then back on and seemed fine, any ideas?

Havent noticed any oil use, but then again i really dont use it that much once every other day, it seems to start fine, as usual just turn the key and it starts itself, it maybe takes a second longer then usual but it has been getting colder recently.................??

Thanks
any idea how much im loking for replacement headgasket and a preacher test?

Jimbob wrote: You need a Pressure test, not a blessing.

Second thoughts, if it is the head gasket you could do with a blessing as well...

Hope it works out ok.  Find out where your local independent BMW shop is and ask them for an opinion.  The BMW dealer probably didn't check for any problems which were not associated to the symptoms you advised them of.

Edited by Chas C

How about this for a therory:

On your old tank your rad cap may have been knackard or the overflow pipe could have been blocked. If either wern't working properly, then any excess pressure in the coolant caused by a headgasket leak may have caused the coolant tank to split as now it is about 8 years old may well have gone brittle with the constant thermal expansions / contractions over time.

I assume however if the expansion tank is new the above would have also have been changed. This would mean any excess pressure, would allow the coolant to escape via the overflow pipe unhindered.

If your drive it may not be obvious where the coolant has gone as it will be dumped along the road.

Furthuremore the misfiring you describe, may well be caused by coolant getting onto the sparkplugs when you thrash the engine.

On a hot engine this could well have evaporated/burnt off before you remove them to check.

Esentially what I am saying is your old tank may have partially masked some of the blown gasket symtoms.

Either way go to any garage (not nessecerryly a BMW specialist) & ask them to check for combustion products in the coolant & to pressure test the cylinders). This will tell you if & where your gasket(s) have gone. You can even buy the equipmet from a motor factor if your keen to DIY.

Am I good ? or full of it ?

it could well be the presure cap on your header tank, good luck for next tuesday.

you are an evil man Hiab!

sevenforty wrote: phoning 1 bmw sepcialist and they said they have never done a 740 before so wouldnt like to do it, said it should be a dealers job, just waiting on another bmw specialist to get back to me with price, does anyone know any trustworthy garages around london that will undertake this?

Try "Beales Wheels", Under the Arches, Albert Square.

Why not try one of these mobile mechanics? I don't see why you need a BMW specialist just to test for a blown HG.

Edited by Selephant

as i said before, header tank CAP. good luck, the presure isent holding so will overflow from the header tank. cheap repair, sorry hiab, put the dust sheet back on the cargo.

Edited by omega man