Hi All..am happy to report the car is fixed and running like a dream......
it has been a journey and a half from diagnosing the problem to fixing it...
the work done in the last month
new radiator, hoses and fan delete mod, modified air-box goes in tomorrow,new engine temp sensor as well,and of course the head gasket which was no mean feat as on this 17 yr old car all of the bolts were either inaccessible or seized meaning just getting the cylinder head off was a long and fiddly task as was replacing it.
those exhaust manifold bolts were a nightmare!
have also fixed the rocking seats re-proofed and re-dyed the hood and gone round and touched in all of the stone chips..
previously replaced ,water pump and thermostat.
head was skimmed and tested all good, interestingly the ends had .42 off and the middle .2 clearly indicating the head had warped in the overheat quite significantly.
in order to skim the head we had to remove the camshafts valves,hydraulic lifters and all of the assorted stuff in the cylinder head.
all the valves were lapped in before re-assembly to ensure good seal and compression.
the cylinder head was then bolted down to torque with the correct sequence as per the haynes manual, Gasket was a 1.74 victor Reinz and the head bolts Elring all from ECP, we also replaced the rocker cover gasket whilst at it, I decided not to go with the thicker head gasket having established on the 318 forum that as much as .45 is ok without using the 2.03 thickness Gasket.
on our first fire up she ran like a bag of spanners! we had used the camshaft locking tool and the flywheel pin as well as marking the camshaft timing wheels so we couldn't work out what was wrong, I suspected timing and was right, and here is why....
for every 12 thou milled of a head the camshaft alignment will be out by one degree, as we had milled of .42 at the ends this meant the timing was roughly 3 degrees out as the distance between the crankshaft and camshaft timing wheels was shorter.
as we have a timing chain rather than a belt we cant move the chain as one tooth represent 12 degrees.
the only option is to adjust the sprocket wheels by the desired amount in the right direction, as the mill advances the timing by 3 degrees you have to compensate by retarding by that amount on the M44 they are luckily adjustable.
as of early this afternoon success! ..running beautifully with smoother idle and a more even acceleration curve, no leaks and despite removal of the viscous fan the lower temp fan switch in the rad means its all as it should be.
A very special thanks goes out to Barry Gadd, not just for his help but in educating a mechanical newbie to the point where I would confidently tackle this again on my own with the odd bit of help here and there..I now feel able to handle all future servicing and overhauls on the car..not bad for a 3 week crash course!..
spurs fan (andy) thanks for not just lending me the timing tool but actually dropping round, also above and beyond the call of duty.
and my mechanic Craig who confirmed the head gasket diagnosis and also was on hand today to do the final cam timing,
top bloke and I can highly recommend him to anyone in the surrey area,has all the kit, right down to a compressor in his A team like van and all of the tools and diagnostic software you could ever need.
and to all for your suggestions and encouragement along the way I thank you very much...
as Vinnie jones would say,it's been emotional.
oil and filter change in the next day or two..
I will then spend the next few days enjoying what I hope will be from here on in be apart form the "normal Z stuff" a trouble free and enjoyable drive.
best all
Joe