Misfiring on Number 8

[cebbyp]

Hi, I have recently experienced loss of power on my e38 (M62). Once the vehicle starts the revs remain low - under 2000 rpm, and do not pick up at all.
I since parked the vehicle and noticed the following:-
- Compression test was done and number 8 piston almost no compression
- Cam Box Cover was removed and one of the valves are loose. I used a screw driver and noticed that the valve underneath the cam follower is loose.

I need to know the following:-
- Whether the valve spring(s) might be broken
- Whether it might be a broken cam - follower
- Whether the valve is burned and need to be replaced.

I here wish to add that there has always been a silght misfire on the engine. I would further like to have more information on the process to be followed to correct the situation, I am familiar with engine overhauls, but the situation described herein gives me sleepless nights.
:bangdesk:

 

[Raybimmer]

My 2 cents...
A burnt valve will still be seating so there should be no play .
Broken valve springs - what keeps the valve against the valve seat then ? What stops the valve from dropping down a bit and being hit by the piston ?
Cam follower - not sure .
If I disconnect one coil pack on the M60 it still idles ok - slight miss but it revs up and pulls till red line , so a single cylinder should not make the motor not rev .
Good luck .

 

[cebbyp]

Thanx for the advice, I also did the following.
1. Removed the pre cat sensors - the vehicle started and picked up revs. There was no smoke,but still noisy valve lifter (number 8). Ran her few minutes and valve lifter quited down completely.
2. Removed cats and insterted straight pipes, then she started burning oil. That was fixed by replacing bad osv.
3. Ran her 50 kilo's and smoke got less,I guess it was burnt oil from bad osv. She still smoked after stopping at red light, puffs at pull away,or after brief idling. This might be the cause of worn/cracked valve stem seals?
4. Then intake was taken of and cleaned. After starting her up again, number 4 valve lifter stated making noise, after 50 kilo drive the lifter is more noisy and hell of ticking noise coming from the driver side bank. Sounds like loose timing chain from the vanos side of the engine. Can this be loose timing chain,or,incorrect chain tensioner due to lack of oil pressure?

I have noticed the following,which can be added:-
1. The engine had an oil change 2000 kilo's ago. She got Castrol SLX.
2. After the decat I had to add oil,could not get hold of SLX, and was advised by the "Stealers" to use Magnatec instead,which they sold to me. Bought 3 liters.
3. Added 1 liter before decat was done - number 8 lifter started making noise.
4. Added again 1 liter when bad osv consumed and number 4 lifter started making noise.
5. Added the last liter and timing chain (I am still not sure if the timing chain is making the noise) started making noise, to such extend that it sounded like loose cam?

If anyone could advise as I think the oils does not blend? I am of the opinion that a proper engine flush,oil pan removed and both oil pick up and sump be cleaned and new oil (Castrol - Maganatec) be filled?

Any other suggestions will be forthcoming.