N62 4.4 Rattle

[Rick G]

This X5 N62 has a strange rattle in the top end. My iSoft thingy says Exhaust Camshaft control bank 1 and sometimes Inlet Camshaft control bank 2. When I start it, it is noisy but nothing very definitive until it warms up then all is quiet and smooth until I rev it past about 2800rpm and then as the revs drop in comes the rattle until the idle is reached and all becomes quiet again. When I hold the rpm above 3000 the rattle slowly creeps back into it and it starts to run rough. I have just finished putting new to it cams and valvetronic gear as well as the hydraulic adjusters and levers in it along with head gaskets. Virtually the complete top end has been rebuilt. When I removed the covers to check things I saw that the exhaust cam was lagging and when I put a spanner on it it very easily returned to the normal position so I swapped the VANOS in the exhaust right bank but it made no difference. The oil is definitely getting through to the VANOS unit because all the moly assy lube had been washed away and good clean oil was present.
I am thinking it must be the solenoid controllers but I have cleaned them and checked they operate but cant be sure they are working properly. I cant find anything on Real oem to tell which is ex and in but if I recall correctly the top is in and lower is ex. Before I go ahead and get some new solenoids can anyone shed any more light on this.
I have been playing with this thing for 18 months now and have long since lost my sense of humour but still have a working flame thrower.
Just to add to it I feel that the oil in the VANOS that should hold the cam advanced is draining without the pressure to hold it there.

[X5Sport]

Have you discovered newtis.info? Copy of the BMW servicing manuals on line. If you have, then good, if not then there might be something useful in them?

[marti]

I presume youve replaced the camshaft sensor??

[Rick G]

Yeah I replaced the sensors. The more I think about it the more I come back to the solenoids being the problem. I think that because of the heat related problems these engines have from running at 105°C and seals, O-rings etc. going hard then the solenoids were sitting out of the engine for quite some months the seals inside are leaking.
I ordered four new ones so when they arrive I will know.
Newtis gave me no clues at all. It's difficult finding descriptions of how these things work so as to formulate an informed decision however I found that Tim Meek had a factory training document on the N73 engines that pointed me in the right direction as to how the VANOS units worked.
I also found a thread on Bimmerforums that gave a sort of similar description to the symptoms of mine but on a six cylinder N57 so I reckon I'm on the right track.

[Greydog]

Vanos oil seals would be my guess, BMW upgraded the seals to viton type yet when my engine was rebuilt the sent the old style seals ?? Took a bit of persuasion to convince them of the error.
Also the lad who rebuilt my engine is an ex BMW tech who employs a BMW/Porsche trained engine specialist apparently some M engines were inherently noisy so 5-40 grade oil was used not 5-30. Also in the Oil Filter cap is a pressure relief valve that is always forgotten you can get them separately worth changing that.
Last but not least having had a major failure caused by timing chain guide failure I fitted a pre-oiler to give oil pressure before engine start.

[Rick G]

I changed the VANOS units put new solenoids in and it's still the same. Little bit noisy in the top end (cams etc.) and when it comes back to an idle from above about 2600rpm the rattle is very distinct for about 1-2 seconds. Fault readout says "VANOS actuator exhaust bank 1".
One question can those new type of VANOS be reconditioned. I have dealt with the spiral spline piston actuated type before but not these vane type things.
Next question what happens when like which units advance or retard and at what revs with these things I cant find any info on them.

[Greydog]

Morning Rick
Have you tried www.newtis.info it is a BMW technical information site or www.pelicanparts.com both may have information that could help

[Rick G]

I haven't had a look at Pelican as yet but they don't seem to have much info on the N62 engines but I will have a look.

[Rick G]

SOLVED The large O-rings at the outer end were preventing the solenoids from going far enough in so that the oil was leaking out onto the front cover and not getting to the vanos units in sufficient pressure to operate them or hold the set position. The O-rings were the recommended size of 35mm x 4mm but there was no way that the solenoids were going to go far enough in so 35mm x 3.5 were used and they fit just fine. the new solenoids are about 0.15mm larger in diameter than the OEM but even the OEM ones did not go in unless the cover plates were removed and a press used to put light even pressure on the solenoid and vaseline and a small screwdriver used to push the O-ring in and they went in. the 4mm O-rings were replaced with 3.5mm O-rings and reassembly was easy with no oil leaks.
Measuring the hole and solenoid there is no way a 4mm O-ring is needed or should be used. My extensive work history in hydraulics and use of seals and O-rings I will say this that BMW strikes again with a real FUP.
Now I know many here will say why haven't others had this problem, well I cant answer that but I can say for sure that 3.5mm is a much better fit than trying to stuff a 4mm O-ring into that space.
Thanks for the suggestions and I hope this can benefit others in years to come until we are forced to drive battery powered Go-Karts and live in mud brick huts.