Re: Tried and Tested Means to De-tox / De-Sludge Your BMW
Tried all different ways to de-sludge via engine flush kits, reduce oil change interval (OCI) from 10k to 5k in the last 8-9 months, but don't think it did any good given the thick level of engine sludge I had.
Finally took the plunge and did a full overhaul for my 2006 e90 320i, mileage 127,000 km after car was diagnosed with engine valve seals gone bad, and top overhaul is required to fix the valve seals.
Condition of engine before overhaul:
Very heavy levels of sludge, and burning oil (started with 1L per 1-2 months, until recently every 2 weeks, so from bad to worse).
Given i know how sludged up my engine was previously, decided to go all the way to de-sludge the engine and change the wear-and-tear parts along the way once for all.
Engine valve cover removed, see the dark colored sludge (oil gel) on every part of the cam shafts and rest of the valve-train:
Cylinder head (top) with valve-train removed exposing the 16 hydraulic valve spring/top assembly, with the same bad sludge everywhere:
Close up of the hydraulic valve-springs (set of 4 at top of cylinder head) with a thick oily gel substance, was advised might as well de-sludge the whole top and bottom:
Cylinder head removed, showing the state of the intake (clean) and exhaust valves stems (carbon coated), this is the cause of the white exhaust smoke:
Engine block (bottom), exposing the pistons. Conditions are worse than i thought, but to be expected with all the oil burning (hence the carbonised build-up):
More oil stains/sludge at the crank-case, where the con-rod connected to the crank-shaft sits. This problem can't be solved with just a top overhaul since the engine oil burning problem affected the while engine block including valve stems, pistons, and also crank-case):
After the entire engine block was stripped clean, this is the brand new result of the cleaned cylinder head totally rid of sludge that was all worth it:
One of the 4 engine pistons with the piston rings replaced, and everything gleaming to a shiny metal finish:
6 pieces of this "semi-circle seats" replaced as wear-and-tear on the crank-case:
All the various engine components (left to right, top-bottom: engine block, crank-case, cylinder head, pistons, crank-shaft) after cleaning, inspected before the re-assembly:
Overall, car spent one whole week in the workshop and after a few K's spent.
All the necessary wear and tie items was changed, including valve seals (16 pcs), engine cover gasket, pistons rings, con rod bearings, timing chain guide (plastic part), alot of other seals/gaskets etc
The result:
Engine revs like a lot smoother now, feels more power restored probably due to increased efficiency (was getting 8.5km/l, now 9.5- 9.8km/l) , and loads quieter than before too. Ticking sound from the hydraulic lifters which is common with e90, not so audible now. So far so good for the last 2 tanks of petrol, ar 1k + travelled (oil sensor level still at full mark) and white exhaust smoke problem solved. Funny thing, it now also smells like normal exhaust now, which i can't quite describe but when it was burning oil, it has this really weird "wet and pungent" smell esp noticeable after i stop the car and open the door.
Using BMW 5w-40 oil now, may want to try Liquid Moly 5w-40 next round as heard it's very smooth.
And finally no more traumatised by the engine sludge, was advised to keep to 5-8k OCI to keep it that way.
