Excessive white smoke when the car revs up after idling for a few minutes.
We started with basic checks: engine breather and pipes; we checked the turbochargers for excessive play and found nothing.
It is well known that on these engines, the valve steam seals harden and cause excessive exhaust smoke.
The valves stem oil seals were to blame
Doing all the necessary checks, we concluded that the valve stem seals could cause our problem. We then proceeded to dismantle the upper part of the engine, checking and replacing, if necessary, the valve stem seals. We removed the left-hand bank cylinder head and inspected the valve stem oil seals, which are hardened as we suspected.
Valve stem seals control the lubrication of the valve stem as it slides in the valve guide. Defective valve stem seals increase oil consumption and produce excessive blue-white exhaust smoke. Also, it can cause a buildup of carbon, leading to valve seat damage and an early valve grind.
These are the valve stem oil seals that are hardened. If you try to pinch the rubber of the valve seals, it is tough compared to the new ones.
What do they do? As the valve stem seals are hardened, they no longer properly regulate the amount of oil needed for lubrication but will allow more oil to pass through. This oil reaches the combustion chamber and produces white exhaust smoke.
As we were with the engine partially disassembled, we advised the customer to replace the chains as well, as they were only a short time away from being changed.
We are now ready to reinstall the left-hand bank cylinder head.
During the inspection, we noticed a leak in the oil return housing, so we changed the seals here as well.
We installed the left-hand bank cylinder head and removed the right one.
Now we have the right-hand bank cylinder head on the bench; we found the carbon deposits on the valves due to the hardened seals.
We cleaned the valves, the inlet and the exhaust, replaced the seals and put everything back.
After the engine was assembled, we did a road test. Everything is fine, with no excessive white smoke and no error codes.