Valve guides shot within 3000kms - due to overfuelling?
My Phase 1 2.0 Twinspark started pushing out oil through the exhaust in the form of a cloud of smoke (especially when under power). But she was starting well (hot or cold), idled beautifully and pulled as strongly as ever.
The engine was rebuilt from top to bottom, by a rebuilder with impeccable track record and using modern equipment. New pistons (still standard size), valves, valve guides, the whole tutti. Valve guides come from Italy - name sound like mereilli - and is used by other Alfa specialists as well.
After this, the car drove, idled, started and sounded exactly as it did during the previous nine years of my ownership. Fuel consumption was as before, between 10kms/liter (28 mpg) and 12kms/liter (33mpg). Problem was only that I was again noticing smoke shortly after about 1000kms - oil consumption was however not excessive. I returned the car to the workshop owner, who took the vehicle to the engine rebuilders and to an Alfa specialist. Verdict: The engine needed some "running in". Even the fuel was suspected of possibly being contaminated. So I drove the car for 3000kms/2000 miles, until I could take it no more. By now the oil level has dropped from being at the maximum mark after the rebuilt to about the minimum mark on the dipstick. Eventually the top was removed in the presence of various role players, including a representative of the retail motor industry body.
All pistons had the same dark colour, with a slightly "cleaner" area towards the rear of the car (inlet side?)
But: The valve guides, especially those of all the exhaust valves were so worn, some people claimed that this was the worst they have seen in many years of working on engines. Miracle that no valves were dropped. Overfueling was cited as the cause of this wear, and the rebuilders claimed that it was not their fault. Fortunately my relationship with my local garage owner goes back about 18 years, and he offered to fix the engine at his cost. (The rebuilders will "donate" their labour as their contribution.) I accept that I will have to pay any costs to cure the overfuelling problem.
I am a lay person when it comes to overfuelling. I have gone through nine years of invoices and emissions were tested on a few occasions during the 50000kms I added. I reiterate - the car showed no signs of overfuelling, except for the wear. I will have the emissions tested as soon as the engine has been assembled again.
a) Is it possible for the engine management system, myself and various mechanics never to have noticed any symptoms of overfuelling?
b) How reliably can injectors be tested, and is there merit in the ultrasonic(?) cleaning of injectors?
c) Did all the Alfa 2.0 twinspark engines use the same Lambda-sensor?
Any help/advice to prevent a recurrance would be appreciated.