The summer 2008 my S3 developed a "diesel" knocking from the area around the valves/head. Little did I know that this would result in a full engine rebuild. And that was with only 103.000 kms on the clock.
Inspecting the valve clearances didn't turn up anything unusual so the head had to come off. My local Lotus specialist, Norsk Chassis Teknikk, finally had time to have a look at it and after much trying and testing foundt that some idiot had put a load of silicone in between the cambelt wheel and the cam. This caused the camwheel to kind og "jump" unevenly around the cam, hence causing the knocking sound. I was damned lucky the valves didn't hit each other or the piston to cause a major engine disaster.
It also turns out that one of the valves had a leak and that some of the other valveseats were very shallow due to a previus skimming of the head. So a regrounding of the valves was ordered.
As one does when the engine is out, one checks to see if there are other things that needs to be done. On inspection of the conrod bearing, the liner for cylinder 1 fell out! I don't know if this is normal, but interesting none the less. Now, the bearings were changed about 30.000 kms ago, but it turned out that the bearing on cylinder 1 was not worn evenly. This could be from the engine being started without oil pressure last time it was rebuilt or due to a slightly oval conrod.
Since nr. one cylinder/liner "fell out" we decided to check the rest. They were loose too and my mechanic suggested that we hone the liners and he sent them off to Oslo Sylinderservice. However when the liners where set up in the jig, it turned out that they were oval and no honing could help that.
So new steel liners, forged Alu LC pistons and rings were ordered from SJ Sportscars. Oslo Sylinderservice also stretched the conrod, so it's now as good as new.
Waiting for delivery of new specification glue for the liners held up progress a bit. And when the engine was almost back together, and my mechanic was doing the valve celarances, he found that 5 of the bolts holding the cam-houses had previously been overtightened. This resulted in 5 helicoil threads being fitted for the bolts to hold the cam housings.
Finally on December 17. 2008 my 'My Precious' heart was beating again....
While the car was in the shop, I had the petrol tanks inspected and they are fine. No visible leaks either inside or out. The insides were checked with a special camera. My mechanic also inspected the fron suspension, and it looks like my steering rack needs an overhaul. A small project for next summer. I also had the stainless exahust fixed by mig welding the metal bracket over the twin exhaust pipes. No more rattles at 2300 rpm.
A list of some of the parts changed:
- Water pump
- Bolts for the head
- Oil filter
- Cast iron liners
- Forged aluminium pistons with rings
- Conrod bearings
- Various gaskets: Headgasket, oilpan etc.
- Copper nuts for intake and exhaust manifold
- Cambelt tensioner
- 5 helicoil threads
- Spark plugs
Click pictures for high resolution image.