001: Engine Rebuild Task
This was an optional unit but one of the more interesting things to do in the first year. The engine is from an old vectra around 1998 (X18XE) and is pretty stripped down having just the basic main components left to remove, inspect, clean and re-install. The following photos are some of the stages from this task.
Head strip down, cam caps etc…
Bottom end sump and oil strainer etc coming off.
Trying to keep everything in some sort of order here !
Bottom end components coming out.
Pistons and bottom end caps out.
Cleaning of the bare cylinder head.
Next years students wont need to do much cleaning on the head.
Perhaps this was cleaned too much as well !
Sticking to who knows best (the book).
Pistons back in @ TDC.
Bottom end oil components going back on.
Time to flip back to the head.
Valves going back in.
Valve collets can be a nightmare. Using a compound or grease like this helps drop them back into their recesses with more precision.
Head bolt order (torqued to 25nm for stage 1, then 90 degrees for stage 2, 90 degrees for stage 3, 90 degrees for stage 4 and 15 degrees for stage 5. Cylinder head bolts were torqued in a reverse spiral pattern as shown in the manual)
Cams going back in.
Taking notes from auto-data. Notice the requirement of a cam-lock and how the tensioner functions.
Timing belt refitted and the engine was cranked by hand to see if it was timed correctly. Luckily mine okay first go !
Here is my conclusion taken from my job card:
Conclusion: In the process of stripping down this engine unit i found 1 crucial scew (1x cam bearing torx cap) to be missing and a half valve collet also missing. The cam cover gasket did not look capable of providing a good seal but the head gasket was in a reasonable used condition. The gasket for the bottom end cover appeared to be in good condition. Having observed the piston walls their condition was acceptable but the piston from cylinder 1 had scoring marks on its thrust side.
I looked up online what could be the problem. Resources suggested that scuffing marks on the exhaust side of the skirt without corresponding marks on the intake side means the lubrication film failed under thermal load on the exhaust side of the piston. The possible cause of this could of been the use of poor quality/wrong type/lack of engine oil. I checked the end gaps on one of the pistons and they were all in the required ranges. On the other pistons though some of the compression rings clearly had gaps too large and these would have to be replaced.
For more info on this task go here: https://onedrive.live.com/?cid=CBE841F72A932C63&id=CBE841F72A932C63!8344