ENGINE REBUILDERS PTY LTD
7 BARRETT STREET, FLEMINGTON VIC 3031,
TEL: (03) 9372 3111, FAX: (03) 9372 3122
ACN: 006 798 492 ABN: 74 006 798 492
TECHNICAL NEWSLETTER
Subject: MGF camshaft oil feed system and casting defect.
Date 05-01-06
Problems:
This head design has two variations:
DOHC. This is the common twin camshaft design and the one we will see most often. Typically, the engine will have failed either from an over heat or from a broken timing belt.
Variable cams. This is the less common engine and actually has three camshafts. The third results from one camshaft being in two pieces with a drive chain at both ends of the head. This design will be the subject of a later newsletter.
The most recent head, DOHC, came in with a mystery overheat only one month after the head had been off for the same reason. Being from one of our “good” customers, we quickly realized that we weren’t doing all of their work as we had thought.
But we are now…….
Cause:
We quickly found a casting defect at the head gasket sealing line from the leaking cylinder. It welded ok and we got a reco job out of it.
Problem # 2: The inspection revealed that the previous reconditioner had applied so much sealant to the camshaft cage, that both holds the cams in position and forms the oil feed gallery to all the lifters and camshaft journals, that the galleries were 80% blocked. Needless to say the engine’s lifters had been noisey as well.
Cure:
The client should have given us ALL of the information at the start to help us. They were aware that for some reason the lifters complaint existed but hadn’t told us.
We didn’t miss it but these problems aren’t always obvious.
The lack of oil had led to scuffing along all journals and the lifters were badly scratched. The client approved us polishing them as best we could and took responsibility.
The assembly proceeded using a thin application of 515 Loctite as our standard procedure. The previous sealant was probably a 3M product that had hardened.
Hedley James