TECHNICAL NEWSLETTER ISSUE 27/OI/00
SUBJECT: FRACTURE IN PLASTIC AIR CLEANER
Problem : Initially, our client had an ACL claim approved as a result of incorrect valve stem seals being packed in a 3Y TOYOTA HIACE petrol engine VRS, At this on-site examination, the bores were examined for glazing or other problems, such as rings and the diagnosis confirmed that the oil consumption had no other factors contributing to the complaint.
However, the oil consumption was again reported some few months later and the engine was placed onto an oil consumption monitoring plan. On a GTX, sg rated oil this engine still persisted to use I l/2 litres per l000kms. The factory was informed and , subject to an inspection of the rings, agreed that the bores may be glazed.
Our client arranged to removed the head and piston assemblies at a time after Christmas when convenient to the owner.
Cause: With the new ringset and gaskets on board I drove to the vehicle with a hone and was determined to verify the bore condition that previously I had inspected as OK. To my surprize ,I could now see clear vertical scratches on all bores. Tho evidence of a dusted engine was further confirmed with telltale sharp edges on the compression rings. Tracing back along the air intake duct from the carby air horn I found slight traces of fine dust until I reached the air filter element, Thc element bad been fitted OK and was clean on the engine side whilst dusty on the atmosphere side. Back along the ducting again and, sure that dust was there, I again challenged every joint for dust entry. Finally, all the way back to the lid of the air filter element housing and confirming that the underside was spotless I almost missed thc crack in this plastic lid.
Cure : Given that this engine had oil consumption since it was reconditioned { valve seals }, and a strong belief in the mechanical shop that dust wasn’t the cause this time, my next step is to pass the diagnosis back to the factory for their report on the ringset. When I removed the rings from the pistons back at our shop, quite severe side wear was clear on top compression rings, so I doubt that the Factory will allow any warranty on this problem.
The “CURE” from our position will consist of :
a : Education of our client by supplying a video on dust control from our library;
b : No charge for our input in reseating the valves again and politely asking for a policy gesture from the factory to assist with the ringset and gaskets. We will not pay for the mechanical shop’s labour as clearly we had no control over this dusted engine.
c: Next time I examine an engine with similar problems I will be carefully looking at the plastic air filter housings.( fractured I am advised, by LPG backfires).
BE ON YOUR GUARD.
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