streaky Posted February 21, 2008 Share Posted February 21, 2008 A single lobe on cylinder number three of my 4.6 cam has mysteriously worn out. What are the most common contributing causes of single lobe wear on the V8's? The cam has done around 6000km (4000miles) only. All other lobs are in A1 condition. During assembly new followers/lifters were fitted. I havn't beed able to look at the condition of the hydraulic tappet yet. Other than a blocked oil gallery...what could cause this? Is there anything that can cause this by poor instalation? If so...what? The cam is a Kent MDC1 268 which is a slightly modified race cam...not exactly 'wild' by any standards. Thanks all. Streaky. Quote Link to comment Share on other sites More sharing options...
Bull Bar Cowboy Posted February 21, 2008 Share Posted February 21, 2008 A number of issues here.................. Firstly it is unusual to see a lobe on No3 worn ............... oiling is more than adequate in that area, I would expect to see 7 & 8 sh@gged and then only on an engine that has poor oil pressure. It could be that the cam was incorrectly run in .............or that the lifter was faulty .............. has the lifter been rotating OK ? ............ is there severe wear on the lifter base ? If the oil gallery was blocked, the engine would be unbearably noisy as all the lifters on that bank are fed from the same gallery. also if the oil feed hole in the lifter was blocked you would have had a noticeable permanent tappet noise. For the moment I'll go with a faulty cam (incorrect hardened surface) .......... a faulty lifter (again, the surface temper is important).............. or the fact that the cam to lifter relationship was incorrectly run in (2000 - 2500 rpm for 20 minutes minimum ........ never drop to idle during that period). It is also important that proper cam lube was used during the build ............... a dry cam on first start up could lead to these sorts of issues. HTH Ian Quote Link to comment Share on other sites More sharing options...
steve_d Posted February 21, 2008 Share Posted February 21, 2008 Failure of the lifter case hardening would get my vote. Steve Quote Link to comment Share on other sites More sharing options...
rejo Posted February 21, 2008 Share Posted February 21, 2008 Hi Streaky DISEASEL ...... you know it makes sense Quote Link to comment Share on other sites More sharing options...
streaky Posted February 27, 2008 Author Share Posted February 27, 2008 I managed to get into town yesterday and went to the workshop to see the cam for myself. The lobe is completely missing! All of the other lobes are in imaculate condition. The cam follower/tappet was heavily concaved too. All of the other tappets are in perfect condition. I will send the cam back to the UK for Kent Cams to examine. During the fitting of the cam they used a heavy EP90 gear oil as an assembly lube. I am now concerned about the metalic fragments that are floating around inside the engine. I told the guys to flush it through a few times with flushing oil and change the oil filter each time as well. Any other idea for flushing out the foreign bodies? Thx. Quote Link to comment Share on other sites More sharing options...
Les Henson Posted February 27, 2008 Share Posted February 27, 2008 Apart from dismantling the whole engine and cleaning it - repeated flushing is the best you can do. A good quality oil filter will trap any particles that are in the system - Micronic filters are very good for trapping smaller particles than most other makes of filter. As the lobe has been wearing for some time it's likely that if there was any other damage, then it would have been done already. I would check the crank bearings - these are quite soft and any damage will be evident. Les. Quote Link to comment Share on other sites More sharing options...
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