JRCWeedon Posted April 22, 2008 Report Share Posted April 22, 2008 Picture the scene - half day testing at Goodwood to set up the new mega shock absorbers for the first hillclimb of the season. Second session of 5 laps return to the paddock knock it out of gear "knock,knock,knock" from the engine followed by numerous expletives. Trailered it home dropped the sump to find one rod had been hammering its way through the sump baffle which had been displaced somehow. I made the mistake of thinking that was the cause of the knock but checked the big ends and replaced them. Most were showing signs of wear but No 1 was seriously knackered. Put new oil and filter in started up and it sounded OK. Took it for a gentle run no more than 3000rpm and within 6 miles the knock was back.Returned to garage off with sump No 1 big end destroyed together with con rod and scored crank!! It seems as though there was total oil starvation of that bearing anyone had a similar experience? I am hoping to pull the engine out this weekend does anyone know the weight of a 6 cyl engine? All comments gratefully received. Regards John Quote Link to post Share on other sites
Guest Wyn Posted April 22, 2008 Report Share Posted April 22, 2008 I'm sorry to hear of your problems, I can't help you on that one I'm afraid but believe the engine to weigh in the region of 400 lbs. Good luck Wyn Quote Link to post Share on other sites
marvmul Posted April 22, 2008 Report Share Posted April 22, 2008 It can be oil starvation , but 6 miles is a lot when there is a total oil starvation, and grippage would be more likely perhaps. If no oil starvation can be demonstrated, suspect ovality of the big end. The big end of the 6 cyl TR engines can get out of shape rather easily by the hammering effect when the bearing is gone. This ovality can't be spotted with the naked eye, hence failure of the new big end bearing is not uncommon. Quote Link to post Share on other sites
IanR Posted April 23, 2008 Report Share Posted April 23, 2008 Hi John, Sorry to hear of your problems. If it is total oil starvation then I would expect to see some significant heat blue on the faces under the bearing i.e on the inside faces of the con rod and cap also lots of globules of melted bearing metal in the sump. If the bearing is just heavily scored down to the Cu backing or beyond with no signs of heating then I would guess contamination of the oilway. Out of interest, were the rods tested for roundness of the big ends before assembly, and were the bearings plastigauged on assembly. In any event a search for the possible cause I guess is required. Since you say most of the bearings showed signs of wear it could be contamination that has worked its way around and No 1 suffering most since the oil pressure at that end of the engine is lower than elsewhere, as shown by Kastner in the 60's. I would have expected some evidence of similar but less wear on the mains as well though. Once the bearing begins to knock a lot then ovality ensues quite quickly as Marvmul says. Let us know what you find Cheers Quote Link to post Share on other sites
jellison Posted April 23, 2008 Report Share Posted April 23, 2008 Picture the scene - half day testing at Goodwood to set up the new mega shock absorbers for the first hillclimb of the season. Second session of 5 laps return to the paddock knock it out of gear "knock,knock,knock" from the engine followed by numerous expletives.Trailered it home dropped the sump to find one rod had been hammering its way through the sump baffle which had been displaced somehow. I made the mistake of thinking that was the cause of the knock but checked the big ends and replaced them. Most were showing signs of wear but No 1 was seriously knackered. Put new oil and filter in started up and it sounded OK. Took it for a gentle run no more than 3000rpm and within 6 miles the knock was back.Returned to garage off with sump No 1 big end destroyed together with con rod and scored crank!! It seems as though there was total oil starvation of that bearing anyone had a similar experience? I am hoping to pull the engine out this weekend does anyone know the weight of a 6 cyl engine? All comments gratefully received. Regards John John - BUGGER. I have been there several time (well withthe 4 not the 6), I have always found that once you get a death knock it is ALWAYS a strip and check (father has done what you have) a few times and it never works, it always need a strip and the crank at a minimum polished or more often machine to the next bearing size! Not sure on weight - er v.heavy though - but fine even with a gearbox to pull up on a big wooded beam. Hope you fix it fast. Jon Quote Link to post Share on other sites
Bald Rick Posted April 24, 2008 Report Share Posted April 24, 2008 John Have sent you PM Tony Quote Link to post Share on other sites
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