ECR Posted August 16, 2002 Share Posted August 16, 2002 Scavenge pump sounded OK with a stethoscope..... (carry on straw clutching please) Edited by - ecr on 16 Aug 2002 16:06:10 Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted August 16, 2002 Author Share Posted August 16, 2002 Posting this here to remind me. Lift TDC 4 & 1 - 180 thou inlet, 160 thou exhaust 100 deg inlet after TDC 160 deg exhaust before TDC Idea from QED - check valve springs by pushing on followers. If outer is broken, it will be palpably different. DaveK, Thanks for your offer of a replacement valve spring - will let you know if it's needed. Alex Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted August 16, 2002 Author Share Posted August 16, 2002 oops Edited by - Alex Wong on 16 Aug 2002 16:45:52 Link to comment Share on other sites More sharing options...
wag Posted August 16, 2002 Share Posted August 16, 2002 Alex, any complaints from work about the oily state of your stethoscope? Link to comment Share on other sites More sharing options...
stevefoster Posted August 16, 2002 Share Posted August 16, 2002 Have you got a fix on the rough location of the rasping noise? Have you done compression and leak down tests? On ECR's request.... Oil pump drive? Water pump? The scavenge pump drive pulley. Only 3 little bolts there. But you would have checked these when thinking about the crank pulley bolt... Steve My racing pics, 7 DIY, race prep. Updated oftenhere Hants (North) and Berkshire area club site here Edited by - stevefoster on 16 Aug 2002 20:41:10 Edited by - stevefoster on 16 Aug 2002 20:43:39 Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted August 16, 2002 Author Share Posted August 16, 2002 Hi Steve, It appears to be the top half of the engine. The noise doesn't appear to be present until 4000 rpm which is just after a flat spot in the power curve. This makes me suspect a valve spring. The outer one can fail leaving the inner one still functioning, but this apparently can cause valve bounce at higher revs according to ECR. QED concurred with this. The four primaries sounded the same on auscultation, as did the four inlets which goes against a valve spring and puts a throttle pot problem as the second most likely cause (I think). I haven't checked compression but having experienced a ring/piston failure before, I don't think this is the problem as low rev power is still good and there's no smoke. The dry sumps belt is running smoothly and although I haven't checked the three little bolts, I don't think this is the cause. I haven't checked the pulley bolt (which has been replaced everytime it's been off) but the noise doesn't seem to be coming from here. Good luck in your race at Brands! Alex Edited by - Alex Wong on 16 Aug 2002 23:19:33 Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted August 16, 2002 Author Share Posted August 16, 2002 Alex, any complaints from work about the oily state of your stethoscope? No, but they're not happy about the oily state of their stethoscope. Mine's nice and clean! Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted August 17, 2002 Author Share Posted August 17, 2002 DIAGNOSIS : Multiple fracture of the outer valve spring for one of the inlet valves for number 1 cylinder. The head's off & the cam and failed spring are out. Had a nasty moment when the head for one of the cylinder bolts rounded off! 😳 ECR took a drill, a dremel and a chisel to it and it finally came out. Scary!!! 😳 Oil galleries were then full of swarf so all the valves on the inlet side are out to allow cleaning out. 7 days to the BMMC sprint - VDU needs to be present to defend it's BMMC Seven Club Class crown!!!!!!!!! The clock is ticking. Alex Wong www.alexwong.net www.slipstream-trackdays.co.uk The Caterham Links Page _________ / __ __ / ___ _//__T/__/_ ___ / (_) (_)/ /`-'/o/ _______ /o/`-'/ / /// ( VDU7X ) // / /___/--_________/--/___/ Edited by - Alex Wong on 17 Aug 2002 19:48:31 Link to comment Share on other sites More sharing options...
scooby dooby doo Posted August 17, 2002 Share Posted August 17, 2002 best of luck alex. HOOPY CYCLE WINGS CUCUMBER Link to comment Share on other sites More sharing options...
mav Posted August 17, 2002 Share Posted August 17, 2002 Glad you have found the problem. Viv and I will be there on Saturday to support the L7C members taking part. Roll on Sunday. Regards, Martin Link to comment Share on other sites More sharing options...
Peter Carmichael Posted August 17, 2002 Share Posted August 17, 2002 Alex, are you going to fit a new valve straight away? ISTR Roger King has horror stories of people who skimp in such matters. Peter *eek*Loadsachequestubs Carmichael Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted August 17, 2002 Author Share Posted August 17, 2002 Thanks Mav and Dave. Peter, What would constitute a proper job? I think I will fit a new valve (the old one was a little stubborn coming out - it looks straight but it might be a tiny bit bent), new springs and new valve seals for all inlet valves, new cam belt, new head gasket and new head bolts. Is there anything more you think I should do? Alex PS - if you meant "am I fitting a new valve straight away or after the Sprint", I'm going to be doing my utmost to get it running for Sunday. You've got to earn that Championship and I have a score to try and settle!!!!! Edited by - Alex Wong on 17 Aug 2002 22:14:21 Link to comment Share on other sites More sharing options...
stevefoster Posted August 17, 2002 Share Posted August 17, 2002 so, uncovered! What was the cause is the big question? The race went fine. Steve My racing pics, 7 DIY, race prep. Updated oftenhere Hants (North) and Berkshire area club site here Link to comment Share on other sites More sharing options...
EFA Posted August 18, 2002 Share Posted August 18, 2002 Alex, Full set of balanced springs on the inlet cam, and a new valve would be the best approach. Getting all that swarf out is critical. Some new GM head bolts would also be a good idea! Fat Arn Visit the K2 RUM site See the Lotus Seven Club 4 Counties Area Website here Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted August 19, 2002 Author Share Posted August 19, 2002 Parts coming in from Burton Power, QED, Demon Tweeks and Caterham...... Will I make the ball in time or will it end up as one big pumpkin??? Link to comment Share on other sites More sharing options...
Peter Carmichael Posted August 19, 2002 Share Posted August 19, 2002 Best of luck with the rebuild. You do realise that last minute repairs mean you will run faster. Best bet is to guarantee you don't get any sleep as well for the last word in performance. Class 4 and class 5 are looking good for some tense championship action. Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted August 19, 2002 Author Share Posted August 19, 2002 Thanks Peter. Shame my front tyres are knackered (getting my excuse in early) Link to comment Share on other sites More sharing options...
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