revilla Posted August 30, 2016 Share Posted August 30, 2016 OK here's an idea - but I don't have enough direct experience to say with any confidence so I would appreciate comments from anyone who can validate what I'm suggesting: When you over-revved it you broke one or more valve springs. Above around 5000rpm the broken valve spring is unable to close the valve fast enough to follow the cam profile down leading to the loss of power and noises you are getting. If this is the case you need to get it sorted very quickly as the next thing will be valve to piston contact, dropping a valve head and trashing the head and piston. I really do think from the noises you are describing that it needs an expert opinion and possibly stripping down for inspection and I would be very worried about continuing to use it in the meantime. Link to comment Share on other sites More sharing options...
John Vine Posted August 30, 2016 Share Posted August 30, 2016 Andrew,I think you may be on to something there. And the noise above 5K could well be piston-to-valve contact, with associated reluctance to rev and loss of power.I'd agree entirely about not using the car until the engine has been thoroughly checked by an expert.JV Link to comment Share on other sites More sharing options...
Wrightpayne Posted August 30, 2016 Share Posted August 30, 2016 If it were my car I'd have the engine out stripped and checked.Ian Link to comment Share on other sites More sharing options...
revilla Posted August 30, 2016 Share Posted August 30, 2016 Yes I have a horrible feeling that, one way or another, there's something going on inside your engine that so far you have just "got away with" ... and unless it is sorted your luck won't last forever. Get it stripped and inspected while it's still a relatively small issue. Link to comment Share on other sites More sharing options...
polo.danny Posted August 31, 2016 Author Share Posted August 31, 2016 Thanks guys looks like its time to take the head off and have a look Andy at PGM suggested taking the head to Rob Singleton at boss racing.Thanks again for the help i wont drive the car now and i will update when i have investigated. Link to comment Share on other sites More sharing options...
SM25T Posted August 31, 2016 Share Posted August 31, 2016 Boss Racing at Longfield build plenty of engines. Link to comment Share on other sites More sharing options...
revilla Posted August 31, 2016 Share Posted August 31, 2016 That sounds like a very sensible decision. Hope you get it sorted quickly. Keep us informed! Link to comment Share on other sites More sharing options...
John Vine Posted August 31, 2016 Share Posted August 31, 2016 Good decision, Danny. Do tell us how you get on.JV Link to comment Share on other sites More sharing options...
polo.danny Posted September 3, 2016 Author Share Posted September 3, 2016 Hi all i have just got the engine to the point where the head can be removed. i have lined up the timing gears so that i can lock them with the locking tool see pic. i then checked the bottom pulley which should be at 90 on the top mark it is at TDC which i believe is incorrect. i took plugs out to see if pistons were level and they were not. i then rotated engine so that the bottom pulley was on its 90 degree mark then checked pistons which were now level the inlet gear is now pointing at 4 oclock ant the exhaust gear is up at 10 oclock the last pic is on its side and i painted the timing mark in yellow the bottom pulley is in correct position the cam gears are now out. In this possition the pistons are all level.i will be at PGM tomorrorw around 3pm ish for their open day and hopefully see some of you face to face.i dont think that CC checked the timing as i had to drill out the rivets holding the appollo tankto the frame so that i could move it a bit to get the long bolt out holding the belt cover on.any ideas?? Link to comment Share on other sites More sharing options...
revilla Posted September 3, 2016 Share Posted September 3, 2016 The timing mark on the bottom pulley should align with the rib on the front of the plastic belt cover when the timing marks on the cams align with each other. This is NOT a TDC mark, it marks the safe position 90 degrees BTDC on No. 1. So when you line up the cam timing marks, don't expect to see the crank at 90 degrees to the timing mark, it should also be aligned. Link to comment Share on other sites More sharing options...
polo.danny Posted September 3, 2016 Author Share Posted September 3, 2016 thanks i believe the pic below is how mine should look. if i set crank at the safe mark on the plastic cover and double check that all pistons level which they are then the cam timing marks are about 15 degrees out which i think is two teeth Link to comment Share on other sites More sharing options...
revilla Posted September 3, 2016 Share Posted September 3, 2016 Yes, the picture in your last post is how things SHOULD look.And now I can get my head round your earlier pictures and yes indeed it does look wrong. As you say, the two cams seem to be timed correctly relative to each other, but wrongly relative to the crank. Two teeth is exactly 15 degrees at the cams (360 / 48 * 2) but remember the cams rotate at half the speed of the crank, so 15 degrees out at the cams corresponds to 30 degrees out at the crank ... which is a very big timing error. No wonder it isn't running very well!Given that you have mechanical noises I think you still need to proceed with removing the head to look for possible valve to piston contact damage - I'm not sure how far you need to get the timing out to run the risk of contact and it will depend on any modifications done to your engine, head skimming etc.At least now you have found something that is clearly wrong and you can work outwards from there. One important question to answer is - how did it get like that? Only two possibilities really, it was put together wrongly in the first place or it has slipped a couple of teeth at the crank pulley. In the second case I would expect to find the cams retarded but in your case they look advanced - unless of course it has actually slipped two teeth on each of the cam pulleys which sounds less likely. Does the cam belt seem to be tensioned correctly?At the very least I would say you should change the cam belt and tensioner when you put it back together again - and do the water pump too as it is driven by the cam belt, is a quick job and if it fails can take the cam belt with it. Link to comment Share on other sites More sharing options...
John Vine Posted September 4, 2016 Share Posted September 4, 2016 This is turning into quite a challenge! First off, I agree with revilla's analysis. Of course, if the cam timing is really out as it appears, we've been chasing our tails a bit given that CC are reported to have checked the timing and given it the all clear. i dont think that CC checked the timing as i had to drill out the rivets holding the appollo tankto the frame so that i could move it a bit to get the long bolt out holding the belt cover on.It's not normally necessary to drill out the rivets to move the tank. Usually, the tank is held in place by a large Jubilee clip, looped around the tab rivetted to the upper chassis cruciform. Simply loosening and lowering the Jubilee clip is enough to be able to move the tank out of the way. You say they checked the cam pulley pins. To do this, they'd have had to remove the upper timing cover (as well as the pulley bolts), so would have been able to see easily whether the cam pulley positions matched the BTDC mark on the crankshaft pulley. Assuming they did indeed perform this check, I'm wondering whether the timing could have moved since? I've been trying to get my head round possible reasons why the cam timing appears to be so far advanced. My brainstorm came up with these: Cambelt not fitted correctly -- seems entirely possible but surely this would have affected performance over a longer period Cambelt has slipped on crankshaft sprocket -- could happen, I suppose, but (like revilla) I'd expect this to cause the timing to become retarded rather than advanced Cambelt has slipped on camshaft pulleys -- seems very unlikely given that the pulleys are still timed correctly to each other Incorrect belt fitted (too long) -- is it? Belt not tight -- could lead to jumped teeth and timing slip Notch in crankshaft pulley not engaged correctly with lug on crankshaft sprocket (yellow arrow in photo) -- even if possible, it's difficult to imagine how this could actually be done accidentally Lug on crankshaft sprocket (yellow arrow in photo) has sheared off -- seems possible, and would easily account for the apparent timing discrepancy (you could check the actual timing by removing the crankshaft pulley and seeing whether the two dots on the crankshaft sprocket are correctly aligned (red arrow in photo) Rim of crankshaft pulley has moved relative to its centre -- a bit left-field as I imagine the pulley is a one-piece construction (or is it?) Can you give us some info about the car itself: How long have you had the car? What is the service record? When was the cambelt last changed? Who changed it? Was the performance ok before your trackday (when you selected 3rd instead of 5th)? Did the current problem begin immediately after the trackday or some time later? How does the performance of your car compare with other similar ones?It may be that you need to take the whole car to BOSS so that they can investigate the timing discrepancy as well as the head itself.JV Link to comment Share on other sites More sharing options...
revilla Posted September 4, 2016 Share Posted September 4, 2016 I would be tempted to do what John suggests. Don't strip the engine down any further, take it to someone like BOSS intact. There may be a lot of clues as to what happened that may be lost on disassembly. Let them see it exactly how it is and they may be able to work out what has happened and why (and how to make sure it doesn't happen again). Link to comment Share on other sites More sharing options...
John Vine Posted October 9, 2016 Share Posted October 9, 2016 Any news, Danny? Did you manage to get the car to a specialist?JV Link to comment Share on other sites More sharing options...
polo.danny Posted October 21, 2016 Author Share Posted October 21, 2016 The car is all fixed I removed the head and took it to boss racing for a check up and refurbish. It is all back together now with new bolts water pump tensioner and belt. I fired her up and she runs perfectly. So after all the faffing about it was the timing belt in the wrong position. I went back to caterham cars and they said " I don't know how we missed that" At some point the timing belt has slipped about three teeth on the top two cam gears or on the crank gear. But not sure how thanks for all the help and advise Danny Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted October 21, 2016 Member Share Posted October 21, 2016 Glad it's fixed.I went back to caterham cars and they said " I don't know how we missed that" Hmmm... are you going to talk to PGM as well?Jonathan Link to comment Share on other sites More sharing options...
revilla Posted October 21, 2016 Share Posted October 21, 2016 Glad to hear it's all OK again. I think you had a lucky escape! Link to comment Share on other sites More sharing options...
John Vine Posted October 22, 2016 Share Posted October 22, 2016 Glad to hear it's running ok.JV Link to comment Share on other sites More sharing options...
John Vine Posted November 4, 2016 Share Posted November 4, 2016 Hope the car is still running well.Did anyone (CC, BOSS, PGM) ever explain to you how the timing error arose in the first place?JV Link to comment Share on other sites More sharing options...
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