Mark Posted May 20, 2021 Share Posted May 20, 2021 Hi all Stopped work on the car as I twisted my back, not to bad now, so gave the car a quick blast at motorway speeds before I start on the sump gasket replacement to hopefully cure a small oil leak. Car goes very well no noises under load, just a couple of noisy tappets. Don't know why but I stabbed at the throttle a couple of times whilst at idle and heard an unexpected rattle. Sounds like a big end, but don't think it is, could be lean on initial stab of throttle, which could cause the rattle, pinking? The noise reminds me of more modern cars I've driven, when in a lower gear under load or not enough revs when pulling away on full lock. Oil pressure 20psi hot at 800 rpm idle. Linked a video of the noise, what do you think? Link to comment Share on other sites More sharing options...
Nick Jones Posted May 20, 2021 Share Posted May 20, 2021 Disconnect the vac advance and see if it still does it? I think that would rule out your pinking thought if it keeps doing it and confirm if it stops. Crank pulley bolt tight? Exhaust clouting something? Link to comment Share on other sites More sharing options...
PeteStupps Posted May 20, 2021 Share Posted May 20, 2021 2 hours ago, Nick Jones said: Exhaust clouting something? That was my first thought. In fact that was my only thought! Link to comment Share on other sites More sharing options...
Mark Posted May 21, 2021 Author Share Posted May 21, 2021 Tried disconecting the vac advance and checked exhaust for clearance, no joy, still a rattle. With the aid of a mechanics stethoscope I narrowed it down to the inlet manifold, then the front SU. Very low oil level and undampened carb piston was hitting the inside of the SU bell which was the causing the rattle. Never come across that before. The inlet manifold was acting like a trumpet, directing the noise into the head and block. I had Started to think it could be cam followers, small ends etc. So relieved. I bought the stethoscope to locate a noise on my mk1 Eunos, and has identified two out of two faults so far, cheap but very useful tool. Link to comment Share on other sites More sharing options...
PeteStupps Posted May 21, 2021 Share Posted May 21, 2021 Random! And a very easy fix. Good detective work. Surprising that it would make such a meaty sound but you're right, it must have resonated along the inlet tract. Link to comment Share on other sites More sharing options...
Mark Posted May 21, 2021 Author Share Posted May 21, 2021 Yes it created a surprisingly loud disconcerting metallic clatter, the noise appearing to come from the opposite side of the engine. Link to comment Share on other sites More sharing options...
Nick Jones Posted May 21, 2021 Share Posted May 21, 2021 Great catch! Interesting..... maybe the strange noise my GT6 engine makes is something similarly trivial....... (would be nice.....) Link to comment Share on other sites More sharing options...
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