Randalla Posted March 1, 2011 Share Posted March 1, 2011 I have a 1972 240-Z that I have been resurrecting after the car had been sitting for 6-8 years. The engine runs with good power and even idle, but has a ticking in the top end that I have not been able to correct. OK, so let's eliminate the obvious things. I first did a valve lash adjustment cold, to spec (.008, .010). The tick persisted so I re-adjusted the valves, hot to spec (.010, .012). No difference. So, then I began to look for missing or broken pieces (everything is there and nothing is broken). I turned the car over with a remote starter with the valve cover off and watched to make sure everything was moving as it should. At this point I discovered one of the holes on the oiling rail was plugged and thought I had found the problem as that cam lobe was a bit dry compared to the others. Notta, same ticking noise after reassembly and running the car. The cam lobes all look good with no excessive wear or damage. The nose seems to be coming from the middle of the valve train rather than the front or firewall ends. I used a stethoscope to eliminate a rod knock. The noise is definitely valve train related. So, what are the next things to check without pulling the head off? The motor has about 140K on it, has good compression and does not burn oil. Quote Link to comment Share on other sites More sharing options...
SHO-Z Posted March 1, 2011 Share Posted March 1, 2011 Here are some old school ways of checking things. Pull one plug wire at a time and see if the noise changes. This will check both rod and piston slap problems. Also you have found that you have oil passage problems. Put 2 qts of ATF in the already hot engine and let it idle for at least 1/2 hr and flush the engine. I put some cardboard in front of the radiator to get the engine good and warm. It sound more like you have a sticking valve due to lack of oil. Flushing the engine could loosen things up and if nothing else will clean up the oil passages so it should not happen again. Quote Link to comment Share on other sites More sharing options...
Pharaohabq Posted March 1, 2011 Share Posted March 1, 2011 I'd say it is probably the normal L28 engine noise. Every L28 I've ever had sounds the same, light tapping noise from the valves. This is tru on a 100K mi engine as well as the recently rebuilt one. The only L28's I know of that don't really "tick" per se are the P90 Hydraulic head ones, and even then it's less but still there. I'd recommend you listen to someone else's L28 and see if your engine sounds the same. I'd bet it does. I was worried about it on my first Z till I heard other engines sound the same. Quote Link to comment Share on other sites More sharing options...
Randalla Posted March 1, 2011 Author Share Posted March 1, 2011 Actually a 240Z has an L24 not an L28, but that makes little difference. I've had ten of these cars and most ran fairly quiet. This one is unlike others I have heard. Thanks for the tip regarding removing one ignition wire at a time to eliminate piston/block issues. I've heard of that before but forgot to try that. I'll also try the ATF in the crankcase to see if that frees something up. Something obviously could be stuck with the engine sitting for so long. I've also checked to make sure all the lash pads are in place (they are). Wondering if bad seals would ever cause ticking like I am experiencing??? Still a bit of a mystery. Quote Link to comment Share on other sites More sharing options...
stravi757 Posted March 1, 2011 Share Posted March 1, 2011 Check you oil levels and oil pressure, If your engine is being starved of oil you will hear a clicking noise coming from the valve train. Quote Link to comment Share on other sites More sharing options...
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