NickA Posted August 21, 2011 Share Posted August 21, 2011 So, for the last few months my car has been knocking every so often. We cannot figure out what it is. It doesn't do it all time. My dad brought the car to a mechanic, but it wouldn't make the noise for them. I have a 1978 280z. Anybody else encountered an issue like this? Thanks! Link to comment Share on other sites More sharing options...
cockerstar Posted August 21, 2011 Share Posted August 21, 2011 Under what conditions does it knock, and where does it come from? Use a mechanic's stethoscope or a large screwdriver to your ear to isolate the location. When did you last adjust the valves and to what specs? Link to comment Share on other sites More sharing options...
NickA Posted August 21, 2011 Author Share Posted August 21, 2011 As far as we can tell there are no certain conditions under which it decides to make noise. I will have to try to use a screwdriver, we could feel it in the oil pan when we put our hands on it, but when we took the oil pan off we couldn't see anything that would make us think that that was where it was coming from. I have no idea when the last time the valves were adjusted was. It hasn't been done since I owned it so that would make it pre 1997(it sat from then until 2010). Link to comment Share on other sites More sharing options...
2eighTZ4me Posted August 22, 2011 Share Posted August 22, 2011 Oil pan would lead one to believe that a crank or rod bearing has gone bad. Normally, you wouldn't see that if you just took off the oil pan. You'd have to disassemble the whole bottom end to get a good look at the bearings. Other option - which happened in my SBC loaded 260 was an intermittent wrist pin knock. It would be fine when it's cold, but once it warmed up, it knocked like a Jehovah's Witness at your door on Saturday morning. Oil pan area though, would lead me to look at the most common items that go bad (especially from sitting for some 13 years) and that would be the bearings. Especially if it sat for all that time and wasn't properly prepared to start up again. i.e. priming the oil pump. Link to comment Share on other sites More sharing options...
NickA Posted August 23, 2011 Author Share Posted August 23, 2011 We pulled the pan and, while I don't have to experience to know, my dad couldn't find a problem. The wrist pin idea is interesting because I think it started doing it around the time it started to heat up...we'll see. thanks alot Link to comment Share on other sites More sharing options...
Pyro Posted August 24, 2011 Share Posted August 24, 2011 (edited) could be a very stretched timing chain. does it knock on shut down? Edited August 24, 2011 by Pyro Link to comment Share on other sites More sharing options...
srgunz Posted September 2, 2011 Share Posted September 2, 2011 FWIW. Mine was the timing chain. Noise was definately from front of engine. Link to comment Share on other sites More sharing options...
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