terribleone Posted June 17, 2010 Share Posted June 17, 2010 My Zed has started making a strange knocking/tapping sound coming from the engine...I'm getting it looked at on Monday, but thought I'd post up on here to see what ideas people might come back with for discussion with my mechanic. I've got a video of the sound here which might help: I'll run through when the noise happens; Start engine up cold, no tapping at all...revving at idle sounds smooth and releasing the clutch just gives the usual thrust bearing grumble which we all have! Driving the car is absolutely fine, no odd noises from the engine and still drives fine and pulls well too (although I have not been pushing it hard since hearing this noise). Stopping the car while still fairly cool doesn't seem to make any sounds either. Giving the car a good 25 minute drive and then parking up you then notice a slight knocking sound, getting out of the car and popping the hood the sound becomes more apparent. Revving the car, the knocking raises with the revs...but only to about 2.5krpm where it becomes quite unnoticeable. Also, while idle the exhaust occasionaly make small pops and splutters although nothing dramatic. So the noise only occurs when the engine is nice and warm, and when at idle or very low revs. It also appears to be coming from the top of the engine to the rear of the intake manifold more than anywhere else. The car has always been well serviced, never thrashed in my ownership and is due an oil change in a couple of months or about another 4000 miles. I'd appreciate any opinions, advice or suggested further tests to pinpoint the source of this sound. I don't want to be paying big bucks to get the whole engine stripped down only to find it was something like a sticky lifter!! I'm quite a bit upset at the thought of my car having something drastically wrong with it after 6 months!! As always, any help would be greatly appreciated!! Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted June 17, 2010 Share Posted June 17, 2010 Fuel damper But as a precaution check your engine oil level. Alex. Quote Link to comment Share on other sites More sharing options...
terribleone Posted June 17, 2010 Author Share Posted June 17, 2010 Fuel damper But as a precaution check your engine oil level. Alex. Cheers for the quick reply...can it really make a sound like this?? I've read that if you hold the damper you can feel it knocking, unless I was grabbing the wrong thing I couldn't feel any knocking from it. Engine oil is spot on the MAX line...I'm pedantic about stuff like that!! Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted June 17, 2010 Share Posted June 17, 2010 Fuel damper But as a precaution check your engine oil level. Alex. Cheers for the quick reply...can it really make a sound like this?? I've read that if you hold the damper you can feel it knocking, unless I was grabbing the wrong thing I couldn't feel any knocking from it. Engine oil is spot on the MAX line...I'm pedantic about stuff like that!! Guess that I will now go and have a listen to your video. Quote Link to comment Share on other sites More sharing options...
terribleone Posted June 17, 2010 Author Share Posted June 17, 2010 Fuel damper But as a precaution check your engine oil level. Alex. Cheers for the quick reply...can it really make a sound like this?? I've read that if you hold the damper you can feel it knocking, unless I was grabbing the wrong thing I couldn't feel any knocking from it. Engine oil is spot on the MAX line...I'm pedantic about stuff like that!! Guess that I will now go and have a listen to your video. Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted June 17, 2010 Share Posted June 17, 2010 That is a strange one. How is your oil pressure? Does dipping the clutch make any difference. Like any type of engine noise best get this diagnosed properly before there is any resulting damage. The fuel damper and pipe is situated off the fuel rail on the rear of the driver's side cyl. head just down the back of the plenum. Where are you based as there are a few 350Z specialists around the UK. Alex. Quote Link to comment Share on other sites More sharing options...
terribleone Posted June 17, 2010 Author Share Posted June 17, 2010 That is a strange one. How is your oil pressure? Does dipping the clutch make any difference. Like any type of engine noise best get this diagnosed properly before there is any resulting damage. The fuel damper and pipe is situated off the fuel rail on the rear of the driver's side cyl. head just down the back of the plenum. Where are you based as there are a few 350Z specialists around the UK. Alex. Hi mate, Dipping the clutch makes no difference, other than quietening down the release bearing enough to let me hear the knocking. Then when a gear is engaged and the clutch released I think the sound is still slightly audible, but again seems to disappear once the revs pick up. I've had an MR2 where the bottom end went before, and that made a rattle higher up in the rev range...and it was a very loud rattle. This however, has me stumped! I live just east of Nottingham...I'm not sure where there is nearby who are 350z specialists, and I'm really dubious of Nissan garages as I think they'd jump on a problem like this and try to get as much money out of me as possible!! Quote Link to comment Share on other sites More sharing options...
andlid Posted June 18, 2010 Share Posted June 18, 2010 weird, could it be a exhaust manifold gasket? Thought I heard 'splutter'. I wouldnt be driving it... Think you're close to a few garages how long would you 'travel' to get there? I'd advice you not to drive it until you get some more feedback on that video... Quote Link to comment Share on other sites More sharing options...
terribleone Posted June 18, 2010 Author Share Posted June 18, 2010 weird, could it be a exhaust manifold gasket? Thought I heard 'splutter'. I wouldnt be driving it... Think you're close to a few garages how long would you 'travel' to get there? I'd advice you not to drive it until you get some more feedback on that video... The exhaust does seem to be doing a little splutter every now and again, it does sound a little burbly now. I don't think a gasket would make a knocking sound like this though. Unfortunately I've been having to drive it this week as I don't live near my work. As the noise isn't noticeable during driving and doesn't seem to make any difference to performance I've just been keeping the revs down low and taking it steady. It's also helped me pinpoint when it's making the noise. The guy looking at it on Monday is someone who's worked on all my cars, he also picks them up which is good as I'm always too busy at work to get to any garages during working hours. If his verdict isn't good, then it's staying with him and I'll be finding alternative transport into work! Quote Link to comment Share on other sites More sharing options...
andlid Posted June 18, 2010 Share Posted June 18, 2010 weird, could it be a exhaust manifold gasket? Thought I heard 'splutter'. I wouldnt be driving it... Think you're close to a few garages how long would you 'travel' to get there? I'd advice you not to drive it until you get some more feedback on that video... The exhaust does seem to be doing a little splutter every now and again, it does sound a little burbly now. I don't think a gasket would make a knocking sound like this though. Unfortunately I've been having to drive it this week as I don't live near my work. As the noise isn't noticeable during driving and doesn't seem to make any difference to performance I've just been keeping the revs down low and taking it steady. It's also helped me pinpoint when it's making the noise. The guy looking at it on Monday is someone who's worked on all my cars, he also picks them up which is good as I'm always too busy at work to get to any garages during working hours. If his verdict isn't good, then it's staying with him and I'll be finding alternative transport into work! wish i;d taken a sound clip of my bike (SV650S) before the valve shot straight into the front cylinder piston... then afterwards it sounds like you could hear the valves through the exhaust pip... (splutter bang bang) Quote Link to comment Share on other sites More sharing options...
terribleone Posted June 18, 2010 Author Share Posted June 18, 2010 wish i;d taken a sound clip of my bike (SV650S) before the valve shot straight into the front cylinder piston... then afterwards it sounds like you could hear the valves through the exhaust pip... (splutter bang bang) Sounds nasty!! I'm hoping it's nothing that serious, although quite unnerved that nobody seems to have any ideas over the noise. Although I should look on the brightside...nobody's said anything bad either!! I'm sure all will become clear next week...either a simple fix or my next purchase will be a daily runabout and and engine hoist!! Quote Link to comment Share on other sites More sharing options...
showtime1 Posted June 18, 2010 Share Posted June 18, 2010 might be the cam chain tensioners Quote Link to comment Share on other sites More sharing options...
terribleone Posted June 19, 2010 Author Share Posted June 19, 2010 might be the cam chain tensioners Not sure if they'd make this sound...unlike the tensioning pulleys you get on cambelts, they're not items which rotate. Quote Link to comment Share on other sites More sharing options...
terribleone Posted June 20, 2010 Author Share Posted June 20, 2010 I've just been looing through youtube for the sounds of various engine problems...it doesn't sound like sticky lifters or bottom end noise from what I've heard on there as the frequency of the noise is too slow. What I have heard which sounds almost spot on for noise and frequency is when a car has a loose spark plug. Now, would this only happen when warm? I would expect it to happen from cold and be there all the time?? I'm very confused now!! Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted June 20, 2010 Share Posted June 20, 2010 I do not think that Andlid was far off when he said exhaust manifold gasket. Loose spark plug would also give a similar noise. Impossible to give an informed diagnoses off a sound track. Peeps on here, including myself, are only giving you there thoughts, which usually always leads to confusion. Any half decent technician should be able to diagnose this if the car was in front of him. I had to replace a manifold gasket on mine recently and it is no fun job. Alex. Quote Link to comment Share on other sites More sharing options...
terribleone Posted June 20, 2010 Author Share Posted June 20, 2010 I do not think that Andlid was far off when he said exhaust manifold gasket. Loose spark plug would also give a similar noise. Impossible to give an informed diagnoses off a sound track. Peeps on here, including myself, are only giving you there thoughts, which usually always leads to confusion. Any half decent technician should be able to diagnose this if the car was in front of him. I had to replace a manifold gasket on mine recently and it is no fun job. Alex. Cheers Alex, as mentioned in my original post I was only expecting people's thoughts and ideas...hopefully to bring up something I'd not yet thought of myself. Everyone's comments have been very much appreciated and will be mentioned to my mechanic when he picks the car up tomorrow. I'm sure he'll have some head scratching to do too. Also, I just popped to the shops to get some Father's day bits & bobs...there's a cycle ride on so even though it was a 15 minute trip back, most of it was at very low revs and very low speed. Pulled up on my drive and even though the car is nicely warmed up there was no knocking sound. So it only appears to be when very warm, not just warm!! The puzzle continues!! Quote Link to comment Share on other sites More sharing options...
andlid Posted June 20, 2010 Share Posted June 20, 2010 I do not think that Andlid was far off when he said exhaust manifold gasket. Loose spark plug would also give a similar noise. Impossible to give an informed diagnoses off a sound track. Peeps on here, including myself, are only giving you there thoughts, which usually always leads to confusion. Any half decent technician should be able to diagnose this if the car was in front of him. I had to replace a manifold gasket on mine recently and it is no fun job. Alex. << me Mmmm you're right re the plugs remember when I was troubleshooting my Altezza's Ignition coils I heard the sounds of a plug that wasnt tightened properly and the sound on the V6 would be coming from the sides... you could check that easy enough I'd say... Quote Link to comment Share on other sites More sharing options...
andlid Posted June 20, 2010 Share Posted June 20, 2010 Oh yeah, had some weird rattle noise before I changed over to my HFC's, it was the heat chielding on the bloody cats that caused it to rattle! Quote Link to comment Share on other sites More sharing options...
terribleone Posted June 20, 2010 Author Share Posted June 20, 2010 cheers andlid...If my mechanic isn't able to shed any more light on it, I think the spark plugs will be my first route of investigation. Maybe while I'm getting various bits off I'll discover something loose elsewhere. I'll see how it goes tomorrow and keep you posted! Quote Link to comment Share on other sites More sharing options...
terribleone Posted June 21, 2010 Author Share Posted June 21, 2010 Ok, very strange... Mechanic picked up my car, phoned me up once he got it to his garage and said it wasn't making a noise. I told him to go take it for a good 15-20minute spin and to give it a bit of revs. He phones me up a bit later...still no noise!!! I told him to flush the engine then change the oil. He did that plus a basic service/inspection. I picked the car up and it was nice and quiet, and when I got it home (30 minute drive, didn't drive it too conservatively) it was sat there, idling and not making this noise. Then the fan cut in...still no knocking....then the fan stopped and the knocking was back!! Confusing as hell and annoying that it wouldn't make the knocking noise when they had it. Next on the list are the plugs...they're almost 5 years old so need changing anyway. My mechanic said if it was his car he wouldn't be too concerned about driving it, with the noise apparently being intermittent whereas something terminal would be present all the time. Quote Link to comment Share on other sites More sharing options...
andlid Posted June 21, 2010 Share Posted June 21, 2010 is it back from cold now too? Quote Link to comment Share on other sites More sharing options...
terribleone Posted June 21, 2010 Author Share Posted June 21, 2010 is it back from cold now too? No..just when very warm, and seemingly after a longer drive than just 15 minutes as they didn't seem to be able to get it knock!? Just popped out to the car for another head scratching session...does anyone know what this is? Is this another fuel damper?? I noticed that if I hold it, it's 'pulsing' at around the same frequency as the knocking sound...but with a bit of a delay, as the pulses and knocks don't quite seem to coincide exactly. Quote Link to comment Share on other sites More sharing options...
andlid Posted June 21, 2010 Share Posted June 21, 2010 fuel feed hose with damper... Quote Link to comment Share on other sites More sharing options...
andlid Posted June 21, 2010 Share Posted June 21, 2010 Maybe this stuff will help? Quote Link to comment Share on other sites More sharing options...
terribleone Posted June 21, 2010 Author Share Posted June 21, 2010 fuel feed hose with damper... Cheers for those mate, I've already looked through the workshop manual almost front to back looking for clues. That section is handy, but is really quite vague as to what they mean by each sound...a 'tap' may be a 'knock' to other people!! Considering there was (somewhere) a TSB about the fuel dampers making a knocking sound, and mine is pulsing...I think I may have found the cause?? I can't remember where I saw the TSB though!! Quote Link to comment Share on other sites More sharing options...
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