OlderThanMe Posted July 9, 2006 Share Posted July 9, 2006 Engine: L26, SU's, header...mild motor. Since I have owned my z there has always been a slight noise coming from the valvetrain. I have started it after it has sat for the last two months and there is a very loud clacking sound coming from the #4 cylinder. here is a video. You can hear it plainly different from the rest of the car. HELP!!!! What is the noise! I hope something is not stuck in the valve or the rocker arm is loose. I need this car to be operational soon. Thanks Quote Link to comment Share on other sites More sharing options...
olie05 Posted July 9, 2006 Share Posted July 9, 2006 sounds like maybe a rod thats about to fall off the crank. Pull your pan and see if anything looks odd. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted July 9, 2006 Author Share Posted July 9, 2006 the sound is coming from the head though! I am thinking a valve is stuck open. I just changed the oil last week too...arg... this is just great...thinking of a worn out wrist pin...I started it just last week and it ran awesome! Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted July 9, 2006 Author Share Posted July 9, 2006 pulled the valve cover and everything looks ok...makes me feel bad about my shortblock...I am suspecting either a valve is stuck or something else much worse. Looked in the #4 spark plug hole and the piston looks fine from what I can see. I may go ahead and pull the cylinder head today if I can't see anything else wrong. I may just put it on jackstands and pull the pan first like you suggested Oliver... Quote Link to comment Share on other sites More sharing options...
76brkracer Posted July 9, 2006 Share Posted July 9, 2006 Is it automatic if so it could be a cracked flex plate had one sound just like that.Also try taking off the valve cover and have someone start it then look closely at every thing real quick so you dont srpay oil everywhere. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted July 9, 2006 Author Share Posted July 9, 2006 it's a standard 4 speed. I am gooing to do just that. I just went about 12 miles of mountain biking today so I am pretty winded...I'll do a compression check too. If the compression check fails then off comes the head...maybe I'll just pull the motor...I've never disassembled my engine past removing the valve cover or any motor for that matter. Quote Link to comment Share on other sites More sharing options...
Guest Abkshelby79280ZX Posted July 10, 2006 Share Posted July 10, 2006 I'll take a guess. Could it be your timing chain rattling? I don't think it's anything in the bottom of the motor. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted July 10, 2006 Author Share Posted July 10, 2006 nope...it is coming from the #4 cylinder...definitely not from the chain...plus the chain is fairly tight... My dad's 944 had a bad chain so I know what that sounds like... I am tending to think it is something with the piston. I think the piston is ratteling on the wrist pin or the connecting rod is. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted July 10, 2006 Author Share Posted July 10, 2006 just turned the motor the hard way. I put the car on jackstands, unhooked the E-brake cable on one side, engaged the e-brake, had my Dad turn the other wheel while the car was in 4th. I tested teh vacuum and it was around 42cm HG on all of the pistons except #4 and #1. The #4 was the worst at 35cm HG. The #1 was at 38cm HG vacuum. Quote Link to comment Share on other sites More sharing options...
veritech-z Posted July 10, 2006 Share Posted July 10, 2006 That doesn't sound good at all....kind of like somebody changed your oil with a handfull of nickels...I really don't have any advice though, hope you can figure it out. It doesn't sound very regular, like a valve event should, it sounds most to me like something is bouncing around. I'd say pull the pan (all thirty of the pan bolts) and check it out...Also see if you can get the clutch inspection plate off and see if anything happened in there, I saw a guy's pressure plate lose a spline once and it sounded kind of like that... Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted July 10, 2006 Author Share Posted July 10, 2006 I am about 95% sure it has to do with the #4 piston. I used a mechanic's listening stethoscope (like what a doctor uses except for mechanical stuff). I have pretty much scratched out driving my car down to college this fall...and since that is the case...I am going to go buy a engine stand and rent an engine lift. The engine may be out soon. I can't get to all of the pan bolts while the motor is in. I took about 10 minutes to get the drivers side steering rack bushing on and about 4 hours for the passenger side one. I am just to the point where when I pull the oil pan off and there is anyhting wrong I will rebuild...there are enough things wrong and horsepower is addictive...I may have a 300, 310 a 320z next year...probably just send the short block off to rebello or to do their magic. Quote Link to comment Share on other sites More sharing options...
olie05 Posted July 10, 2006 Share Posted July 10, 2006 I can't get to all of the pan bolts while the motor is in. Yes you can. I did it, and you can too! The oil pan bolts will come off, maybe with a wrench on some of the ones behind the crossmember. Once the oil pan is off the block, stick your ten wrench in and undo the bolts holding on the oil pickup tube/ strainer. Oh, And I say you should rebuild your own engine, not pay rebello too much money to do it for you. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted July 10, 2006 Author Share Posted July 10, 2006 true...I have been thinking about it...since a shop has never touched my car since I bought it... Except a tire shop and I watched them very carefully. I just need to figure out what parts I need to make a good 280hp NA...I like turbos but I want this car to be a NA car...someday a track car... I'll drain my oil tomorrow and pull the pan. Quote Link to comment Share on other sites More sharing options...
TheNeedForZ Posted July 10, 2006 Share Posted July 10, 2006 Haynes manual lists several causes of engine noises : 1. Wrong valve to rocker clearance 2. Worn crankshaft bearings 3. Worn cylinders(piston slap) 4. Slack or worn timing chain and sprockets Before you open up the bottom end, check #1. Quote Link to comment Share on other sites More sharing options...
iaconsultants Posted July 10, 2006 Share Posted July 10, 2006 one thing before you tear down your engine did you do a compression test across all 6 cylinders. First see if there is a problem with your number 4 that way. I believe in checking things out as much as possible, to find the problem then fix the problem, not just dive in and take the engine apart and try fixing something you are not sure what it is. Also yes you can pull your oil pan without removing your engine, any suspension, or any thing but the oil pan screws. You will need a 10mm small socket wrench and a 10mm open end/closed end wrench, 2 flat screwdrivers, and a straight razor blade. I have done this many times and never had a problem with it. Simply remove all the 10mm bolts and pan support steel, use the two flat screwdrivers to work the back of your pan loose (might need the razor here a little to get it started), and just work it loose, once the pan is loose you will need to slide it and twist the rear towards the drivers side and it should be out. After all that use the razor to clean all the surfaces very well. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted July 10, 2006 Author Share Posted July 10, 2006 I don't have a tool o test compression so I did a vacuum test and 4 of the cylinders read in the 40-42cm HG vacuum range. The #1 cylinder read 38cm HG vacuum #4 cylinder read 35cm HG vacuum. I used to have a problem with the #1 misfining like crazy when I would rev the engine and then when I let off the gas it would drop about half the sparks. When I cranked it before the noise appeared I was not dropping any sparks. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted July 10, 2006 Author Share Posted July 10, 2006 oil is draining. Getting ready to pull the oil pan. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted July 10, 2006 Author Share Posted July 10, 2006 oil pan removed. I will post pics in a few minutes when I clean up. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted July 10, 2006 Author Share Posted July 10, 2006 these pics are very large so I will just post links. the piece of metal on the pan. http://x3e.xanga.com/4f1a3b427703065512431/w43958536.jpg close up #1: http://xed.xanga.com/285a57427663365512395/w43958512.jpg close up #2 http://x59.xanga.com/905a25765113365512324/w43958458.jpg I am making a wild guess but I don't think that was supposed to be sitting in the bottom of the oil pan. Looks like a piston oiler to me. I'll get under the block and take some more pictures. It possibly looks broken off on the side furthest from the large hole. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted July 10, 2006 Author Share Posted July 10, 2006 hmm...the coloring on my crank and connecting rods does not look oem to me... full size: http://x72.xanga.com/4b7a557b6513265521474/w43964468.jpg balacning...don't know if that is OE either...this shot is the rear side of the crank. full size: http://xc2.xanga.com/f31a35450763065521431/w43964438.jpg front side of crank: [/url] full size: http://x56.xanga.com/719a52400533365521386/w43964410.jpg a further away shot. full size: http://x8f.xanga.com/3aca344103c3065521332/w43964373.jpg Quote Link to comment Share on other sites More sharing options...
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