DCZ Posted October 4, 2006 Share Posted October 4, 2006 Posted this on another site, now I need opinions from the experts: Short version: Loose timing chain guide. Pulled cover, top bolt was halfway out, bottom bolt missing. Replaced bolts, checked cam position, distributor timing, everything looked right. Started up, idled great for 30 sec then clack, clack, clack. Problem was described in more detail here: http://www.zcar.com/forums/read.php?f=1&i=685346&t=685346 compression test 180, 170, 170, 140, 150, 180. I made two videos, the first with the plugs out turning the motor over. Seems perfectly normal. The second is a short startup/idle so you can hear the clack. What do you think? First video Second video Not sure how to troubleshoot and am nervous about running it any more than I have. What do you think I should do next? Quote Link to comment Share on other sites More sharing options...
riverz Posted October 4, 2006 Share Posted October 4, 2006 Did you ever find the other bolt that was missing might be in your oil pan or other places. Also that is the sound my engine made when it spun a bearing because of a loose rod bolt. Quote Link to comment Share on other sites More sharing options...
SHO-Z Posted October 4, 2006 Share Posted October 4, 2006 Old Shade Tree Mech trick. Start the engine an let it idle. Pull off one spark plug at a time. If the noise goes away on any of the plugs it is a rod. Quote Link to comment Share on other sites More sharing options...
SU'dCrazy280 Posted October 4, 2006 Share Posted October 4, 2006 sounds like too slow of a clack clack to be valve noise, I had some bad valve noise and it wasn't as loud, and way faster clicks. Also, you didn't drop anything small into the intakes while changing a filter or anything did you? A mechanic accidentally dropped a small nut into the carb of our boat engine once, and got sucked right on top of the number 3 piston, and it sounded a whole lot like that for a while, until it chipped one of the valves apart and ruined a piston, after that it was more of a boom boom!! If you do think you dropped a small piece of something, do not turn over the engine anymore, and immediately take off the head. Good luck!! Quote Link to comment Share on other sites More sharing options...
DCZ Posted October 5, 2006 Author Share Posted October 5, 2006 Thanks for the suggestions. I didn't take the air cleaner off so it's not likely something got sucked in. I never did find the tensioner bolt, but then I didn't take the oil pan off when I changed the front cover either. I'll try pulling the plug wires one at a time and let you know what I find. Thanks BTW, when it rains, it pours. My daily driver 73 240zt and only running car just lost the power booster. The Z Gods are Angry!! Quote Link to comment Share on other sites More sharing options...
SU'dCrazy280 Posted October 6, 2006 Share Posted October 6, 2006 whoa, not the plug wires, the plugs themselves. because then all of the compression can escape out the plug hole. Quote Link to comment Share on other sites More sharing options...
DCZ Posted October 9, 2006 Author Share Posted October 9, 2006 Tried pulling the spark plug wires one by one and it was inconclusive. I didn't pull the plugs like you suggested SU'dCrazy. I said screw it and pulled the oil pan. Measured rod bearing end play (longitudinally along the crank shaft) and it was between 0.2 and 0.3 mm on all rods which is in spec. I could not get any other play on any of the rods and everything looked good as I rotated the engine by hand. All the bearing caps were tight, though I did not check the bolt torque on them. All the piston skirts look good and the cylinder walls I could see looked good also. Anything else I should look into while I have the oil pan off? I did find the lower timing chain guide bolt in the sump. Do you think the crank could have been hitting the bolt and making the noise? The pan is a little dented but I could not see any evidence that they were new dents and none of them were "bolt-shaped" LOL! Quote Link to comment Share on other sites More sharing options...
srgunz Posted October 10, 2006 Share Posted October 10, 2006 Sounds like the valvetrain area to me. You need to pull that valve cover and look again at cam and rocker arms. I really think it might be the timing chain. Something must have broken in the front cover. Quote Link to comment Share on other sites More sharing options...
DCZ Posted October 10, 2006 Author Share Posted October 10, 2006 I should start taking bets . . . I'll figure it out eventually. Quote Link to comment Share on other sites More sharing options...
DCZ Posted November 2, 2006 Author Share Posted November 2, 2006 Referring to my previous posts: http://forums.hybridz.org/showthread.php?t=115269 If you don't want to read back, short synopsis is: L28, carbed, 15K miles on rebuild. I noticed timing chain guide was loose, pulled front cover, replaced guide bolts, started up and all was well for 30 sec. before lots of clacking ensued. video here: Checked cam timing, all marks line up. Rotate engine by hand - no problem. Rotate engine by starter with plugs out watching valve train - no problem. Valves adjusted - no problem. Compression test (cold) 180, 170, 170, 150, 160, 170. Rod bearing clearances tested with plastigage - all within spec. Finally borrowed a leakdown tester - 5%, 11%, 15%, 17%, 5%, and, (drumroll please) 47%. Looks like #6 has some major problems. I don't understand why #6 had such a drastic leakdown when compression was good. Also, when I pressurized #6, I could feel air escaping out of #4 and slightly out of #2 spark plug holes. Air escaped out of #2 very slightly when I pressurized one of the other cylinders but I forget which one (notes not in front of me). All other leaking air seemed to be going into the crank case. I could detect no air leaking into the intake or exhaust. Are these enough clues for anyone to tell me what is wrong? Somehow air is leaking out of #6 and coming back through #4 so I must have broken rings or cracked a piston or 2 (?) Is it time for me to pull this engine and break it down to see what else I find? Do I have any alternative at this point other than pull the head and/or pull the whole engine? Thanks. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted November 2, 2006 Share Posted November 2, 2006 Is it time for me to pull this engine and break it down to see what else I find? DCZ: I'm not an engine guy so take what I say with a grain of salt. Also, some folks act like pulling an engine is no big deal, and all though it's easier in these cars then a lot of others, it's still a big job. BUT... if you just rebuilt this thing 15K (barely broken in IMHO) ago, and compression and leakdown results like that, pull that thing out and take it apart and see what's up. Quote Link to comment Share on other sites More sharing options...
DCZ Posted November 2, 2006 Author Share Posted November 2, 2006 mom'sZ - Pulling an engine is not THAT big a deal for me since I have a garage and hoist, etc. Just that right now I have NO time for this whaaa, whaaa, cry, cry! I have never rebuilt an engine. This one was done by the PO right before I bought the car. It has always run well, dyno'd at 123HP and 130TQ. Had much better compression when I bought it. I'd like to find out if this is something I did or if it is a result of the loose timing chain tensioner. Quote Link to comment Share on other sites More sharing options...
Guest 2slo4u Posted November 2, 2006 Share Posted November 2, 2006 Sounds like valve train issue Quote Link to comment Share on other sites More sharing options...
DCZ Posted November 2, 2006 Author Share Posted November 2, 2006 Do you think this could be a blown head gasket? I haven't had any coolant/oil mixing. Quote Link to comment Share on other sites More sharing options...
naviathan Posted November 2, 2006 Share Posted November 2, 2006 I think you broke some ring lands for some reason or another. Quote Link to comment Share on other sites More sharing options...
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