ZR8ED Posted July 30, 2003 Share Posted July 30, 2003 Ok A quick update on my situation. new engine rebuilt in winter. 1000+ miles on new engine. engine is 1987 VG30ET. bottom end totally redone.. balanced shotpeened, polished etc.. hydrolic lifters are used and not matched to the cam. (1 newer cam from different engine) Car has been great during the breakin. took the car to a track day.. no probs. Thought I heard some minor clacking noise .. noisy lifter? at least one lifter made noises for a few seconds on start up.. (used lifters) I checked the oil, and it was down 1/2 litre approx (1/2 quart approx) due to front main seal leakage.. (minor) Car made the odd noise as rpms/load changed on drive home. came off highway and slowed to residential driveway, and the engine suddenly made MUCH MUCH louder constant clacking that sped up and down with rpms, but the decibles (loudness of the clacking is the same at 500rpm as 3000rpm.) turned car off.. towed car home to be safe. listened with stethascope..could not id.. sounded slightly on the right side bank. Mech thinks it is lifters.. not bottom end noise (99.9 percent sure).. 25++ years Z experience. (also built my motor.) ended up pulling both valve covers.. could not see visible damage to lifters/rocker arms, valves, springs cam etc... Car is to be put on hoist, and the rods/crank to be checked to be thorough. distributor is cam driven, and so is the oilpump (i think)..pretty sure water pump is belt driven. car still ran smoothly on 6 cyl no smoke from tail pipe.. deposits are brown/grey colour on muffler tip. no coolant in the oil. have not checked compression or plugs yet... compression felt good while hand turning. (seat of the pants) Possible sources of prob? lifter or lifters failed/failing conecting rod/bearing/wrist pin rings or ring lands????? not much else can make a clacking noise...??? ideas suggestions? the next step is to inspect the bottom end to be sure... if it is ok.. I may be forced to buy all new lifters.. ($79) each I recall. is there any way to test them?.. visually everything looks good. This will happen hopefully early next week.. anyone like to cast their opinion on what they think it is? I'll post the answer as soon we find out.. Thanks.. ahhh the cost of speed.... Quote Link to comment Share on other sites More sharing options...
Cruez Posted July 30, 2003 Share Posted July 30, 2003 Sound like a spun bearing?? Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted August 1, 2003 Author Share Posted August 1, 2003 We all agree that it does not sound like a spun bearing, but hey..anything can happen I suppose. It looks like the car is not going to the shop till next week.. I simply do not have the time to have it moved..ie and babysit it. The car does not fit on flat bed trucks worth a damn. I use long 2x12's to make starter ramps to get the car to clear the main ramp. (air dam is too low...doh!) Quote Link to comment Share on other sites More sharing options...
yo2001 Posted August 1, 2003 Share Posted August 1, 2003 Have you try to take the valve cover and turn the motor over? If it is a sapn rod bearing,then the noise should go away when you pull a spark plug wire off. (whichever its knocking) Or you can avvance the timing and if the noise gets quieter. Other thing on the Nissan motor is non floating wrist pins. I hear they can get worn out or get gummy which makes tapping noise. Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted August 1, 2003 Author Share Posted August 1, 2003 We have pulled both valve covers. removed the rocker arms/lifters. we inspected each lifter, each rocker arm, each cam lobe.. nothing unusual so far. the valve springs are all good.. inner and outer. all the valves have come up the same amount. Well I'm just about ready to take off for the weekend. I'll think about cars when I get back home. Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted August 12, 2003 Author Share Posted August 12, 2003 well this is getting messy now. what we have tried/looked at lately.... put engine back together minus the valve covers.. can't see anything wrong. car runs..valve train looks good..nothing seems to be moving at the same interval that the "tapping" is. cam gears are tight and so is the tensioner, and no sign of rubbing on the covers etc.. main pully was tight.. no problems seen there either. looked at tailpipe again.. deposits are pure perfection.. o2 guage is reading approx 14:1 air fuel ratio.. perfect. alternator and water pump are disconected during this restarting phase ...just a quick startup to try and isolate the noise with all this other stuff off the engine... noise still there. main pully is off to. here is an interesting note.. when the engine fires, this noise makes a "ratattattatatat" as it starts then just goes "tap tap tap tap tap tap" as the engine idles.. (idle is near perfect..it has a few vac leaks with the valve covers off.) when you turn off the engine, the "ratatatatatat" noise happens again.. then engine is shutting down (slowing down) yet the "tap" noise speeds up.. kinda like something being whipped around. we checked the clutch/tranny (as the clutch was installed just days prior to the event) it does not feel like it is coming from there.. (held a hand against the tranny while the engine was running) with a hand on the front of the pan, it kinda feels like it is coming from that end of the motor. could a oil pump loose its prime?.. hmm it is driven by the crank in a vg motor... oil pump is brand new nissan unit. this is getting frustrating, as my summer dwindles away.. any ideas comments? Quote Link to comment Share on other sites More sharing options...
Tim240z Posted August 12, 2003 Share Posted August 12, 2003 Scott, Did you look at the flywheel while the engine was accessible? My neighbor's maxima had a noise that sounded just like a really bad tappet, or bearing knock. I had heard that maximas were somewhat famous for cracked flywheels and that that caused a very similar sound. Don't know how likely that is in your case, but if you are truely at a loss, it's worth looking into. Tim Quote Link to comment Share on other sites More sharing options...
Tim240z Posted August 14, 2003 Share Posted August 14, 2003 Ever figure this one out? Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted August 17, 2003 Share Posted August 17, 2003 I second the cracked flywheel noise... Have you ruled out exhaust leaks? Do you maybe have a bad plug wire that could be arcing? Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted August 18, 2003 Author Share Posted August 18, 2003 no news yet. car goes into the shop tommorow.. power outages permitting hehe the flywheel/clutch is starting to sound more likely.. especially with the engine running so well... except for the tapping.. I hope it is.. much cheaper to fix... Quote Link to comment Share on other sites More sharing options...
pparaska Posted August 18, 2003 Share Posted August 18, 2003 I didn't know about that engine family having a cracked flywheel history, but as I was reading down this thread, the flywheel bolts, or PP bolts came to mind. Or a broken clutch disk hub spring. Good luck. Quote Link to comment Share on other sites More sharing options...
technicalninja Posted August 18, 2003 Share Posted August 18, 2003 Another possibility is the cam shaft locater plate on back of cam. remove 3 6X 1.00 bolts on cover and check tightness of bolt which holds it to back of cam. I once repaired a v6 trunk that had been to 3 shops to get noise fixed (2 Nissan Dealers!). The noise was as you described, rattle on start up changing to a rythmic noise at idle. This is easy to check before you take car to shop. Keep us informed. Rick Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted August 22, 2003 Author Share Posted August 22, 2003 Well guys the verdict is in... Spun #5 bearing.. chewed it up actually...sound was piston hitting top of cyl head... How the Friggin $*&@!@* did that happen on a brand new engine?...I'm starting to think that maybe the oil in the pan was sloshing around and then it starved the pump for a second... Well the motor is out of the car at this point.. nothing upon preliminary examination looks damaged beyond repair,.. but then we haven't measured any of the tolerances yet either.. I hope to find out more today or monday. Quote Link to comment Share on other sites More sharing options...
Guest BigWhyteDude Posted August 22, 2003 Share Posted August 22, 2003 ouch man. That really sucks. Sorry to hear that. Hope it is not really and truly F'ed up. Good luck to you man. Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted August 23, 2003 Author Share Posted August 23, 2003 I got it right between the eyes today. Engine is done..finished..kaput..dead..gone..*$@! Crank is worn out of spec, one rod needs resizing, cyl bore is damaged, one head has a partial piston imprint in it. Got some $ estimates.. safe to say, I might as well rebuild the entire thing and start again... Mechanic refuses to install critical repaired parts in a high performance engine..(I think he knows me hehehe) Well the car will be up and running by Sept 5th. I am going to throw in a JDM engine, throw my intake and turbo on it, flywheel and clutch.. water pump, and anything else we can verfiy as good off my other engine...and a new timing belt and tensioner. I'm not wasting any more time on this car. Pissed off may be an understatement at this juncture. Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted August 29, 2003 Author Share Posted August 29, 2003 Well Progress is being made, and I've been spending most of my time investigating this failure. The other day, the mechanic who built the engine went over the situation with me, and the machine shop is going to get in on this. All of the tolerances were absolutely dead on, and the same across all 6 pistons. All six were the same to 2 decimal places. The engine was built to the middle of the nissan spec range.. ie if the tolerance spec for the crank was 2 thou under to 2 though over, mine was built right down the middle. The reason being he didn't want to build the engine too tight, but not as loose as one of my race prepped engines from before. Now what is done is done. But we are all pretty curious as to what may have happened. The crank journal is polished, so everyone is in agreement it was not oil starvation.. there is no black or blue marks on the crank. the rods and crank were used, but were minor polished, shotpeened, and everything was balanced. ARP rod bolts were used, and everything else was genuine nissan parts. ie bearings, seals etc... Esentially what happened was the lower bearing spun and stacked itself under the top bearing which gave it enough clearance to allow the piston to reach the cyl head. (piston visually looks ok.. rings are good etc... What kind of things can cause a spun bearing?.. on a rebuilt engine? very little metal was found in the bottom end, and everyone was mildly suprised to see how little there was in the pan...etc.. (engine had 2500km's on it, and had 1000kms before the first oil change.) I was only running approx 9psi of boost. I ran some 15 psi runs in 5th gear as I was setting up the boost controller. The engine temps have always been reading dead in the middle of the guage, oil pressure is approx 20psi at idle and 70 at WOT. My O2 sensor reads 1.1 volts (near stoich) and at 3Krpms and part throttle, reads full rich (4.8 volts) Could someone give me some basics on what could have caused the failure.. we are really scratching our heads at this point. When we have some more time on our hands, we will finish disecting the old engine down and looking at more of the insides... Thanks. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted August 29, 2003 Share Posted August 29, 2003 Rod bearing failure usually caused from excessive rpm. Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted September 9, 2003 Author Share Posted September 9, 2003 Well its back!! I am now running the jspec vg30et. using my manifolds, turbo, intake, etc etc.. boost is set to 10psi. (not bad) All new seals, gaskets, belts etc. new alternator as well (mine had oil in it, and caused some issues when I came to pick up the car... after a test drive, it had only 8 volts ) Its a long story, that I'll tell when I have some spare time.. still unsure of the original cause of the failure. I'm running some mineral oil in the car for a couple of hundred K then I'll change the oil and switch to synthetic. Then I may start playing a bit with some more tuning.. (no more shop time that takes away from driving the car) I want to enjoy the car before our season is done.. Thanks guys for the responses and help! Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted September 15, 2003 Author Share Posted September 15, 2003 The car is running great. I have identified my weak link. FUEL. or not enough of it. 11 psi and that is it. it is running at 13:1 a/f.. and this is too risky for me. I've got several hundred k's on the engine now, so Its time to bring it back and put in the synthetic. Castrol syntec 5W 50. (recommended by the guys who did the engine work.) Next step is to give it some more fuel. Any ideas on an adjustable fuel pressure regulator. do I keep my aftermarket pressure regulator and get a rising rate that is on the return side? Not too sure. I'm not going to go too nuts with this project.. just a few more lbs of boost.. (yeah I know I've said that before..) I've got a really good Mallory unit. and a 70gph 125psi fuel pump. I can bump the fuel up slightly over stock, but that is going to make me rich accross the whole rpm range. I"m going to start some research and find out some options. As for the other engine. its still dead, and a mystery. I've tired with that mess, and I just want to move on. I'll let the engine builder and machine shop come up with their own conclusions. In the mean time, I've driven the car every day and been having a great time doing it. I've forgotten how much attention it gets cruising around... several race offers and many more stop light challenges.. Its probably a high 13 or low 14 sec car at the moment. Feels pretty strong though. If I could launch it just right, I'm sure I'd be surprised. Even just driving around easy, I have plenty of torque, and I haven't reved it past 5k. I'll keep everyone posted on the results. Thanks. Quote Link to comment Share on other sites More sharing options...
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