Guest 73Turbo240z Posted January 25, 2006 Share Posted January 25, 2006 I'm tired so i'm going to abbriviate this post and get more info in tommorow, but the brunt of it is this. Went to a meet tonight, hung out, talked, got a couple runs in and the car performed much better than expected (took out a grand national w/ a built motor, TA52, and 3000rpm stall, and a mustang w/ a very reworked 306 and nitto 555rs.) Car did very well the whole time, then as my friend and i were driving home on the feeter at about 60 in 4th gear suddently the motor just totally cuts out, dead... i clutch in, try to restart, starter is going WAY too fast... Pull over and try again, still way to fast, check fuel, check spark, all good... pop the oil cap off and watch the cam as i turn the motor over, it sits in place. Well ****. So we call my house and have my truck brought out, and drag the Z home. It's sitting outside now, i don't know what has happened officially yet since i won't tear into it till tommorow, but it looks like the timing chain is gone. Which as i understood it was a fairly hard thing to accomplish as they are known for there resiliance. This was a brand new timing kit i did when i built the motor too.. so it's really confusing. I'll photo it all tommmorow as i do the teardown. This will make the 4th time in 6 months i'll have taken the front end of the car and motor apart, it's getting old. On a secondary note, i need a better clutch bad, this stocker slips hardcore in 3rd and 4th. Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted January 25, 2006 Share Posted January 25, 2006 I bet the bolt that holts the timing sprocket on has come undone and popped off. Happened to a mate. He bent a valve in the process, hope you didn't. Dave Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted January 25, 2006 Share Posted January 25, 2006 l28 crank, l24 rods, az pistons, unshaven p90a and f54 decks, and a hks 2mm headgasket... hoping that saved my ***. Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted January 25, 2006 Share Posted January 25, 2006 I've never heard of that happening but, I guess it could. Focus on how good it was running and fix whatever happened that made the cam not spin anymore. Quote Link to comment Share on other sites More sharing options...
george.bryant Posted January 25, 2006 Share Posted January 25, 2006 ****! that sucks... Quote Link to comment Share on other sites More sharing options...
slownrusty Posted January 25, 2006 Share Posted January 25, 2006 Sh!t that sucks...let us know what you discover.... Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted January 25, 2006 Share Posted January 25, 2006 I had a simular thing happen to me one time. I had just put together a turbo'd L6 and put my brand new Malvern Racing adj. cam sproket on. While driving around town to break her in, I hear and feel kinda the same thing you described. Long story short.... the allen head fastners holding the cam gear together all backed out but one, and caused me to bend a few valves. Its a good thing I was only cruising at aprox 25 mph when it let go, or who knows what all it would have taken out. It was my fault for not checking all the adj fastners before using the cam gear. I just assumed since I did not make any adj. to the gear out of the box, that they were tightened all up.... I ended up drilling holes in the heads of the fastners and running safety wire thru them. Its hard to belive your timing chain snapped... Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 25, 2006 Share Posted January 25, 2006 Sometimes the dowel comes out of the end of the camshaft and then the cam gear spins on the end of the cam until valves get bent. That's another unpleasant possibility. Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted January 25, 2006 Share Posted January 25, 2006 just took the valve cover off... cam gear and chain are still there, the cam gear is sitting crooked on the cam, as if the dowel was wedged in there somehow, i'll be taking photos here in a little bit to post up. can anyone crunch the numbers on my setup to see if i might have enough room to have saved me from bent valves? or is it almost garanteed that i've screwwed this head? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 25, 2006 Share Posted January 25, 2006 Just because the valves are bent doesn't mean the head is totally screwed. Depends on how much interference there was. When I was on the way to my wedding reception my Toyota truck snapped the timing chain and bent two valves. It wasn't even running, I just hit the starter and it spun really fast and had no compression. I ended up changing the timing set and driving it home on 2 1/2 cylinders. It was BARELY an interference engine, so the valves weren't that bent. Ended up throwing two exhaust valves in it, and doing a valve job and that was it. Didn't even need valve guides on the two that hit. Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted January 25, 2006 Share Posted January 25, 2006 alright, i just bumped the starter w/ the valve cover off, the cam gear is free spinning on the camshaft, so i'm guessing the dowel sheared in half or backed out or somthing. gotta take it all apart before i'll know more. Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted January 26, 2006 Share Posted January 26, 2006 well i skipped the pictures and just cracked down to working on it, i took the entire front cover apart, redid the timing chain setup, regasketed it all, fixed my chewwed up front timing cover crank seal, and got the oil pump driveshaft and pump back on.. i did a compression test to try and at least get a remote feel for if my valves got munched, i got 150psi across the board, so for what it's worth there? tommorow i'll throw the dizzy on, retime the motor, and put the intercooler/radiator and all that crap back. see if i can't have her on the ground and running tommorow evening. this time retaining all her oil lol. Quote Link to comment Share on other sites More sharing options...
Workinprogress Posted January 26, 2006 Share Posted January 26, 2006 I gotta ask, did you fix the problem or just the end result? Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted January 26, 2006 Share Posted January 26, 2006 the problem, as in the camshaft bolt that backed out and allowed the gear to walk off the cam? yes.. its now resecured with blue threadlock in addition to the FSM 103ft lbs... better not go anywhere. Quote Link to comment Share on other sites More sharing options...
Thumper Posted January 26, 2006 Share Posted January 26, 2006 NM he answered. Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted January 26, 2006 Share Posted January 26, 2006 NM he answered. yea... plan on coming over tommorow w/ that timing light of yours... looks like i'll make the weekend deadline yet. Quote Link to comment Share on other sites More sharing options...
Thumper Posted January 26, 2006 Share Posted January 26, 2006 Yeah I'll be over to come over just give me a call. I was talking about getting the clutch and wastegate fixed though and by next weekend cause thats when my z should be running. Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted January 26, 2006 Share Posted January 26, 2006 twerbo on teh way? Quote Link to comment Share on other sites More sharing options...
burntz Posted January 27, 2006 Share Posted January 27, 2006 Who'd a thought? The exact same thing happened to me on Sunday. Only I wasn't as lucky as you. I ended up bending 11 valves, don't know if there is anymore damage than that. I took my head to the machine shop yesterday. Quote Link to comment Share on other sites More sharing options...
Guest norm[T12SDSUD] Posted January 28, 2006 Share Posted January 28, 2006 Just a question. Did either of you guys use a large lock washer on the cam bolt?? Quote Link to comment Share on other sites More sharing options...
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