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rocker arm spring?
took the silvia out for a run the other day, took a tight gap, and had to floor it in 1st and 2nd, and i noticed more ticking than usual coming from the top end:confused: so i got it home took the rocker cover off and found the bolt holding the rocker spring on inlet valve no 1 had ripped out, taking the thread with it, leaving the rocker arm flailing about:(
http://i45.photobucket.com/albums/f8...t/IMG_1386.jpg http://i45.photobucket.com/albums/f8...t/IMG_1389.jpg so ive put a slightly longer bolt in and threadlocked it in, and im hoping it doesent come out again.....i just changed the clutch yesterday so ive got to put some easy miles on it anyway:ghey |
Mate thats fubared. Chanced are you've snapped the shaft. I wouldn't rev it to the limit, it will defo rip the new bolt out. Helicoil it asap.
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Are you running stock valve springs? That bolt looks like it only wound in three threads... or did some more material come out but not stay round the bolt?
Has this happend to anyone else? |
Its pretty common, I had it on my first Silvia, pukaasilvia has had it, and the owners mate of Nishan Tandoori in Hornchurch has had it as well. We got talking about S12's when I went to pickup some food.
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It it worth replacing those bolts? Does it always pop near No1?
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it did seem to tighten up alright, but i wouldent be suprised if it did pop out again, then it will deff need a helicoil, but i havent done any helicoils before so i dunno what i need/how to do it, ive probably got a mate who could help, but he's always busy.......:( |
Snapped the actual rocker shaft that you are bolting down. I've seen them snap.
Its best to remove it completely and check for cracks. |
i see.....i did have a good look around it, and it seemed alright? i have got a few spare heads i could pull one off..... but it doesent seem worth taking it off now, until i get a helicoil kit?
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this might help explain....
http://www.roadstarmagazine.com/modu...rticle&sid=233 30psi.... I take it that's what you meant? |
jesus that engine is clean inside, I must have been mad to let you have that car for that money
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i have changed the oil about 5 times in 5000 miles tho, all with genuine filters:)
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so does anybody know what size helicoil kit i would need, or should i just take the bolt to my local motor place and ask them?
i think a rev limiter is gonna have to be next on my list........ |
Don't the MKII Ecu's have limiters in them? Is it not set high enough?
I guess that the Helicoil needed would have to be matched to the bolt you were using. I don't know if this is the best place to get them from but it'll ballpark it for you... http://www.workshopsupplies.co.uk/in...tml&lang=en-gb |
from what ive heard mk2 rev limiters are crap, i think im gonna get a omex:)
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Shame, that's another item added to my ever growing list then :D
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Yeah that engine is as clean as mine inside! |
Do you think that dropping a longer threaded bolt in that hole would stop it from happening?
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You'd need to see how deep the thread goes. Also it maybe be possible to go deeper after helicoiling them. The beauty will helicoiling is that its a stronger thread. The issue with the larger holes being drilled is that they get awfully close to the cam bearings.
The issue isn't how deep the thread go to be honest. The issue is that the aluminium weakens (becomes brittle effectively) and allows the threads to be broken away. Similar to the exhaust studs as well which are known for falling out. |
I might whip the cover of mine at the weekend and see if I can't squeeze a bit more thread down there, even if it's only a couple more turns its got to re-enforce it a bit as you'd be spreading the load over almost twice the area.... i think :confused:
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Helicoil size is M8x1.25 I had to do Four of my mates old car that snapped the Exhaust rocker shaft. I've still go the kit with Six left. You can have them for a tenner If you want
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i notice on mk1s its bolts holding down the shafts and on mk2s its studs and bolts,would it possibly be worthwhile using just studs maybe loctited in and doing away with the bolts as long as the threads are good,i know its the soft alloy thats the main cause of the problem
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Well currently I've only got bolts, but once did notice studs on a bluebird. I suspect that its hard to tell what it has, but they look like bolts to me in the pic.
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your inbox is full northener:) yep i think i'll take them, does it have the drill bit/thread cutter or is it just the helicoil inserts?
is paypal ok:) yep mine's all bolts, i think tbh it will probably be fine as it is, but i would like to get the helicoil done as the engine does get a bit of abuse, and i wouldent like it to pop the bolt out when im drifting 100+miles away....... |
It has the Helicoils Tap and tool to screw in the Coils but No drill bit but I'm sure its not a special one. Inbox emptied :cool:
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Its an 8.3mm drill size...
if it hasnt snapped the rocker shaft you would be very lucky. check for hairline cracks in it. You need a m8 helecoil kit. Dont risk anything else. I was lucky that my bolts although ripped out were just bouncing about in the stripped hole and not got jammed up inside the head. Helecoil the lot. its very easy compared to doing exhaust stud thread replacements http://www.toolsnextday.ltd.uk/Helic...icoil_kits.htm |
you really think its worth helicoiling all of them:confused: i might just threadlock them back in? i will probbaly change the rocker shaft tho as ive got loads of spare heads, etc
it seems to be doing alright at the moment, ive done over 100miles with it, don't think its seen the redline yet, but probably hasent been far off:o |
Loctite will only help the problem if it's caused by the bolts coming loose and vibrating the threads to bits. I think it's more likely that its beacuse the threads are stressed that they rip out.
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ok well ive already got the helicoil kit thru - thanks for the speedy delivery northener:) now ive just got to get a drill bit and have a go sometime this weekend.......
went out for a play in it last night and it held up alright, it did seem to be a bit more 'ticky' than usual, but thats probably just me noticing in more |
valve clearances or bent/damaged rocker shaft may be causing it to be more ticky.....
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Probably the valve clearances need to be set.
Out of interest how did you stop the sward falling into the bottom of the head? |
yeh i did check the valve clearances, the inlet valve on no1 which pop'd the rocker spring off was the most out so i tighened it a bit, the others seemed to be alright(ish:o ) but i'm not used to using a feeler gauge for anything other than sparkies so i don't know how accurate im being:confused:
i'm probably gonna do this tonight, just gotta find a 8.3mm drill bit...... |
snapped
ok finally got around to doing this today..........the helicoiling, etc went alright and its all tightened back up & running.
but at the moment thats the least of my worries:( cos whilst cleaning some of the excess oil out of the head before starting work i noticed the head bolt second in from the cam belt on the exhaust side was loose and after having a fiddle i realised it has snapped so i pulled it out and had a look and to me it looks like its been snapped a long time:confused: so now i don't know what to do, im going drifting a week today which doesent help matters.....but as i said it isent a fresh snap on the bolt so it must have been holding up for a while so hopefully it will be ok for a bit, im gonna pull my spare lump out and start getting that ready but im in two minds as to weather i should do it now or wait for the inevitable:furious my rev limiter came thru today tho so i'll be getting that in and set nice and low...... |
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I found this on my vert first S12. You will be able to remove the remaining bit of the bolt, as chances are it exposed, but obviously you need to have the head off.
Judging by how clean the head is, it pretty possible the head has been rebuilt, but someone got carried away tightening them up. |
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