my upper timing chain broke off when i started my car up for the first time. is there any way u guys think that i might of bent my valves? the car started for no more than 5 secs. i also snapped the exhaust cam right up. i compression tested and found 0 zero compression b4 i pulled my valve cover off this morning. any feed back would be nice!
Modified by sunnys14 at 3:42 PM 2/20/2006
upper timing chain broke
Re: upper timing chain broke (sunnys14)
even more more pics
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Iamjohnhayes
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Re: upper timing chain broke (sunnys14)
well i can say for sure your valves are not timed right which could lead to the zero compression.
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deviousKA
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Re: (sunnys14)
Pop all of the camshaft bearing caps off and look for signs of seizing. If it wasnt that, it was due to incorrect cam timing and a valve hitting a piston, locking up your cam.
There could also be a slight possibility that the cam had a latent crack to begin with, doubtful as the chain is broken, you cam seized.
Edit: was the cam gear and the portion of the broken cam still sitting half way in the journal, or was it laying down in the front cover? If it was laying down the front cover, the chain breaking was the last thing that happened.
Start pulling the head.
There could also be a slight possibility that the cam had a latent crack to begin with, doubtful as the chain is broken, you cam seized.
Edit: was the cam gear and the portion of the broken cam still sitting half way in the journal, or was it laying down in the front cover? If it was laying down the front cover, the chain breaking was the last thing that happened.
Start pulling the head.
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deviousKA
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Re: (sunnys14)
cams are brittle, and they can break when valves hit a piston, doesnt always happen, but it can. Is this a cam that has been through bent valves before?
check you cam journals, your cam locked up one way or the other.
Or, the cam was already cracked and let go trying to turn over all of your freshly installed parts.
Only one way to find out, take it apart. You have bent valves again anyways so just start pulling the head. When **** happens you have to clean it up.
check you cam journals, your cam locked up one way or the other.
Or, the cam was already cracked and let go trying to turn over all of your freshly installed parts.
Only one way to find out, take it apart. You have bent valves again anyways so just start pulling the head. When **** happens you have to clean it up.
Re: (sunnys14)
Don't hate on KA's just hate on the KA24DE's they are weak like that... I had soo many problems like that with my DOHC ka's swapped in sohc, much better motor for me, and much stronger!sunnys14 wrote:i hate KAs...
Swap in SOHC and turbo it!
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Craving4Boost
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Re: (S13 240SX)
hey nick change your sig....your back to eating pizza
Looks like incorrect valve timing to me. Everyone seems to get the upper chain right (lining the marks up on the cam sprockets), but did you also line up the marks for the lower chain as well? ...Did you do it when the #1 cyl was at TDC?
Also I noticed that you have the red painted cam on the intake side of your motor. Usually the red cam goes on the exhaust side. ...Did you do that on purpose?
The valve most definitely contacted the piston if it pushed your cam up like you described. Something had to be wrong with the timing for that to happen.
Also I noticed that you have the red painted cam on the intake side of your motor. Usually the red cam goes on the exhaust side. ...Did you do that on purpose?
The valve most definitely contacted the piston if it pushed your cam up like you described. Something had to be wrong with the timing for that to happen.
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Nismo_Freak
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I'm willing to bet those are 91 cams, and they are in an S14 engine.
Many years ago my KA met it's death that way. Intake side valves and the pistons fought for the same space. Broke off two valves, and bent the others. Come to find out a few months later a few other people ran into the same issue.
Turned out Nissan changed the colors on the camshafts between the S13 and S14. So if you match color to color you will get banged up valves.
Many years ago my KA met it's death that way. Intake side valves and the pistons fought for the same space. Broke off two valves, and bent the others. Come to find out a few months later a few other people ran into the same issue.
Turned out Nissan changed the colors on the camshafts between the S13 and S14. So if you match color to color you will get banged up valves.
yeah, i have a s14 engine. its 248 s13 exhaust on the intake side and a stock 232 s14 cam on the exhaust side. i did everything when the motor was at tdc. i have done countless cam swaps and i just dont get why the cam sprocket can break off and snap my chain like that.
on the other note, i examined the valve caps that touch the cam lobes and all of them seem to be touching the lobes. i have bent the entire intake side valves b4 and when that happened, all the valves fell and didnt touch the cam lobes anymore. i hope i didnt bend the valves....
on the other note, i examined the valve caps that touch the cam lobes and all of them seem to be touching the lobes. i have bent the entire intake side valves b4 and when that happened, all the valves fell and didnt touch the cam lobes anymore. i hope i didnt bend the valves....
With the damage youre talking about, the valves HAVE to be destroyed. If they arent, you must've had something really weird happen. Valve interference is the most likely explination here by far.
Are you SURE you were able to turn the motor by hand for at least 1 full rotation before you buttoned everything up?
Are you SURE you were able to turn the motor by hand for at least 1 full rotation before you buttoned everything up?
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LEMHEAD16
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Re: (sunnys14)
When building the motor did you ever drop the cams or bang them against anything (even lightly) . I used to work in a machine shop and I can't tell you how many cams I broke by dropping them in the bead blaster or wash cabinet. They are brittle like Devious said.
The only other explanation I could give would be over torqe on the cam bolt or cam tower bolts. If the cam towers were to tight you still maybe able to spin it by hand but when you crank it up to 750-1000 rpm there may be to much drag on the cam causing the nose to break off and other calamity.
Just my .02
The only other explanation I could give would be over torqe on the cam bolt or cam tower bolts. If the cam towers were to tight you still maybe able to spin it by hand but when you crank it up to 750-1000 rpm there may be to much drag on the cam causing the nose to break off and other calamity.
Just my .02
Re: (Craving4Boost)
hahahaha being fired sucks!!!! eat pizza and play ****ing playstation2 all night long and sleep in late. lolCraving4Boost wrote:hey nick change your sig....your back to eating pizza