stretched chain, is it that bad?

A DOHC japanese engine with an upper and lower timing chain. The upper lost it's slack and it hits the valve cover. I've had this car for 3 years and it never caused any problems. I decided to go gung-ho and jump into replacing the timing chains and tensioners and when I took the valve cover off, everything looks fine. Does it really need to be replaced when everything's working? Is hitting the valve cover that bad?

If its stretched its throwing off the timing some. It should be fairly simple to replace.

If its stretched its throwing off the timing some. It should be fairly simple to replace.

Someone's telling me it's the timing chain guide's fault, there's the one on top and the passenger's side of the chain is scratching the valve cover a bit. Just that side.

If its a high millage Nissan (which I assume it is) then just replace the chains and tensioners.
Far safer than having a chain break, skip a tooth, and stretch even further.

If its a high millage Nissan (which I assume it is) then just replace the chains and tensioners.
Far safer than having a chain break, skip a tooth, and stretch even further.

99k

you are supposed to change it at 65k. Unless you like bent valves and broken parts, CHANGE IT.

you are supposed to change it at 65k. Unless you like bent valves and broken parts, CHANGE IT.

You change your timing chains at 65,000?

Timing chains have a much longer life than 65,000 miles (100,000km) which is the norm for a belt.

I know Nissan do recomend a change period, but I forget what it is.
However, I believe its around twice that of a belt, so at 100,000 miles its possible the chain has stretched.

If I remember correctly those engines have a timing chain that is very long, and had a shorter "life span" than most chains due to the extra length.

Oh yea. i was thinking if a belt. But it seems like it's obviously stretched, though.

I've seen nissan chains wear all the way through the timing cover, dump all the oil out, and seize the motor.

And then, it could always break too.

Not something I would just ignore, but I assume you're talking about a 2.4L, they aren't the funnest chains to do. Been a while since I've done one, but I think they call out for 12 hours of labor or so

If it was me, I'd replace it. If it breaks, there's a good chance it will total your motor. Isn't a weekend worth at least that?