I have a 94 Altima with 173,000 km. Lately I've noticed some noise from
the timing chain area at idle. It's always had some noise there, but it
seems like it might be more pronounced now. Basically it's a sort of
threshing mechanical sound, but it's got a sort of "beat" to it that happens
at a rate of about 4 or 5 times per second at idle. When it's cold in the
morning, I also get an occasional "crunch" type sound from this area, but
I'm not sure it's coming from under the valve cover or not. I had it
checked by the dealer a couple of times, the first time I had it in for
service and they checked, but didn't hear anything. They did note that the
upper guides had been removed already.
In the last couple of weeks, it's been -18C and below a few days, and I've
noticed another sound that's more pronounced than usual (maybe I'm just
paranoid!). It's a rotational sound that I can hear only when accelerating
lightly or keeping constant speed with little load on the engine.. it
almost sounds like a dull metal-on-metal knock... but it's not really
abrasive sounding.. I had a water pump go bad on an old Civic, and it
almost sounds like that did. I don't know if this is at all related to the
timing chain sound or not, but it almost sounds like it could be. I had it
down to the dealer last week for a road test with their shop foreman, and he
was able to hear the rotation sound once he got behind the wheel, but didn't
think it was anything serious. His only real suggestion was that it might
be something in the transmission. While I had him trapped away from the
dealership, I had him listen under the hood, for the timing chain noise, and
he thought there might be some slack in the chain, but again it didn't seem
like he thought it was anything critical. I'm fine with that, but it's my
engine and I hear it all the time, so it's not as easy for me to dismiss,
although maybe I should since he's the expert. I just would hate to have
been right all along and have the timing chain snap on me.
Anyone have any suggestions as to what I should do? I guess there aren't
many options, but I'm wondering how often anyone's seen these engines blow a
chain, and if there's usually any warning sign or not. According to the
dealer, they can't really inspect the chain without getting into a lot of
work, so if I was going to get them to do that, it sounds like I might as
well get the chain replaced anyway.
Would you folks recommend replacing the chain at this age? If so then maybe
I'll just do that and put my mind at ease. The car runs great otherwise and
still has lots of spirit, so I don't think there's anything really
fundamentally wrong with it. If there's anything I could do to maybe help
better identify what I'm hearing, I'll do it!
Thanks as usual for the help.