Okay, so I've been searching around about the infamous "rattling/knocking" sound of the KA timing chains...and have found out a lot of contradictory information.
I've had my valve cover off numerous time and have had my camshafts removed twice since I've had my car. On my upper timing chain, I noticed two of the links were somewhat damaged--They did not seem to be "terminallY" damaged, that is, they seemed to be structurally strong enough to be fine (otherwise I would have replaced the chain.). However, it seems that ever since I replaced my camshafts with higher lift/duration cams, the engine has been making that weird rattling/knocking sound that I hear of so frequently...The sound is not that loud, but is pretty easy to hear at idle, and the sound NEVER goes away, warm or cold, idling or not (although I can't hear it when I'm moving bc of the turbo sound/exhaust).
However, it did NOT make this sound prior to my getting aftermarket camshafts. (the sound could have cooincidentally ocurred right after instaling the camshafts, as well, because prior to this I wasn't really listening for sounds coming from the camshafts). And it has nothing to do with valve lash; I've had 2 sets of custom shims through my head to make sure the valve lash is in spec. The sound seems to be coming from everywhere on the head, not just toward the front of the engine, although the sound seems to be more prominent toward the front of the engine. Would the higher lift/duration cams, along with the perfectly in-spec valve lash cause this sound? Or is this sound being caused from my timing chain because it's not in too good of shape? (I have ~95k miles, btw, and my car's NEVER been abused..and i hear that they're good for another 55k miles...).
My question is: I hear a lot of people discussing removing the top/side chain guide. What are the adverse effects of this? Can you access the side chain guide WITHOUT removing the cam sprocket cover (it's a pretty involved removal.) Does it sound like removing them would cause the annoying sound?
Number two: Would the fact that the timing chain has some "chips" it would appear on 2 of the links cause this sound?
Numer three: Could this sound be caused JUST from the fact that I have high performance camshafts in my engine?
Number four: How concerned should I be with these "chips" to the links of the upper timing chain? I would NOT want that chain failing under high load!! (i'm boosted as well, btw, 9 psi)
And number five: If I DO end up replacing the upper timing chain (which I may very well do), after you remove the cam sprocket cover/cam sprockets, does the upper timing chain just slip off of the idler sprocket? Reading my FSM they make the timing chain seem like an INCREDIBLY involved process, which i assume is because they're discussing doing a COMPLETE timing chain overhall (they say to remove the intake/exhaust manifolds, cylinder head, oil pan, etc...). If it's just a matter of removing the camshaft sprockets/the timing chain cover (cam sprocket cover), then it wouldn't be too bad of an install.
Anyway, I'd love some factual, 100% true information from some of the guys who have done it or know exactly what they're talking about.
Thanks a lot in advance....Marc
PS--Can anyone host a video (small mpg) that would convey the sound I'm trying to explain?
Upper timing chain woes...
-
O0ooAJoo0O
- Posts: 80
- Joined: Tue Aug 13, 2002 2:03 pm
- Car: computers and cars
mine makes that sound too. its been doing it for about 3 years. started after i replaced the chain. yes, it is somewhat involved process. you need to remove the entire front of the engine, which involves taking off the manifolds, water pump, front cover, everything. my car was down for a good week when my dad did it. ill host your video for a bit. email it to me and ill post it in this thread. im going to do that same with mine, (read "strange sound coming from valve cover")
-
O0ooAJoo0O
- Posts: 80
- Joined: Tue Aug 13, 2002 2:03 pm
- Car: computers and cars
-
O0ooAJoo0O
- Posts: 80
- Joined: Tue Aug 13, 2002 2:03 pm
- Car: computers and cars
Thanks...so it makes the same sound even after you replaced both upper/lower timing chain?
Could you post an exact link when you get a chance so the ppl browsing won't have to search around?
When I was browsing around Paul_Ward's website in his profile..I came across a useful pic.
http://thetweakshow.com/photos...1.jpg
Which answers my question, yes, you do need to remove the cam sprocket cover to get at the side guide--from this pic though..do you think if I just remove the cam sprockets/tensioners/guides that i'd be able to get it off of the idler sprocket and replace the upper timing chain?
Later
Could you post an exact link when you get a chance so the ppl browsing won't have to search around?
When I was browsing around Paul_Ward's website in his profile..I came across a useful pic.
http://thetweakshow.com/photos...1.jpg
Which answers my question, yes, you do need to remove the cam sprocket cover to get at the side guide--from this pic though..do you think if I just remove the cam sprockets/tensioners/guides that i'd be able to get it off of the idler sprocket and replace the upper timing chain?
Later
-
O0ooAJoo0O
- Posts: 80
- Joined: Tue Aug 13, 2002 2:03 pm
- Car: computers and cars
you can replace the top chain by removing the valve cover and top chain cover(and distributer).
you dont have to remove the head.
the book only says that because of the gasket between the head and the top chain cover :oface
the bottom chain is the all day sucker if you have double bump sticks....you gotta drop the pan..which means ya gotta drop the crossmember...and the rack...and the struts..and the sway bar...and the motor mounts...
you dont have to remove the head.
the book only says that because of the gasket between the head and the top chain cover :oface
the bottom chain is the all day sucker if you have double bump sticks....you gotta drop the pan..which means ya gotta drop the crossmember...and the rack...and the struts..and the sway bar...and the motor mounts...
Sweet! Upper timing chain, here I come! So how much "finesse" (and by finesse, i mean force) does it take to get it off of the idler socket, or does it just slide right off?
When i dropped my pan I didn't need to remove the struts, the rack, or the cross member--just undid the motor mounts, swaybar and jacked it up high enough.
When i dropped my pan I didn't need to remove the struts, the rack, or the cross member--just undid the motor mounts, swaybar and jacked it up high enough.
my 96 240 makes that noise when it's cold. I don't think it's that loud, but, it does come from the front of the valve cover. The car has about 98,000 on it. The noise stops when it warms up, so, I'm not all that concerned. I plan on building another KA to drop in it next year anyway, with forged internals.
-
SunshineAcid
- Posts: 149
- Joined: Fri Nov 28, 2003 9:22 am
- Car: 89 240sx Ka24de swap
- Contact:
i just replaced the chains, guides and tensioners on my 95 240. the only part that had any wear was the upper tensioner. the two upper chain guides[ one on top between cams and the other is on distributor side ]are no longer used. the upper tensioner needs to be installed with new bolts as they are longer than the originals.
UPDATE
Everything's installed. It fired right up, the engine runs beautifully. No more obnoxious sounds. Just sits there and purrs...
I replaced the upper tensioner too, but I didn't need new bolts...I left out both guides...Man, this makes my day
I replaced the upper tensioner too, but I didn't need new bolts...I left out both guides...Man, this makes my day