timing chain slack?

Post by **Touchdown038** » Mon Mar 08, 2004 1:28 pm

Today I pulled the valve cover off my ka24e and had a look around, and I am surprised at what I found. The slack side (the side without the tensioner) really WAS slack, like I could move the chain about a half inch to the inside. Is this normal for a new chain and replaced guides?

I AM getting the rattle on startup, and I don't think there's supposed to be slack on a new chain. Could it be possible that I installed the chain off a tooth, but then installed the oil pump shaft a tooth off as well, setting it neutral?

Post by **DAEDALUS** » Mon Mar 08, 2004 1:28 pm

I think by convention that's actually defined to be the tension side. The tension side is under natural tension from the crankshaft, thus it doesn't need a separate tensioner, as the slack side does.

Slack in that leg doesn't mean much since the cams can rotate ahead of the camshaft due to valve spring compression when you shut off the engine. Turn the crank by hand, and the slack will disappear.

Post by **Touchdown038** » Mon Mar 08, 2004 1:28 pm

So then which side of the cover does the startup rattle come from? The side with the tensioner?

Post by **DAEDALUS** » Mon Mar 08, 2004 1:28 pm

I don't know. There's all kinds of stories on NICO of odd sounds coming from different places on different engines. It makes sense though that the chain is more prone to rattling on startup because it may take a few seconds for the tensioner to pump up. I assume the ka24e has a hydraulic tensioner. I also hear stories here of the chain hitting the upper guide on DOHC engines, but not just at startup. A decent mechanics stethoscope can be bought pretty cheap. Using it is pretty fun, and you can narrow noises down pretty well with it.

"Ahhh...so those are the injectors, and those are the valves...and there's that bad wheel bearing."

Post by **DAEDALUS** » Mon Mar 08, 2004 1:28 pm

http://www.nissaninfiniticlub....52444

Post by **Touchdown038** » Mon Mar 08, 2004 1:28 pm

I actually did pick one of those up today, and I listened to it, and the noise it seems is coming from the water pump area - I'm guessing the noise is coming from right behind it where the chain is. Not a good sign.

Now, the noise has started happening when the engine speed is anywhere above 2000, but especially in the 2000-3000 range.

Post by **Big Red** » Mon Mar 08, 2004 1:28 pm

If you have the original tension guides in there they are probably in bits in your oil pan, the rattle is the slack chain rubbing against the coolent port of the timing chain cover (just behind the water pump), first it's just at start up and then at mid rpm's as well, you should be able to see the tops of both guides with the valve cover off, if all you see is a rough stump of black plastic surrounding a bolt then you need to replace the guides before you eat a hole through the coolent channel, otherwise it's another $120.00 for a new cover.

Post by **Touchdown038** » Mon Mar 08, 2004 1:28 pm

Big Red: To make a long story short, I changed the guides, tensioner, and chain out last winter, and they should be rattling after a little more than a year. The guides I pulled out also did look like the new style ones, not cheap plastic ones.

I'm concerned because the chain shouldn't be this loose this soon after performing the job. The rattling has returned as well, so I'm wondering why.

Post by **Big Red** » Mon Mar 08, 2004 1:28 pm

Your right! once you put the new guides in they should be good for many years.

Can you see if the chain is rubbing on the cover?

Post by **Touchdown038** » Mon Mar 08, 2004 1:28 pm

I'm sure it is, unless the rattling sound is the chain rubbing the guides. I'm not sure what metal against that plastic would sound like.

Did you say you think the chain rubs against the coolant channel? Correct me if I'm wrong, but looking from the front of the car, that would be to the left of the side without the tensioner? If so, it is a very good possibility that it is because I could wiggle the chain a large amount in each left/right direction.

Post by **Big Red** » Mon Mar 08, 2004 1:28 pm

The tensioner is on the left side (passanger side) the coolent channel is on the right, the wiggle play in the chain is normal on the left side when the engine is not running, there is a spring in the tensioner but it really only does it's job once the oil pressure is high enough.

Post by **Touchdown038** » Mon Mar 08, 2004 1:28 pm

The wiggle in the left is normal? That's very strange, because my chain was extremely tight on the side with the tensioner. The slack was all on the other side.

Post by **DAEDALUS** » Mon Mar 08, 2004 1:28 pm

You're worrying about a condition that changes as soon as you start the car. The crankshaft turns first, it pulls the chain, the chain pulls the cam. The tension-side is straight and taut, except maybe when you let off the gas suddenly from high RPMs, and when you shut off the engine. There are spring forces that may be pushing on the camshaft after you shut off the engine. The crankshaft stops turning before the camshaft does...hence the slack you're seeing.

Post by **Touchdown038** » Mon Mar 08, 2004 1:28 pm

Thanks for the info Daedalus, turning the crank by hand a little bit took away the slack on the side without the tensioner.

My question now is, if all the guides are in place and not worn away, and the tensioner and chain are also new, is the chain rattling against the guides rather than the front cover? I dont' see how the chain can even touch the cover when the guides are in place. And why is the chain rattling if the tensioner is new? Low oil pressure maybe?

Post by **DAEDALUS** » Mon Mar 08, 2004 1:28 pm

The rattling chain could be low oil pressure, which isn't too hard to measure as long as you can find the right threads for the gauge. It's really difficult to say. Do you hear the rattle all the time, when speeding up, when slowing down, etc? Look for wear marks along the chain route. You say the guides are in place and not worn away, but are they worn at all? Any wear on the guides will increase dynamic clearances, allowing the chain to flop around more.

Post by **Touchdown038** » Mon Mar 08, 2004 1:28 pm

Alright, I just got done driving across Washington today and I made a couple of observations. The chain rattling only happened when it is cold, and it only happened on startup and when the RPMs were in between 2000-2800 or so, again only when it's cold. I also pulled the VC and tried pushing on the tensioner with a screwdriver, and it took quite a bit of force to push it in, so I don't think that's it.

But the way I see it right now, it should be fine for a while, it's probably just eating away at the new guides anyways. Should be good for at least until the summer when either a swap or a rebuild is coming.

timing chain slack?

timing chain slack?

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