Nissan Dualis Pricing and Specs

If the noise is a metallic rattling noise, then you might be on the right track here. But as well as the timing chain, it could also be the tensioner that keeps that timing chain tight at fault. The fact that the noise goes away after a few seconds suggests that the tensioner, rather than the chain, is at fault. But they could both be worn.

What’s happening is that the tensioner is hydraulically operated and needs engine oil pressure to do its job. When the engine has been sitting overnight, there’s a slight time delay between it starting and enough oil pressure reaching the tensioner to tighten the timing chain and stop the noise. What you’re hearing is the chain flailing around until the tensioner steps up and takes the slack out of it, at which point it stops rattling and goes silent.

Why doesn’t it happen every time you start the engine? Because the tensioner needs time for the oil to drain completely out of it. If the engine has only been stopped a short time, there’s sill enough oil in the tensioner for it to build up pressure quickly and keep things quiet.

In conventional automatic transmissions, a delay when selecting gears (often reverse) indicates worn internals and the need for a rebuild. Your Nissan is fitted with a CVT transmission rather than a conventional auto, but it still operates on the basis of hydraulic control. Which means that the problem could still be one of internal wear. A transmission specialist is likely to be your best point of contact for this problem.

The first thing to do, though, is check the level of fluid in the transmission. A level that is low can mean delays when selecting gears and even slipping of the transmission under load. However, if the level is low, there must be a leak somewhere as these are sealed systems and should not require regular topping up.

A car that continually breaks the same component time after time probably has a bigger problem than simply the part that keeps breaking. It sounds like you need to have the transmission and torque converter checked for alignment and correct interface. Any problem with the way they fit together could explain why an O-ring keeps failing. Continuing to replace the O-ring won’t fix a more complex problem.

Either that, or the mechanic who is changing the O-rings is making the same mistake over and over again and not using the correct lubrication or fitting procedure.