5 replies to this topic

[vtecn8ive]

I just got done putting a motor in a friends car and its making a bad noise. I am not sure if its a spun bearing or valve lash.

Its a tick or similar. I shut it off right away. What should be done?

-Shane

[EPcivic]

I'd start by pulling the valve cover and looking at everything. Valve lash would have to be WAY out to sound as bad as a spin bearing. Next, I would turn the motor by hand with a wrench after removing all the plugs to release the compression. The motor should turn with smoothly. If there is a tight spot, then a spun bearing is a likely source. My next step would be to either remove the rocker assembly or back off all the adjusters so none of the valves are trying to open. Then try to turn the motor by hand again. If it still has a stiff spot, it's time to pull the pan. On most motors, if a rod bearing spins, it will be easy to figure out which one it is. A normal rod will have a tiny bit of side to side play at the crank. When they spin, they get tight and won't have that play. You may also find a lot of gold colored metal in the oil pan which indicates a bearing failure.

Good luck - Chris

[vtecn8ive]

How does that work if i back off all the rocker assembly? wouldn't all that do is prevent the valves from opening and how would that matter?

Thanks for the advice though. Just kinda lost why I would do that step .

-Shane

[EPcivic]

How does that work if i back off all the rocker assembly?  wouldn't all that do is prevent the valves from opening and how would that matter?

Thanks for the advice though.  Just kinda lost why I would do that step .

-Shane

<{POST_SNAPBACK}>

If the motor has an obvious stiff spot when turing it by hand, then you know there is something wrong, either in the head or in the bottom end. By removing the rocker assy or backing the valve adjustment way off, you are removing any effect of valve problems. If the motor is still stiff with the valves not opening, then the problem is in the bottom end. If the stiffness goes away then the problem is in the head.

The catch here is that the motor should be a lot harder to turn with the valves opening, because they take some force to open. It should feel consistant from one cylinder to another. With the valves not opening, the motor should turn easily and smoothly.

-Chris

[vtecn8ive]

Another person said to run it and pull a spark plug wire and see if the noise gets less or goes away and said the compression puts less stress on the cylinder preventing it from be to harsh on the bearing.

Also another guy said it could be the LMA any input on that?

[tom91ita]

i'd go with the advice in already in this post.