Engine tick/ knock only when hot - Engine 3B on BJ40 (1 Viewer)

[Luis Moniz]

It ONLY does this when it gets warm and comes up to temperature.
Has anyone else out there had this same problem ???
Have any ideas? Let me know, thanks

Please check the video


I'm restoring a BJ40. If you're curious, visit my Facebook page. https://www.facebook.com/lc.bj40/

 

[handcannon]

Hard to tell for sure with all the other squeaks and rattles common to a cruiser, but it sounds somewhat like an exhaust leak at one cylinder right where the manifold bolts to the head.

Don

 

[Luis Moniz]

Thanks Don

I found in the exhaust manifold a small crack next to a bolt. Could this small crack be the cause of the knocking noise?

 

[Splangy]

Doubtful. Doesn't really sound like an exhaust tick, anyways. Hate to say it, but it sounds worse, but internet videos never sound like the real thing.

 

[handcannon]

I doubt that the small crack you are showing is the source of the noise. In order for an exhaust leak to sound like what is in your video the leak would have to be much larger, and right next to an individual cylinders exhaust port in the head. And it wouldn't have to be a crack in the manifold. It could be a break in the gasket. Every time that cylinder was on the exhaust stroke the open spot (crack or break in gasket) would have to leak (with each exhaust stroke of that cylinder) in order for it to create the sound.

The picture you put up doesn't look to me like the head mating surface of an exhaust manifold. I'm used to that surface being completely flat. I would agree with Splangy that a video would have a hard time representing exactly what you hear.

Don