Noisy tapping sound on 4AGE after rebuild

[ChezzaV8]

Hi,

This is my first attempt at a rebuild after I had a bottom end failure on a track day at Donington. I've rebuilt it, it seems to be running okay apart from this annoying tapping noise. Above 3000rpm it gets quite loud, and then is particularly loud on overrun. I've checked all the valve clearances and they are fine. I think the timing is okay, the compression is okay and it seems to run okay. There's a high probably that I've put some of the valve springs in upside down as I didn't realise there was a right way up.

The engine is a small port 4AGE out of a toyota corolla.

Has anyone got any ideas?

Here's a vid of the noise:

https://www.youtube.com/watch?v=UYv0qfhJ1Ho

[Bennachie]

Piston slap or little end? Are the bore clearances correct?

[stevieturbo]

It isnt piston slap and it isnt a small end.

It does sound like a top end noise though, ie head/valvetrain.

Springs, if they're parallel springs, then there isnt a top or bottom.

[Bennachie]

Piston deck too high and contact?

[Kinkell]

Valves kissing pistons due to mis-timing of the cams.

[ChezzaV8]

I think it's something in the bottom end. I checked the valve timing and its all okay. I also checked the valve drop at TDC and there's plenty of clearance.

I think it's the rod bush. I'll have to take it out and remeasure the big end clearances and check the rod bushes. Will also check the rings and skirts for piston slap.

[stevieturbo]

Bennachie said:

Piston deck too high and contact?

Possible

[Polome]

Don't know this engine but had a very similar noise on an E type engine a few years ago. Turned out the sleeve for the cam bucket to work in was loose in cylinder head. When engine warmed up the sleeve was allowed to float up and down within its counterbore. When the rotating cam lobe came round and smacked it back down it made the same noise as your video. May be irrelevant to your engine though. Good luck.

[Mr2Mike]

Do you have a cut down sump for ground clearance? Just wondering if one of the big end bolt heads is catching on something - this would naturally become worse at higher RPM and under load.

[ChezzaV8]

I've got to the bottom of the issue. It's contact between the pistons and head. The squish clearance is too small so at higher rpm the extension of the rod is causing the contact. Time for a thicker gasket.

[Pumaracing]

So you rebuilt it with a thinner gasket than it had originally?

[Bennachie]

Kerrrrrchiiiiing!


Thanks for letting us know what it was. Lots of people don't...............