Knocking when warm.

[kelvinwannell]

Knocking when hot. After much work, new head gaskets, heads skimmed etc. fitted adjustable push rods and set up, now runs well, but when warmed up, I get a knocking from what appears to be no. 1, up top around the first valve. OK when cold.

Any help from you wonderfull guys would be appreciated.

[McAuslane325]

Hoping this isn’t the cause, but sounds similar to the issue I had with my 450. All fine until about 20 minutes into a journey, then the knocking would start. Never a problem when cold. Very long story short, ended up being diagnosed as a slipping cylinder liner (No5 if I recall), ultimately leading to a rebuild with top-hat liners. Sounded like (and I was hoping it was) a hydraulic-lifter problem, but after all the necessary top-end work the problem still persisted. Feel free to PM me, I’d be happy to give you my contact number to chat you through the 450’s ‘journey’….regards, Bruce

[Belle427]

I would double check the clearances on that particular cylinder rocker and all is tight.

[kelvinwannell]

It is hard to check clearance on no. 1, what do you think the issue is?

[blaze_away]

Check the rocker pads (the bits on the end that contact top of the valves) they are just interference fit and can become loose. I had a couple that you could pull out by hand, replaced and all good at the top end.

My rattle/knock showed up when warm but pnly at 3000rpm plus.

Turned out to be 1 very slightly worn big end. All replaced and knock disappeared completely.

Big ends easily checked and teplaced from underneath engine in-situ.

[Boosted LS1]

Which head gaskets have you used? I worked on an engine with a similar issue and it turned out the owner had fitted rover head gaskets (thinner) and not the TVR gaskets (thicker). The car was quiet until he increased the revs.

Do you know what the piston head clearance is on the engine? You can slip a feeler guage in beside the gasket. I wouldn't like anything less the .040".

If it's a rocker issue as others have mentioned then also check the rocker isn't hitting the side of the valve cover. Yella terra's can foul the cover.

Edited by Boosted LS1 on Monday 25th April 17:13

[dalecan]

Can you post a video of it?

[cheeseblock]

Its piston slap on that piston
Different expansion makes it happen when hot due to the difference in bore and piston metals