top end knock after over rev

[Mk2zetec]

my 2002 has a hideous diy accelerator pedal setup which makes the throttle either on or off. ive been meaning to look at it for ages and yesterday it finally threw in the towel and stuck on wide open throttle. i turned it off quickly but buzzed the engine and its now got a top end knock. i know its an impossible ask but any suggestions on likely cause of knock- how do the m10's deal with over revving? bent valve? really annoyed with myself for not sorting sooner ?

[Schnellvintage]

An easy check for a bent valve it to check the valve clearances.  You can also perform a leak down test, without tearing down the engine.  My first step would be to remove the valve cover and spark plugs.

 

Hoping it's a spun eccentric,

Matt

[stephers]

My first step would be to fix the throttle set up     small simple things fix bigger problems

[TobyB]

If it went over 6500 at a reasonable dv/dt,  the intake rockers break.

 

If it headed for the sun, all bets are off.  But take off the cover.

You'll see the problem.  I've never bent a valve without breaking

a rocker, but I suppose it could happen...

 

The rotating mass is very tolerant of over revs...

 

t

 

[Mk2zetec]

4 hours ago, TobyB said:

If it went over 6500 at a reasonable dv/dt,  the intake rockers break.

 

If it headed for the sun, all bets are off.  But take off the cover.

You'll see the problem.  I've never bent a valve without breaking

a rocker, but I suppose it could happen...

 

The rotating mass is very tolerant of over revs...

 

t

 

Thanks Toby 

[7502]

So what did you find?

[Mk2zetec]

On 4/3/2021 at 10:59 PM, 7502 said:

So what did you find?

Funnily enough I’ve been looking this weekend. Nothing obvious so far but the valve clearances are too large. Setting them this week and will start the engine and see if the knock is still there. 

[Solarphil]

Don’t forget to fix the throttle linkage first ?