Engine noise

[CMJ]

5.0 ltr Chim going great. Due at factory next week for 18,000 mile service. (19,000 on the clock but last service done at 13,000 so still only 6000 between the two). I have today noticed an expensive sounding engine rattle when I lift my foot off the accelerator as the car de accelerates. It only makes a noise between 1500 and 1000 rpm then everything sounds OK. There is a slightly noisy tappet on RHS on tick over but when warm disappears. I have just started to use Optimax having tried BP's version a couple of times and prior to this run on normal ULG. I have only noticed the noise since using Optimax. Anyone any ideas ? BTW Car defintely runs better on Optimax overall but must also be set up for normal ULG as no real issues with this either. Noise sounds like a serious tapping/rattle.

[homerj]

A leaky exhaust manifold gasket can sometimes sound like a noisy tappet which might explain why it goes when warm, and could also be the source of your rattling.

Very difficult to describe noises though, so could be completely wrong.

[MOD500]

My 500 sounds the same, scared me to death at first Asked Harrogate Horseless, Richard Thorpe (R.T Racing), and Mark Adams - all who said it is fine. According to form its the cam that moves to and fro alittle, as its not quite 'secured' properly if you know what I mean - at least thats what I gathered from the above people.

What oil are you using? I use Mobil 1 15W/50 motorsport, I believe using 0W/40 can make matters worse?

Mine does it just before returning to idle, and chatters for 3 secs and then its quiet again.

Hopefully someone with more tech knowledge will post something

[IPAddis]

MOD500 said:

My 500 sounds the same, scared me to death at first Asked Harrogate Horseless, Richard Thorpe (R.T Racing), and Mark Adams - all who said it is fine. According to form its the cam that moves to and fro alittle, as its not quite 'secured' properly if you know what I mean - at least thats what I gathered from the above people. What oil are you using? I use Mobil 1 15W/50 motorsport, I believe using 0W/40 can make matters worse? Mine does it just before returning to idle, and chatters for 3 secs and then its quiet again.

Likewise. Sounds expensive but the bods at V8 developments assume me it's OK. Often caused by not having the serpentine cam retaining plate because a) the replacement cam doesn't fit it and/or b) the vernier timing gear gets in the way.

Apparently 15W50 oil is the minimum recommended.

Ian A.

[CMJ]

You have made my day. It does sound like a chatter and although a little higher in the rev range than idle and can see what you mean. I have been using 0/40w Mobil 1 as the bible tells me so (will get factory to put 15w in next week) and it does sound exactly as you have all described.