Thread: 3.9 V8 engine knock

If you keep using it then that double-row chain will keep grinding off ally which will keep getting into your oil.

I know because I've just replaced the timing cover on my old Rangie and whoever had put in the Rollmaster gear had ground off some of the timing cover for clearance, but not enough. So there were some clear marks where it had been rubbing, and lots of aluminium dust at the bottom.

If you pull off the timing cover you'll no doubt find the same thing. I know it's a pain undoing your own work as I had to pull off the cover and water pump and reseal them as I used the wrong gasket goo and it leaked coolant!

Fair enough but why can't I see any aluminium inside the timing case? The original timing wheel was double-row as well,

Cheers Charlie

Good question, but I think the oil washes it down into the sump. If the timing sets are slightly different it may only take that much to cause some trouble. Really, with a new cam and lifters there's supposed to be enough angled force on the cam to keep it back in the block but then these engines are known to sometimes have the cam tapping the timing cover.

When I put my new timing cover on I stuck some Blutack on the chain and put the cover on without a gasket after I'd ground the cover a bit. The Blutack got squished in between and that way I could check the clearances. And I have to admit that with one tappy lifter it's no doubt time for a new cam but with all that extra work and a bit of a deadline I didn't go for it. (But I know I will soon enough.)

You could start by taking the sump off and looking up into the cover, but really the timing cover has to come off for a good look. I know - who wants all that extra work - but at least that way you'll know if that's the problem or not.

OK; you have convinced me to have a look inside! Thanks for the advice Davo - at least I am a dab-hand at getting the sump off nowadays, this will be the third time in three weeks

The tip about the blu-tack is a good one

Cheers Charlie

Ooh, that's sad, isn't it? I'll bet your neighbours think you're loony. Be sure to let us know what you find.

Well; I have removed the timing cover only to find all is as it should be!

No signs of anything rubbing so I can only presume that the bits of aluminium must be coming from the camshaft rubbing on something but I can't imagine what! Whatever it is, it is getting better; however; hardly any aluminium in the oil this time and the knock only appears briefly on start up and then disappears.

Thanks to everyone for their suggestions,

Cheers Charlie

That is good news! Don't you feel better having checked? The only other thing I can think of the cam rubbing on is the thrust face on the block, though it should be flat already so that is mysterious.

It is a strange business!

The knock appears when the engine is hot but I can't hear it when driving the car. Very low speed, or idle is when it appears and then not always.

I think I will keep driving it for now and see what happens,

Cheers Charlie