Mysterious Engine Knocking

[andyb]

 m https://www.youtube.com/watch?v=8h60L0PW09A m

Checked the big end bearing clearance and the rod thrust clearance, all well within spec so I'm open to any suggestions to what's making this knocking.

I also checked the diameter of the rod bolts and they are all OK but what's the consensus reuse or replace?

Big thanks to Carolyn for all the above specs.

[jonbill]

Is that from before you stripped it down?
Did you measure clearances with old or new bearings?
How are the main bearings?
Have you checked the Valve clearances?

[andyb]

The video is from before I stripped it down.
The clearances are with the old bearings.
Haven't checked the main bearings or the valve clearances.
When I stripped it down I found no metal in the sump or oil, had a oil change about 6 months ago and oil level has never needed to be topped up.

[andyb]

Forgot to mention, the knocking varies. Its never there when I start it up and it comes and goes. Seems loudest at tick-over (when its there). If I hold the revs at 2000 it seems to disappear.

[Carolyn]

Chain tensioner?  Doesn't sound like a rod.  By 'strip down' do you mean engine out and dismantled, or sump off?  You can reuse the rod bolts, just measure the thickness at the stretch portion (as Jon advises).  Also worth checking valve clearances, and having a good poke around with a stethoscope (all the pulleys).

[krazysteve]

Have you checked the aux belt tensioner?

[andyb]

Thanks for all the replies.
Strip down was sump off.
Chain tensioner, Aux belt tensioner, pulleys. Well that should keep me out of trouble for a while  s:) s:)
Its done 75000 miles now so checking valve clearances would be a good idea just for peace of mind if nothing else.

[Carolyn]

Paul at TCB (in 'affilliates' section) has got chain tensioners in.  I don't know how many, but quite a few on here want them, so get one before they're gone.

[andyb]

Back again! I don't think it sounds like a main bearing but what's the clearance supposed to be. Won't hurt to check as its apart anyway.

[Carolyn]

Generally speaking, mains don't knock (no reciprocating motion).  However, 0.015 – 0.032 mm (0.0006 – 0.0013 in.)

[jonbill]

+1 on checking the belt and the bearings on alternator, water pump etc. My other car had a vaguely similar knock that stopped when I reduced the tension on the belt.

[Carolyn]

Have you got the engine out of the car?

[andyb]

Doing this with the engine still in the car.
At least after doing all this I'll know the condition of my engine.
So thanks again for all the suggestions, looks like its going to be a case of elimination until I find the cause.

[Carolyn]

I've sent you a Private Message. (see top right corner of this page).  I must confess I'm mystified as to how you measure main bearing oil clearances without removing the crankshaft and cleaning the oil off the bearings?

[carolineasb]

I'm afraid to say, the engine sounds just like ours in Oldie  s:( s:(  she was fine for a time while we waited to get her stripped or a new engine and then, just when we got the engine we found the dreaded metal filings in the sump  s:( s:(

She now has an 06 engine and waiting on a new Cat (hubby managed to damage it during the strip and rebuild  s:( s:( )before she's back on the road!