Thread: The dreaded Engine KNOCK KNOCK :- (

That can be a partially collapsed lifter but I am more inclined to say you've done a big end and the piston may even be hitting the head, I am assuming it increases as you rev it up.

All guesswork until you start tearing it down.

Start with just getting the rocker covers off at least for an eyeball of the valvetrain.

I've had an exhaust manifold gasket blow that sounded like that, but not on a Landy. Pulling plugs one at a time is the quickest, easiest diagnosis too. If i'm wrong, you will know in 5 minutes. It's also the least scary option!

Mike

havent made a comment for years. This particular one is a familiar sound, down low, motor drives well, idles fine. Didn't see the cab, but is it an auto? if it is then;
FWIW my money is on the flex plate, Ive had two go in a short period of time, the sound I can liken to the bottom end bearing knock, obvious when sitting in the drivers seat, where it sort of sounds like a hammer being belted on the lowest portion of your motor. But yet no problems with your motor. Ive still got the broken ones in the shed.
No reflection on expertise but I did get two very experienced mechanics look at it when it happened the first time and they both came up with big end knock with possibly a harmonic balancer problem as well( each way bets).

Best of luck.

John

The bit of hose trick worked for me too...that allowed me to diagnose blown exhaust manifold gasket when for all the world it sounded like worn tappet. Anyway the hose to the ear trick would be the cheapest and best way to start closer diagnostics mate. Cheers

Another bit of info that has me thinking its a flex plate , is that the engine for ages had a very slight tick in it ... very slight ...

This louder tick literally started after a fuel stop in the middle of a 800klm run we made on that week end ... The engine was fine , we stopped , turned her off , then restated and bingo , the misses said , what is that noise ? Go figure ..

You guys throwing you time in to give your thoughts are an inspiration and give a bloke hope I can tell you !! I am going to start trouble shooting over the week end and I am still leaning towards the flex plate having ch-it its self :- ) ... not a good thing but better than my mechanic that just wanted to rip the engine out after not even lifting a spanner to her to check anything ... :- (

thanks to everyone :- )

Originally Posted by Discodance

Another bit of info that has me thinking its a flex plate , is that the engine for ages had a very slight tick in it ... very slight ...

This louder tick literally started after a fuel stop in the middle of a 800klm run we made on that week end ... The engine was fine , we stopped , turned her off , then restated and bingo , the misses said , what is that noise ? Go figure ..

You guys throwing you time in to give your thoughts are an inspiration and give a bloke hope I can tell you !! I am going to start trouble shooting over the week end and I am still leaning towards the flex plate having ch-it its self :- ) ... not a good thing but better than my mechanic that just wanted to rip the engine out after not even lifting a spanner to her to check anything ... :- (

thanks to everyone :- )

Does definitely sound like a big end gone. If it was cam related you would have a misfire, even if it was slight you would tell.
If you can narrow it down to one bank or cylinder, take the plug out and wind that cylinder just over tdc and stop turning so the piston is on its downward stroke. See if you can move the piston down in the cylinder through the spark plug hole using some round bar or something, just round the end off so it doesn’t mark the piston crown. If it’s a big end you’ll get a bit of movement and hear the clearance too.

Originally Posted by Discodance

Another bit of info that has me thinking its a flex plate , is that the engine for ages had a very slight tick in it ... very slight ...

This louder tick literally started after a fuel stop in the middle of a 800klm run we made on that week end ... The engine was fine , we stopped , turned her off , then restated and bingo , the misses said , what is that noise ? Go figure ..

You guys throwing you time in to give your thoughts are an inspiration and give a bloke hope I can tell you !! I am going to start trouble shooting over the week end and I am still leaning towards the flex plate having ch-it its self :- ) ... not a good thing but better than my mechanic that just wanted to rip the engine out after not even lifting a spanner to her to check anything ... :- (

thanks to everyone :- )

I have owned 8 Land Rover/RR/P76 V8s. They are prone to cam lobe wear if idled in traffic a lot and lifters just sieze sometimes especially if the oil gets a bit thick or dirty.
Big end noise is normally more of a clonk than a tap and happens twice each crank revolution whereas the cam lobe is operating at half engine speed. Also bigend noise gets louder under load and gets worse a lot quicker than a noisy lifter/ lobe. If it is not a lifter, I would suspect the flex plate. have a listen with a tube on the tourque converter (bell) housing while someone alternates between DRIVE and REVERSE at idle and see if the noise changes.
Good luck for a happy diagnosis.
5380

Originally Posted by Chris D

I replaced the bottom end on an A30 from underneath years ago but its a huge risk as I found out. Don't do it.
As for the sound, from my experience you'll need a stethoscope to pinpoint the source although any noise tends to ricochet around inside the block. Maybe try just a piece of garden hose and go right around the outside of the engine (being careful to avoid the fan).
I doubt its a bottom end because the sound will rise and fall depending on the load on the engine, possibly a con-rod but its usually much harder to hear. To be honest my gut tells me its the crankshaft pulley - the key and overall fit has to be 100%, absolutely no looseness at all otherwise it clatters like mad. Maybe try running it for 10 seconds with the fan belt removed - if its a loose pulley you'll notice straight away.
Keep us posted.
Chris
(Disco 4, Freelander 1 and 2, Rover 3500 etc etc ........)

An A30 you said? You could turn that over like a suitcase to make your life easier.