Thread: disco knock

Originally Posted by spook

i have a 95 3.9 disco it has a knock in the motor not real bad but can here it especially in the morning it doesn't blow smoke or use oil and runs smooth i think it maybe piston slap but how can i tell the difference between big end knock and piston knock thanks Luke..

More likely to be a worn timing chain and sprockets. How many Kms on the clock?

If you are really worried I was told of this old trick:

Do compression check of a cylinder with compression gauge
Refer manual and see what it's meant to be.
If its low squirt some oil in the cylinder and quickly check again
If it goes up its bottom end if it stays the same it's top end.

This may help decide if it's piston slap or not

Originally Posted by Old Farang

More likely to be a worn timing chain and sprockets. How many Kms on the clock?

its got 250kms on her have done a compression test they are down a bit around 130 but all are close to the 130

Piston slap tends to be loudest when cold, if it goes away as it warms up it's of no concern. Big end knock tends to be louder as the oil thins with a hot engine, often most audible at light throttle and higher revs.

Originally Posted by spook

its got 250kms on her have done a compression test they are down a bit around 130 but all are close to the 130

Piston slap tends to a "sharper" sounding knock. I have run these V8 engines in various vehicles since 1972 and have never noticed piston slap, or bottom end noise either, for what it is worth. 130 compression is fine, particularly as they are all near the same.
At the mileage you have quoted I would be willing to bet that it is a stretched timing chain, if original. A new timing chain kit, and a cam shaft with a set of new followers will transform your engine back to near new. cheers.

Originally Posted by bee utey

Piston slap tends to be loudest when cold, if it goes away as it warms up it's of no concern. Big end knock tends to be louder as the oil thins with a hot engine, often most audible at light throttle and higher revs.

ok thanks well its not the big end it could be my timing chain and cam

Originally Posted by Old Farang

Piston slap tends to a "sharper" sounding knock. I have run these V8 engines in various vehicles since 1972 and have never noticed piston slap, or bottom end noise either, for what it is worth. 130 compression is fine, particularly as they are all near the same.
At the mileage you have quoted I would be willing to bet that it is a stretched timing chain, if original. A new timing chain kit, and a cam shaft with a set of new followers will transform your engine back to near new. cheers.

thanks this sounds like what it maybe is hard to get at the cam chain to see if its got play there thanks Luke..

Could it knock if you he collapsed engine mount as well? Just a thought