Strange random 'dinking' noise from bottom end...

[randall977]

I fully rebuilt my engine a few months back including new liners and pistons and started it again on Saturday after replacing the starter solenoid. There is a strange metallic 'dinking' noise coming from around the bottom end but it is random and in no way relates to the revs. It almost sounds like a piece of metal being picked up in the sump and dropped randomly? Any ideas?

[Chris Mountford]

Hi,

 

I would guess the timing chain tensioner blade has broken and keeps getting picked up by the chain.

 

You may also hear the chain clattering about inside the cover if you can do the 'mechanics stethescope' routine on it - Metal bar on the timing cover and the other end in your ear!

 

Quite a common failure and a (relatively) straightforward fix if it hasn't damaged anything else.

 

Usual caveats apply

 

Chris

[RogerH]

Christian,

if you do the 'mechanical stethoscope' approach make sure you have no loose clothing (especially ties, crevats etc). 100BHP is quite a lot to try and stop with your neck.

 

Could it be 'pinking' - very metalic sound!!!?

 

Roger

[randall977]

Thanks Chris, it was a thought... I've only started the engine a few times so hopefully no damage done if so. I did actually reused the original tensioner (or chain - or both - can't remember) as they seemed better quality than the new so maybe a new / old reaction has occurred. Will be careful Roger.

[graeme]

Another possibility is the half moon shaped plate covering the bottom of the gearbox behind the sump.

 

If this plate is installed the wrong way round, the raised areas can touch the flywheel randomly depending on the position of the crankshaft end float.

 

Check and ensure the raised areas are outward, its easier than getting to the tensioner!!

 

Cheers

Graeme

[randall977]

Hi Graeme, at least that's one bit I know it's not as I took the gear box out and put it back in 4 times in a week! If it wasn't for that then I would definitely check it out -thanks for the suggestion.

[Smokey]

One possibility, especially with a noise at idle, is a worn key on the distributor driveshaft. I changed the key and driveshaft, but my noise did turn out to be caused by a wobbly stud for the timing chain tensioner spring, which allowed the chain to eventually wear a hole in the timing chain cover, leading to a major oil leak.

[Ade-TR4]

It could also be a worn oil-pump drive shaft from the underside of the dizzy.

Even if you've used a brand new drive shaft, beware, as there are some out there that are too short and rattle.

 

Ade

[88V8]

And on a similar theme, check the crank pulley bolt is tight.

 

Ivor