Bad Engine 'Clatter'

cheffy

Hi,

My sons '51 plate Vectra engine had been getting steadily noisier and noisier so, after reading about the problems with timing and balance chains on these engines, I bought both replacement kits and fitted them, including all gaskets etc as recommended, new oil filter and obviously new oil.

The old chains both had some slackness in them when I removed them and the balance chain tensioner was seized solid. I was convinced I had found the problem and merrily put it all back together, anticipating phoning my son and telling him the good news.

I fired the engine up and, as the car had been standing for some, time I gave the throttle one or two VERY gentle blips initially and all seemed okay. I let it idle for a good while making sure everything was up to temperature and well lubricated. There was a knocking sound that speeded up and slowed down very slightly with any slight variation in the tickover of the engine, but nothing like before - or so I thought. I made a mental note to investigate further, but still pleased that the loud 'clattering' had stopped I started to rev the engine a little more. Now that the engine was warm the loud clattering returned exactly the same as before. I'm not sure exactly where abouts in the engine it is coming from because I killed the engine straight away - plus I was working outside and it was getting a little dark!

I'll investigate further tomorrow but in the meantime does anyone have any initial thoughts as to what the problem might be?

I'm okay at fixing engines when I know what's wrong with them but I'm afraid I'm useless when it comes to diagnosis! 🙁

Any pointers would be much appreciated.

Thanks in advance for any help,

Cheers,

Martin.

vocky

check that the cam chain tensioner has activated, you can do this by undoing it whilst keeping it in place with one hand, don't remove it from the head just allow it to be undone.
Once the last thread is undone it should require a little pressure/effort to get the first thread started, if it can easily be refitted then the tensioner hasn't activated.

the knocking noise might also be the bigend bearings, it's possible the chains became noisy due to low oil pressure

cheffy

Hi Vocky,

Thanks for the reply. I fitted the new tensioner with it already 'activated' as I saw you'd recommended doing in an earlier thread so I know that's okay.

I think you may be right about the big end bearings, the oil level was pretty low. I'll see if I can pin point more accurately where the noise is coming from tomorrow. But that would explain why the noise gets worse once the oil gets hotter and therefore thinner though I guess.

If I were to replace the big end bearings, would I not need to replace the main crankshaft bearings as well?

Thanks again,

Martin.

vocky

you should be ok with just replacing the big end bearings

cheffy

Thanks again Vocky, I'll give that a go.

Martin