Tagless Big End Bearing Shells

[ukkid35]

Mr2Mike said:

Treat the PCV as a service part, change the oil regularly and ensure both spark plugs on each cylinder get replaced when they should and these little engines can last a good while. It seems many/most of them are ignored until they go wrong.

Thanks for the advice. The problem with the PCV is that access to the front of the engine is very restricted, so although the valve is in plain view few people seem to bother to change it. In comparison changing the 'lower' plugs is relatively easy, but as you know they don't get changed too often either.

I will also be using engine flush each change in the vain hope it helps free up sticky oil control rings. I already change the cheap cartridge filter every couple of months as that takes about three minutes and costs under £3.

[ukkid35]

I have a follow up question for anyone who can advise:

Having put it all back together and started it up, the rattling that I assumed was timing chain related, has instead become more obviously a knocking noise.

Fortunately I have very little experience of this (apart from my first ever car a V6 Capri that threw a rod at VMax plus as I was going downhill at the time - truly spectacular in the middle of the night), so what I don't know is whether I am likely to have suffered any damage to the crank. The engine has only been run for 30 seconds at most while obviously knocking.

Thanks in anticipation

[99hjhm]

How long has it run for total? Was it OK to start with?

[ukkid35]

99hjhm said:

How long has it run for total? Was it OK to start with?

My best effort to explain the engine history is as follows:

I bought an engine minus ancillaries with supposedly just 30k miles

I paid someone else to do the heavy lifting, but I did the induction and exhaust myself (mainly due to lack of working space).

On completing the job I took it for an MOT and on the way home after very short period of high revs a distressing noise developed such that I switched it off within 15 seconds and towed it home.

I assumed it was timing chain slap and replaced the entire mechanism including the oil pump chain, and then restarted the engine earlier this evening.

Sure enough the unpleasant sound has not done away, so now I'm assuming something fairly critical has failed.

[227bhp]

Lessons to be learned from this thread:

1.(This is the main one) Always give a full and frank explanation (with history) of what you are doing, why and what you hope to achieve.

2. Whenever working with bearing shells get some Plastigauge, it is cheap and easy to use. If you can get digital micrometers with ratchets they are a good addition, but a bit pricey.

3. When anyone sells a used engine (although mainly breakers yards) they always have 30 odd thousand miles on them, it's been this way since the 1980s.

[99hjhm]

I'm confused, did you touch the shells? Did you fit another engine and then take that apart!??

[ukkid35]

99hjhm said:

I'm confused, did you touch the shells? Did you fit another engine and then take that apart!??

I have bought four 599cc Smarts with burnt out exhaust valves, trading up each time, it was the only way I could afford a Smart. I've rebuilt each one with new valves, rings, bing end shells.

I removed one of the big end caps on this engine (number 5 so far) to check the condition of the shell, it was tagless and appeared nearly new. I reckon this means someone has been in before and attempted a rebuild.

[Boosted LS1]

Maybe there are identification marks on the back of the shells?

[Mr2Mike]

The tagless shells are perfectly fine, the fit within the conrod is what holds the bearing in place. If a big end bearing picks up, tags won't stop it spinning within the con rod!

[DVandrews]

Bearing pinch shoild keep them in place, but the tags are helpful for correct initial location of the shell both radially and centrally.

Dave