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MG Midget and Sprite Technical - Timing Chain Rattle after BE/Main Rep.

Hi Folks,

RE: '75 midget with 1500 Motor

About 1000 miles ago I had the timining chain and tensioner replaced. Normally I do all my own work, I'm a time served instrument Engineer by trade so small engine work is no biggie. However I had just moved house and not got my garage in order so I had a local garage do it. Bit of a mistake. Though the chain was quiet now, the mechanic had stripped the usual threads in the aluminium front piece so it always leaked a bit from the bottom of the cover. Not outrageous, just annoying.

Last weekend I dropped the sump and replaced the main, big end bearings and the thrust washers. The job was without complications. Getting the front top main out was a bit of a pain, I had to loosen the other two main bearing caps and take the fan belt off so the crank dropped a few thou to allow the new bearing to be inserted.

I repaired the threads in the aluminium front plate using thread inserts and put the car back together and it fired up fine, and run quiet without issue. No more oil leaks. The oil pressure when hot was back up to 20-25 psi from 8 psi before the bearing job.

However when it has been running 15 to 20 mins you can hear a rhythmic tick-tick every 3 or 4 seconds coming from the timing chain cover. It's definately the chain hitting the cover, but it's not all the time. Just a few (quite noticeable) rattles every few seconds.

So the only things I can think are:

1. Possibly the chain got stretched when I loosened all the main bearings at once and the crank droppeed a toiny amount. However I can't see it because surely it would just take up some of the slack thats in the chain.

2. Something to do with the fact the aluminium front plate was now back in properly and everything was back tight.....maybe there's some inbterference somewhere.....

3. It's all just a coincidence. Maybe the timing chain or tensioner was just garbage and didn't last long and nw I;m just relating it to the work I;ve just done but it isn't really.

Any thoughts or suggewstion or simnilar experiences would be gratefully appreciated.

Alan.


A Phillips


sorry for the spelling errors, I was typing in the dark :)
A Phillips

This thread was discussed on 11/08/2011

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.