On removing the timing cover of a LM4 to see the condition of the timing chain and to see what type of adjuster was fitted i was plesently suprised to see that the cover was fitted with a newish looking gasket and a self adjusting tensioner and unstreched looking chain. BUT what i did find was that the timing cover was being marked buy the chain, the marking are fresh as the alloy is bright and the casing are slightly brownish. I noticed that the pins of the chain (a JWS brand) are slightly polished, i also note that the pins seem to me to stick quite proud of the end plates,something that from memory that Renolds chain do not, although i cannot verify this as i have no renold cam chains new or use lying about to look at. I did wonder why i was finding non magnetic slivers in the sump when i removed it to fully clean it before replacing with a new filter.ralph2012-04-08 23:05:44
These are pictures of mine before and after renewal:Old Chain New ChainYou’re not wrong. The new chain pins do seem to protrude very slightly further out. Not done a filter change on mine since the new chain went in but will look for signs of wear when I do.
I had further investigation and can find nothing else amiss .I’m convinced that it is purely down to the pins protruding further through the end plates.I have ground a slight grouve in the timing cover along the chain line as clearance. I can see no other bits of alloy anywhere else other than the sump so i hope thats it.Although i should realy strip the whole motor just in case.
daft as it sounds could the front cover gasket be to thin?
I used a thick metal one supplied by Mark at Rockingham. Far thicker than the old paper one that came out I would have thought.
could the chain be fitted the wrong way round? ie the heads on the other side are less proud?
Gasket is a new one, could be thicker i suppose.The new gasket i fitted was identical in looks and material to the old i removed I did not remove chain to see if pins were any different. Will remove the cover again to recheck chain pins and gasket thickness.
Have you got a pic of where it is wearing
have a look to make sure all the sprockets are on tight with ne free play in them if rubbing at bottom i have seen a engine with a gasket on the oil pum that spaced it out (no need for a gasket on it)
The new gasket is more metallic than the old paper one I wonder if the reason is to space the cover out more? Have to say the timing chains IF you pop one of the auto tensioners in seem to last a looooong time Paul Harris did mine last time and that was a fair few years and miles ago …not a problem at all since.
Gasket is 0.5 mm thick, i’m sure iv’e had better looking and quality. Gasket is NOT a paper one .If i had had 2 gaskets i would have use both.Everthing is tight. Pins are 1.06mm proud of the plates. Engine back in frame.ralph2012-04-11 09:16:29
[QUOTE=Ex smokingbiker] Have you got a pic of where it is wearing
Â have a look to make sure all the sprockets are on tight with ne free play in them if rubbing at bottom i have seen a engine with a gasket on the oil pum that spaced it out (no need for a gasket on it)
Sorry no photo but the scrapes were just above the crank oil seal and on the web to the right of the cam sprocket.
no idea of the internals here so I’m throwing in a wild guess . . . is it possible to put any of the the sprockets on upside down? and if so is there a small offset ?
are there any blemishes on the rear of the sprockets that would prevent them sitting down fully?
sprocket back to front is a good posibility, i would remove the bottom sprocket and check to see if any spacers behind or damage to the key / key way preventing it seating properly