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DISCUSSION => Engine + Driveline => Topic started by: mark_i on December 22, 2008, 02:30:28 PM

Title: M42 rebuild:new parts and oil circuit priming
Post by: mark_i on December 22, 2008, 02:30:28 PM: Hi All

Got the timing case welded up and the parts arrived to replace the chain, sprockets and guides. Even installed profile gasket using the feeler gauges.

The new parts look different to the 18 year old originals

1/ the crankshaft sprocket has a rubber seal/ring bonded to the front and rear that almost cushions the chain
2/ the guide rail has an adjustable screw at the top position to align the guide

Normal...?

Also, how to prime the oil circuit?

when the idler gear boss fractured and the teeth chewed into the case, I collected the grindings from the sump, oil filter housing and the oil pickup screen, hoping that none had entered the gallery, main/crank/cam bearings
But when I rotated the engine on the crankbolt there was a lot of resistance to movement. Eventually freed up with some WD40 on the exhaust valve stems and was able to spin on the starter. I could hear a burp and fresh oil appeared to splash out from the chain tensioner.
The engine had been laid up, under cover since May this year.
Title: M42 rebuild:new parts and oil circuit priming
Post by: peerless on December 22, 2008, 04:14:23 PM: Yes there are numerous upgrades from the factory for the M42. The crank sprocket has the additional rubber o-rings on the crank gear to further absorb harmful vibrations. The chain guide is now a all nylon material instead of the stamped steel POS that likes to shatter. It interesting about the oil pump and debris. They have also upgraded the oil relief piston valve, again the original one was/is made of steel, this galled the bore in the timing cover and could cause the relief valve to stick open losing all oil pressure and blowing the engine. I have personally seen this happen. Regarding oil priming, make sure its full of oil and crank over the engine without any spark plugs, spark, or fuel. Sounds like your getting some pressure if you seen it squirt from the tensioner lubricator spout. (http://img.photobucket.com/albums/v176/peerless/M42oilreleif.jpg)
Title: M42 rebuild:new parts and oil circuit priming
Post by: colin86325 on December 23, 2008, 11:41:05 AM: You'll want to flush out your oil filter housing extra well, and debris can accumulate in its passages.