Hello all, I have just found this great resource. I am the second owner of a M21, it sits for extended periods and wet sumps, this isn't a problem but the clutch ends up full of oil. The gasket is sealed pretty well (I think), what is the most likely cause? I am assuming the crank
seal. How do I go about replacing the crank seal, can it be done from the primary side or do the cases need to be split? Thanks, Jonesy Australia
There is no oil seal between the engine & the primayr drive so it is going to fill up when the engine wet sumps.
To slow this down get a new ball bearing and spring for the anti syphon ( wet sump ) valve that sits behind the small bolt just under the timing cover.
No one ever replaces them because they "still fee springy " but it is a very soft spring so a slightsettlement of the spring will render it ineffective.
To live with it simply remove the drain bolt and put a catch dish under the drain hole.
Get a filter funnel ( old drip coffee machines work a treat ), tip the drained oil into it and let it filter through a coffee filter then pop it in an "old oil" bottle and use it to top up before you go for a ride.
Place the drain bolt on your fuel cap, saddle hang it off the kick start, brake lever etc so you remember to put it back before you go for a ride.
There is a bit over 1 hour in a full oil tank & M20's will run quite happily with very little oil if you accidently start it without the plug replaced but you will blow oil all over our rear tyre which will be interesting the first time you back off or try to go round a corner.
I removed the drain plug and drilled and tapped through it to take a 5mm allen screw....That way you can drain the cases without having to constantly use the thread in the crank cases (with the inherent possibility of failure of the thread in the aluminium cases)....
I spent some time lapping in the (2)anti drain valves and achieved a great improvement...Ditto Trevors comments about replacing the ball and spring in the timing cover...C&D Autos do the ball and spring as a kit for a couple of quid...
If, or when, you strip the engine replace the outer drive side bearing (6205 C3) with the same type but with rubber seals fitted (6205 C3 2RS)...It's a metric bearing and thus readily available in a branded make from any bearing outlet...Remove the inner seal before fitting the bearing. This markedly reduces the tendency for leakage through the bearings if you forget to remove the drain plug and it does wet sump....Ian
I've heard of it by gluing a ball to the end of a thin rod. But probably best done when the timing cover is on the bench. The usual cheap skate method is to give the ball a light tap onto its seat with a small punch to encourage a better seat after squirting it out with cleaner or WD40 and an air line. It might just be a bit of shite holding the ball off. Ron
Yes, starting with the simplest method first is the golden rule...
I did, in fact, set the balls into the end of a piece of steel rod, the diameter of which suits both the internal diameter of the 'tube' in the base plate of the oil pump and the timing cover...
However, note that the ball in the timing cover is 1/4" diameter but the one in the base plate of the oil pump is 7/32" diameter so two different tools are needed...I counter drilled the ends of the bars to the major diameter of the balls, just deep enough for the ball to fit and then Loctited them in place with 'retaining' Loctite..
As Ron surmises the job must be done with the cover off the bike so that it can be thoroughly washed out on completion of the work...The oil pump also has to be removed and completely stripped to do the job.
That is worth looking at anyway to ensure the pump is not overly tight to turn...but that is something for another post...Ian
