With the invaluable help of friends, I finished the restoration of my M20; so she was ready for the first kicks to bring her back to life. She did in fact, and ran for nearly one minute, but then we had to shut her off, because no oil was bubbling back in the tank.
Now, before we start dismantling the engine again, what can we do to check the whole oil system: where can we put in oil to prime the oil pump, other points to check? HELP !!!
Dont know a lot about m 20s but i would take the sump plug out to see if there is oil in there if there is take the return pipe of and see when the engine is running if it returns then
Hi Hans,
One minute for the oil to return is not that long. I would run a little longer. If your worried about the lack of oil you could put some on the piston through the timing plug.
And you can check the plug with spring and ball in the timingcover.
Good luck, Michiel
email (option): m.wijbenga@hotmail.com
As far as I understand the oil system, the main function of the ball on the bottom of the oilpump is there to keep the return gears primed.
So that it start pumping right away and not until the oillevel in the cases reaches the gears itsself.
When the engine is rebuild there is not yet much oil above this ball and I can imaging that the return gear are sucking air for a while.
Putting a little oil into the return-oil line will probably speeds up the return flow as it then can't suck air from above.
BR Michiel
email (option): m.wijbenga@hotmail.com
First of all check that you have the oil pipes on the right way round, cannot go wrong really as they are marked on the engine as return and are straight, inside engine pipe to the inside of the oil tank union, and outside engine return pipe to the outside tank union. Blead oil down to the engine by slackening the feed pipe at the engine union. You will have built the engine with all the moving parts lubricated as you put it together so you can run the engine till the oil returns. This could take over a minute as the sump has to fill with oil over the suction pipe before the pump will lift it to return it.
If you are worried about this then take the plug out, blead the feed pipe to the engine union, tighten this feed pipe back up. Then remove the return pipe from the engine, kick the bike over till you see oil coming up the return pipe engine union, this won't take too long. once you see oil here put the plug back in and start the engine, oil will be pushed up the return pipe and into the top of the tank return pipe. You will never see a full flow when the oil level in the engine is correct, just spits of oil with air bubbles this is normal. If you have a full flow when first started it is because there is too much oil in the sump and the pump is shifting excess oil till the sump is the correct level.
email (option): t.j.walker@btinternet.com
Hans the first and simplest check is make sure the ball in the timing cover is not stuck on it's seat. Ron
email (option): ronpier@talk21.com
Good morning Hans,
I read somewhere some years ago that an Aussie had the same problem. It was the return pipe inside the tank that was dirty.
Try to blow air compressed into it
email (option): drossi54@hotmail.it
Thanks everybody for your comments and tips; first a squirt of oil through the plug hole, then try to wait longer before shutting off, and then if no success, all the remaining points...:relaxed:
Hans,
let us know how you get on.
We can all learn here,
Hello Hans,
You do not really have to bleed the oilpump, as gravity feeds oil downwards into the system.
First of all, you can try to rotate the engine without a ball in the valve on the timing cover.
Then, once the system work, put it back before you get oil in the sump.
Secondly, there are cases where the return pipe stem in the oil tank is rusted and punctured under the oil line,
So you DO have oil returning into the oil tank, but you cannot see it. It has no reason to climb to the top of the straw.
Personally, before I first start a rebuilt M20 engine, I take the spark plug out
(alternatively, you can press the exhaust valve lifter, but it is harder)
Then I put the bike on 2nd gear and walk it around a bit. (better to put some oil in the barrel when you take the spark plug out)
This way you operate the system without the risk of running her dry.
Usually, I do it while looking from time to time into the opened oil tank cover.
At some point it happens and you see the spit back to the tank.
BTW,
Maybe a stupid question from my side,
But if you have an additional anti wet-sump valve, it would not pump till you to have oil between the valve and the pump,
As the pump cannot “pull” the oil with air in the line. A kind of an air-lock.
Good luck,
Noam.
You have a point there Noam ! I DO have a wet-sumping valve installed....:grin:
How Hans... :smile:
email (option): noam10@gmail.com
You were right Noam! We took out that valve, and after a few kicks, oil was bubbling as it should be:joy:
Thanks !
How valves in the supply line can wreck an engine. Chapter 2. Para. 1
They are truly the Devil's work.