I have been following this forum for quite a while but this is my first post.

My M20 was idle and in pieces for 40+ years. It was recently restored to running condition. It starts and runs well, and I ride it for very short distances in my driveway because it isn't registered yet. I start and ride it every few days though it may sit for several weeks. There was a constant small pool of oil in the skid plate which dribbled out on the driveway when I drove off. There was also some oil oozing around the head gasket. The oil level had gone down about 1/4 over several months. Minor issues, so all was well.

Recently, after it sat idle for 4-5 weeks, i started it and there was a huge cloud of smoke from the exhaust, and the drain tube just behind the skid plate belched a big puddle of oil--maybe 2-3 ounces. I assume it came from the drain tube which is right above the spill.

What I understand from my looking into this is-- its a dry sump system, so oil is scavenged out of the sump continually, and if oil collects there after sitting, it will burn off when the engine is run. The cause could be leakage past the oil pressure valve in the timing cover.

That's as far as I can figure this out. What is happening to cause this? What should I do to correct it? If there is excess oil in the sump can I drain it, or just burn it off? Once burned off will the problem resolve itself or do I need to clean the oil pressure valve as well? Is that a likely source of the problem? Any guidance will be much appreciated.

I plan to register it and ride in New Hampshire, where I will be moving in a couple of months. Thanks in advance

email (option): perryhq@frontiernet.net

Hi Rob,

When the bike is standing for a while,
Oil from the oil tank in seeping down into the sump,
Going through the spring valve and seeping back through the oil pump.

There is no need to clean the valve because of this,
But it would be a good idea to tap on a 1/4" ball bearing on the seat of the of the valve,
In order to re-face it, and to clean and even lap the other oil valve,
Positioned on the bottom of the oil pump.

When you start the bike with a wet sump, the oil is being pumped back into the tank,
But also burning with the engine power stroke, till the sump is dry.

Another option to mend it, is to fit a tap on the feed line, (On the oil tank)
And close it when parked, (But NEVER forget to open it before starting..)
Or to fit an automatic valve on the oil input port of the engine, (I did, works great for 7 years)
Which only opens under pressure, but not everybody like this system,
As if the valve fails for any reason, and there is no oil circulation,
You have no indication..

Noam.

email (option): noam10@gmail.com

I don't know why,
I cannot edit my post, only few min' after posting..

Anyway, you can find a lot on this subject on the forum.
Try the search option with few key words..

this is one of the threads on wet sumping:

http://pub37.bravenet.com/forum/static/show.php?usernum=3155626639&frmid=16&msgid=1295037&cmd=show

Noam.

email (option): noam10@gmail.com

Noam-- Thanks for the information. Is there a reason for a big belch of oil ( maybe 2 ounces) out of the drain tube? I don't know if this happened while it was running or just after I shut off the engine. I had not run it long enough for the smoking exhaust to turn clear.

As more background-- many times previously the bike had sat idle for several weeks and did not show the same symptoms when i started it. No exhaust smoke. There had been only the small puddle of oil in the skid plate, and a bit of seepage at the cylinder head gasket. The smoking problem just started within the last few days. Is the leakage that ends up in great amounts of exhaust smoke a problem that can "suddenly" appear, or is it a sign of something else?

Thanks for the help.

Rod

email (option): perryhq@frontiernet.net

Hi Rod,
(Sorry, I see I called you Rob before.. )

I do not know about the big spill,
But I am sure that the wiser guys here (Most are!) will come up with a theory.

The only thing I can think about is that you may have added oil to the tank
And then started the bike.
As the engine ran, it pumped up the oil from the sump in addition to the oil
Which was already added to the oil tank, causing it to over spill. could it be?

Regarding the wet sumping-
Yes, basically, if the smallest piece of anything in the oil stream contaminated
The seat of one of the oil valves (Under the pump body or in the timing cover)
Or of the spring caught in it's squeezed position,
It could happen immediately, and it is an easy fix..
Just check and clean.
I would start with the easier one- the oil valve on the timing cover..

Cheers,
Noam.

email (option): noam10@gmail.com

Hi Rod ,
When you say drain tube do you mean crank case breather tube? If so, another symptom of wet sumping is oil out of this tube as the pressure in the crank case with it full of oil quickly overwhelms the breather valve and dumps the oil out of the tube.

If you suspect the engine has wet sumped before starting drain the oil from the bottom of the crank case.
And as Noam suggested reseat the ball valve in the timing cover and replace the ball.

email (option): spacemonkeym@gmail.com

One thing to note... When these bikes were daily riders, Wet Sumping wasn't an issue.. and bizarrely, my M33 hardly ever does, but the Rocket 3 is terrible, but I put that down to a poor engine re-build by me!!!

email (option): ian(at)integsci.com

Thank you for the advice and explanations. I will drain the sump and clean the valve and ball and run it more often.
This forum is a big help.

Rod

email (option): perryhq@frontiernet.net