Wet sump fix

Hi there,

Had the engine on my Commando re-built 5 years ago - runs fine, but I'm a bit of a novice when it comes to keeping on top of those niggling problems that come with a classic bike.

I find after about one week that the bike wet sumps. I know this is a common problem, but have heard that refurbishing the oil pump could help eliminate this. Is there any step by step instructions on how to do this? Or is things best left alone? I've heard that anti-wet sump valves are available, but for the miles I do per year it's not really worth the risk of the valve failing.

Any help appreciated

Neil

Hi Neil
Your bike should not wet sump so quickly. If you remember to push the pistons to TDC after riding this certainly slows it down.
The pump certainly is worth refurbishing in my opinion. There are a number of mods you can do to stop it happening, but be carefull, some are dodgy, and some are downright dangerous. I have none. My bike can be left about a month no problems. I just refurbished my oil pump.
You can fit a check valve in line which holds the head of oil in the tank but which is opened by the suction of the oil pump. The problem here is at idle you may find your oil pressure is very low and therefore restricted by the valve.
You can fit a 'tap' but you must find a way of making sure you open it before starting or its terminal for your engine. Some folk have done this electrically with a microswitch tied in with the ign system.
Do some searches on this site for anti wet sumping.

To refurbish the pump, which is a gear pump, you must eliminate the side play. I believe the instructions are in the manual.
I did mine like this:-
Strip and clean up both end plate inside surfaces with a surface grinder or valve compound on a sheet of thick glass until no sign of gear rubbing can be seen.
Carefully reduce the thickness of the body using the same method until when you rebuild it with the screws tight you get a slight dragging effect on rotating the gears, i.e. you have eliminated all the side play. You should see rub marks on the side plates showing even contact.
Wash debris out carefully and rebuild.

I have heard of seals being installed but know nothing about this modification.

Don't forget to check the timing chain play while you are in there. 8)

It will still wet sump, of course, but much less.
What oil are you using? Thinner oil will wet sump sooner. I use 20-50, some folk use straight 40 or even 50.

Stu.

I would caution putting anything in the oil pump intake line. IMO, it's a potential for disaster. Converting to the oil pump outlet check valve, such as the 1975 Mark III, is no doubt the safest anti-sump mod. The pump itself will leak into the timing cavity. This can be addressed with the "O" ring mod of the pump.http://www.amr-of-tucson.com does an excellent job of both the check valve and "O" ring mod.

Have a look here for details of a valve with electrical interlock switch, If you order one tell Andrew that it's for a Commando as the pipes are a different size to the AJS. I've just fitted one to my 850, (£38.00.)
http://www.ajs-matchless.com/Ads_G_TradeList.asp

I use an anti sump valve in the feed line per manufactures instructions. No problems w/ valve if installed correctly.
I start bike and check for return to oil tank before stepping off. It has been in service for 15 months now w/o any problems.
Last winter I let the bike sit. Spring I looked into oil tank and oil down about 1/3. Started w/o any worries and circulation resumed and returned oil to tank.
The valve has worked for me and I understand the idea comes from a factory application used on the Velocettes.
Just make sure there is circulation befre you step off.
MarshalNorton :mrgreen:

I assume you are using the spring loaded ball check valve. I tried one. I also have an oil pressure gauge. Ya', I'm one of those guys. At startup there is no problem with oil pressure. Unfortunately, once the oil is at normal operating temperature the oil pressure at idle is zero. That's with a fresh bottom end, a new oil pump and straight 50W oil. The pump intake just can't overcome the spring pressure of the check valve with hot oil at idle. Check the oil return once the oil is hot. You may be surprised.

I did use a non return valve for a while but chickened out and removed it after hearing of some horror stories! Also I do have an oil light and I noticed that it took quite a long time for it to go out when the bike had been standing for a couple of months. I have heard the idea originally came from Velocette, I once had a Venom which had one, the difference is that the Velo uses roller big ends which are quite forgiving regarding lack of oil pressure for a short time, not the case with shells! I'm using the tap with electrical interlock switch now as I mentioned on another thread.

There are several types of anti sump valve out there. I'm currently using the type Colorado Norton uses and so far it's fine. I've only got a few months on it though. Oil pressure is fine at idle.

Cookie,

Are you referring to item #1601 on this page?

http://www.coloradonortonworks.com/catalog/engine.asp

I was thinking about getting this and installing this too. Is it just a matter of plugging it into the oil feed? Where did you put it in your line?

Thanks!

Yup,

Mine is a Commando engine in a featherbed so it's a bit different and more trouble to install. You'd just cut the feed line. Very good directions in the kit if you need them.