Wet sumping

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Wet sumping

Postby Wagoner » Tue Jun 25, 2019 10:21 am

Hi everyone I'm Wagoner and new to the club ,I have a lovely 16m which is being spoilt by wet sumping any ideas how to stop, must be a regular question but any help would be nice cheers trev

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Re: Wet sumping

Postby clive » Tue Jun 25, 2019 1:42 pm

Welcome to the forum. Wet sumping is not normally a significant problem on the singles what makes you think it is wet sumping and over what timescale does it occur. Give us the age of the bike too. Recent forum discussion suggests that pattern oil filters in the oil tank may have the felt too far at the top so obscuring the return outflow. This could cause wet sumping as could a knackered pump or the pump operating pin being installed the wrong way. Try the oil filter as first point to check. run it without the filter to see if it wet sumps.
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Re: Wet sumping

Postby Mick D » Tue Jun 25, 2019 2:04 pm

Hi and welcome

I see from your profile the bike is a 1954 model, but it's always advisable to give year and model when asking a question ;)

A few more details would help:

If the bike is wet sumping, (crank case filling up when parked / stored), what timeframe is involved and about how much oil?

Or

Is the bike suffering from poor scavenging, are you getting oil leaks from the primary chain case?

Regards Mick

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Re: Wet sumping

Postby Wagoner » Tue Jun 25, 2019 4:21 pm

Hi many thanks for quick reply ,it is a 1954 16m supposedly rebuilt but the more I get familiar with it I doubt it ,it seems to be about a fortnight and then becomes harder to start and throws about half a cup of oil out through the breather, there,s no leaks from primary ,return seems good,I,ve ridden her for about a couple of hundred miles with no issues and rides really good cheers trev

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Re: Wet sumping

Postby Andy51 » Tue Jun 25, 2019 8:55 pm

The problem is often a worn oil pump plunger tunnel in the crankcase - my '54 G80S suffers from it. Back in the day the factory offered a service where the crankcase tunnel was bored, lined and reamed to correct size, but that service hasn't been offered for for over 50 years! I approached a local engineer but he declined the task, saying that while he could do the job, it would require making special jigs and tools that would be so expensive that no one would be able to afford the cost (well into 4 figures 15 years ago). I tried a cure somewhere in tech articles involving making a tell-tale plunger to ensure oil plump plunger returns to set position but it did not work for me. You can go for a tap in the return pipe and hope you never forget to turn it on, or run the bike regularly to clear the sump, or drain the sump before use - I suggest you modify the drain plug by making a drilled and tapped hole for a smaller steel/brass insert to be removed to drain the sump so you are not unscrewing/screwing into aluminium frequently. Hope this helps, Andy

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Re: Wet sumping

Postby Mick D » Wed Jun 26, 2019 7:18 am

Andy51 wrote:You can go for a tap in the return pipe and hope you never forget to turn it on


Hi

If you adopt Andy's suggestion of a shut off tap and heed his warning never to forget to turn it on, it's best to put it in the delivery line, (going to the lower connection on the crank case), ;)

Do you know what oil is currently in the engine? it should be SAE50, if you have a lighter or multigrade oil it will be less viscous and tend to leak past the pump more quickly.

I would start the bike once every 10 days or so and run it long enough to clear the sump. I'm not a fan of shut off valves as I'm sure no matter how many precautions I took I'd forget it one day. I'm also not too keen on draining the sump before starting as I feel that removes the bottom end splash lubrication until the sump fills to normal operating level, which on these bikes can be anything up to three or four minutes.

Regards Mick

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Re: Wet sumping

Postby SPRIDDLER » Wed Jun 26, 2019 8:04 am

Welcome to the forums, Trevor.
I am always circumspect about 'rebuilt' bikes. Nevertheless, wet sumping of our old bikes when left standing for a while is generally just something we have to live with.
It is usually accompanied by excessive smoke when starting and difficult starting due to the spark plug becoming fouled with oil when attempting to start a wet-sumped engine.
As already advised, run the engine every 10 days or so to clear the oil before it accumulates. How often you run it depends upon the severity of the wet sumping. A rough indication of the progress of wet sumping can be gauged by observing by how much and how quickly the oil level falls in the oil tank.

I don't know how familiar you are with these old engines but the way to ascertain when the crankcase has been emptied is by removing the oil tank cap when the engine is running. If it has wet sumped oil will return in a continuous flow until the crankcase is nearly empty at which point the oil will return in a 'hit and miss' intermittent manner. This is because the scavenge rate of the oil pump is greater than the delivery flow rate.

I would also advise against fitting an oil tap. If your engine has the correct N1 magneto it won't have the cut-out button on the points cover so an oil tap with an ignition cut-out can't be fitted and you will be at risk of forgetting to turn it on with very serious consequences. (Personal experience :( )

As an aside, manuals for your bike can be found in the link below, under 'Books'.......
http://archives.jampot.dk/
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Re: Wet sumping

Postby Wagoner » Wed Jun 26, 2019 9:11 am

Wow thanks everyone for the enthusiastic response ,I can relate to all the suggestions ,I,m not sure what oil is in it but I,ll try an oil change and remove the filter and see what happens, I see on another link there seems to be problems with filters,any advice on that would be good,in the folder that came with the bike is a leaflet for a pressure valve antisump device, any views on this ? Many thanks trev

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Re: Wet sumping

Postby SPRIDDLER » Wed Jun 26, 2019 9:46 am

Wagoner wrote:.....in the folder that came with the bike is a leaflet for a pressure valve antisump device, any views on this ?

In short, don't fit one.

(Other opinions are available, but in my opinion mine is always right ;) )
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Re: Wet sumping

Postby Mick D » Wed Jun 26, 2019 10:10 am

Wagoner wrote:in the folder that came with the bike is a leaflet for a pressure valve antisump device, any views on this ?


Hi

This could indicate that the previous owner has fitted one - if this is the case it will be visible in the oil delivery line - this is the pipeline which goes from the lower connection on the crank case to the bottom of the oil tank. Originally both pipes exiting the bottom of the oil tank would go direct to the crank case.

Regards Mick

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