Is your sludge trap clean?

[Greybeard]

Saw these scary pics on Facebook 

[Topdad]

Gb ,thought you were being rude      but nowwww I understand ,actually as you say quite scary indeed.

[jachenbach]

I'd bet it took a lot of years for that crap to get that dried out. I'm guessing someone started a "barn find".

[Rex]

I've just cleaned out the trap on my 1951 A7 (a slightly different design to the one shown) and the muck inside was like a hard clay consistency. Getting it out was done with a drill bit and a day in the parts washer, but hardest of all was removing the two plugs as they'd been centre-popped four spots on each.
It took a morning to drill ever-larger holes centrally until the thin shell remaining could be pushed inwards and removed, but given the contents it was an essential job.
Getting the correct small journal plugs from a well-known supplier was another saga....

[RoyC]

Fitted new trap & filter.

[t20racerman]

I've run a cartridge filter on the oil return of mine for 30 odd years, plus also used modern detergent multi grade oil, in the belief that my sludge trap would never fill up. Stripped the crank after about 30,000 miles and was shocked at how much crap there was in there - it was fairly full! 😨

Is there any way of regularly flushing it out for the filter to collect, other than by stripping it (for regularly used bikes, not barn finds with solid crud)? Are flushing oil products any use? Often wondered this.

[Greybeard]

I've run a cartridge filter on the oil return of mine for 30 odd years, plus also used modern detergent multi grade oil, in the belief that my sludge trap would never fill up. Stripped the crank after about 30,000 miles and was shocked at how much crap there was in there - it was fairly full! 😨

That is very interesting and worrying.

[kiwipom]

hi guys, the only way to flush the sludge trap as i see it is by passing the sludge through the big ends as they are are at the end of the lubrication line, if you could reverse flush it may work but even then the sludge would have to be forced through every bush and bearing on its way out so no not in my opinion, cheers

[orabanda]

The higher performance (particulate removal efficiency) the filter is, the less sludge will be in the oil (and consequently the sludge trap). If the trap fills with sludge whilst an in-line filter is installed, then clearly the filter is is not removing enough particulate. The average $20 filter with cellulose (paper) element media is low technology, and low efficiency. Further, the elements are changed on time (mileage) intervals; it could have been blocked and on bypass for some (or most) of that time.

For the best results from the filter, review the performance (data) sheet and select a filter with preferably an inorganic fibre media (hard to find, and much more expensive than the cheap low quality paper elements), and fit a small pressure gauge upstream; change the element if the pressure exceeds the bypass valve (possibly 1.5 - 2 bar) when the oil is cold, and the engine is at 3,000 - 4,000 rpm.

[Triton Thrasher]

The sludge trap catches carbon black particles, which are small enough to pass through any paper filter of the full flow type.

There is no need to feel guilty, or worry about something being wrong with your return line filter, just because you found the usual rubbery black "clay" in the sludge trap.

[BSA_54A10]

A sludge trap is called a sludge trap because people are too lazy to call it by it's real name.
Full flow centrifugal particulate filter.
And they are the best type of filter for removing fine particles even invented if you exclude multi stage electro static ones.

However no oil filter can get all the gunk out, if it did the oil you put in would be almost the same colour as the oil you take out.

If you are getting a lot of entrapped debris then either your oil change intervals are too long or the filters you ae using have too low a bypass pressure.

The other problem is plain old cheapness.
people see cheap filters on evilpay and they buy them to save $ 20 only to find latter on they were cheap because they were defective.
If a filter cartridge does not have a company name and a batch number on it, don't fit it.

[Triton Thrasher]

Full flow oil filters operate down to about 20 micron particle size.

Carbon black particles are less than 1 micron.  Good luck filtering that out in the scavenge line.

Frequent oil change and good engine tune must slow down the filling of the sludge trap though.

[RoyC]

What about if you are running the bike the way it came out of the factory and change the oil regularly ?

[coater87]

What about if you are running the bike the way it came out of the factory and change the oil regularly ?

 Your going to fill the sludge trap faster. Without a filter, your not even filtering the 20 micron + particles from the system.

 Lee

[Dynamo Regulators Mike]

And with much of the sludge consisting of carbon it is well worth ensuring that you are not running rich. So many old bikes seem to be set up smelly, sooty and over rich. Maybe to aid poor starting or believing that performance will be improved.

Fitting a decent filter is a no brainer to me.