The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: manxman on 09.08. 2017 15:17

Title: Sludge trap
Post by: manxman on 09.08. 2017 15:17
I pulled the sludge trap plug and there was no tube insert. Is there none used in the early small journel cranks? I did not see one in the parts book either.
Title: Re: Sludge trap
Post by: Greybeard on 09.08. 2017 16:43
I pulled the sludge trap plug and there was no tube insert. Is there none used in the early small journel cranks? I did not see one in the parts book either.
There was not one in my '55 semi-unit engine.
Title: Re: Sludge trap
Post by: KiwiGF on 09.08. 2017 22:19
I pulled the sludge trap plug and there was no tube insert. Is there none used in the early small journel cranks? I did not see one in the parts book either.
There was not one in my '55 semi-unit engine.

There was no tube in my 56 pre unit engine with SJ crank, the sludge trap is much smaller, some have said non existent in SJ cranks but I found what I believe to be deliberate "pockets" for catching sludge under the caps/plugs.

The small tube made in the crank connecting the big end feeds was almost completely blocked on my crank so you will want to check that out on yours, from memory it's only about 8 mm diameter.

If you could post photos it would help clear up some confusion on the sludge trap on SJ cranks  *smile*
Title: Re: Sludge trap
Post by: JulianS on 10.08. 2017 09:39
The sludge trap , or oil tube, was introduced when the large journal crank was revised to the type with 3 radial flywheel bolts in 1957.

Below is a rather poor copy of parts service bulletin GA2 date unreadable, showing the part numbers for the original small journal A10 crank, the original Road Rocket large journal crank and the revised large journal crank, together with the engine numbers when the revised LJ crank was introduced.
Title: Re: Sludge trap
Post by: JulianS on 11.08. 2017 09:50
Another service sheet on the sludge trap crankshaft, note what it says about the big end shells.