Oil Weeping issue - Help

[gentlemanjim]

My '75 XS650 has a bit of oil seeping down the cylinders. Not a serious leak, but just not a pretty sight. I can't identify the source. Torqued the head checked all connections. Still persists. Looking for a solution.

 

[Paul Sutton]

Some possible sources of oil leaks:

1. Poor seal between head and the cylinder head valve cover. This requires significant work so would be my last resort.
2. Front oil feed line to the valve/OHC assembly (Copper washers).
3. Faulty O-ring or gasket behind the valve tappet covers.
4. O-ring between the OHC bearings and the points compartments.
5. OHC oil seal behind the points.
6. One of the bolts that holds the front timing chain rubber guide/slider in place may be loose - they should have a copper washer.

With the exception of the 1, these are all very easy to check.

Note: Copper washers work harden with time so I heat them to red heat on the gas stove. When cool they will be softened and seal a lot easier. I also treat new copper washer in this manner before use.

 

[gentlemanjim]

I'm afraid it's #1 all else checks out AOK

 

[Paul Sutton]

If at sometime you decide to lift the head to reseal then the following article gives an explanation regarding the 4 rubber washers on the head and suggests replacing them with copper. Could the oil leak be coming from under a rubber washer as suggested in the article?:

http://www.650motorcycles.com/CopperWashers.html

You may already know that loosening the studs with the rubber washers first prevents them getting jammed in place and this makes it easier to remove the cylinder head valve cover.

 

[fredintoon]

I'm afraid it's #1 all else checks out AOK

Hi Jim,
before you get all medieval on the engine, didja swap out those four composite head nut washers for something that works better?
Those washers ain't right for their task. They have a rubber layer like half an Oreo cookie where they should be a steel ring with a rubber ring inside.
(Check out "Dowty Seals". Drummond-McCall sells them.)
What most folks do is replace them with solid copper plain washers because you can get copper washers just about anywhere.
Even the used ones that were on your front brake banjo bolts that are coincidentally the right size.
Just Bernz-torch them dull red & quench to anneal them.
Note that copper don't care if it's quenched after heating red hot or if it ain't, it'll still be annealed either way. Just that quenching lets Mr. Impatient pick them up without getting blisters and it pops the oxidation off the washers so they look nice.

 

[MaxPete]

If you do the torch thingy on the copper washers - you must allow them to cool slowly in air.

If you plop them int water to cool them quickly, they will be come even harder.

 

[fredintoon]

If you do the torch thingy on the copper washers - you must allow them to cool slowly in air.

If you plop them into water to cool them quickly, they will be come even harder.

Hi Pete,
gotta call WRONG! on that one.
Quenching from red heat to harden ONLY works on steel with 1% or more Carbon in it. Don't even work on low Carbon mild steel, come to that.
Non-ferrous metals and alloys plain ol' CAN'T be hardened by heat treatment, they can only be annealed.
So quench away regardless so you don't burn your fingers.

 

[MaxPete]

acccckkk! I think you're right on that one Fred. Sorry about that.

 

[Paul Sutton]

I just heat to dull red and let them cool. I sometimes burn myself due to high heat capacity/impatience. I also heat treat new copper washers and clean the oxide off by gently rubbing in circles on some fine wet and dry. Annealing softens the copper and you get a better seal without using excessive torque to tighten.

Copper washers are quite easy to make on a lathe if you are ever desperate:

1. Drill holes in copper sheet and trim to approximate OD with metal shears.
2. Stack between two steel washers and thread onto bolt and clamp tight with nut.
3. Place in lathe and trim to correct OD.
4. Remove burs and heat treat.

When turning to size the copper will flow, hence the steel washers to control this. Best if the steel washers have greater than or equal OD. If greater than OD then just trim them down along with the copper (I imagine you could use a bench drill and file but have never tried this).