Forum

[Dennis C]

As some are reminiscing on the past. As a spotty yoof I had a 1946 BSA B31, now in all the time I had this bike it never once needed an oil change, I just kept putting clean oil in the tank and the bike automatically removed it's own spent oil and left in pools on the road.

[papasmurf]

Dennis C, I used to own a Leyland "Mothercare" that used so much oil it was not worth the bother of changing the oil.

[Edward]

PeteF,I would venture to suggest that flushing your oil will be of more benefit to your new mechanic than you.

[jefrs]

You'll not seen clean oil out of a diesel because yes they have a much higher compression that causes blow-by, they produce a lot more carbon that will get into the oil from the cylinder wall (not necessarily forced past the rings by combustion), they burn oil and do burn up the lubricating oil on the cylinder wall (under serious fault conditions they can consume their sump oil and refuse to stop).



The main thing that uses up oil is the motor chopping the molecules up, the oil gets thinner and thinner until it is as much use as water; that's why to change it and one to keep an eye on. Discolouration is the detergent collecting debris which is an indicator of engine health.



My only recommendation for flushing was to remove all debris that had been found in this (top post) engine. If you find debris in the filter there will be sure to be some left in the motor, it is important that it is all taken out so it does not act like adding grinding paste to the oil.

[PeteF]

Jefrs, the main reason a diesel can run away is the seals on the turbo failing. A diesel engine will happily burn the lubricating oil thus released into the intake. The only way of stopping the engine is to stall it (if you can) Turning off the key has no effect in this situation. The engine will stop only when it has consumed all the oil in the sump(if it doesn't blow up first)

[jefrs]

That is correct PeteF, runaway is a pretty serious fault. Apparently the best way to stop it if it is careering down a motorway out of control is to deliberately blow the engine up by selecting neutral and then brake safely to a halt; move away to a safe distance and not try to stuff a rag into the air intake. I don't like diesels much even if I do drive one.



Some old bikes could only be stopped on the decompressor. I dimly remember starting a Panther or Sloper up without its silencer and then finding its decomp had jammed; we had to retire to a safe distance and wait until it ran out of fuel in its float bowl.

[Phil Ashbrook]

My big end went and bits of bearing came out the crankcase drain plug so now I know what the worst looks like .

[jefrs]

Phil, oh dear. There's a good word for that but it's rude. I'm sorry for your loss.



Not quite the same as extracting fine metallic silt. Not good, best is none, but what the filters are there for. Trouble is if you leave it in there it's abrasive and makes matters worse.