Author Topic: WET SUMPING  (Read 1283 times)

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« on: 24 July, 2019, 17:16:49 »
Hi, I have a 1968 Rocket 3 that is wet-sumping that upon a no-use time, some oil is draining through the oil pump and by passing the non-return valve to the sump. Apparently, if the non-return valve is not seating properly, then this can occur. It causes a starting issue and sometimes oils the plugs, but often will disappear upon travel. Now, I have a 1969 workshop manual that shows the non-return valve and the pressure control valve accessible from the outside of the engine. Mine is 1968 and neither valves are present as per 1969 illustrations.
So, where are they? Perhaps internally - can anyone assist?


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« Reply #1 on: 09 April, 2020, 21:55:11 »
Slightly at a tangent, I had a similar problem with my T160. I could remove the ball and spring and they looked fine. I decided to replace them both as the bits were cheap. I even dressed the seat by holding the ball against it and striking it smartly with a pin punch to recut the seat.

None of this made any difference to the drain down. You can by a replacemeny filter with a built in non return valve to stop this. You could buy a non return valve - be careful of the spring pressure and fit that in series. If you are confident of remembering you could insert a shut off valve below the oil tank but have to remember every time to turn it on.

At the moment, if I haven't used my bike for a while, I start it up, let it tick over gentle to pump the oil out the sump then remove and clean the plugs. Bit of a faff but stops the plugs fouling. 

Y13 Alan G

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« Reply #2 on: 23 April, 2020, 17:45:02 »
Hi Patrick, I have a 1970 Mark One R3 which I have owned since new. After I had owned it for about 10 years it began to suffer from wet sumping when unused for a few weeks. I cured it by fitting a non return valve in the oil pipeline from the oil tank to the engine. 40 years later I still don't have a problem.
The Workshop manual says " The non-return valve is the smaller of the two valves and is situated in the oilway between the pump and the engine bearings (i.e. inside the engine).
The large chrome domed nut at the bottom of the right hand side of the crankcase is the pressure reiief valve and has nothing to do with the non-return valve.
I don't know whether or not a separate non-return valve is still available. If not you could fit a large inner diameter tap to stop it wet sumping. Of course don't forget to turn it on every time you use the bike! Hope this helps,
Regards Alan