no oil returning to the tank

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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no oil returning to the tank

Postby willowbedone » Wed Oct 17, 2018 3:44 pm

HELP
I've just returned from a 40 mile ride to find the oil tank was not at all warm. And when checking oil return to the tank nothing at all. I removed the sump bung and about a quarter of a pint of hot oil came out The oil was returning before I left home Any help would be appreciated
THANKS IAN

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Re: no oil returning to the tank

Postby Mick D » Wed Oct 17, 2018 4:06 pm

Hi

Is the oil supply blocked? - undo the supply line at the crank case and see if oil flows - no oil flow indicative of blocked pipe and / or strainer.

Is the return line blocked? - undo the return line from the engine and try to blow air up it into the tank - no air flow investigate blockage in the pipe line.

Is the pin still in the pump? - just a visual check at this stage, screw still in place

Is the pump rotating? - whip the front cover off and have a look at the pump while someone turns the engine for you, (you should also see the pump moving axially which confirms the pin location).

If yes to all of the above you probably have a blockage in the engine internal oil ways

Regards Mick

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Re: no oil returning to the tank

Postby willowbedone » Wed Oct 17, 2018 5:42 pm

Thanks for reply I will check as you advise Does anyone know if the oil plunger can be replaced without removing the engine
Thanks Ian

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Re: no oil returning to the tank

Postby REW » Wed Oct 17, 2018 6:31 pm

Do you have a felt filter in the oil tank? If so, check it has not flopped sideways in the tunnel and restricted the return flow to the tank.
Ron

1951 Matchless G3L, thumping round the Durham Dales

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Re: no oil returning to the tank

Postby Dixter » Thu Oct 18, 2018 6:58 am

Hi Ian: Yes, the pump plunger can be replaced with the engine still in place. But, before you pull the cover on the rear of the pump, here are two very quick tests.

To "Test" the availability of oil at the supply end of the pump: Rather than disturb an existing 'well sealed" oil line at the engine inlet, and risk breaking the engine cases, simply remove screw #4. This screw opens into the oil gallery which is supplied by the oil line, and is at the inlet to the supply end of the plunger, and is far easier to remove and reseal. Gauging the flow from this opening will help determine if a supply problem exists.

Scavenge test. This test is quick and easy, and a bit of explanation may help. The return side of the pump requires an absolutely "air tight" seal, for the pump to lift oil from the bottom of the engine and pass it up to the oil tank. In essence, if you have an air leak at the cover, your pump has lost its "prime". and will not pick up. Over time, the smallest of leaks can develop at this cover (being adjacent to the guide screw #5 and 6). Air being thinner than oil, the quick test is to smear a thick coating of wheel bearing grease, sealing all four sides of the cover, and the screw heads. Since the failure mode is suction, the grease should seal any air leak for the few minutes needed to safely check the output of the pump.

You can speed up watching for oil being returned by adding 6 ounces of engine oil, pouring the oil thru the rocker box cover, and if your oil tank has a removable filter, remove the cover and flood the filter gallery.

oil3.jpg


Since knowing exactly what failed is valuable information, when trouble shooting, make one change at a time and than test to see of the outcome.

Ciao,
Dick
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Last edited by Dixter on Thu Oct 18, 2018 1:52 pm, edited 1 time in total.
Dick Casey
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Re: no oil returning to the tank

Postby willowbedone » Thu Oct 18, 2018 10:28 am

thanks I will give it a try and let you know what I find
ian

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Re: no oil returning to the tank

Postby willowbedone » Thu Oct 18, 2018 3:11 pm

Thanks for all help and advice I've done all the tests But have found the oil pump plunger gear stripped I did not build this engine so unsure of its history .Does this mean a full rebuild Any help and advice please
Ian

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Re: no oil returning to the tank

Postby Mick D » Thu Oct 18, 2018 3:30 pm

Hi

If you mean the oil pump worm gear, the engine will require a full strip down to check for secondary damage the results of which will determine the level of rectification required.

Do you know how long the engine has run since the last intervention?

Regards Mick

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Re: no oil returning to the tank

Postby Expat » Thu Oct 18, 2018 5:19 pm

Sorry to hear the bad news. I feel pig sick for you..... :headbang: :headbang: :headbang:

Steve
Keep shiny side up.

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Re: no oil returning to the tank

Postby Pharisee » Thu Oct 18, 2018 7:51 pm

If it's the teeth cut into the pump plunger that are damaged, it's almost certain that the worm gear on the timing side axle will be damaged as well. That will mean a complete strip-down, I'm afraid. The bore that the pump plunger runs in is likely to have suffered too from stray steel swarf so timing side the crank case half may well need some remedial work. That's a real bummer... :(

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