VH wet sumping

[hugh.leonard]

Greetings everyone. I'm a new forum member in Australia, although I've been an AOMCC member for many years. I'm nearing the end of a very long-term restoration of a 1955 VH and would be grateful for a little advice.

I rebuilt the engine and gearbox of my VH back in the early 1980s but then had to put the project on long-term hold because of work commitments. Over the years I've started the engine every few months and run it for about 10 minutes to circulate the oil and check that it was still a goer. When I retired I completed the restoration of the bike and have been preparing it for registration. Last weekend I encountered a problem that I haven't had before. The bike became very difficult to start and then I found oil was pumping out through the breather pipe on the crankcase. Off with the sump and sure enough a large amount of oil poured out.

I've been advised by experts in my bike club that this is a common problem and that I should fit a tap in the oil supply line from the tank to prevent it happening if the bike is not run for some time. The only way I can see to do this is to put a tap between the short curved pipe on the tank and the oil hose. Can anyone advise me if it is possible to buy such a tap with the correct threads on it to do this. If so, where could I obtain one? Alternatively, is there another way to prevent this wet sumping from taking place?

Any advice would be much appreciated.

Hugh

[nevhunter]

With the Ariel type of double plunger pump wet sumping is not common. Either the gasket behind the pump or the spring loaded ball is not sealing/seating. Nev

[brenton.roy]

Hi Hugh,
A single Ariel shouldn't wet sump unless something is wrong. The bikes that do wet sump generally have gear type pumps.
Air sealing could be poor between the pump and timing case or the ball valves in the pump could need reseating (sharp tap on each bearing with a small hammer and drift).
There is a round paper gasket over the oil way behind the pump. This might be leaking, or the pump gasket itself might be leaking air. If so, you could try two gaskets.

[robjameson]

1955 is the year that they removed the second check valve from the inner timing cover, so I would put one in for a start.

I'd also remove, clean and refit your oil pump.

I would never advise fitting a valve to the oil pipe, they are known in my family as a self destruct button, because sooner or later you will forget to switch it on and blow the engine.

[david.anderson]

Hugh
as previously stated, being a plunger oil pump the bike should not wet sump when left standing. It will wet sump when running if the return plunger in the oil pump stops pumping. Start the bike and check that oil is returning to the oil tank, which it probably is not doing. The oil pump will only fail if it sucks air. the most common cause is a bit of grit has lodged on the seat of the ball under the return plunger. other causes are gasket failure, the screws holding the pump in position have come lose or the scavange pipe that extends to the sump has come lose in the crankcase.
the only way that the bike can wet sump when left standing is if there is grit, lodged under the supply side oil pump plunger ball. this may be possible if the back up ball is not fitted in the timing chest immediately behind the oil pump. In such cases the oil supply to the engine is not going to be satisfactory, but this point can be checked as above by checking the oil is returning to the tank. if so it is probably a supply side plunger ball problem.
the attached dicument shows the back up balls that Rob referred to. After dismanling and cleaning the oil pump it would also be advisable to fit the back up ball valves to supply and return if they are not fitted. the parts are available from Drags.
David

ariel oil pump.pdf

(263.57 KiB) Downloaded 435 times

[hugh.leonard]

Many thanks Nev, Brenton, Rob and David for your fast and very helpful responses. I'll certainly take a good look at the oil pump as soon as I can and make the suggested modification.

Actually, in all my years of messing around with bikes, including Harley, Triumph, Velocette and various Jap machines, I've never experienced wet sumping before. So I guess it's not as common as I was led to believe.

Thanks again, fellas, and I'll come back when I have something further to report.

Hugh

[Keith.owen]

This is interesting!
The other day I removed the sump plate from my VH and as expected a reasonable amount of oil came out (I'd expect the oil circulated around the engine to continue to drain down after it had stopped).

When it had stopped dripping into a container, I placed some news paper underneath and left it overnight to see how much more would drop out; some but not a lot.

I then connected a bit of tube to the return pipe and placed this into a jar of oil and started the engine (as per waller). Interestingly enough, although oil was sucked from the jar it looked as though oil was being thrown out at a greater rate than was being scavenged - a fair amount ran down the tube back into into the jam jar!!

Point being, is there any consensus as to what the scavenge rate might be when observed in this way? I did confirm that the supply side worked well, however.

According to most literature on the subject, on starting the engine a steady flow of oil should be observed initially which then tails of to a stream of bubbles.

I also made a point of ensuring that the breather hole in the filler cap was not blocked.

The reason for all of this has been a mixture of curiosity mixed with the fact that the other day, my bike started smoking like a two stroke when started, having not done this before, neither again when taken out for a further run!

I'm not sure that I've actually found anything wrong!

Keith

[hugh.leonard]

I must admit I'm slightly confused about the modifications in the service bulletin you have kindly supplied, David. Is it necessary to insert new springs and balls into both the supply and return lines? While the instructions are quite clear about where spring 2154A-41, ball S9-1 and seating 2150-57 go, the location of spring 2220-29 and ball S9-1A is not clear to me from the diagram. I'm about to order the necessary parts from Drags so I have them on hand before I take the timing cover apart. Further advice on this would be much appreciated.

[nevhunter]

The return (scavenge) pump output is many times the output of the supply pump but it can part fail for a few reasons. The copper pipe can crack, there can be an air leak between the cam case and the crankcase at the join of the return line( There should be an extra paper ring gasket there) or the ball check valve in the pump may not be sealing well.
The extra check valve in the feed to the big end is to provide pressure to the oil line to the OHV gear, in models up to 1954 OTA). This is supplied from the return line to the oil tank on the later models and is not needed in the later models. It won't do much harm as it will provide a secondary back-up to the check valve on the pump. The pump relies on small springs,( that can rust), to seat the balls . The balls also can rust on motors left sitting for a while, and they don't seal. If they don't seal they don't fill with oil on the suck (fill) stroke Nev

[david.anderson]

Hugh
Ariel singles originally had a valve located immediately behind the output of the oil pump. From 1941 the valve consisted of a ball S9-1, spring 2154A-41 and plug 2150-57. This assembly, spring then ball then plug, fits in the deeper hole at one end of the shallow elongated hole behind the supply plunger. The plug is an interference fit to hold the assembly in place. This valve was necessary to create oil pressure to supply the rockers and the pressure could be read on the oil pressure gauge. In 1952 Ariel stopped the pressure feed to the rockers and supplied the rocker oil from the return line. As such the valve was no longer necessary to create the oil pressure to supply the rockers, the oil being pumped only to the roller bigend with the remainder of the bottom end and cylinder being oiled by what was flung from the big end. Ariel then stopped fitting that valve in 1953. This valve however provided a backup in case the oil pump failed due to grit on the seat stopping the oil pump valve seating properly. The second valve would then provide the seal and suction necessary for the pump to function properly. So after a couple of years without the backup supply valve Ariel reintroduced it. A complete failure of supply oil was always unlikely though as the oil tank would feed the oil pump by gravity so it would still pump, even if at a reduced rate.
The return oil is however different in that a perfect seating oil pump ball was always necessary in order to provide the suction to suck the oil from the crankcase before returning it to the oil tank. Anyone who has travelled large mileages on an Ariel single will at some time have experienced a return oil failure due to grit on the oil pump ball seat stopping the proper sealing. So in 1956 Ariel decided to also fit a backup valve to the return oil supply. The valve consists of just a ball S9-1A and spring 2220-29 that are normally lost the first time the oil pump is removed as it is only held in place by the oil pump. The ball fits against the hole in the back of the oil pump. In order to fit this valve, a pre1956 timing chest is modified by drilling out the return oil hole (the lower right hand hole of the 4 holes behind the oil pump) with a 9/32” drill to a depth of 7/16” as specified in the service bulletin. 1956 and later timing chests are already drilled to suit. This operation must be carefully done on a post drill with the height stop set and the cover firmly held in place as the enlarged hole goes close to a supply oil hole.
Do not mix up the springs and balls as they are not interchangeable, so ask Drags to mark them before posting.
David