1950 VB oil pump problems

[bevanclark]

Hi folks,
The recently acquired VB has had a moderately bad leak from (I assume) the magneto/timing case seal. To date, on starting, there has always been a good flow of oil from the oil tank return pipe which diminished quite quickly to bubbles, which I gather is correct.

Today, I did a quick (5 min max.) ride around the block to verify that the reassembled clutch was working correctly. On my return, I discovered prodigious amounts of oil peeing down from the magneto/timing case seal area and no bubbles seen in the oil tank. No oil seemed to be coming out the engine breather. Prior to the ride, I had topped the oil up to the level mark on the outside of the tank. I had also tried, unsuccessfully, to remove the timing chest engine breather to inspect it (seems it is impossible without first removing the magneto ??)

Before I rip stuff apart, am I likely to be correct in concluding that the scavenge pump has failed ???

Cheers,
Bevan

[nevhunter]

Most likely oil pump related, likely grunge under the ball or the ball is worn oval or spring rusted. Pull the base plate off and clean it. Check the sludge trap in the flywheel at the same time. This is sort of normal maintenance. The copper oil pick up pipe can crack (RARE) so fit a rubber hose over the end and suck on it with your finger over the top hole. (Under the pump). This will also check the gasket between the cover and the crankcase is still sealing. Anytime the return oil doesn't work the engine will leak oil and run a bit hotter, due to the high level of oil in the crankcase causing oil drag. Normally there's not much oil in the outer case to leak out near the magneto unless there's something wrong like the return pump or the rings are allowing a lot of blowby. Nev

[bevanclark]

Thanks Nev for the instant response
Was studying the lubrication section of the Singles manual when you replied. I have recently purchased a suitable socket and was intending to check the sludge trap etc. this weekend, so I guess this flood is timely !
Cheers,
Bevan
ps some of your heat wave has made it over here - its 37 C now and a lot hotter in the garage, so investigation may wait until tomorrow. You are welcome to have the hot air back if you like, the tar on the roads is melting.

[simon.holyfield]

This might help:

https://ariel-square-four.blogspot.com/ ... r.html?m=1

[Simon.Gardiner]

The mag/timing chest seal can be a problem. I think originally a felt seal was used, I've found large rubber seals in some gasket sets which look to be about the right size so I now use one of these. Works well but you do have to make sure you've pushed the mag tight (and square, and with the correct mag chain tension!) against the back of the timing cover before tightening it up.
The breather on the back of the timing cover is difficult to remove - might be easier to check by putting a piece of tube over it and seeing if you can suck/blow through it (similar to what Nev's suggested for the sump pick-up pipe but there's not much need to check for air leaks!). Bear in mind that there should be a free ball-bearing in the breather elbow, to allow stuff out but not back in.
The ball valves in the pump can fail with grit/gunge stuck on the seats (although equally they can also to pass all sorts of nasties from a piston seizure without any trouble). The return side is more vulnerable to this.
The worst I had was when I used silicon sealant on the engine joints and over time bits of silicon that had squeezed out on the inside of the engine broke off and killed the oil pump return. I had to strip the engine again to fix that permanently. I'm a bit of an oddity round here now as I'll never use silicon sealant again, but some folks love it

SG

[bevanclark]

Thanks for the useful info Simon. I've a similar oil leak problem with my BSA Sloper, which has a fairly useless felt seal behind the mag pinion.
I'll check the breather as you suggest - if i can find some suitable tubing.

I've taken my pump off and cleaned it out. Here's a clip of it:
https://youtu.be/r5cPChWzAr0
Also a photo of the pump mounting face:

What's the socket head bolt (indicated in red) for ?
Since this is the first time I've seen one, any comments would be welcome.
Haven't removed it yet, but the current paper gasket seems incredibly thin. The thinest gasket paper I could buy this morning is 0.4 mm - is this o.k. for this purpose. I assume that you smear engine oil on both sides of the new paper gasket when refitting ? Also, do I need to prime the system prior to starting ? if so, how ? Cheers, Bevan

[john.whiting]

Bevan,have you looked at the previous post re the 350 oiling system......if so you would see that the bolt is being used to block the rocker oil feed take-off point...the side valve oiling system also has a special valve somewhere or other which is grooved to allow oil gauge pressure to bleed off when the engine stops........Haycraft also makes a big point of the extra thin paper washer in addition to the main paper gasket......as to silastic,well all I can say is my fridge is full of the stuff,and I wouldnt be without it.......and I might add ,the worst I have ever been caught with gasket goo was the brown #2 stuff which smells nice but is useless.

[bevanclark]

Hi John, Thanks for pointing out the relevance of other posting; as I'm new to Ariels, I'm still not used to there being so many common features between models. If I've interpreted the Waller book correctly, the other ball valve & 0 005 washer(s) are accessible if you remove the magneto pinion etc and the cover. I won't do this quite yet. Have got tank off and am in sludge removal mode at present. Would like to verify that I've got the pumping system functional again once all is clean before I take it any further apart. All good learning for me. Extracting the oil purifier is the next task Cheers, Bevan

[nevhunter]

Thicker gaskets need retightening. Thick ones are more likely to fail with a big gap and no oil happens. I've had them fail on Nortons gear pump with the Mazak body, which warps. With Nortons, I now face the pump surface very accurately and use NO gasket or silastic at all. Just metal to metal and no problems. They sump anyhow through the gears. You can easily check if it has sealed by pressuring the oil lines. In an oil system silastic can be a real problem especially Japanese engines with fine oil holes everywhere. There's no need to leave the gasket out of an Ariel unless you are stuck somewhere, and want to ride it home, but I certainly wouldn't use a thick one. The gasket you have there is perfectly serviceable. Re the magneto seal it's only there to prevent dust getting in. IF you put a neoprene spacer there. I HAVE used a Peugeot 203/403 spark plug tube seal and it's good but the oil if there's an excess will end up in the magneto as it has no seal to prevent it. Nev

[bevanclark]

Thanks Nev; the gasket does look ok and fortunately I haven't yet tried to remove it.
Just had a small win - the oil purifier bolt is a perfect fit into a 7/16 af socket so came out without drama. Also, it looks new and is completely clean. Tank has some sludge though, so have some kero in it soaking; no obvious rust inside, but will get a better look when its clean. Thanks again for your assistance. Cheers, Bevan