oil leakage timing case / magneto

[Jeroen v.d. Wetering De Rooij]

Dear all,

I have a gorgeous squarfour, totally restored, year of manufacture 1939. Everyting is OK, there is only one problem: heavy oil leakage between timing case and magneto unit. Does anyone have any suggestion as to how to resolve this problem in such a way that no droplet of oil will ever leave my timing case?
First requirement ofcourse is a tight, oil and heat resistant joint between timing case and magneto unit. Any suggestion what to use and how to apply a liquid jointing compound? The dowel at the bottom of the unit makes it not easier.
I have replaced the original plunger oil pump with a Morgo pump and have been told that these pumps may lead to some 'over oiling'. Is this maybe part of the problem? In addition, I have been told that improving crankcase breathing may be helpful as well, though I do not understand how this can reduce oil leakage in an engine where two pistons go up simultaneously with two going down at the same time. Anyway, I am looking forward to your suggestions.

Best regards

Jeroen.

[Dave.Barkshire]

I'm sure that an expert will be along shortly to give a better answer but my first instinct would be to ask whether the engine breathing is ok?

[nevhunter]

I'm not calling myself an expert, but alll engines "breathe' when they are running,.They harder they run the more they breathe. This is caused by blowby past the pistons, so pressure will build up in the crankcase if the outlet restricts the flow of gas. Some people bolt a dummy plate on the head gasket face and tension it , when honing the bores to get the same distortion as when the head is bolted on so the bores remain truer. This is common in blueprinted engines for competition. They will still distort with uneven heating anyhow, but everything helps.It is possible that your rings are not sealing well. If the motor is new give it a while to settle in. Even though it is a four, you should still be able to feel the compressions on the kickstarter , though they are not very big pistons.
Any how you either reduce the pressure in the case or seal it better. That is the essence of the situation. Nev

[Keith.owen]

Hi,
I have never owned a square four. I do beleive that the same holds true for all engines. When talking of breathing, I think what is meant is the crankcase breather which is a device that relevies the pressure in the crankcase which builds up as a result of blow past of the piston rings. If the breather is blocked or not functioning correctly then it is probable that leakage will occur at the 'weakest point'. It might just be worth checking the crank case breather (your machine is certain to have a crank case pressure releif device / breather somewhere) . I repeat that I have no experience of the sqariel, but, the singles have two breathers, one on the crank case (behind the primary chain case) and a scond on the timing case.

It is easier to check the simple things first and who knows..

Keith

[david.anderson]

One of the best ways to reduce oil leaks in any Ariel is to fit a PCV valve to the crankcase breather (the timing chest breather on a VH is a poor PC Valve) . Although in theory the square 4 crankcase pressure should remain even, blow by will increase crankcase pressure. By fitting a PCV the breather cannot suck air back into the engine and as such pressure in the engine remains low, which keeps the oil in. I originally fitted one to my Commando which used to seep oil from most joints. After fitting I had an oil tight engine, no seepage anywhere. It also works with my Mk11 and VH. The best PCV to fit is from a XS650 Yamaha as it seals better than most others and it is meant be fitted in line, but any PCV is better than none. Of course check that the breather is clear and I would also be checking that the oil drain hole between the timing chest and the crankcase is clear as too high an oil level in the timing chest will result in the timing chain throwing oil at the magneto sprocket. regards
David

[Vincent.vanGinneke]

Hello Jeroen and others, found this on the www.

Reed type Positive crankcase ventilation Valve. Valve hooks to engine top breather vent and allows expelled air out but reed prevents air re-entering quickly so a very small vacuum is created in the crankcase. A small power increase has been noted during dyno tests (most notable on pre 77 engines) and the crankcase vacuum helps prevent crankcase pressure from pushing oil past oil seals and case joints 13 euro part number: 15-0677
For sale at Heiden Tuning in Amersfoort.

http://www.xs650.biz/p/28/2501/mo8-cg%7 ... -pvc-valve

regards, Vincent

[chris.shearwood]

Hello Jeroen,
I've spent much time over the past week or two trying to solve oil leakage problems from the timing case of my 1946 Square Four and while looking for ideas on this Forum I came across your posting of more than a year ago. Did you ever resolve your problem? If yes, please describe your experiences. If no, please let me know as I may be able to help you.
Regards, Chris Shearwood

[john.nash]

I put one those XS650 PCV valves on my single and it DID make a noticable difference to oil leaks

[Peter.Barclay]

Hi Jeroen,

I would be interested to hear if you have got any where with your iron 4g breathing. I am currently building a 39 1000cc and intend to fit the Morgo pump. I have heard people talking about over oiling with the Morgos but i dont think this is case. As I understand it the return side of the pump is always designed to have a greater flow than the feed. I think the problem with the iron 4g is the pressure regulator let off is vented to the timing case. I think the Morgo pump will pump more oil than the plunger but this is limited to the rockers and journals by the pressure regulator. The excess oil discharged is dumped into the timing case and it fills up quicker than the drains can get rid of it into the sump and of course is splashed every where with the timing chain. In my MK11 (let off is attached to the pump and also discharges to timing case) I got round this problem by fitting a modified breather as advised by Peter Kemp. In the MK11's there is plenty room for this unlike the Iron engine. On my Iron 4G I would like to discharge the let off directly into the sump where it can get scavenged straight back up to the tank but have not thought of an easy way to do this yet. (I think the let off on the MK1's was fitted to the front crank). The other option a friend of mine took was to remove the Morgo and refit the plunger pump which solved the problem which I guess is ok when the engine is in good condition.

All the best

Peter.

[chris.shearwood]

I own a 1946 Sq4 fitted with a Morgo pump. It is definitely true that the increased flow of the Morgo causes an over oiling problem at moderate to high engine speeds. The increased flow through the pressure relief valve into the timing case is drawn to the rear and upwards by the timing chain and either flows directly out the breather or is splashed into it. I attached a small cannister at the outlet of the breather pipe and would find roughly two ounces of oil in it after a 15 mile run at about 55 mph. I suspect that the problem Jeroen describes in the original post on this subject has very little to do with oil coming out between the mag and timing chest but a whole lot to do with oil pouring out the breather.
To solve the problem I decided to extend the breather pipe in the inside of the timing case such that the "entrance" to the breather is at the front upper part of the case where, even with a Morgo pump, there is basically no oil. To do this I removed the hollow bolt that connects the breather banjo to the case and cut a few threads off the end of it such that it would not extend more than halfway into the threaded hole in the case. I then scewed it back into place (holding the banjo and pipe). I ordered another hollow bolt from Draganfly and cut a few threads off the end of it too. I had a spare banjo so I soldered a short length of copper tubing to it and then attached the banjo and pipe to the inside of the timing case by screwing the hollow bolt into the threaded hole. I don't think these banjos are commercially available but it would be a simple job for any competent machinist to make one up. I had to file off some of the head of the hollow bolt such that it would not contact the timing cover when the cover was put back in place. The last step was to wire the copper tube in place against the upper bolt of the oil pump. This solved the over oiling problem. I can't see the need for PCV valve but I would recommend the drilling of a small hole in the top of the rocker box cover to provide more breathing. Very little oil escapes through the hole but it is surprising at the amount of air coming out of it.
Regards, Chris