Sudden oil leaks indicative of high dilution?

[mosu]

73 M110...

Strangely, around the time I put on the Weber, oil began leaking at pretty much every gasketed joint of the engine. I had a change of 10W40 in there from the colder days. Even so, oil is suddenly getting past all seals?

I did find a nice puddle of gas left behind in the manifold by the Solex when I removed it so I'm wondering if the oil got broken down. Dipstick and oil cap have a faint gassy smell, but nothing major.

Also the breather hose used to have slight vacuum, now it's pushing a steady stream of oil vapour....

Any thoughts?

[79Mercy]

Something in the crank case vent is clogged, common on the early M110's. Its building up pressure in the crankcase forcing it to leak oil. Remove the oil cap while the engine is running and observe.

[mosu]

But there's smoke billowing out of the vent hose, doesn't that mean it's free? And if it is clogged, how can I unclog it? And what does clog it so suddenly?

[79Mercy]

which hose exactly? The one that is on the top right part of motor(right side- looking at the motor from front of car)?

[mosu]

Correct, the one leading to the air cleaner.

[79Mercy]

hmm, hows the engine running? does it sound like it has a dead cylinder?

Doesn't sound like the vent system is clogged if air is coming out of that hose.

[mosu]

It's fairly smooth, with some idle misses. I suspect some oil fouled spark plugs from more suspected bad valve stem seals. Billows smoke coming on gas after being at closed throttle at more than 60 mph.

However, the oil leaks developed quickly and from everywhere, including under the oil cap. It's as if the oil just got a lot thinner...consumption's still around 12l/100 km, so I don't know what to make of it. Fuel pumps a brand new Pierburg so I'm fairly sure that it's not leaking.

[kraakevik]

If the vacuum pump is still installed the diaphragm or the big in-line check valve may be leaking--this provides a direct path for crankcase oil/vapors to be burned in the intake and compromises intake-side integrity and vacuum



Tim Kraakevik
kraakevik@voyager.net
Four M110's

[mosu]

You're saying this unbalances the normal operation of the breather?

[kraakevik]

The normal breather between the cam tower and the intake manifold has a shielded orifice just 2.5 mm in diameter to limit flow between the engine crankcase gases and the intake tract below the throttle plate. This functions mainly during idle and low-power conditions.

The hose from the valve cover to the air cleaner exchanges air/gases between the crankcase and the air cleaner intake, above the throttle plate. This pulls fresh air into the crankcase when the breathing requirements exceed the flow rate of the orifice.

With the vacuum pump or check valve compromised there is a direct large-diameter path for crankcase gases to pass directly into the intake tract below the throttle plate--a torn diaphragm will allow copious amounts of oil mist to be sucked into the intake manifold and burned.

I would suspect you have an intake-side problem or that the new carb setup has disturbed normal engine breathing somehow. Oil leaks are symptomatic of high crankcase pressure and poor engine breathing.


Tim Kraakevik
kraakevik@voyager.net
630 474-9164

[mosu]

Spot on. I found it. The Solex had a cutout in its plastic spacer that allowed blow-by to enter under one of the primary barrels. The Weber's adapter plates did not. For now I made a wide cut into the thin plate and we'll see if that allows it to work properly. If not, I might have to remove the thicker adapter plate and gouge a passage into it.

Thanks all for your help!

[mercmad6.3]

Being a US spec engine,you also have a large crankcase breather pipe under the intake manifold with a air pump for the exhaust gas recirculation. A lot of problems such as you describe come from that pump not working or the valve on the exhaust manifold burnt out inside with actual exhaust gas pumping into the crankcase causing a lot of over pressure. In your case i would remove the intake manifold and check all the crankcase vent hoses and the EGR system.