Crankcase breather restriction

[Roger Long]

I don't know if you've been following my sudden oil loss situation over on my forum but I have a question. I've gotten suggestions that the problem and it's sudden onset might be related to crankcase breather restriction.

The oil separator I installed at your suggestion had a bit more oil than usual in it when I did the oil change a day before but it was far from full. The element has turned oily and black but I assume that is normal since its job is to filter oil out of the flow.

I just pulled the hose off the crankcase nipple and tried to blow through it. I can just barely get air to go through. It seems consistent with what I would expect blowing through an oil soaked piece of foam but far from the pressure of an oil pump driven lube system.

Do you think this is significant or is it just a fact of life that a main crank seal that was installed in 1979 could now be failing?

There were no oil low pressure warnings while running the day after the oil change. The low pressure light and alarm went on for a couple seconds on start up which is unusual and prompted me to look at the dipstick and under the engine. The dipstick read half at that point. By the time TowboatUS arrived, the dipstick was dry. No engine operation during this time.

This is an engine that didn't burn more than a dipstick scratch mark line's worth between 50 - 80 hour oil changes. It had begun to burn about 1/8" but I've put about 800 hours on it since last July so I'm not surprised to start seeing a bit of oil burn in a 1979 engine,

 

[Maine Sail]

I don't know if you've been following my sudden oil loss situation over on my forum but I have a question. I've gotten suggestions that the problem and it's sudden onset might be related to crankcase breather restriction.

The oil separator I installed at your suggestion had a bit more oil than usual in it when I did the oil change a day before but it was far from full. The element has turned oily and black but I assume that is normal since its job is to filter oil out of the flow.

I just pulled the hose off the crankcase nipple and tried to blow through it. I can just barely get air to go through. It seems consistent with what I would expect blowing through an oil soaked piece of foam but far from the pressure of an oil pump driven lube system.

Do you think this is significant or is it just a fact of life that a main crank seal that was installed in 1979 could now be failing?

There were no oil low pressure warnings while running the day after the oil change. The low pressure light and alarm went on for a couple seconds on start up which is unusual and prompted me to look at the dipstick and under the engine. The dipstick read half at that point. By the time TowboatUS arrived, the dipstick was dry. No engine operation during this time.

This is an engine that didn't burn more than a dipstick scratch mark line's worth between 50 - 80 hour oil changes. It had begun to burn about 1/8" but I've put about 800 hours on it since last July so I'm not surprised to start seeing a bit of oil burn in a 1979 engine,

Refresh my memory on which PCV device you went with... They really should not "accumulate" much oil just maybe some vapor and perhaps a little bit of liquid oil. You should be able to blow through it fairly easily or it is way past cleaning..

It is possible that motor sailing or an errant over fill caused the oil in the PCV device... As for the rear main they usually don't just "let go" like that. It is usually very gradual.. Of course the spring on the seal could have failed, if it is that type, and is allowing oil to leak by the seal.

This is one reason I've never like the Yanmar panels all they have is a low oil pressure light as opposed to an oil pressure gauge. With a gauge you notice slight changes....

It does seem odd that this coincides with a recent oil change...? Could this be a failure of the pan gasket? It can be very close to the bell housing weep hole..?

 

[Roger Long]

Refresh my memory on which PCV device you went with...

This one:

http://www.jegs.com/i/JEGS/555/52205/10002/-1

The amount of oil it collects did significantly increase in the last couple of weeks.

It's possible that motor sailing or an errant over fill caused the oil in the PCV device...

Please explain this as I actually was motor sailing the day before for a considerable period. It was dead downwind though and with no significant heel. I'd been sailing but it was a pain going straight downwind and the extra quarter knot of having the main set was nice on a long leg when I was racing the sunset.

I doubt that it was an overfill. This engine takes exactly a gallon less one mark on the gauge built into the Rotella jugs.

 

[DeniseO30]

Hope this is verified as the cause and you don't have to pull the engine Roger!

 

[kloudie1]

5 Microns seems mighty small for a breather .... If it gets wet with cooler liquid oil, it is not going to pass a lot of gas.. could be a big part of the problem.. The max recommended pressure for the lip seals are around 3 PSI Exceeding that number shortens the life .. If ya lucky, removing/decreasing the crankcase pressure should slow the leak a good bit but the lip may have been worn prematurely.. The troublemaker is the Gough-Joule effect which increases lip tension with heat .. more pressure makes more heat .. if the pressure is sufficient to overcome the initial compression designed in, ya can wear it a lot.. Bypass the separator and see what happens.. Ya might get the rate low enough to continue.. Good Luck with it, Roger..

 

[Benny17441]

What is the oil separator you are talking about? Is it an aftermarket unit? If so I would remove it. I would remove the valve cover and check the condition of the valve train and how oil may be flowing through it and flowing back into the cranckcase. Oil does not dissapear an engine either burns it, leaks it or collects it in places that should not be. Try and diagnose wich is happening.

 

[Roger Long]

Oil does not dissapear an engine either burns it, leaks it or collects it in places that should not be.

No mystery there. It was all in the oil drip pan under the engine. Well, about half of it anyway. It went down to the bottom of the dipstick which is roughly the level of the aft crank seal.

 

[Roger Long]

If it gets wet with cooler liquid oil, it is not going to pass a lot of gas.. could be a big part of the problem..

We're on to something here. When I disconnected the hose from the block and tried to blow through it, I could just barely get some air through. It was clearly over 3 psi, way over.

I just tried again this morning and air whistles right through effortlessly.

The separator collected about as much oil as you see in the picture over the first couple thousand miles. I noticed that it has been filling faster in the past couple of months but I've been operating pretty much as a powerboat.

During the oil change one day of operation before the bleed out, I found the separator filled about half way up and drained it. I've also noticed that the dipstick has been coated with oil all the way up when I pull it after a run. If I wipe it off and reinsert it, it reads properly. This is new so something seems to have been changing in the engine.

 

[Maine Sail]

This one:

http://www.jegs.com/i/JEGS/555/52205/10002/-1

The amount of oil it collects did significantly increase in the last couple of weeks.

Odd, it should not have..? I wonder if you have a fuel leak over filling the oil?

Please explain this as I actually was motor sailing the day before for a considerable period. It was dead downwind though and with no significant heel. I'd been sailing but it was a pain going straight downwind and the extra quarter knot of having the main set was nice on a long leg when I was racing the sunset.

DDW should not be an issue. Some engines burp some oil out the PCV if heeled that was my only concern. I would try and capture some crankcase oil and sent it out for analysis to be sure you don't have diesel over filling the crank case.

I doubt that it was an overfill. This engine takes exactly a gallon less one mark on the gauge built into the Rotella jugs.

Probably not but I have seen it so many times that I had to ask.

BTW the 5 mic element can often be removed from that separator and then you are just using it as a "catch basin" for any liquid oil that makes it out the crankcase vent. Those elements need to be cleaned periodically. I suspect that if you can still blow though it that it is not what caused the seal issue. A human would have a tough time making much PSI.... I have seen plenty of cars with "plugged tight" PCV's and they've not blown out the rear main.. Your rear main is on a large plate that I believe also uses a gasket to mount the plate to the block so it could also be that....

Last time I was in my bell housing I preemptively changed the rear main as she had 3200 hours on her at the time. It was not leaking but the seal was $40.00 and I was already in there. If I had not changed it Murphy would have surely bit my arse..,

 

[Roger Long]

Some engines burp some oil out the PCV if heeled that was my only concern.

That could be where this all started. Powering into the anchorage during the explosive frontal passage a couple running days before, I was heeled nearly to the rail under bare poles. That's also the side the PVC is on. I was also doing some pretty spectacular heaving and pitching. It was only for a few minutes but could have put the big slug of oil into the separator.

What I can't figure out is why it was so plugged last night and so free this morning. It didn't feel like anything popped through the system.

I haven't seen any rise in the oil level. I've been checking frequently in the past couple of weeks as the engine has finally started to burn a little oil. There used to be about a dip stick scratch mark of consumption between 50 - 80 hour changes and it's gone up to about 1/8" in the past couple of months.

I have been finding oil all over the dipstick when first pulling it recently. That's new. However, if I wipe it off and reinsert, I get normal readings.

 

[Roger Long]

Alibi

Now I know how the cops feel. Even though I found the guy leaning over the body with a smoking gun, he has an ironclad alibi. Always look at the obvious first.

When I did the quick and dirty test last night (after situation appropriate consumption of imported beverages) I had to pull on the breather tube to get my mouth on it. That kinked the hose at the back of the separator. This morning, with the engine compartment opened up, there was no tension on the hose. I just spliced in another piece of hose and was able to recreate last night's back pressure by pulling the hose to the position I had it in when I tried to blow through it.

I now have no evidence in hand to indicate that pressure restriction in the PCV system has any relevance to this situation.

 

[Bill Roosa]

You could always repeat the situation. a rear main seal (RMS) leaking will not kill the engine as long as you keep oil in it. does make a mess underneith though.
Perhaps you have a gremlin/cosmic ray shower/glitch (that last is a NASA term BTW) and it 'healed' itself.
Clean up the bell housing weep hole then put some oil in her and see if she leaks. If she leaks then you know (it does not really matter why does it). if it does not leak then start the engine and watch.
You said something Roger that has me puzzled. The oil level is at the level of the RMS??? Your engine must be at a pretty steep angle to get that to happen. I've never seen an engine with that much tilt to it. If she is that full of oil then it is no wonder the dip stick is showing oil splash as the crank is beating the oil to a froth. And if she is that canted and you never saw oil on the stick before then something like a splash guard may have come adrift down in the oil pan.
Going out on a limb here, is there a breather hole at the top of the bell housing....... lots of splashing going on that was not before so mayby all that is happening is oil is getting through ...... like I said, out on a limb.
Also, you mentioned early on about water in the oil. Did you figure out where that was coming from?
Got you on my prayer list guy.

 

[Roger Long]

I've never seen an engine with that much tilt to it.

Neither have I and Yanmar would never issue an approval or guarantee for the installation today. It's one of the complications of repowering these boats. You have to use a down angle gearbox.

However, this is 2012 and there are a lot of these boats still running with this 1970's engine and I've never heard of a problem aside from the blocks finally rusting through.

The dipstick is at the aft end so "full" is still at the proper relationship to the crankshaft. It just means less total overall oil capacity. Very convenient having an engine that takes just about exactly a gallon.

I've watched closely for signs of frothing since I read what the maximum shaft angle was supposed to be.

Did you figure out where (the water) was coming from?

It was already there. I saw it when I found excess oil at the oil change which I thought was just not getting the filter off quick enough or let the plastic bag I put over it slip. There had been several days of rain and I have some cockpit leaks that can find their way down to the drip pan.

When I cleaned up after the big bleed out, there was no sign of water under the oil. I just assumed there was until I get in there with the rags.

 

[kloudie1]

True, Bill.. Did a delivery once where the engine leaked about a quart every two hours.. We put an aluminum bake pan under the flywheel cover drain hole and caught the oil and poured it back into the engine while running.. Messy but not so bad as long as there were other people on lookout.. did that for three days.. It was a little Universal two cylinder diesel .. oil pump and cover are inside the flywheel cover.. it was either an oil pump cover leak or the rear main seal. Never found out which..

 

[Sefuller]

Similar symptoms

Just read this thread with interest. I have a Universal M25 in a 1983 Oday 34. The crankcase used to vent to the old air intake which was a round can like device with wire mesh around the perimeter, and a piece of foam tied around it with a string. Needless to say I had lots of unwanted diesel fumes and soot in the engine compartment. Last season, I added a K&N filter with a homebuilt oil collector inline. The first run of the year - from the storage yard to the marina - about 6 miles of motoring - drenched the K&N with oil and clogged my homebuilt collector. I cleaned the filter and installed the Jegs collector Roger linked to. During the rest of the summer, I did not have any significant oil accumulation in the separator in several hours of motor use - some of it in gale conditions. I do note that my experience with the dipstick is similar to Rogers - the first pull of the dipstick nearly always has it covered in oil, but cleaning and reinserting it yields a proper reading.

I attributed my initial oil soaked filter to the first start up of the engine after layup with a little longer crank time - since it never did it since then.

--
Scott

 

[Roger Long]

I do note that my experience with the dipstick is similar to Rogers - the first pull of the dipstick nearly always has it covered in oil, but cleaning and reinserting it yields a proper reading.

The friends I was cruising with earlier had a Universal the didn't run quite right. It had an unfiltered air intake but with a metal screen cast into it with holes about 3/32" diameter. The breather hose was run next to the intake, as it should be. I found 75% of the holes solidly plugged and the whole inside of the intake housing coated with over 1/8" of oil sludge. We cleaned that out and the engine ran significantly better. I also had them put in the same oil separator.

If science is to be believed, not a politically popular concept at the moment, there has to be some increase in crankcase pressure with an oil separator. It would not surprise me to find that it is well within the limits the engine can handle but enough to push some oil up the dipstick tube, perhaps on startup before combustion pressures fully seat the rings.

Why have a separator? Some oil condensate usually comes out the tube on many engines that is heavy enough to not be sucked back up into the intake. The configuration of my engine was such that it ended up in the alternator and starter windings. My friends were running with severe intake restriction. I've also noticed that my engine space and boat smell considerably less "enginey" since I installed this unit.

I used to fly a plane that took 6 quarts according the the POH (Pilots Operating Handbook and the bible of an aircraft's operation). If we put in 6 quarts, the dipstick would read 5 after the first flight and I would be out lying on the tarmac cleaning a whole quart of oil off the belly. Thereafter, oil consumption would be normal.

The mechanics at the shop said, "Yeah, we know but we can't put in less than 6 if we don't want trouble with the FAA." The solution we worked out was that I did the oil changes which was permitted as an owner/operator. I could put in just 5 quarts because I didn't have a certificate and job to worry about. Everybody was happy.

The strange thing is that identical aircraft with the same engine don't blow the 6th quart out the breather tube. Ours did it both before and after a total rebuild including new pistons. Engines can be as individual as people.

 

[Bill Roosa]

Perhaps the motor is entering puberty and just need a good whack on the back of the bell housing?
Seriously Roger, can you duplicate the problem now by putting oil in it?


Dave bowman
"What do you think the problem is HAL?"
HAL computer on the Odyssey
"We've seen these things before Dave and it has always come down to human error"

 

[Roger Long]

Seriously Roger, can you duplicate the problem now by putting oil in it?

I've just looked through the manual. The only place the oil could have come from, unless the block itself corroded through, is the rear seal. There is oil inside the bell housing.

I'm going to leave it all up to the mechanic now. My back has been getting slowly worse since my big anchoring adventure. That could turn out to be a bigger problem than the engine. I'm not going to risk having to do another drip pan clean out in a position which is just about the worst strain I can put on my lower back.

 

[DeniseO30]

Hope your back pain is easing up Roger. Wondering what the status is on your engine.

 

[Roger Long]

Hope your back pain is easing up Roger. Wondering what the status is on your engine.

Back was good today but, bored as I am, I am resisting the temptation to start removing the fuel polishing system, alternator, and all the other stuff around the engine to keep my bill down. Just leaning over to clean out the drip pan set me back a couple of days.

No word on parts until Monday so I sit here in limbo. 99% certainty it is the shaft seal.

Now that we know my PCV was clear and this whole thread got started because I kinked a hose while testing it, all these questions (which I appreciate) should be moved over to to my forum.


Later: It was not the shaft seal and I almost ended up having my engine pulled unnecessarily and spending thousands of dollars on nothing.

Some engines, like Yanmars, have dedicated intake manifold connections for the crankcase breather to keep the crankcase under negative pressure. My PO removed the hose from that fitting and I missed it.

Learn more at:

http://forums.sbo.sailboatowners.com/showthread.php?t=139226

These oil separators must NOT be installed on engines with a crankcase breather hose termination that returns oil to the engine. Read your manual carefully.