Universal 5432 (M40) - Oil problem

[rb1685]

Hello all,

I have a Universal 5432 (M40) with high hours - the chrono says 4600, but because it is not original to the boat, I don't entirely trust it. Recently, the crankcase vent started puking a LOT of oil. I'm talking quarts. I'm just getting my feet wet with diesel engines, but I do that crankcase pressurization is typically not good.

From my initial googling, I suspect that this blowby can be caused by scored pistons, worn rings, amongst other things. I'm thinking of having a mechanic come do a compression check as a start.

Potential rebuild in the near future...

Any suggestions?

[Lepke]

Large amounts of oil or oil vapor from breathers is almost always blowby. If you restrict the breather it can blow out seals. Most likely worn rings and cylinders. But not always both. If money is tight, new rings and new cross hatching might solve it. Some engines have .002" oversize rings available.
Only other common reason for oil out the breather is oil level too high.

[jimbunyard]

With a proper pathway (usually through the dipstick tube), normal crankcase pressure can blow all the oil out of an engine in about a minute, though given your description this seems unlikely.


A quick check that crankcase ventilation isn't restricted is to run the engine without the oil filler cap. If the problem stops, there's probably a restriction somewhere.


If the engine starts quickly, runs smoothly, doesn't smoke, runs up to full RPM and makes good power, chances are that the rings and valves are good.


Just a thought...

[rb1685]

Originally Posted by Lepke

Large amounts of oil or oil vapor from breathers is almost always blowby. If you restrict the breather it can blow out seals. Most likely worn rings and cylinders. But not always both. If money is tight, new rings and new cross hatching might solve it. Some engines have .002" oversize rings available.
Only other common reason for oil out the breather is oil level too high.

Thanks! I did an oil change in April, and though the manual calls for 11.5 quarts, I only need 9 before the dipstick read full. Strangely, the superseding M40 manual from Westerbeke only calls for 8-8.5 quarts.

Originally Posted by jimbunyard

With a proper pathway (usually through the dipstick tube), normal crankcase pressure can blow all the oil out of an engine in about a minute, though given your description this seems unlikely.


A quick check that crankcase ventilation isn't restricted is to run the engine without the oil filler cap. If the problem stops, there's probably a restriction somewhere.


If the engine starts quickly, runs smoothly, doesn't smoke, runs up to full RPM and makes good power, chances are that the rings and valves are good.


Just a thought...

Funny you should say that. I accidentally left the oil fill cap off after topping the engine up on Sunday. We ran for about two hours before I realized it was off, but I did notice the breather was not puking oil. So assuming there's a restriction, where do you suppose it would be?

Something also curious. I replaced the gauges and senders earlier this year. The oil pressure gauge was working - until this problem showed up. No the gauge shows zero pressure. Could these two problems be related?

[jimbunyard]

Originally Posted by rb1685

Funny you should say that. I accidentally left the oil fill cap off after topping the engine up on Sunday. We ran for about two hours before I realized it was off, but I did notice the breather was not puking oil. So assuming there's a restriction, where do you suppose it would be?

Something also curious. I replaced the gauges and senders earlier this year. The oil pressure gauge was working - until this problem showed up. No the gauge shows zero pressure. Could these two problems be related?

Probably the most common restriction is in the breather itself, there is often an 'element' or 'filter' that gets dirty or clogged. Are you sure the oil is coming from the breather and not somewhere else?

At first blush, it doesn't seem likely that the two are related, but anything is possible. According to the parts manual, the oil pressure sender is in a pretty standard location on a rail at the back on the left side of the block just below the block/head joint. If there is some kind of pressure side restriction after the cam bearings but before the rocker arm feed, it could cause that symptom. That could be checked while you have the valve cover off to clean the breather; there should be plenty of oil evident in the upper part of the engine. Also, if you know how to kill the engine manually, you can start the engine without the valve cover to check it, but if you're getting the proper amount of oiling it will throw oil everywhere, so you've got to shut it down quickly. Maybe better just to get a cheap manual gauge from the auto parts store...

It is unlikely that the two are related because the usual causes of the symptoms you describe are unrelated; oil pressure is one system, crankcase ventilation is another, i.e. there is no way for the oil pressure to pump oil directly out through the breather system because there is no physical connection between them.

For starters, I would take the valve cover off and disassemble and clean the breather. If clogged it will be pretty apparent. If it's not clogged, it may be that there is a compression sealing problem, or there could be another (unspecifiable) issue. At some point, a good mechanics' on site opinion and advice becomes invaluable...

[rb1685]

Originally Posted by jimbunyard

Probably the most common restriction is in the breather itself, there is often an 'element' or 'filter' that gets dirty or clogged. Are you sure the oil is coming from the breather and not somewhere else?

At first blush, it doesn't seem likely that the two are related, but anything is possible. According to the parts manual, the oil pressure sender is in a pretty standard location on a rail at the back on the left side of the block just below the block/head joint. If there is some kind of pressure side restriction after the cam bearings but before the rocker arm feed, it could cause that symptom. That could be checked while you have the valve cover off to clean the breather; there should be plenty of oil evident in the upper part of the engine. Also, if you know how to kill the engine manually, you can start the engine without the valve cover to check it, but if you're getting the proper amount of oiling it will throw oil everywhere, so you've got to shut it down quickly. Maybe better just to get a cheap manual gauge from the auto parts store...

It is unlikely that the two are related because the usual causes of the symptoms you describe are unrelated; oil pressure is one system, crankcase ventilation is another, i.e. there is no way for the oil pressure to pump oil directly out through the breather system because there is no physical connection between them.

For starters, I would take the valve cover off and disassemble and clean the breather. If clogged it will be pretty apparent. If it's not clogged, it may be that there is a compression sealing problem, or there could be another (unspecifiable) issue. At some point, a good mechanics' on site opinion and advice becomes invaluable...

Thanks for your advice! It's starting to get cooler here, so it is a good time to dive into this issue.