Oil or diesel in raw water exhaust

[brian chalk]

I haven't run the engine for a few months. Started it the other day and checked the raw water exhaust output as I always do. That's when I noticed a light oil sheen in the water emanating from the exhaust. Obviously oil or fuel is getting mixed in with the raw water. I am not as mechanically inclined as many on this board, so thought I would ask for help with diagnosing.

For background, the engine is the original Westerbeke 40 with a Paragon hydraulic transmission. In addition to the coolant heat exchanger, the engine has a lube oil cooler, and a transmission oil cooler. 

When I noticed the problem, I shut down the engine and  immediately checked the oil level. I would say the condition of the oil and the oil level looked normal to me. I also checked the oil in the transmission. The thing I noticed there was that there were bubbles in the oil on the dipstick. Can't say if I recall ever seeing that before or if it is normal. I have also read where unburned fuel passing through the exhaust could cause the sheen.

Does anyone have any advice on how I should go about troubleshooting this so I can find and fix the culprit?

[Dale Tanski]

Brian,

I wouldn't get too worried at this point.  It could be lots of things but your comment about unburned fuel from startup is right on.  I would run it for a while to get it up to temperature and the next time you start it see what you get.  If at that point you are seeing evidence of "oil" out of the exhaust then I might get concerned.

Dale

[jpendoley]

I'm with Dale on this. My Perkins starts a little smokier now that its getting cooler in New England-thins out as the engine warms.  A few less degrees and I would not be surprised to see a little sheen on startup. Good luck!

[Della and Dave]

Like Dale Jp and I also wouldn't worry about it either unless it happens a lot with the engine warm.  One thing that can happen is a small amount of oil can leak down the valve stem into the combustion chamber with the engine sitting over a long period of time.  As that gets purged on start up it could leave a sheen.  It only takes an incredibly small amount of oil to leave a sheen.   A small amount of oil down the valve guide lubricates that valve guide and is fairly normal in spark ignition infernal combustion engines, but I don't have a lot of experience with Diesels however.   

If you use the faux glow plug, that is also a source of raw diesel in the induction, and then the exhaust if it doesn't ignite the first revolution.  That is normal operation. 

[PeteW]

If you want to get a better sense of what's coming out the exhaust, divert the raw water from the mixer as a test. I'd expect to see a bit more smoke.

The 15 degree down angle on the Pearson 365 allows oil to puddle up in the head over the valves for #4. Worn out guides and seals will let oil collect in the cylinder over time. When I changed gearboxes I got one with an 8 degree down angle on the output shaft. My motor now sits more level at 7 degrees. Oil drains into the crankcase now.

But you can't deny that your motor is old and it's got 35 years of wear. So as long as it starts up when cold, some amount of oil consumption and smoke is to be expected. If the oil consumption gets unmanageable you might consider a rebuild or repower. Eventually near end of life, years from now,  it will loss enough compression and it will become difficult to start.

The tone of Dales reply seems accurate. I wouldn't get too worried either.   Pete

[jpendoley]

Pete,
Great post.  I have a 4-108 in my 365 and have the perennial real oil seal leak. Do you think the 15% down angle exacerbates that problem?
Would changing over to the 8% down angle help alleviate the problem?

[brian chalk]

Thanks to everyone who replied to my post about an oil sheen in the raw water exhaust. We had to travel for a few days after making that post but got home yesterday. I went out to the boat today intending to run the engine up to temperature as suggested. Before starting the engine, I checked the oil level, and found the oil level reading extremely high - probably 1" above the max fill line on the dipstick. Needless to say, I did not start up the engine. When I ran the engine previously (and discovered the sheen) the oil level was about 1/2 quart below max.

So clearly something is contaminating my oil. I assume it is raw water. My first guess would be the oil cooler. Does that sound right? I assume the fix would be to remove the oil cooler and have it pressure tested to verify that it has an internal leak, and replace it if it does. Is there anything else I should check first, before assuming it's the oil cooler? I'd appreciate any thoughts or advice on this.

[Dale Tanski]

Brian,

If it was water in you engine oil and you have run it, the oil will emulsify into the oil and it will appear milky color. The more water the milkier it will be.  If there is no color change my guess would be diesel fuel in the oil.  Either way, not good.

Dale

[PeteW]

You need to have the motor running to generate fuel pressure so it seems impossible for your crankcase to fill up with diesel just sitting for a month. Old school mechanics like me have been know to taste the motor oil to see what's in it. You should at least be able to smell large concentration of diesel in your motor oil if its really there. I get some erroneous dip stick reading if I don't clean the stick off and check it a couple of times.

I suppose you could have an injector that's stuck on. It will spray so much of diesel into the combustion chamber  that the cylinder will not run (combust). That would be easy to find and fix. It's the one injector that doesn't get hot like the others after a few minutes of running.

Or it might be a simple as an exhaust valve tappet clearance that's closed up. This should be easy to remedy provided you haven't burnt the valve or valve seat. You will have no compression in that cylinder and as a result of the tight valve and raw un-burnt  diesel with blow out the exhaust port. Valve adjustment is all part of a regular tune up.

Neither of these possibilities explain diesel in the oil however. Which is why I'm doubting that to be true.

Pete

[SVJourney]

A totally stuck injector would eventually add oil as the fuel would wash the cylinder and get past the rings.  But I'd think you would notice if your engine was running on 3 cylinders.

The input seal in the pump where it mounts to the engine failing could pump fuel into the oil. 

The lift pump can fail internally and have fuel go into the engine that way.

But I agree with Pete.  Its easy to get fooled by the 365 dip stick, esp as you are probably checking it by braille from under the sink base in the galley. Wipe the stick, dip, repeat until you are sure.  It can only be fuel if it looks like oil, but is thinner.  If water it will be milk, and it doesn't take much water to make it look that way.

[brian chalk]

Thought I would update on my water-in-oil problem. As I mentioned above, I checked the oil level and found it alarmingly high. The next day I pumped out the oil using my Moeller oil extractor through the dipstick tube as I do for oil changes. I got about 6 and a half quarts out and nearly 2 quarts were obviously water. The pick up tube on my extractor must have gone to the bottom of the sump as clear water came out first before oil started coming out with it. I changed the oil filter, and refilled with fresh oil. With the raw water seacock closed, and the engine stop engaged, I turned the engine over a few times for 3 or 4 seconds each time trying to circulate the new oil a bit. Then I took the oil cooler out. The oil cooler clearly had oily water in both circuits. It was pressure tested and failed instantly. So I have ordered a new oil cooler which should be here Monday, and the engine is sitting with fresh oil.

When I get the new oil cooler installed, I am thinking I'll want to run the engine briefly to check my plumbing work and connections, then do another oil change. My question is how many oil changes would I need to do to be confident that most or all of the water is out of the oil? I thought that each time I changed the oil, I could keep the extracted oil in clear containers for a day or two so I can see how much water settles out. Once I get to the point where I can't see any more water settling, I should be good?

[Dale Tanski]

If you run the engine for any length of time the water won't be separate from the oil it will emulsify and mix with the oil.  That is the milky stuff we referred to.  Once its gone to milk a complete change should do the trick. 

Good luck and good detective work on the oil cooler.

Dale

[jpendoley]

Brian,
Thanks for the update and glad you were able to isolate the problem. It really helps others to hear about not just the proble, but the resolution too.

[PeteW]

Brian,  Glad to hear that you got to the bottom of the problem. Funny none of us were able to give a correct diagnosis. But what you discovered exposes something I always thought to be a bad idea. And that would be running raw water through any of the oil coolers. I think raw water should only go through the main heat exchanger. That's the one with the zinc in it.

A failure of the heat exchangers for engine oil and hydraulic fluid can cause catastrophic damage. Engine coolant that contains fresh water and antifreeze  is designed to inhibit corrosion. I think those circuits would be more reliable if they were cooled with engine coolant.

My Westerbeke (W58) abides by this rule. But when I added the Borg Warner 5000 gearbox I ran raw water through that cooler as a matter of expediency. It sounds like the 40 does not, which explains why you were able to detect the problem initially. This is a reminder to all of us why its import to check and inspect you oil and hydraulic fluid for signs of water.

Beyond re-plumbing my gearbox cooler, I would like to add a valve so I can quickly flush the raw water circuits with fresh water. People I know that lay their boats up for months at a time go one step further and pickle the motor with a mixture of fresh water and vinegar.

Pete

[Della and Dave]

I don't know if there is any way for you to do it in your boat, but if you can get to the drain plug and drain the oil from there, instead of using the extractor, you will get more of the water out.  I would love to have a banjo fitting on it myself, but haven't gotten to that job yet.   Sliding a shallow aluminum foil pan with oil absorbing pads in it under the engine once I have gotten as much oil as I could out with the extractor was what I was considering to replace the plug with a fitting.   Don't know if it will work though without making a mess.   

You should be able to get to it from under the sink.