Diesel or oil Discharge?

[zinbaad]

Perhaps I didn't notice it before but on starting up & returning to my slip I notice a light film of what appears to be diesel or oil around Mahalo. Just wondering if this is normal. It might just be less than an ounce but I dont recall seeing it before. Valve issue?

[loubennett]

I am going through a similar experience with the Yanmar 315 in Quest. I'll share what I know so far. I notice a sheen on the water on startup and when I returned to the slip. I thought it was unburned diesel fuel and the mechanic went through the fuel system - changed filters and put in an additive. He suspected it was because the engine was running rich at low speed and the additive would clean the injectors. The amount of smoke in the exhaust reduced dramatically, but the sheen persisted. I was also having a symptom where the prop would turn significantly when the transmission was in neutral. Checking the transmission fluid level showed it was quite low. Filling it helped the neutral problem, but also revealed water in the transmission fluid. (My bad for not checking it more frequently.) This condition comes from a leak in the transmission cooler. Transmission fluid gets in the cooling seawater and water gets in the transmission. We now think that the sheen is transmission fluid, not diesel fuel. Fortunately I think we caught it before the transmission was badly damaged. The mechanic will be replacing the transmission cooler and flushing the transmission in the next few days. With luck, the transmission is fine and the sheen will go away.

The message here is be sure to check your transmission fluid. Replacing the transmission cooler is fairly expensive, but less than rebuilding or replacing the transmission, with the inevitable stranding when it breaks down. I new from the start that my problem was not engine oil. Not a drop was missing from the engine. I thought the only other source was unburnt diesel fuel, but it's not.

[zinbaad]

Uh ogh I better go down and check it today. Thanks for the info. Any pic of the tranny cooler location?

[RobS]

Ed, the cooler is usually mounted over the tranny, it will have 2 hydr lines to the tranny and obviously be part of your raw water cooling system, so 4 hoses altogether, 2 small, 2 large. You won't see much just looking at the cooler without taking off the cooling water hoses and inspecting it internally or pressure testing it. Inspect the coolers externally for obvious signs of corrosion and check the tranny fluid to be sure it is at proper level and free of water. Some tranny coolers have zincs, some do not, some have been removed and replaced with a fitting for the cooling pisser for the dripless shaft seal....

[loubennett]

I don't have a picture and mine is on a 28 TE engine box so it oculd be different on yours. On mine it is located above the transmission. It is a horizontally mounted cylinder with the cooling water hoses attached to the ends and the transmission oil hoses attached to fittings on the top. On the 28 engine box it's right in front of you when you open the engine cover, but that's because the engine is "backwards" with the tramsmission toward the bow. You should be able to determine if the cooler is the problem by checking the fluid level in the transmission. If you have the problem, the level will be low and/or you will have water mixed in. Water mixed in automatic transmission fluid makes a pink, frothy mixture that looks something like a strawberry milk shake. If it's very low, mine was off the dip stick, fill it to the correct level, run the engine for a short time, and check the dip stick. If there's water it will be apparent and don't run the engine until it's fixed to avoid transmission damage. If you see clean transmission fluid on this check, you still could have a problem that you caught very early. It seems more transmission fluid goes out than water comes in and there may be a period where the water is unoticeable. In that case check the fluid level very frequently. If it's going down (and not dripping into the bilge via a leaky seal) it must be going out through the cooler.

I think transmissions may be the most frequently neglected pieces of machinery on boats. I know with previous boats (mostly sailboats with small transmissions) my attitude was that if the transmission fluid is not leaking into the bilge, it must still be in the transmission. That's not a good frame of mind for larger transmissions with coolers.

You didn't mention anything about smoke from the exhaust. After my experience, I have the opinion that if the exhaust gases are clean, you have fairly complete combustion, and any oil is probably not diesel fuel. Thats only speculation, but makes some sense to me.

[RobS]

Here's a picture of the cooler

[zinbaad]

Thanks for the pics & info Lou & Rob, looks like, if it is the cooler, removal should not be too hard(for a midget anyway). I am leaving work in a few minutes, first will check tranny fluid for level & contamination, If it looks fine change the Racors, dump in a gallon of Luk for the injectors & I change the oil which is over due.
I'll let you know how it goes tommorrow

Glad you mentioned it would be Raw Water as I thought the tranny used the antifreeze

[jleonard]

light film of what appears to be diesel or oil around Mahalo. Just wondering if this is normal

I have yet to see a marine diesel that does NOT leave a sheen. Some are very light. Some dependant on ambient temperature.A diesel needs to have the cylinder temp up there a bit before it will combust the entire charge. Block heaters and air heaters are there to reduce that smoke and resultant sheen.
You need to establish what is normal for your engine and go from there.

[zinbaad]

Update
Started up diesels not noticeing any white smoke or discharge of oil/tranny fluids
Pulled out the dip stick for both Trannies, no foam, clearish pink, no milky look,starbord seemed to be within the full levels, Port clearish pink, no milky look and also clearish ping. added an ounce or two on port. Small amount of corrosion on starbord cooler around raw water hose. I did not disconnect to view insides since fluids appeared ok
Proceeded to change racor filters adding quart Lucas additive & diesel to to each one to clean injectors. No water visible in filters, minimal crude on bottoms. Ran diesels, no smoke no fluids discharged. Not bad after 130 hours @ est 13.50 gph
Decided to change my over due oil with Rotella & the Jacor Bucket system. Stuffed down that 1/4 inch hose in the dipstick, what a freakin mess i made. Switched over to the Garden hose adapter & I was only able to get out 2 gallons oil in each engine. Changed both filters, yuck. Starded up engines, no smoke, no discharge.
Hopefully with these changes I wont see excessive smoke or fluid discharge.
Lessons
Change oil at least every 100 hours ( discharge could possibly be drop in viscosity of the contaminated oil allowing fuel passage through valves?)
Install oil change setup with bank valve & additional oil pan adapter at dip stick to make "FULL"oil changes easier (I wonder if it can install adapters with engines in boat)
CHECK Tranny fluids Regularly!
Hey Rob any input on the oil pan adaptors I saw you had installed!
Lou thanks for the push to get down & check the tranny, whew so glad there was no water in it

[RobS]

Funny you posted this, I changed my oil last night too.

Yanmar recommends 6months/125hours. In diesels the engine oil becomes contaminated with acids as a biproduct of combustion that washes down the cylinders. This is why it's so important to change just prior to winter (or any) layup. I always change at haul out and then again mid-season. These high-speed low-displacement diesels are not the engines to skimp on your maintenance, especially lubrication and cooling.

Unless you were gonna install an on-board oil pumpout setup (which it appears you are considering), the oil drain hose assembly is not that important. I only elected to install it since the engine was out so it was a pc of cake. I have managed to become quite the "Harry Houdini" on my 28 when it comes to accessing the tough areas under and around the engine. Not sure how tight your 31 is but I'm pretty sure I would be able to get to it on my 28. Rather than using the garden hose adapter on the dipstick tube, a short length of the blue wash down hose fits nicely over the top of the dipstick housing and then secure that to a larger hose to the pump. I sucked oil from both places last night to be sure I got every bit I could.

I have changed my oil several times and also changed the oil w/Matt on his boat and he does not have the added drain hose so it goes out via the dipstick. There seems to be very little difference when comparing them as far as ease of use and amount of oil removed.

I manage to get nearly the full 10+ qts into her on the refill. Yeah, the inverted oil filters certainly suck. I just completely pack all the areas underneath with oilsorbs and rags and have something on the ready to drop the filter into. Then Mr. Houdini gets down there to wipe up a few drips.

Don't forget about changing the tranny fluid. I believe this is recommended to be done annually. I have changed mine each year. It is easier than the engine oil since the filter just sits in a housing cast into the tranny body. You'd have to really screw up to make a mess changing the tranny fluid and filter but it's always possible

[zinbaad]

Took Mahalo for a cruise to Little Neck Bay with about one hour cruise time. All seemed fine,
I do wonder why I removed 2 gallon Oil, (dip stick said full) & replaced 2 gal & a bit more than quart, on each engine. Starbord engine required another quart, checked dip stick 3 times. Checked tranny fluids ok

[RobS]

Since you checked mulitple times I am sure you are good but just be sure not go over the FULL mark, you're better off slightly under ADD then over FULL for a short time. I don't remember the numbers but I know it's designed that you can be several qts under ADD and she'll still get sufficient oil.

Ed, do you have the 2nd dipstick? It's a smaller one tucked underneath on the opposite side of the engine, basically under the intercooler near the oil cooler.

[zinbaad]

Yes I do have double dip sticks. Checked both for comparisons & needed to add a little more to starboard engine. Went out to Oyster Bay & back Labor Day and seemed to run fine. Damn I hate it when Labor Day is over!!.

[loubennett]

An update on my transmission cooler
The mechanic installed the new transmission cooler today and flushed the transmission. He flushed it four times and changed the filter. The good news is there is no evidence of transmission damage so everything should be fine. He also wants to flush it and change the filter again after some use. There is still a small amount of oil coming from the exhaust, but it is greatly reduced and we think it will just take a little while for the raw water cooling system to flush it all out. I'm relieved that there was no damage tot he transmission. It must be pretty rugged to have come through this episode unscathed. Now I can resume my vacation cruise plans.

[Pitou]

An update on my transmission cooler
The mechanic installed the new transmission cooler today and flushed the transmission. He flushed it four times and changed the filter. The good news is there is no evidence of transmission damage so everything should be fine. He also wants to flush it and change the filter again after some use. There is still a small amount of oil coming from the exhaust, but it is greatly reduced and we think it will just take a little while for the raw water cooling system to flush it all out. I'm relieved that there was no damage tot he transmission. It must be pretty rugged to have come through this episode unscathed. Now I can resume my vacation cruise plans.

That's great news. Thanks for the lesson and raising my awareness.