7.4L expelling fuel/oil out exhaust creates sheen on water

[km1125]

UPDATE: I swapped IAC and ECM from the port engine and problem remains.

IAC won't really cause a rich running engine, but it will cause a poor or erratic idle.

You did say that the plugs looked like the engine was running rich. You could isolate whether that's just at idle or all the time if you run the engine hard for a bit (a bit of time at cruise speed would be fine) then shutdown with as little idling as possible and pull the plugs and then check them again. If they look much less "rich", then you can concentrate on things that make it rich at idle rather than things that make it rich all the time. The things that would affect mixture could be a cold engine (either actually cold or perceived as cold by a bad temp sensor), a bad reading from the intake air temp sensor (bad sensor or default values because the ECM can't read the sensor due to a wiring issue), dirty or defective MAF sensor, malfunctioning fuel pressure regulation (could be either an internal fault or some wrong in the manifold reference vacuum lines), etc...

 

[Triniborn]

UPDATE: I will be capturing the water out of my exhaust and will be sending it for analysis to determine if in fact the sheen is due to oil or gas.

 

[scoflaw]

That should be obvious enough just by looking at the plugs.
Dry sooty= fuel
black crusty= oil

 

[Triniborn]

That should be obvious enough just by looking at the plugs.
Dry sooty= fuel
black crusty= oil

 

[Triniborn]

View attachment 120230 View attachment 120231 View attachment 120232

The top picture is a different spark plug from the spark plug in the bottom two pictures. Most plugs are like the last two photos.

 

[techmitch]

The top picture is a different spark plug from the spark plug in the bottom two pictures. Most plugs are like the last two photos.

Sorry if I missed it above. What is the gap reading on those plugs, who installed them, what is the spec. for that engine and are they they exact correct plug?

 

[dwna1a]

I agree the gap looks different, it is a photo and hard to tell. I’d still recommend a complete tune up. Plugs wires, cap.

Mine show a sheen in the water on start up but only after to day or two sit.

 

[Triniborn]

Purchased spark plugs from a Sea Ray dealer, I installed them. "The NGK BPR6EFS standard plugs come pre-gapped as specified by your engine manufacturer." The sheen issue existed before I replaced the plugs, just sharing for analysis by the group. Definitely carbon fouling based on some charts I'm looking at.

 

[techmitch]

Gap looks super tight and, it's a good pic. maybe it's right but I would have check, myself.
Note to self, read the whole thread if I you want to help.

 

[Triniborn]

View attachment 120230 View attachment 120231 View attachment 120232

Purchased spark plugs from a Sea Ray dealer, I installed them. "The NGK BPR6EFS standard plugs come pre-gapped as specified by your engine manufacturer." The sheen issue existed before I replaced the plugs, just sharing for analysis by the group. Definitely carbon fouling based on some charts I'm looking at.

Also, I think I should mention that the plugs on the port and starboard engine were replaced with the same spark plugs. They look identical as it relates to carbon fouling, except the port engine is not putting a sheen on the water. I will be running the boat to check to see if the plugs change with little idle time as recommended. Think I still need to do the analysis since I see signs of excess fuel and oil on the plug.

 

[Wanderer 290]

So there is fuel, maybe too much but from 8 individual injectors probably not unless there is an ECM failure.
Definitely have air?
So, is there hot spark, blue, at every plug? If not the coil may be suspect? And has the timing been checked?
Lastly, it was mentioned the compression was checked, what were the numbers?

 

[Triniborn]

So there is fuel, maybe too much but from 8 individual injectors probably not unless there is an ECM failure.
Definitely have air?
So, is there hot spark, blue, at every plug? If not the coil may be suspect? And has the timing been checked?
Lastly, it was mentioned the compression was checked, what were the numbers?

Not sure on the quality of spark. I do not recall the compression numbers but they were within specifications and not too much variance.

 

[Triniborn]

UPDATE: I might be oil after all out the exhaust. I tried collecting some water in a bottle for sample but it appeared clear. I then used a white bucket to collect a decent amount and I noticed what appears to be oil. See pictures.

The engine does smell rich but that might just be how it is at idle or just the 2000 454s in general. I’ll troubleshoot that later, my main concern is the sheen on water. If this is oil, the oil cooler was bypassed. So potentially a more serious issue

 

[scoflaw]

The shiny top plug pic says oil. If oil consumption isn't that bad I would run it, try some thicker oil like 20-50. Probably valve guides but you could change the valve seals for starts.

 

[markrsimon]

When you say bypassed the oil cooler - did you tie the water lines together, or tie the oil lines together? Just want to make sure you’ve set eyes on the water output side of that cooler and there is no slick there.

 

[Triniborn]

The shiny top plug pic says oil. If oil consumption isn't that bad I would run it, try some thicker oil like 20-50. Probably valve guides but you could change the valve seals for starts.

Yeah, I’ll probably look at replacing valve stem seals, if I’m losing oil. Need to monitor it more closely to confirm.

 

[Triniborn]

When you say bypassed the oil cooler - did you tie the water lines together, or tie the oil lines together? Just want to make sure you’ve set eyes on the water output side of that cooler and there is no slick there.

I tied the water lines together with a brass coupler, and still noticed a sheen on the water, which took me down the fuel rabbit hole.

 

[mrsrobinson]

A boat I had under contract last year had the 8.1s. During sea trial, while idling away from the dock I could smell gas from the starboard side exhaust thru hull and saw blueish smoke and a sheen. When the surveyor tried to put her up on plan that engine shut down and would not restart.

We limped back to the dock, replaced the fuel/water separator, which had brown muck in it, tried again, no better. Switched the fuel tank that motor pulled from, same result. Pulled the fuel rail off, cleaned it out, reinstalled, same result. I left at this point, literally 3-4 hours trying to fix the sellers issue. Seller was not present, he sent a buddy.

Later learned the seller let the fuel tank run dry the last time he had the boat out, and filled it back up the morning of the sea trial. Post sea trial he had the tank cleaned, some more cleaning and allegedly the engine finally started. I never went back as he was a bit of a jerk about it. He offered me 2 water fuel separators in the sale to resolve the issue.

Long story short I later learned the exhaust fuel smell turned out to be the value seals.

 

[Triniborn]

PROGRESS UPDATE: It was a bad oil cooler after all. TBD if sheen will go away once cooler is replaced.

Now this wasn’t simple as it should have been and I’ll take some of the blame; however, I want to share my story from the beginning to help other boaters.

BACKGROUND:
I purchased my 2001 Sundancer 340 in July 2020. The survey mentioned the sheen out of the starboard exhaust among other things: port shaft seal, rudder packing, etc. Things you would expect for a ~20 year old boat.

The boat’s first voyage after purchase was from the broker in Anacortes, WA in the Puget Sound to Kenmore, WA (Lake Washington). During the 4-5 hour trip we noticed the starboard engine lose <5 psi in oil pressure. We checked the oil and everything looked good, so we proceeded to Lake Washington.

Once the boat was docked at the marina, it was used a couple times with friends. One day I decided to diagnose the sheen on the water coming out of my starboard exhaust. I examined the service manual to understand the raw water cooling system after reading helpful forums like clubsearay.com. Raw water is sucked from the seacock, through the strainer, through the water impeller, through the transmission cooler, through the fuel cooler, through the oil cooler, through the heat exchanger, through the exhaust manifold and finally out the riser and into the exhaust tube. The oil cooler seemed like the logical part that was failing. Given the sheen and the loss in oil pressure.

I proceeded to remove the oil cooler and noticed contaminated oil (milky) coming out of the cooler and the oil lines. My initial reaction was like this sucks but at least you know the problem…or so I thought at the time. Needless to say I ordered a new OEM cooler ~$400.

MISTAKE 1:
I flushed the oil system the best I could and replaced the faulty oil cooler with the new one. When I ran the starboard engine, I noticed the same sheen after several minutes of running. I was immediately discouraged making the stupid assumption that still seeing the sheen after only a few minutes of runtime that the original cooler was still good.

MISTAKE 2:
I took the original oil cooler home to pressure test it. However, instead of pressure testing with compressed air and looking for bubbles while submerged, I used water and looked for water to leak out the oil flares.

MISTAKE 3:
I was too cheap and returned the new cooler back for a refund and reinstalled the original cooler. Since it passed my stupid pressure test. Yes, I’ve kicked and cursed myself for the time and money I was about to spend.

EXHAUST MANIFOLDS AND RISERS:
The survey called out that the exhaust manifolds and risers would likely need replacement due to signs of corrosion (paint flaking on riser). I also read countless posts from other boat owners mentioning that faulty manifolds/risers can introduce water into the exhaust port of the head and into the crankcase. So I ordered OEM manifolds and risers in hopes to correct my oil contamination issue. While the old exhaust manifolds where removed, we did a compression test and all cylinders read great. After several runs the oil contamination issue seemed to have been gone; however the stubborn sheen remained.

FUEL SYSTEM, IGNITION SYSTEM, ECM:
I had a mechanic take a quick look at the sheen and he said it might be fuel based on the iridescence in the water and the smell. He checked the spark plugs and noticed that the plug for #4 cylinder looked noticeably cleaner than the other plugs and thought it might be a stuck open/dirty injector. Anyways, that got me down the fuel rabbit hole that was discussed in the aforementioned posts.

OIL DROPS IN BUCKET OF EXHAUST WATER:
In my previous post I explained that I captured water out my starboard exhaust and noticed what looked to be oil. At this point I’m thinking valve stem seals.

WTF MOMENT:
During a routine oil check with the dipstick I noticed the oil color was off. To confirm contamination, I removed an oil line from the oil filter mount and sure enough the same contaminated oil (milky). At this point I’m like WTF is wrong with this engine. Blown head gasket? Cracked head? Blown intake gasket? How is this possible, since the compression test results were ideal.

PROGRESS:
So before getting into the removal of heads I wanted to make sure that was the issue. They have tests that detect exhaust gases within the heat exchanger, which suggests an issue with the head. I ran the test and no exhaust gases were detected, which left the possibility a blown intake gasket. Before doing the coolant pressure test I decided to remove the oil cooler again and this time pressure test it using compressed air. Needless to say, I don’t think I’ve ever been so happy to see bubbles.

LEARNING MOMENT:
How does water get into the oil and why didn’t the oil contamination show up after the manifolds where replaced? The oil pressure is greater than the water pressure, which will leak oil out the exhaust; however, when the engine is shutoff the water pressure is now high enough to potentially leak into the crankcase. This happens little by little, therefore taking time for the contamination to show up.

CONCLUSION:
I’ve ordered new oil coolers and transmission coolers for both my starboard and port engines. I will also be looking to replace my fuel coolers and heat exchangers soon. I’m hoping the sheen will go away in time once the residual is removed from the exhaust hoses. It could be an unrelated issue; however, I’m hopeful it’s the oil cooler.

ADVICE:
For any new boaters out there buying a used boat, a marine survey helps tremendously; however, it doesn’t tell you what is the cause of an issue and/or how to fix said issue. Also, if certain parts are past their manufacture recommended lifespan, especially relatively inexpensive parts like oil coolers, just replace them.

RECOMMENDATIONS:
https://nuwavemarine.com/ - Mercruiser OEM Dealer
https://lencoheatexchangers.com/ - High Quality OEM Replacement Heat Exchangers and Coolers

 

[markrsimon]

PROGRESS UPDATE: It was a bad oil cooler after all. TBD if sheen will go away once cooler is replaced.

Now this wasn’t simple as it should have been and I’ll take some of the blame; however, I want to share my story from the beginning to help other boaters.

BACKGROUND:
I purchased my 2001 Sundancer 340 in July 2020. The survey mentioned the sheen out of the starboard exhaust among other things: port shaft seal, rudder packing, etc. Things you would expect for a ~20 year boat.

The boat’s first voyage after purchase was from the broker in Anacortes, WA in the Puget Sound to Kenmore, WA (Lake Washington). During the 4-5 hour trip we noticed the starboard engine lose <5 psi in oil pressure. We checked the oil and everything looked good, so we proceeded to Lake Washington.

Once the boat was docked at the marina, it was used a couple times with friends. One day I decided to diagnose the sheen on the water coming out of my starboard exhaust. I examined the service manual to understand the raw water cooling system after reading helpful forums like clubsearay.com. Raw water is sucked from the seacock, through the strainer, through the water impeller, through the transmission cooler, through the fuel cooler, through the oil cooler, through the heat exchanger, through the exhaust manifold and finally out the riser and into the exhaust tube. The oil cooler seemed like the logical part that was failing. Given the sheen and the loss in oil pressure.

I proceeded to remove the oil cooler and noticed contaminated oil (milky) coming out of the cooler and the oil lines. My initial reaction was like this sucks but at least you know the problem…or so I thought at the time. Needless to say I ordered a new OEM cooler ~$400.

MISTAKE 1:
I flushed the oil system the best I could and replaced the faulty oil cooler with the new one. When I ran the starboard engine, I noticed the same sheen after several minutes of running. I was immediately discouraged making the stupid assumption that still seeing the sheen after only a few minutes of runtime that the original cooler was still good.

MISTAKE 2:
I took the original oil cooler home to pressure test it. However, instead of pressure testing with compressed air and looking for bubbles while submerged, I used water and looked for water to leak out the oil flares.

MISTAKE 3:
I was too cheap and returned the new cooler back for a refund and reinstalled the original cooler. Since it passed my stupid pressure test. Yes, I’ve kicked and cursed myself for the time and money I was about to spend.

EXHAUST MANIFOLDS AND RISERS:
The survey called out that the exhaust manifolds and risers would likely need replacement due to signs of corrosion (paint flaking on riser). I also read countless posts from other boat owners mentioning that faulty manifolds/risers can introduce water into the exhaust port of the head and into the crankcase. So I ordered OEM manifolds and risers in hopes to correct my oil contamination issue. While the old exhaust manifolds where removed, we did a compression test and all cylinders read great. After several runs the oil contamination issue seemed to have been gone; however the stubborn sheen remained.

FUEL SYSTEM, IGNITION SYSTEM, ECM:
I had a mechanic take a quick look at the sheen and he said it might be fuel based on the iridescence in the water and the smell. He checked the spark plugs and noticed that the plug for #4 cylinder looked noticeably cleaner than the other plugs and thought it might be a stuck open/dirty injector. Anyways, that got me down the fuel rabbit hole that was discussed in the aforementioned posts.

OIL DROPS IN BUCKET OF EXHAUST WATER:
In my previous post I explained that I captured water out my starboard exhaust and noticed what looked to be oil. At this point I’m thinking valve stem seals.

WTF MOMENT:
During a routine oil check with the dipstick I noticed the oil color was off. To confirm contamination, I removed an oil line from the oil filter mount and sure enough the same contaminated oil (milky). At this point I’m like WTF is wrong with this engine. Blown head gasket? Cracked head? Blown intake gasket? How is this possible, since the compression test results were ideal.

PROGRESS:
So before getting into the removal of heads I wanted to make sure that was the issue. They have tests that detect exhaust gases within the heat exchanger, which suggests an issue with the head. I ran the test and no exhaust gases were detected, which left the possibility a blown intake gasket. Before doing the coolant pressure test I decided to remove the oil cooler again and this time pressure test it using compressed air. Needless to say, I don’t think I’ve ever been so happy to see bubbles.

LEARNING MOMENT:
How does water get into the oil and why didn’t the oil contamination show up after the manifolds where replaced? The oil pressure is greater than the water pressure, which will leak oil out the exhaust; however, when the engine is shutoff the water pressure is now high enough to potentially leak into the crankcase. This happens little by little, therefore taking time for the contamination to show up.

CONCLUSION:
I’ve ordered new oil coolers and transmission coolers for both my starboard and port engines. I will also be looking to replace my fuel coolers and heat exchangers soon. I’m hoping the sheen will go away in time once the residual is removed from the exhaust hoses. It could be an unrelated issue; however, I’m hopeful it was the oil cooler.

ADVICE:
For any new boaters out there buying a used boat, a marine survey helps tremendously; however, it doesn’t tell you what is the cause of an issue and/or how to fix said issue. Also, if certain parts are past their manufacture recommended lifespan, especially relatively inexpensive parts like oil coolers, just replace them.

RECOMMENDATIONS:
https://nuwavemarine.com/ - Mercruiser OEM Dealer
https://lencoheatexchangers.com/ - High Quality OEM Replacement Heat Exchangers and Coolers

Happy that you’ve finally found your issue.

Now many oil changes have you done? I probably did around 5 when I had my oil coiler leak. Sat at the dock with the engine running to get everything up to temp and the oil nice and hot. Then drained, changed the filter, filled her up - and repeat. I could have gotten away with less, but an oil change is far cheaper compared to replacing an engine.

Get yourself a 5 gallon bucket of oil (or maybe two) and several cheap fram filters, and 1 good final filter.

One last note - buy one more oil cooler, you’ve got another engine sitting over there. Also add trans coolers to your list for next year.