6.2L MPI Horizon MIE Oil Analysis Shows Antifreeze

[Greg_E]

Changed the oil in preparation for winter storage and sent oil samples out for analysis. The report for one engine came back with with high levels of the elements found in antifreeze along with wear metals elevated. Roughly 50 hours on the oil and 650 on the engine. Engine seems to be running OK at cruising speed but the last couple times I used it the temp gauge for that engine was about 5 degrees higher than the other. Exhaust risers were replaced in 2017. In 2019 some old pieces of impeller were found in one of the cooling hoses creating a partial blockage which caused the engine to go into limp mode at around 3800 RPMs The raw water impeller was intact so I don't know how long the broken pieces were in there. Problem seemed to be resolved but now I'm concerned that the previous problem is related to the current issue. Check of the coolant level revealed that the level was down some but I did not notice any excessive steam in the exhaust or smell any antifreeze fumes. The oil I changed out has been sitting for about three weeks and no water or antifreeze has separated from the oil. Compression test was done last year and was excellent in all cylinders. Hopefully I have caught this in time.

I'm new to Inboard engines so I need some help diagnosing the cause in a logical manner. Unfortunately the boat is being hauled this week so I will not be able to run it to test.

 

[Scott Danforth]

change oil

then drain coolant and pressure test glycol side. you most likely have a head gasket going south, or the intake gasket is leaking. this is common for a motor that has been overheated (your event from the blockage of the old impeller)

the only place where oil can be contaminated by glycol is either a gasket failure, or a block or head failure.

 

[Greg_E]

Thanks for the reply Scott. Will I need any special equipment other than the the hand pump with pressure gauge that mounts onto the heat exchanger? I don't have that tool so I want to be sure I have the right equipment when I go to the boat this weekend. Also assuming there is a drop in pressure how do I pinpoint the source of the leak?

 

[alldodge]

If you didn't see any foaming or milk in the oil sample a pressure test may not show. Go to the local auto store that rents tools and get a radiator pressure tester. If it does show a leak, do a compression test. If compression test shows good, it could be in the intake

 

[Greg_E]

If you didn't see any foaming or milk in the oil sample a pressure test may not show. Go to the local auto store that rents tools and get a radiator pressure tester. If it does show a leak, do a compression test. If compression test shows good, it could be in the intake

Thanks. I'll see if I can get that done this weekend. If the coolant leak is between the oil and coolant passages could you have a leak between the head and block and still have good compression in that cylinder? I suppose if that was the case though, all of the missing antifreeze would have been in the oil and I don't see signs of that.

 

[alldodge]

Don't see a leak in the passages, only with gaskets (head or intake). If it was in the passages there would be lots of AF in the oil

You can have good compression and still have a leak if its real slight, and over time it will get worst. Biggest issue with AF in the oil is the AF attacks bearings

 

[scoflaw]

Testing the AF would tell you if combustion gases contaminated it. When the oil heats up the AF mixture would evaporate out of the oil to an extent.

With high levels of wear metals I'd tear it down.

 

[Greg_E]

Don't see a leak in the passages, only with gaskets (head or intake). If it was in the passages there would be lots of AF in the oil

You can have good compression and still have a leak if its real slight, and over time it will get worst. Biggest issue with AF in the oil is the AF attacks bearings

I assume that is why Scott said to drain the antifreeze and change the oil. I did change the oil when I took the samples, but I used the boat one time after that so if there is AF in the oil I will do what he recommended. The lead readings were high so yes the AF has been working on the bearings. Other metals were higher than normal averages but nothing like the lead. After 50 hours of use the lead was 149 with the universal average being 7. 149 is bad but how bad I don't know. Oil pressure is still good so hopefully minimal damage has been done to the bearings. Rebuilding the engine is not something I will be doing so I will try to fix the problem and see how things go.

 

[Greg_E]

Thanks for the reply Scott. Will I need any special equipment other than the the hand pump with pressure gauge that mounts onto the heat exchanger? I don't have that tool so I want to be sure I have the right equipment when I go to the boat this weekend. Also assuming there is a drop in pressure how do I pinpoint the source of the leak?

I have already winterized the raw water side of the cooling system. I would prefer not to have to do that again. No harm is removing the serpentine belt so I'm not turning the raw water pump when I do the compression test, it there?

 

[Scott Danforth]

your over-thinking it.

the raw water pump wont move enough glycol on the raw water side to matter. however you can remove the belt if you like.

 

[alldodge]

No harm is removing the serpentine belt so I'm not turning the raw water pump when I do the compression test, it there?

No problem

 

[QBhoy]

It would be a great result if the thing you used to pull the oil out was perhaps previously contaminated or used to pump coolant out ? What ppm was shown of AF in the oil ?

 

[Greg_E]

It would be a great result if the thing you used to pull the oil out was perhaps previously contaminated or used to pump coolant out ? What ppm was shown of AF in the oil ?

Antifreeze was listed as a percentage 1.32% Potassium 68 vs a universal average of 4 and Sodium 658 vs 18
No water found.
No chance of contamination from oil change equipment.

Got to the boat this weekend. Coolant tank pressure tester had every possible adapter except the one I needed so I didn't get that done yet. I changed the oil and partially drained. the engine coolant by removing the large hose on the engine water pump. Got about 2.5 gallons out. Any easy way to remove the remainder and do I need to remove it to do the pressure test? I have a different tester on order. Scott, I assume you want the coolant drained so when it is pressure tested I am not forcing more antifreeze into the oil. Is that correct?

I pulled the plugs and did a compression test. All the plugs looked about the same. I will post pictures when I have time but I have a busy day today. The compression numbers were fairly even but significantly lower in all cylinders vs the results when I had the boat surveyed last November. I was using a compression tester that I have not used before so I want to verify that it is reading correctly before I post results. Sprayed fogging oil in a couple cylinders and only had an increase of a couple lbs. Ran out of time, so that is where I'm at now. It isn't looking good.

 

[alldodge]

Your leak will be on the top end so no need to drain more coolant for pressure test. The coolant is removed because air will pass easier then coolant.

 

[Scott Danforth]

you need a completely empty system because as AD mentions, you are looking for a small leak, and air molecules will go in places that coolant wont, and with coolant in the system, you may not find it.

has nothing to do with forcing more coolant in your oil

 

[Greg_E]

Your leak will be on the top end so no need to drain more coolant for pressure test. The coolant is removed because air will pass easier then coolant.

Thanks for the reply. I thought it was OK but it doesn't hurt to check.

When I do the pressure test, will I be able to narrow down the source of the problem, or am I just confirming what we already know from the oil test report? Assuming for now that I can't narrow down the source of the problem my only options would be to remove the intake manifold and hope I find the source of the leak and if not replace the inboard head gasket. and recheck to see if the leak is fixed. Is that correct or is there a better way to go about this? It is not possible to pull the outboard exhaust manifold and head with the engine in place. Having the engine pulled is not an option until spring and in another month it will be too cold to work on it anyway.

 

[Bondo]

When I do the pressure test, will I be able to narrow down the source of the problem,

Ayuh,..... When yer doin' the pressure test, yer goin' to Listen for the air escaping,......

So the coolant level needs to be below the leak,....
You'll want to open all the holes in the motor to listen through,....
Pull the spark plugs, the valve covers, 'n open the throttle plate,....

Once you hear the hissin' sound, follow the sound to the leak,....

 

[Greg_E]

AD, Scott, and Bondo. Thanks for providing the explanation for why I am doing certain tasks and tips on troubleshooting this problem. I have fixed a lot of stuff in my life but this particular problem is new to me.

I tried to upload a couple pictures of the spark plugs but was getting a server error. I'll try again later.

 

[Greg_E]

Here are pictures of the spark plugs. I don't know if they offer any clues but here they are.
Left to right cylinder 1-8. I probably should have arranged them 1,3,5,7 and 2,4,6,8 but too late now.

 

[alldodge]

Look fine to me