Engine Oil Analysis

[S/V_Surya]

Originally Posted by Charlie

Not an expert here but it is my understanding that diesel oil is different from gasoline in that it is a lubricant. I have the same problem as you do on a yanmar engine. I was told by a wise mechanic in Mexico that it would be a good idea to change the oil. Run the engine for a half hour with the new oil and then to change the oil again. I resolved the problem with the lift pump by bypassing it completely and installing an electric lift pump. When I returned home from Mexico I replaced the lift pump but am once again having the creating oil problem. Long story short. The diesel will decrease the viscosity of the engine. The question as to whether it will damage the engine or not depends on the level of diesel contamination. I have been told that the contamination can also come from injectors that are not atomizing the fuel properly.

Thanks, yes Diesel can act as a lubricant that is one reason they last so long. I have heard that the additives in the Diesel is source of the damage to main bearings and other parts. I may have had this problem for some time. My feeling is running or a couple hours wont cause significant damage.

[hellosailor]

Charlie, diesel and gasoline engines can often use the same oils but oils are normally rated with both a "C" and "S" rating. The "S" is for spark engines (Otto Cycle, gasolibe) and the "C" is for "Compression" fired engines, i.e. diesel.

AFAIK the main difference is that a diesel tends to form ash and carbon residue in the oil, which is also why the oil in a diesel engine turns black almost instantly, from carbon being picked up by the oil.

And if there's diesel (aka "fuel oil") leaking into the lube oil, it will actually reduce the viscosity, diluting the oil. Diesel won't lubricate as well as lube oil, so there's increased wear when the lube oil is contaminated by fuel of any kind.

[Charlie]

Originally Posted by hellosailor

Charlie, diesel and gasoline engines can often use the same oils but oils are normally rated with both a "C" and "S" rating. The "S" is for spark engines (Otto Cycle, gasolibe) and the "C" is for "Compression" fired engines, i.e. diesel.

AFAIK the main difference is that a diesel tends to form ash and carbon residue in the oil, which is also why the oil in a diesel engine turns black almost instantly, from carbon being picked up by the oil.

And if there's diesel (aka "fuel oil") leaking into the lube oil, it will actually reduce the viscosity, diluting the oil. Diesel won't lubricate as well as lube oil, so there's increased wear when the lube oil is contaminated by fuel of any kind.

Agrees HS. I just reread my post and see that I wasn't clear I should have said diesel fuel oil is a lubricant. What I was trying to get at (and didn't succeed) is that gasoline will scour the oil off of the internal parts of an engine where as diesel will not. so that having diesel fuel oil in your lubricating oil is not as bad as having gasoline in your lubricating oil.

[S/V_Surya]

I just got a call from Blackstone labs to tell me I have significant moisture in my oil and 6% diesel contamination. Great. The moisture was in keeping with antifreeze contamination which is what I run through the engine. Will update when I get the report emailed to me. Time for more diagnostics. If it is antifreeze it is from water pump or head. I am going to pull the injector pump also to get it looked at.

[Cheechako]

I had a problem with diesel getting in the oil. It was making a lot of oil on the dipstik, turned out to be a bad injector in one of 4, could hardly tell, it ran good. When running, crack off the nut on each injector, the engine should slow down with each one, if not, thats your bad one.

[S/V_Surya]

Originally Posted by Cheechako

I had a problem with diesel getting in the oil. It was making a lot of oil on the dipstik, turned out to be a bad injector in one of 4, could hardly tell, it ran good. When running, crack off the nut on each injector, the engine should slow down with each one, if not, thats your bad one.

My engine runs good also, no smoke. I have noticed that it is difficult to start if it sits for a while. I thought it was air getting in cause filters not set tight. But now I am thinking it could be a slow leak from injector pump. They say one should replace injectors as well as injector pump when doing this service.

[hellosailor]

"They say one should replace injectors as well "
If you have the time, it is often economical to have injectors rebuilt. Cleaned and recalibrated, so they are all firing the same fuel volume. If you don't have the time--then it pays to replace them and STILL send them out for rebuilding, which will leave you with a spare set for the future. Shop around for price, some places seem to add an extra decimal point just because they can.

[Cheechako]

Injector pump issues are somewhat rare, so check for other issues first. You shouldnt have to replace the pump with injectors. I believe most pumps last the life of the engine, someone correct me if thats wrong.

[svcattales]

Originally Posted by Cheechako

I had a problem with diesel getting in the oil. It was making a lot of oil on the dipstik, turned out to be a bad injector in one of 4, could hardly tell, it ran good. When running, crack off the nut on each injector, the engine should slow down with each one, if not, thats your bad one.

Surya, this is a simple test and can be a great aid to diagnosis. When you're doing this, take note of RPM reading as you crack open the fuel-line nuts going into the injectors one at a time. The RPM drop should be almost equal on each cylinder. If you have one injector where the RPM drop is less than the others, that may be your bad injector or point to a different problem. I would not remove the injector pump at this point. It is a complicated, expensive part so make that the last thing you touch until you have checked everything else.

I also had antifreeze in my oil and the RPM drop in cylinder #2 was significantly different than the other cylinders. The cause turned out to be a small crack in the cylinder head water passage. Water was leaking into the cylinder and one of the valves burned from corrosion and I lost compression. Because I diagnosed the problem via oil anaylysis, the head was repairable and I avoided a major engine failure. Your symptoms could describe the same problem. The head crack could allow the moisture into the oil and loss of compression could account for unburned fuel running down the cylinder wall into the oil sump.

Good luck with your troubleshooting.

[perchance]

Originally Posted by Cheechako

Injector pump issues are somewhat rare, so check for other issues first. You shouldnt have to replace the pump with injectors. I believe most pumps last the life of the engine, someone correct me if thats wrong.

Yes the pump should last the life of the engine but it may be wise to have it bench tested and calibrated at the same time as the injectors.
It is usually done if your are doing a major overhaul.

[Chief Engineer]

The idealized diagrams of a four-stroke Otto cycle Both diagrams:
the intake (A) stroke is performed by an isobaric expansion, followed by an adiabatic compression (B) stroke. Through the combustion of fuel, heat is added in an isochoric process, followed by an adiabatic expansion process, characterizing the power (C) stroke. The cycle is closed by the exhaust (D) stroke, characterized by isochoric cooling and isobaric compression processes.


I like suck-squeeze-bang-blow

[S/V_Surya]

Thanks for the input.
Here is the report I got from Blackstone:

"RICHARD: Thanks for the notes. Physically, the oil doesn't look too good. Your increasing oil level is likely a combination of fuel and moisture. Fuel was found at 6.0%, which is in our cautionary range and could show a leaky injector. The bigger issue though may be moisture. The oil was a milky gray color andinsolubles were very high at 40.0%. Potassium, silicon, and sodium might show coolant, though these levels aren't too excessive. The viscosity was higher than our charts go, so this oil was basically a sludge. Wear was also quite high. Change this oil out and check back."

I like the idea of checking the injectors first and I will try the diagnostic test proposed by svcattales first after I have replaced the fresh water pump ($110 from TAD diesel) and raw water pump. Svcattales did you see any white smoke from exhaust with your problem. The reason I do not think it is head or cylinder involved is my exhaust looks normal no black or white smoke.

As for injector pumps lasting the life of the engine, I wish it were true. On my previous boat which I owned for 20 years the injector pump lasted about 10 years (volvo MD6B). My boat was built in 1975 and engine is I am sure original. Do not know history of motor.

Thanks for all the great input guys!

[S/V_Surya]

Well the good news is TAD. I ordered the fresh water pump Thursday at 4PM and when I got home after work on Friday there was my pump. Great service. The bad news is looking at my new pump and removal of old pump I think it is highly unlikely this is the source of my moisture problem. Even a bad pump would not have contact with oil. Even looking at raw water pump that would have a hard time being source of moisture. I am going to call TAD today to get their opinion but I may have to pull the head. The oil cooler is a possible source but the one I have is only 4 years old.

[hellosailor]

Surya-
I'm not sure if this could affect you (your oil cooler) but a friend of mine just had an "oil all over" mystery in a Saturn car. Turns out there's an internally mounted oil cooler assembly in the engine and they need to be installed with a "special" sealant that can take constant immersion in hot oil and coolant. His was replaced two years ago by a shop that used generic sealant--and now it has to be done all over again with the right stuff.

So if any of those suspicious parts are 'sealed' and it looks like generic gasket material or silicon seal might have been used, there's reason to suspect them. Anything facing constant immersion needs to be sealed with the right sealant.

5200 perhaps? <VBG>

[S/V_Surya]

Thanks for the reply. I hope it is not the problem but TAD Diesel just told me if that was it I would be losing oil, as oil pressure is high than freshwater pressure.

So here is TAD recommendation: Do not panic over one oil sample. They said change oil a few times and the filter and then run engine and check again. As far as the diesel in the fuel he said 99.9 it is the seal on the injector pump.

So that is what I will do for now. Sailing season almost over here on Mid-atlantic so now I have a winter project.