What’s the point of getting oil samples before purchase???

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Steve91T

Guru
Joined
Sep 12, 2016
Messages
898
Location
USA
Vessel Name
Abeona
Vessel Make
Marine Trader 47’ Sundeck
It’s virtuely meaningless without a trend. One of the mains was perfect, the other showed some signs of wear, an the gen was a mess. But it starts, runs, holds a load, doesn’t smoke and has great oil pressure. The sample place themselves it really doesn’t mean much unless there is a trend.

Thoughts?
 
Post the reports here. Pre-purchase samples do have value, but they are imperfect tools. I've interpreted several hundred, so might be able to add something here.
 
Here you go. Thanks guys!
 

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It’s virtuely meaningless without a trend. One of the mains was perfect, the other showed some signs of wear, an the gen was a mess. But it starts, runs, holds a load, doesn’t smoke and has great oil pressure. The sample place themselves it really doesn’t mean much unless there is a trend.



Thoughts?



Trends are important, but some materials found in the oil are major red flags, eg: salt, coolant, bearing metals.
I walked away from a purchase when the engine survey & oil analysis revealed a raw-water leak into the turbo, meaning salt water was being added to the combustion cylinders.
A costly parting.
 
They can show materials or liquids that shouldn't be there... like antifreeze, possible high sodium showing salt water, etc......

One right after an oil change...maybe not so much...its a judgement call, but for $25 per engine, its one of the cheapest insurance policies you can buy.

It may NOT show a hidden problem, but then again....it MIGHT.
 
Steve

Good question. In addition to oil sample results and meaning if any, look for:

Soot on the transom, oil burning smoke after warmup, does the engine immediately start, how much oil consumed between changes, by the book oil changes, ER condition, oil leaks, history of over heats etc.

This is where obtaining the maintenance logbooks prior to purchase pays off. And being able to talk with the maintenance provider(s). On go fasts forget all of the above.
 
So what do you guys think then of the samples that I posted?
 
The reports were unreadable for me. Need higher resolution.
 
Hrm...it’s how they uploaded. Any ideas how to upload a high resolution image? I’d love to get opinions soon.
 
Trends are important, but some materials found in the oil are major red flags...
Exactly. A one-time analysis could show up some materials that are WAAAY out of whack for the time that is supposed to be on the engine. That's a big red flag. Things that seem a little off? Those don't tell you anything without the trend.
 
We get regular reports from oil samples taken in the field of both diesel engines and hydraulic systems. While it's instructive to watch trends, what usually pops up the yellow and red flags (same Cat analysis results form as yours) are really bad things like high water content and dirt levels (hydraulics) and water/dirt/coolant/metals in the engines.



What triggered the yellow and red flags on those two reports?
 
Diesel generator
Ford Lehman 225 mains. Over 5000 hrs on mains and gen. Oil hasn’t been Changed in a while. 30 hrs on mains but 2 years ago. Gen is unknown

Generator:
Interpretation Text:IRON IS ELEVATED WITH EXTREMELY HIGH ALUMINUM AND SODIUM. LEAD, CHROME, SILICON AND POTASSIUM ARE ABOVE NORMAL A WELL. TEST FOR GLYCOL WAS NEGATIVE. VISCOSITY IS LOW. GC INDICATED 2.99% FUEL DILUTION. POSSIBLE WEAR SOURCES: BEARINGS, PISTON RINGS, CYLINDER LINERS, VALVES, CUT FILTER OPEN AND INSPECT FOR METAL, REPAIR AS NECESSARY. AFTERWARDS; CHANGE OIL AND PULL ANOTHER SAMPLE AT 25HRS TO MONITOR.

Starboard main:
Interpretation Text:AS COMPARED WITH YOUR PORT SIDE ENGINE. IRON APPEARS ELEVATED. COPPER AND LEAD APPEAR ABOVE NORMAL AS WELL. POSSIBLE WEAR SOURCES: BEARINGS, VALVES, CHECK FILTER FOR METAL/PLUGS. VISCOSITY IS LOW. GC INDICATED 1.88%% FUEL DILUTION. MONITOR SYSTEM'S OPERATION CLOSELY AND PULL ANOTHER SAMPLE AT 25HRS MONITOR.
 
My last generator sample came back like yours. It was hard to start. 10 hours later the engine would not start and all three cylinders had below minimum compression pressure. My thoughts are you are looking at least an engine rebuild in the near future.
 
I test my oil once or twice a year depending on hours. I centrifuge the oil so don't change unless I get a bad report, and that's never happened. The filters get changed once a year and get cut open to see what they're catching.
An oil test can catch things many hours in advance. It keeps a minor repair from becoming a major repair.
 
My last generator sample came back like yours. It was hard to start. 10 hours later the engine would not start and all three cylinders had below minimum compression pressure. My thoughts are you are looking at least an engine rebuild in the near future.
If the engine is diesel, you can add a block heater and get a few more easy starts. But watch for oil in the exhaust.
 
Steve

My 2 cents worth.

If you really like the boat, suggest you price in the cost to professionally rebuild engine(s). A less than stellar rebuild carries a risk. Time too.

The reason for a survey is to detect problems and fatal flaws. Looks like you found some. The other tell is no regular oil changes. Stick to your guns.
 
Man you guys are making me nervous. I know that there was no smoke and it had great oil pressure (50-60 psi). It did have low water flow out the exhaust and auto shut down due to overheat. The owner is having the impelled changed and will go from there if that doesn’t fix the issue. I’m going to have that mechanic check for blow by. If there is blow by, we are going to ask for money off the purchase price.

The generator is diesel, and it did crank for a few seconds before starting. It seems similar to my gas generator that I had. I’m not sure if diesel generators are supposed to start faster than gas generators.
 
Regarding oil analysis before purchase:

Had oil analysis done on my engine, transmission, and generator even though they all had less than 1,000 hours. Oil analysis on the transmission showed a significantly elevated sodium content. The transmission cooler had a slow leak and salt water was getting into the transmission oil. Renegotiated the price based on a Cummins dealer estimate to replace the transmission cooler (along with some other deferred maintenance). The $75+/- cost of oil analysis reduced my purchase price by over $1K on the transmission alone. Did the work my self and sourced OEM parts at a better price than the dealer estimate. In my case, oil analysis paid huge dividends between saving me money and identifying a potentially severe problem that was completely resolved.

Ted
 
With "extremely high aluminum and sodium" there is definitely some sort of problem. So would expect to have to get into the generator engine before too long no matter how good it ran. And yes, under normal circumstances diesel engines should start almost instantly.

Ken
 
Are you perhaps overthinking this?
Most agree that oil analysis trends are important as part of an ongoing maintenance program. Most boats don't have them unfortunately!
Serial samples when available for a prospective purchaser also confirm that the most recent analysis is valid (i.e. the seller did not simply change all the fluids before sea trial to hide something)
An isolated pre-purchase normal sample is potentially reassuring but not definitive since trends are best.
The (presumably) one time pre-purchase samples you posted are valid to you the prospective purchaser because they are a red flag that you are going to have to spend some $$$ on at least 2 of the 3 engines. Use this information to ascertain the potential cost of repairs/rebuild/replacement (do this yourself if you have the knowledge base or invest in a mechanical inspection by a pro knowledgeable about those specific diesels/transmissions) Use this cost to either get a commensurate reduction in purchase price or walk.
 
The problem I’m having is trying to value this boat as it is with a known generator problem.
 
I can barely read the posted analyses. Any way to post them more clearly?
 
The analyst's text is not what I look at. Really would like to see the numbers.
 
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