Oil sample results not good

[Michael Muessel]

I’ve got a purchase and sale agreement on a boat powered by 2001 Cummins 6CTA8.3-M3 with 850hrs serial #’s 4664812 and 46050752. Both engines start easily, smoke very little at all rpm’s and reach 2650 rpm WOT. I know they are propped a little heavy, but I will correct that. The boat has mostly been cruised at under 2000 rpm by the preset owner.

My problem is that the oil samples came back within specs except for the aluminum levels which are high at 97 and 117 ppm and that is in the “severe” range according to the analysis company. The oil is Rotella T 15-40, and has about 150 hrs on it.

The boat has sat mostly unused for the better part of a year. Do you think we’ve got a piston scuffing issue caused by a lack of frequent use? Unfortunately I don’t have any older oil sample reports for comparison, but I’m thinking the best solution is to do an oil and filter change, put some hours on the engines and then sent out another sample before closing. Any other thoughts would be appreciated!

Topic

[Rob Schepis]

We are jumping ahead a bit here but it’s nice to know what you could be facing regarding the aftercoolers: If replacement is needed the entire unit pricing is a bit more than Philip posted but if the cores are good the housings are also available without the cores. I included both links above.

If I were in your shoes with this purchase and the boat itself “checked all of my boxes” then I would go thru the bullet points that Philip noted and verify all, then put the oil sample aside and move forward. That is just my $0.02, but everyone has to base their own decision on all things considered..

Engine room photos would be very useful here as to the big picture so we can see what you are seeing.

[Philip]

Oil sample problem

Here is the real problem with any oil sampling at this point. There is knowone that will be able to say exactly what level of AL is normal or acceptable if you were to change the oil, run 5 hours, and resample. And anyone that tries to tell you that the sample is normal doesn’t really know anything. Part of the trending function of a true oil sample program includes a constant rate of useage on each sample to compare to. Wear levels are not linear so you can’t say if in 100 hour a level was 100 ppm that in 5 hours it should be 5 ppm or less…. there in lies the predicament you are faced with. So don’t waste your time and money resapling after the expense of an oil change expecting to get any valuable information from a 5 hour or 10 hour sample. Your trying to eliminate future risk with no information or information you can’t get at this point.

At this point in the purchase I would be placing more emphasis on:

– how quick does it start from dead cold cold cold
– does it smoke at start
– what is the max rpm both static and under load
– what are the fuel burns at 200 rpm intervals compared to spec
– smoking under loads
– vibrations at any rpm

And don’t forget big items like age of batteries as that cost can add up – next boat I purchase I’ll have a load test on batteries Pre purchase. Batteries can be $300+ and add up fast.

Like Rob says if you want the boat try and get some credit for AC replacement/servicing. BTW aftercoolers can be $2500+ depending on model plus labor to R&R.

Got any pictures? Maybe we can point out something….

[Chris Dahl]

You’re in a little bit of a pickle- Oil changed 150 hours ago and aftercoolers done 20 hours ago, both are “reported” and doesn’t seem like any pictures were taken. Not that an oil change needs pictures, but aftercooler service sure would be nice to have some picture documentation to show what was done. If the aftercoolers were really pulled and properly greased up then you could simply have aluminum left in the oil from before the aftercoolers were serviced. Certainly changing the oil will get you some place to start, but you will be utilizing “hope” unless you can safely determine the AC’s were pulled and done right.

Does 20 hours ago mean 3 years ago with 20 hours of use in those 3 years, or 20 hours over 4 months?

[Rob Schepis]

As I read the “Yanmar” under your name I posted the Yanmar aftercooler pics link. Here’s some Cummins pages showing the construction and issues..

Aftercooler Disasters

Aftercooler Condensation – A different way to look at air

100% Genuine Cummins Complete Aftercooler for Cummins C-Series, QSL9, & WET QSM Engines

Cummins Aftercooler housing for Cummins C Series Engine

[Rob Schepis]

The AL is the housing, not the tube bundles:

Yanmar Aftercooler Maintenance

[Michael Muessel]

Intercooler corrosion question

I’m curious about the intercooler corrosion. What causes the tubes to corrode, and how can that be prevented? The intercoolers were serviced as recommended by Tony 20 engine hours ago and ultrasonically cleaned. Will that cleaning reduce the volume of AL being ingested into the engines? I was planning on doing an oil and filter change and another oil sample to see if the cleaning had a positive effect on the results.

[Rob Schepis]

Yes, a great post by Philip. Sounds like the aftercoolers are just sitting and corroding away, at that point could be a combination of saltwater and condensation fresh water. Many deals become problematic when a buyer wants to start disassembling engine components. If that’s the case, after all other negotiations are in place try to finalize the aftercooler issue with a final purchase price reduction equal to the cost of one new aftercooler. That could be fair for all involved..

[Tony Athens]

Michael,

This is real simple. I wish they were all that easy..

LISTEN TO PHILLIP

Tony

[Philip]

Another thought

Oil samples are of little use without multiple samples with real hours on each, not a few hours. You need to have a baseline and a trend and even then oil sampling can be subjective and sporadic depending on who and how the samples are taken.

Having said that, I had a similar issue with high levels of AL. Changed oil and resampled after 5 hours and ended up buying boat. Fast forward a year later and it turned out the AL was from a corroding aftercooler even though the seller had a receipt showing aftercooler service and I personally talked to the mechanic who assured me the coolers were serviced seaboard way and good to go – not. The coolers were deteriorating and the AL in the oil was showing just that. New coolers (expensive) and the high AL is gone….

If I had it to do over again I would have gotten my own mechanic to remove and inspect coolers to set my baseline as part of the sale. By either factoring that into the sale price or having it done prior to sale is what needs to be done no matter what if you truly want to be on top of your game – meaning proactive vs reactive.

And BTW if the engine is overpropped at less than max RPM it’s still overpropped and overstressed at 2000 RPM. Easy enough to fix but did the extra load do to the engine if any is the real question.

If you had piston scuffing or bad rings it would show with poor start (low compression) etc.

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