Advice needed on potential purchase. Engine decision?

[Raylee]

I am looking at a vessel with Detroit engines. As background, both Engines had an overhaul about 10 years ago. During the survey, the engines smoked heavily on Start up on a pretty warm day. On borescope rust & pitting were found in the cylinders, also no crosshatches were seen in the walls.

Subsequently, the engines were tuned up which reduced the smoke to some extent. Mechanic declared the engines sounded and run ok and the smoke is acceptable. The rust in the cylinders was attributed to the fact that the boat had been sitting unused for 2 months in a salt air environment. Oil analysis showed high iron & copper. The mechanic recommended running the boat for a couple of hours to reseat the rings??. Before walking away from this boat, would compression testing be a useful next step? I have heard that engines can run ok even with below spec compression.

I was told that overhauling the engines would be the way to go until this last mechanic who thinks the engines are ok for now. These days, the cost of an overhaul for both engines is $$$$.

I would appreciate comments and opinions very much.

Raylee

 

[READY]

For sure I would at a minimum get the compression check.
Lots of different opinions about oil analysis. Mine is that unless you have a baseline/history it is not all that useful unless something is extremely high.

 

[tiltrider1]

You really didn’t tell us which engines you are looking at. We talking 2 stroke, 4 stroke, 400hp 4-53’s or 290hp 6-71’s?

 

[Raylee]

Engines are 2-stroke.. 71 series. 450HP

 

[Blissboat]

71 series Detroits can be loud and messy, but they are pretty hard to kill. If they run okay and the rest of the boat satisfies you, try making a deal at a price that leaves you with some financial cushion to address engine issues down the road.

 

[tiltrider1]

Well a 450hp 6-71 would be a real problem. A 450hp 12-71 would be a minor issue. I am guessing they are 6-71’s. Sounds like the Bearings are toast. If they are 450hp 6-71’s expect a full engine rebuild. If this is unacceptable then move on. A compression test isn’t your answer.

 

[mvweebles]

Iron and copper are both wear metals that can presage failure. Copper especially is a marker for lower end bearing failure as @tiltrider1 suggests and has nothing to do with sitting in a salt water environment for any amount of time (2-months is a lame excuse, BTW).

There was a recent thread about a Hatt 58 that was recently purchased and headed to Tampa from the Mississippi area (I forget exactly). One engine was a bit slower to start than the other one but the buyer proceeded with the purchase. The engine self-destructed a dozen engine hours later. Since the owner was on his way to Tampa, I can only assume he thought the engine was good enough - I wouldn't be surprised if he was given a dismissive explanation along the lines of "run it for a few hours to re-set the rings." Talk is cheap when you don't have skin in the game.

Attached is a very good article from Steve D'Antonio on interpreting oil analysis.

Good luck. Please update on your progress.

Peter

 

[mmullins]

Engines are 2-stroke.. 71 series. 450HP

As tiltrider1 alluded in post #6, it depends how many cylinders. 8-71's and 12-71's you would probably be ok. 6-71's you're ringing a lot of horsepower out of them. My mantra on old diesels of any flavor (CAT, Detroit, etc) is to stay under 1hp per cu inch.

 

[Raylee]

Thank you all for the great comments. It’s what I anticipated to some extent but I really do like the vessel, which is why it’s such a hard decision. However, I would not want to be in a situation similar to the that vessel heading to Tampa.

To clarify further, the vessel had been sitting longer (possibly 6 months or more) then had a sea trial, then sat again for 2 months before the oil analysis. Also, the engines satisfy the 1hp per cu inch that @mmullins mentioned.

I will study the Steve D’Antonio article, thank you mvweebles for that.

Again, I do appreciate the input very much.

Raylee

 

[mvweebles]

@Raylee - during the sea trial, was the boat run at WOT for at least 5-mins?

As an aside, in my opinion, the seller's representative should be at the helm of the boat during a sea trial to avoid any liability to the buyer. They could of course decline to put the boat through their paces - many owners are nervous about WOT even though diesels are designed for WOT operation for at least shorter duration periods.

Peter

 

[mmullins]

Thank you all for the great comments. It’s what I anticipated to some extent but I really do like the vessel, which is why it’s such a hard decision. However, I would not want to be in a situation similar to the that vessel heading to Tampa.

To clarify further, the vessel had been sitting longer (possibly 6 months or more) then had a sea trial, then sat again for 2 months before the oil analysis. Also, the engines satisfy the 1hp per cu inch that @mmullins mentioned.

I will study the Steve D’Antonio article, thank you mvweebles for that.

Again, I do appreciate the input very much.

Raylee

On the other end of the spectrum from the guy with the Tampa bound vessel, I bought an early 70's Hatteras 43 that hadn't left the slip in over 6 years. Due to time constraints (I arrived at 11 at night and had to leave the next morning) I didn't have time to change the oil or fuel filters. I embarked on a 750 mile (protected waters) trip. Other than some erratic temperature readings for the first 45 minutes and some leaky injectors, she ran the trip without issue. The engines were 8v53's.

 

[mvweebles]

BTW - here's the thread about the Hatt 58 that has a major engine blow.

58’ Hatteras detroit diesel 8v92TI with serious engine problems

Saw this on the Hatteras Owners Forum.

www.trawlerforum.com

The over issue for the OP is there is no way to be reasonably certain there is/is not a problem. The seller will likely offer a small concession to get the deal over the line but unlikely to go very far if there is a major issue. The seller is likely to think that single oil analysis tests are not much help so he'll change the oil and obfuscate the next offer.

Boats are such an emotional purchase. I definitely feel for the OP here. I would have had a hard time walking away from buying our boat that we fell in love with immediately.

Peter

 

[twistedtree]

No further analysis required, just soul searching. I would only buy the boat with the assumption that both engines require a full rebuild. That means not just the cost, but the time, inconvenience, loss of use of the boat, and dealing with trades people who don't show up, do crappy work, and create other things that need to be fixed. And the boat won't be worth anything more when you are done.

Only you can decide if you are up for all that.

 

[Raylee]

After reading the article by Steve D’Antonio and looking at the oil analysis.. the gear/transmission oil has high levels of both Iron & Copper with Copper being higher. So wear & tear or worse for sure. Engine oil had only high Iron. The labs recommendation is to keep an eye on the oils & I am assuming retest sooner than later. Although the engine oil is changed regularly, I doubt if the gear oil has been changed in a long while. Maybe I should be concerned about the transmission as well.

Interestingly, I spoke with an experienced marine mechanic that I used years ago in VA.. he mentioned that rust in the cylinders is not unusual if the boat is sitting unused with iron showing up in the oil analysis.

To twistedtree & mvweebles comments, I doubt that the seller will agree to a price accommodation for a rebuild but possibly a percentage? Even if we come to satisfactory financial agreement, as twistedtree mentioned, the time, loss of boat use & inconvenience is even more of a factor for me.

Probably best to move on. A real shame.

Raylee

 

[DavidM]

This is based on your latest post that says the engine has high iron in the oil analysis, but the transmission has high iron and copper. Right?

Given that, it seems the iron in the engine is due to the rust that accumulated on the cylinder walls during storage. That should resolve itself with a few hours of moderately hard running and an oil change.

What is the oil pressure. If ok, say 30+ psi then the main bearings are not badly worn.

I would take a chance with a price reduction of half the cost of a rebuild.

David

 

[Raylee]

Thank you very much DavidM, that’s very valuable input. The oil pressure at warm idle 687rpm P:23, 551rpm SB:19… 1000rpm P:30, SB:28.. 1500 & 2000rpm are similar P:50, SB:47.

The report of lack of crosshatches seen is concerning to me?? but I suppose a rebuild would bring things back to healthy again..

Raylee

 

[tiltrider1]

There is a saying, garbage in garbage out. We have been given a shortage of information and then the information changed. The opinions expressed are only as good as the facts received.

This is not ment to insult the Poster. This statement is for others, the better the information, the better the advice will be.

Raylee, if you decide to pass on the boat could you point us to the boats listing. I would enjoy looking at the boats details to see if we can better understand the condition of the engines.

 

[DavidM]

Thank you very much DavidM, that’s very valuable input. The oil pressure at warm idle 687rpm P:23, 551rpm SB:19… 1000rpm P:30, SB:28.. 1500 & 2000rpm are similar P:50, SB:47.

The report of lack of crosshatches seen is concerning to me?? but I suppose a rebuild would bring things back to healthy again..

Raylee

The crosshatches hold a tiny bit of oil which helps lubricate the pistons. Not sure that the remaining rust pits won’t do as well.

Oil pressures that you report sound decent but not great.

If it were my boat, I would just run it and see what happens. I think you could get a lot of hours out of it with little work.

David

 

[rslifkin]

No crosshatching indicates some wear to the cylinder walls. I'd want a compression test personally. If compression is good, then the wear isn't excessive at this point and they've still got some in the pistons / rings / liners before it's rebuild time. If compression is low, then they're probably about due for a rebuild.

 

[Raylee]

Thank you again DavidM and rslifkin for your constructive & insightful comments. Lots to consider.

Raylee

 

[Taras]

I don't see anywhere the hours on these motors after the rebuild 10 years ago? I'm assuming the hour meters are not correct? Is there a Log Book which lists the hours where the motors were rebuilt? Perhaps there are receipts from the rebuild? If so, the mechanic may have listed the hours? Lastly, previous surveys on the boat would have hours listed.....

 

[Raylee]

Hello, total hrs are just over 4000, about 1000 hrs since overhaul. Yes, there are receipts for the overhaul.

Thank you

 

[Comodave]

How much did the overhaul cost? It may have been a quick and dirty rebuild for fewer dollars or a full rebuild for lots of dollars. May give you an idea as to how extensive the rebuild was.

 

[slowgoesit]

Out of boat rebuild for Detroit Diesel 2 strokes were recently quoted to a friend of mine at $10,000/cylinder all in . . . . I thought that was kind of high, but for two each 671's, that would be $120k . . .
If I already had the boat, I'd monitor and use . . . .
But it's not a boat I'd buy into now without a serious $$$ concession. 2 months sitting to explain rust on cylinder walls IS a lame excuse!
1000 hours since a rebuild . . . . IF the engines were indeed rebuilt, I'd expect to see some cross hatching on the cylinder walls . . . . so, I'd expect to see some serious documentation on the "rebuild".
Personally, I'd pass on the boat

 

[Raylee]

From what I recall, the rebuild receipt shows around $30,000 for both engines back then. I have no idea what was $$ standard back then.

 

[Comodave]

When was it?

 

[slowgoesit]

Dave, from his first post, "about 10 years ago"

 

[Lepke]

671s were originally designed for about 200 hp. There have been improvement to materials, cooling, etc., but a 450 hp 671 is like a racing engine. If the PO ran at full throttle most of the time then you can expect 3,000 hours about average between overhauls. I've got more than 7,000 on the same engines, but babied them from the start. And I kept the oil clean.
Those engines are shot. Yeah, you might get another 1000 hours, but more likely, spin a rod or main bearing.
If they do, a rebuild is more expensive and may not be economically possible. A rebuild kit is about $2,200 per engine. The heads cost about $1500 each to rebuild. A mechanic doing the overhaul for himself can do an engine for about $4-5,000.
If the price is right and you really want it, find a couple natural 12v71s in good condition. They could last a long time. Same hp, no turbos. High exhaust gas temperature is what ate up the rings and sleeves. Dirty oil is what ate the bearings and helped wear the rings and sleeves.
Detroit 2 cycles are some of the most reliable engines I've run. No power needed, no electronic sensors, no computer, no electronically controlled injectors, no injector pump. Some Detroit naturals have reached 50,000 hours.

 

[Comodave]

Dave, from his first post, "about 10 years ago"

Ah yes, I did read that but CRS disease had kicked in…

 

[Mainship Pilot]

Those 6-71's are pretty stout, however, those stats above are very troublesome! If you were out here in So Cal, most owners run their detroits at 8knots in almost all conditions based on our fuel prices here. If you were going to do the same, then,as suggested, work on a deal that could pad the inevitable repairs down the road, but at 8 knots, you are gonna have a lot of hours left in them!