Reply
 
Thread Tools Search this Thread Display Modes
 
Old 01-07-2018, 01:14 AM   #1
Member
 
iflypby's Avatar
 
City: Port Saint Lucie
Join Date: Nov 2017
Posts: 17
Engine TBO

In buying a used trawler type vessel, what would be the maximum operating hours or years in service of the Diesel engine beyond which an overhaul would be considered necessary for reliable service? I know that you can perform SOAP samples and cylinder compression tests as a aid in diagnostic analysis but these will not necessarily show the degree of corrosion on the internal components. As these marine diesels are very expensive to overhaul, a low time, thirty year old set of engines might not be such a good bargain.
With aircraft engines, I look very carefully at an engine with more than 10 years of service. Aircraft with more than 20 years since a new or overhauled engine, I consider “runout” no matter what the number of hours are.
I understand that aircraft and marine diesel engines are very dissimilar power plants but the marine environment is a tough act. Many of these power plants are pushing 40 years without being opened up for inspection. Commercial vessels often go 30K-60K hours between overhaul, but they are run hundreds if not thousands of hours a year. A 1985 trawler with 3500 hours has been run an average of less than 100 hours per year. Sitting idle for extended periods without the manufactures preservation instructions having been accomplished is never good for any engine.
__________________
Advertisement

iflypby is offline   Reply With Quote
Old 01-07-2018, 01:39 AM   #2
Veteran Member
 
crashley's Avatar
 
City: hazelwood north
Vessel Name: GULL
Vessel Model: WW2 Work boat
Join Date: May 2014
Posts: 39
The hours makes no difference If it has had proper maintenance and regular oil and filter changes it will last many many years but if it is neglected it wont last long at all
__________________

crashley is offline   Reply With Quote
Old 01-07-2018, 02:11 AM   #3
TF Site Team
 
Comodave's Avatar
 
City: Au Gres, MI
Vessel Name: Never Say Never
Vessel Model: President 41 DC
Join Date: Jul 2015
Posts: 11,833
I agree.
Comodave is offline   Reply With Quote
Old 01-07-2018, 07:20 AM   #4
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 21,954
"proper maintenance and regular oil and filter changes"

So when first looking at a boat take a look and see what the owner has on the shelf.

Car oil or diesel rated ?, car antifreeze or diesel with SCA if needed?.

A bit of eyeballing will tell a lot about the maint.

Someone that keeps an engine maint log might be a better investment that a "what me worry" owner.
FF is offline   Reply With Quote
Old 01-07-2018, 07:23 AM   #5
Valued Technical Contributor
 
DavidM's Avatar
 
City: Litchfield, Ct
Join Date: Aug 2012
Posts: 5,867
Airplane engine life is an entirely different situation than marine engine life. Airplane engines operate in a narrow power band and by law undergo annual inspections. Also no operator in his right mind would skimp on maintenance.

There is a wide variety of good, bad and ugly maintenance and operation of marine engines which makes engine life impossible to predict. If you maintain it by the book (and then some) prop it and operate it reasonably then it can last 10,000+ hours or enough that the vast majority of recreational owners will never see the end.

David
DavidM is online now   Reply With Quote
Old 01-07-2018, 10:45 AM   #6
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Join Date: Jan 2013
Posts: 6,541
For buying an older engine, I think I would check blow by, and otherwise just check for smoke and all the usual stuff. Then go cruising.

In my completely unscientific observation, marine diesel engines that require rebuilding are 99% of the time a result of abuse of high output engines or sea water intrusion because of crappy exhaust designs. And 1% of the time because the engine actually failed or wore out.
__________________
MVTanglewood.com
twistedtree is offline   Reply With Quote
Old 01-07-2018, 11:22 AM   #7
Technical Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 6,183
I do engine surveys (or call it assessments, inspections, whatever) and the above posts have it about right. Run time hours have little bearing on engine condition, well until you get up in to the super high hours. 3500hrs is no where near that. What takes these engines out is corrosion both inside and out, running outside of the desired operating envelope, and sudden catastrophic death from things such as overheats or loss of lube.

Wear from hours almost a non issue, unless you are talking about a boat that runs on plane for a big part of the duty cycle (sportfish, fast cruisers, etc).

The condition of the engine can be assessed to about an 80% level of confidence regarding its condition. Real hard to get that last 20% without tearing it down and inspecting each part, but that is simply not practical.

Since the consequences of an engine failure on a boat are no where near as severe as on an aircraft, it is usually ok to roll with knowing 80%.

Different brands and models of engines have different weak spots so no way to tell what to look at except in the most generic terms.

Post what model engines you are looking at. Most likely someone here owns the same and can tell you what to look for.
Ski in NC is offline   Reply With Quote
Old 01-07-2018, 05:18 PM   #8
Veteran Member
 
CaptRonn's Avatar
 
City: Houston
Join Date: Dec 2017
Posts: 83
Quote:
Originally Posted by djmarchand View Post
Airplane engine life is an entirely different situation than marine engine life. Airplane engines operate in a narrow power band and by law undergo annual inspections. Also no operator in his right mind would skimp on maintenance.
General Aviation aircraft suffer from the same condition as many privately owned boat, the owners can buy them but they can't afford the maintenance. You would be shocked to see the condition many of these airplanes are in with owners continuing to fly them.

And you see the same thing at marinas, boat after boat that hardly ever sees and preventative or routine maintenance.
CaptRonn is offline   Reply With Quote
Old 01-08-2018, 07:53 AM   #9
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 21,954
"sea water intrusion because of crappy exhaust designs."

No question , but how many folks carry 3 oil changes aboard so the engine can be flushed and operated after the problem is repaired?

Mostly only ex long distance sailors.
FF is offline   Reply With Quote
Old 01-08-2018, 12:34 PM   #10
Senior Member
 
City: Washington
Join Date: Nov 2017
Posts: 468
I've always wondered why engine run hours is used as the basis for maintenance (oil change every XXX hours) or remaining life. Wouldn't 100 hours at 3600 RPM be a lot more wear than 100 hours at 1800 RPM?
aboatman is offline   Reply With Quote
Old 01-08-2018, 01:13 PM   #11
Valued Technical Contributor
 
DavidM's Avatar
 
City: Litchfield, Ct
Join Date: Aug 2012
Posts: 5,867
Quote:
Originally Posted by aboatman View Post
I've always wondered why engine run hours is used as the basis for maintenance (oil change every XXX hours) or remaining life. Wouldn't 100 hours at 3600 RPM be a lot more wear than 100 hours at 1800 RPM?
Yes, definitely. Manufacturer's recommended oil change intervals are just an approximation that fits everyone. When I cruised a twin catamaran long distance with 36 hp Yanmars, I didn't think twice about extending the oil change interval to 200 hours rather than the manufacturer's recommended 100 since I was running moderately loaded and put a lot of hours on it every month. I did run an oil analysis once at the end of 200 hours and fuel and soot were fine.

In fact on our new Mini Cooper the engine's ECU integrates load over time and tells you when to service the engine, supposedly between 10,000 and 15,000 miles or every 12 months. I think you will see more of this on automobiles and maybe electronic marine diesels. The data is there to figure it. You just need to get customers used to this plan. The operating manual didn't say anything about the 12 mo limit, so I had to call the dealer to figure it out when the message came on at 12 months even though the miles were less than 10,000.

David
DavidM is online now   Reply With Quote
Old 01-08-2018, 01:35 PM   #12
Guru
 
BandB's Avatar
 
City: Fort Lauderdale. Florida, USA
Join Date: Jan 2014
Posts: 20,285
Quote:
Originally Posted by aboatman View Post
I've always wondered why engine run hours is used as the basis for maintenance (oil change every XXX hours) or remaining life. Wouldn't 100 hours at 3600 RPM be a lot more wear than 100 hours at 1800 RPM?
Actually what the manufacturers would prefer to use is fuel burn. However, long ago hour meters were installed, not floscans, and so hours became an approximation. i'm not convinced fuel burn would be better.
BandB is online now   Reply With Quote
Old 01-08-2018, 01:42 PM   #13
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Join Date: Jan 2013
Posts: 6,541
Quote:
Originally Posted by djmarchand View Post
In fact on our new Mini Cooper the engine's ECU integrates load over time and tells you when to service the engine, supposedly between 10,000 and 15,000 miles or every 12 months. I think you will see more of this on automobiles and maybe electronic marine diesels. The data is there to figure it. You just need to get customers used to this plan. The operating manual didn't say anything about the 12 mo limit, so I had to call the dealer to figure it out when the message came on at 12 months even though the miles were less than 10,000.

David
My 2011 truck (diesel) does the same thing. It tells you what % "consumed" your oil and fuel filters are. I don't know exactly how it's calculated, but it might be fuel burn. Unlike days gone by, the ECU in a fuel injected engine knows exactly how much fuel has been burned, so that would be an easy way to do it.
__________________
MVTanglewood.com
twistedtree is offline   Reply With Quote
Old 01-09-2018, 12:37 AM   #14
Member
 
iflypby's Avatar
 
City: Port Saint Lucie
Join Date: Nov 2017
Posts: 17
I found an article by Caterpillar that recommended engine overhaul at 30,000 gallons of fuel consumed. This was for a 3208 engine in a motorhome chassis. They seem to be the most concerned with the rod bearings as the recommendation was to replace these bearings at 25,000 gallons. I would imagine that the motorhome installation would present a similar operating load history as the installation in a trawler.
30,000 / 4.5 GPH = 6,666 hours. No mention of time in service, only fuel consumed. If you ran it hard, like a DeFever 53 POC on plane, you could realistically average 10 GPH? 30,000 / 10 GPH = 3,000 hours.
iflypby is offline   Reply With Quote
Old 01-09-2018, 06:59 AM   #15
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 21,954
Measuring engine life by gallons consumed is by far the most accurate method.
__________________

FF is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



» Trawler Port Captains
Port Captains are TF volunteers who can serve as local guides or assist with local arrangements and information. Search below to locate Port Captains near your destination. To learn more about this program read here: TF Port Captain Program





All times are GMT -5. The time now is 11:23 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012
×