Marine Gas Engines, Life Expectancy

[brian eiland]

I saw a number of references to gas engine life expectancy in this article....
Marine Engines : Gas Engines - by David Pascoe, Marine Surveyor

...but what surprised me is nothing about 'engine hours' of life??

I know that many marine engines are equipped with 'hour meters', and certainly there sure be some approximates as to engine life in man-hours.

How about it, any folks want to contribute their figures to that subject?? I've been told to avoid anything with over 1500 hours on it as likely they all requires rebuilding or replacement as they approach 1800-2000 hours. ??

 

[bshillam]

Thats what I have, Crusaders one with 1300 and the other 450 both w/i specs on compression. I have seen Crusaders with over 3k on them. It's all how you take care of them. Crusaders usually go further than others.

 

[psneeld]

Coming up on 5000hrs on a Marine Power carbed 454 in my assistance towboat...it's been run overheating for many hours, at the pin for many hrs with the prop cavitating like mad during ungroundings...only maintenance is replace when something is broken and cheap oil change every 200 hrs.

that engine sees more in one day than many marine gas engines see all season in a private boat...it's going on 12 years old and gets abused every year.

No sign of failure yet.

 

[CPseudonym]

No hour meter on my boat but the 45 year old original lump was replaced with a brand new crate 350 and all new Osco manifolds and such. The mechanic essentially put new gaskets and plugs in the old motor and dropped it into another boat he had and it still running today.

 

[FF]

Gas or Diesel, most engines are replaced because they were KILLED, not worn out..

Diesels are easier to kill by ignoring required maint than gas.

 

[brian eiland]

Avoid Overheating

So avoiding overheated operation seems to be a primary objective with these gas engines, ..(or for that matter any engine).

From my little bit of reading it appears as thought the cooling systems on the Crusader 454 is superior (and a bit more extensive/sized) than the Mercruser 454's, and this gives them a better life expectancy?

These are both fresh water cooled with heat exchangers? I imagine its important to keep a watch on the heat exchangers, and keep them properly zinc-ed.

 

[alberto]

I saw a number of references to gas engine life expectancy in this article....
Marine Engines : Gas Engines - by David Pascoe, Marine Surveyor

...but what surprised me is nothing about 'engine hours' of life??

I know that many marine engines are equipped with 'hour meters', and certainly there sure be some approximates as to engine life in man-hours.

How about it, any folks want to contribute their figures to that subject?? I've been told to avoid anything with over 1500 hours on it as likely they all requires rebuilding or replacement as they approach 1800-2000 hours. ??

A 120HP Ford Lehman is estimated to run up to 10.000 hours, when being perfectly maintained, and before hauling for remanufacturing.

This has not been exactly my case, but it is Bob Smith and others estimations on data based in more than 5000 units running in boats.

It totally depends on the use or abuse, and preventive maintenance.

 

[brian eiland]

I imagine the gas engines are cheaper to repair, with a much greater abundance of parts available, and cheaper parts ??

I seem to recall getting a big CAT engine repaired long ago after a failed turbo charger incident. the CAT parts were NOT cheap.

Most gas engine mechanics can work on these, whereas diesel engine repairs might seek out a more specialized mechanic familiar with particular brands of diesels ??

 

[psneeld]

the marine power block is the same as a mercruiser block (GM) as far as I know and severe overheating is actually pretty difficult...

I tow with clogged strainer/oil cooler a lot and the temp rarely get above 250 degrees as long as I keep it below 2000 rpm....but I have many hours with it at 225 plus and the alarm going off till I get it all straightened out and continue the tows.

Overheating below 250 doesn't seem to harm the engine one bit unless you keep the coals to it.

 

[brian eiland]

Associated Gearboxes

Can the gearboxes that are normally employed with these 454 gas engines be allowed to rotate without the engine being run? I had read long ago that some of these transmissions did not like to be 'rotating' without the engine being on concurrently.

In other words if one was running on just one engine (slow cruising times) would there need to be some sort of 'shaft brake' to keep the idle side rotating prop from turning the transmission/gearbox??

 

[brian eiland]

Marine Engines : Gas Engines - by David Pascoe, Marine Surveyor

excerpt.....

Hands down, I give my top award to the Crusader Division of ThermoElectron Corporation for their Crusader line of engines. Coming to this conclusion was easy because their engines simply outperform all others in terms of service life. The fact is that Crusader engines keep going long after others have had overhauls, engine replacements, or replacements of expensive parts such as manifolds, risers and cooling systems, often giving reliable service life in excess of 100% over other engines.

But that's not all. Several years ago, I had the opportunity to tear down a Crusader 454 engine and that of a competitor, side by side on the bench, and make a detailed comparison.* I was quite surprised to find that even the engine blocks were not the same, for the Crusader block was considerably better.

Start with the fact that the Crusader had 4-bolt, stepped and stabilized main bearing caps, whereas the other engine had a 2-bolt, unstepped, unstabilized main bearing caps. As some of you may know, GM has long made two lines of basically the same engine, the better of the two being named the "TargetMaster" line of heavier duty, more precision engines for trucks. While I don't claim to be intimate with the GM product line of engines - the last time I personally rebuilt a TargetMaster was 10 years ago - there isn't any doubt in my mind that Crusader is using the TargetMaster line. The basic block was an all-around better block than it's competitor's. The basic differences were in the lower end, as well as obviously larger cooling passages.

In the real world, Crusader outperforms all others in terms of reliability and longevity. Its not unusual for me to find Crusader engines 15-20 years old that are still going strong in the seawater environment, whereas its rather rare to find other engines going this long. There are two primary reasons for this: (1) better cooling system design, and (2) better gaskets.