Why such a short life span?
 

Can someone explain to me the reasons that marine engines (gasoline) have such a short life span in running hours as compared to vehicle engines, or other equipment with similiar engines?

300 hours, time for top end rebuild, another 300 hours, total rebuild.

Other engines in vehicles, generators, pumps, etc last for thousands of hours without rebuild. What makes these engines so short lived? Is it the fact that the cooling is an open system without radiator?

I was told that the engines are worked very hard while in a boat, at high RPM, not much different than some equipment mentioned above.

Is it the fact that the engine has many high performance mods in it that in itself makes it prone to self destruction at a stock level?

IF that is so, how would a stock vehicle engine last if modded to use the marine cooling system and installed in a boat?

If the same engine was in a vehicle, how would it hold up? Any different?

I have a 454 on a 12" water pump with 3000 hours on it, still running.

On diesel engines, "they say" that the time to rebuild is really based on gallons of fuel burned more than on engine hours. That is probably true on gasoline engines too, because fuel burn equals work which probably equals wear.

Say your truck gets 10 miles per gallon. After 150000 miles you have burned 15000 gallons. On a boat that burns 40 gallons per hour per engine, that is 375 hours. Not far off from observation for factory engines run in a fast boat. Boost it up and burn 100 gallons per hour, and 100 to 150 hours and the engine needs a rebuild.

That's probably the key issue.

On my boat, I can only run as fast as the ocean allows, so at 750 hours per engine I've still got good compression numbers, no rod knock, everything seems fine, but I burn about 10-15 gallons per hour per engine, so I should see 1000 to 1500 hours. Seems about right.

Marine engines are always under load,its kinda like if you were pulling a house around with your car

Remember those numbers aren't written in stone. It all has to do with operating style and quality of maintenance. You can save tons of rebuild money with an annual (100hr) visual inspection combined with compression and leakdown, and oil sampling at each fluid change. I've got over 1000hrs on my motors. They're past due for major service, but they still run perfect.

Road-going vehicles see no where near the load a boat motor sees. Imagine your tow vehicle pulling your boat around full time, mostly at highway speed, without overdrive. Every so often you mash the pedal to the floor and occassionally you get to coast downhill. How many miles/hours ya' think it would put up with that? :D

I see your point, my 6.0 diesel is already puking coolant while towing my 382.

I guess the difference is the load transfer on the engines.

My old stock 454's had over 1,000 hours and still ran OK....500's are a little different. As far as your cars.....put your car in second gear and drive around ALL the time in second gear. Let me know how long your willing to drive on the interstate like that. (but you do it all the time in your boat)

has no one developed a multi gear drive? Would this be impossible?, or add too much weight?

Gensets run 1800 to 3600 RPM.. Your pump probably is in the 3600 RPM range I would guess..

HIgh rpm and high load is the reason. Multi gear transmission would not stop the load cruising or at high speed just get you to speed faster. How often does a car run at 4000-5000rpm at nearly full throttle going up a steep hill? Same thing as a boat on the water.

Had the opportunity to ride in a Spectre with Yanmars and ZF two speeds.. VERY odd sensation when it shifted, but man, what a blast!!!

I had a friend with a Powerplay ask the same question the other day, comparing his 350 in his boat with the 350 in his pick-up. I used the example of running in the park versus running in the pool, which one is harder to do. Or should I say substantially harder!

Unless it's blue I'd expect to get at least 1500-2000 hours MINIMUM out a bigblock before needing any freshing. Seems most underestimate the duribility of the black bigblock.

Out of 30000 OSO members, I think you'd be lucky to find 20 that own or have owned any Merc gas bbc engines with that many hours.
It just doesn't happen too often without a major failure.

So, your saying OSO members are brutal on their toyz??

Err, wait, never mind.... :D :D

driving a boat is comparable to driving a car up a 60 degree incline with your foot in the floor and the tach glued to the reline. How long would your car motor last under those conditions?

Take your truck and a 10,000 trailer and pull uphill at 5,000 rpm for its whole life and see how long it lasts !!!!!!!!

Marine engions never get to coast,,,, they are always under heavy load.

Wow.

Real word estimates from my limited experience tell me that if you see over 800 hours on ANY marine engine other than an oil burner you are doing something.

BTW, I have black big blocks. 291 hrs. on one, 287 on the other. (20 years of time though).

I am assuming if I get two more seasons without major overhaul I have done well.
More than likely I will try to get rid of it after this coming summer though.

Your 6.0 is puking coolant because it has a head gasket/bolt problem. You should fix it before you need a whole new motor.

I brought it to Dealership, and wsa told by mechanic that they are having alot of trouble with a internal water cooler that gets stopped up, causing pressure to build up, and causes to puke.

Truck is a 06 model, 6.0, and is supposed to have a improved head gasket from the earlier 6.0's. I have to bring in my truck to have the cooler replaced. He showed me one, have to take the top half of the engine apart to change.

Then again, may be the head gaskets too. I have an Edge programmer, but I always turn it to stock while towing. Only leave it on level 3 for regular driving. Increased fuel mpg by 3.4 mpg.

Mechanic also told me that the new 6.4's have to have the cabs lifted off frame to work on anything major on the engine.

I can imagine how many rattles you will have after having that done at a local dealership

I was going to sell my Dually 2002 with the 7.3 and decided to hang onto it its the last of the mohican's

I saw the cab removed from the frame at my local ford dealership and thought holy chit! It is much easier and faster to unplug the wiring harness and take the body off.You have to remove the fenders on the 2008's. Ihad 2 6.0 fords and no trouble thank god.Sucks either way

Yes, maybe if it was idling around the harbor it's whole life, and it had a roller follower cam (flat tappet cams don't last long idling). I spoke to an engineer who use to work for GM Marine Engine group. He said their engines have to pass a durability test of 300 hours with 55 minutes of that at full throttle, and 5 minutes idle. That's tougher than most users usage, but some on this board put their engines through similar usage. They build the long blocks for Merc black engines.

Michael

Michael

[QUOTE=carcrash;2346624]On diesel engines, "they say" that the time to rebuild is really based on gallons of fuel burned more than on engine hours. That is probably true on gasoline engines too, because fuel burn equals work which probably equals wear.

Say your truck gets 10 miles per gallon. After 150000 miles you have burned 15000 gallons. On a boat that burns 40 gallons per hour per engine, that is 375 hours. Not far off from observation for factory engines run in a fast boat. Boost it up and burn 100 gallons per hour, and 100 to 150 hours and the engine needs a rebuild.

That's probably the key issue.


You're right on the money. GM now uses fuel consumption to guage oil consumption, because it is indicitive of load. I have seen a charter fish boat with gas small blocks go 3500 hrs, still runs well. BUT mostly idle time vs WOT. I think the average pleasure boat will get more hours from its motor than we do from our performance boats, as shown by our increased fuel consumption. Guys with bayliners aren't usually blowing through 100 gallons a day.

If you run the boat every day, I'd agree. For the average pleasure boater though, with long periods of sitting, I'd say black big blocks should get to 1,000 hours if taken well care of, and not pushing a mega load.

What I mean by load is there's a big difference between pushing a 22 Donzi classic and pushing a 27+ foot boat with full cabin.