Boat motors, wear and tear = an Interesting 1/2 truth

[Silvertip]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

Porsche built a version of there pancake engine that was a roller bearing engine and if memory serves me right it was termed the RSK. Sounded like someone threw a handful of marbles in the engine before they buttoned it up but was quick.

 

[H20Rat]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

Install a vacuum gauge on your boat and keep engine vacuum at 8 - 9 inches or more and the engine will provide optimum service. The same holds true with a car or truck. Engine vacuum and rpm are two key factors in how the ECM on vehicles are able to get the mileage they do these days.

vacuum? I've got 100k miles on my car and it often seens 18 psi of pressure, not vacuum!

anyway, agreed, vacuum is a good indicator of engine load. so the higher the vacuum, the happier the engine is with you, the less fuel it is burning, and you will have an engine that lasts longer.

 

[Howard Sterndrive]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

gallons of fuel burned is a much more accurate wear indicator

That's why truck fleet managers schedule engine rebuilds based on so many thousands of gallons of fuel burned, not miles or hours.

miles or hours tells you very little about the load on the engine. Fuel gives a much more complete picture.

 

[Bronc Rider]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

I know my mercruiser 3.0L 4cylinder still had cylinder wall crosshatching when I did the headgasket a week ago....and it is a 19 year old motor....wont see that in a 19 year old car truck eng, it would be like glass in the cyl, highly polished and worn. also there wasnt much in the way at all of carbon build up on the pistons or cyl head dome/valve faces.......

Its actually very common to see crosshatching on old engine. I have taken apart several engines with over 200,000 miles that stilled showed crosshatching.
Its all about the proper maintenance. Cylinder walls last a very long time with regular oil changes.

 

[Home Cookin']

Re: Boat motors, wear and tear = an Interesting 1/2 truth

we burned out a motor that was underpropped. After 2 years it looked like a commercial crabber's motor. Mechanic said that running at 6500 instread of top 5500, was adding an hour of use for every minute it ran. So one factor in this discussion (as was said, it's how it's run) is whether it was over or under propped.
Seems like the manufacturers expect 100 hours a year, based on the repair manual's maintenance tables. Obviously depends on where you live.

 

[NSBCraig]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

I've read in a lot of places about people trying to use car motors in boats and they don't work.

As people stated above a boat is motor needs to run high load, high rpm.

Boat motors wear faster then car motors- plain and simple.

 

[Bronc Rider]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

I've read in a lot of places about people trying to use car motors in boats and they don't work.

As people stated above a boat is motor needs to run high load, high rpm.

Boat motors wear faster then car motors- plain and simple.

Why wont the engines work? The brass core plugs, different cam grind, SS head gasket and SS circulating pump impeller do not make it more durable. Those items are swapped for corrosion purposes only. The actual mechanical parts that make the engine are the same. I actually know several people running car engines successfully in their boats (I'm one of them).
Boat engines will wear out quicker due to the added stress and sustained high rpm's.

 

[NSBCraig]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

Why wont the engines work? The brass core plugs, different cam grind, SS head gasket and SS circulating pump impeller do not make it more durable. Those items are swapped for corrosion purposes only. The actual mechanical parts that make the engine are the same. I actually know several people running car engines successfully in their boats (I'm one of them).
Boat engines will wear out quicker due to the added stress and sustained high rpm's.

Huh?

Different cam makes huge difference. So do valve seats and some other things.

Corrosion resistance is durability, so I'm real lost there.

There are lots of articles on the web and in mags discussing it and it seems that you can get away with it in low power situations but as the horsepower increases than nothing that works in a car works in a boat.

Do some looking you'll find um'.

 

[Bronc Rider]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

Huh?

Different cam makes huge difference. So do valve seats and some other things.

Corrosion resistance is durability, so I'm real lost there.

There are lots of articles on the web and in mags discussing it and it seems that you can get away with it in low power situations but as the horsepower increases than nothing that works in a car works in a boat.

Do some looking you'll find um'.

The cam is basically the same grind you find in trucks. How would the cam effect durability anyway?
Corrosion resistance I guess does fall under durability. I saw it more as a longevity thing but I guess thats the same thing. What you need to keep in mind is that unless you go in saltwater those items are not necessary. If you are going in freshwater you could just stick a trucks engine and call it good. Those items are not really part of the engine either.
I'm referring to the things that actually wear out on an engine like cylinder walls, crank, pistons and connecting rods. Go look at a rebuild kit, it wont come with any of the items you think are part of the engine. (it will come with a cam but, thats pretty much an automotive unit to begin with).
I will also say I have taken apart Merc engines and compared them to regular truck engines and they looked the same inside (same vintage different applications). I take it you have done the same and found them different inside? Care to share witch engines you disassembled? I'm really curious.

EDIT: They also come with regular heads (no special valves the way you assume).

 

[NSBCraig]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

Well first why build a boat that can never go in salt?

I'm lost right there? If you sell it are you gonna disclose that it's not the right motor?

The motors operate in different enviroments, under different loads, at different rpm's.

Seriously I'm no real mechanic but it doesn't take long growing up around boats to listen to too many jokes about people who think it's all the same and stories of the horrible mistake. This only gets worse as people try to make more than stock power because then nothing that works in a car works.

When it all comes down to it you can do what ever you want with your boat, that's the fun part of things being yours.

Can you make it work? sure.
Will it last as long? no way.

Do some research you'll find stuff on it.

And yes cam makes big difference (rpm at load) and a valve and a valve seat are to different things.

 

[vegasphotoman]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

I have professionally rebuilt (crank, bearings, re-ring, hone etc) over 30 ford engines, and installed over 50 reman short/long blocks....

on boats.....NONE overhauled or replaced YET.....
I do have a 302 OMC motor in the garage, it has water in the oil...cam eout of my newman boat, omc stringer drive etc....the boat had 2 to 3 feet of water in it at one time so Im hoping its external water instrusion....lol hoping!

Ive come to the conclusion that there ARE some differences in boats vs car motors....either way....they pump air/gas and make HP.....

 

[Bronc Rider]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

Well first why build a boat that can never go in salt?

I'm lost right there? If you sell it are you gonna disclose that it's not the right motor?

The motors operate in different enviroments, under different loads, at different rpm's.

Seriously I'm no real mechanic but it doesn't take long growing up around boats to listen to too many jokes about people who think it's all the same and stories of the horrible mistake. This only gets worse as people try to make more than stock power because then nothing that works in a car works.

When it all comes down to it you can do what ever you want with your boat, that's the fun part of things being yours.

Can you make it work? sure.
Will it last as long? no way.

Do some research you'll find stuff on it.

And yes cam makes big difference (rpm at load) and a valve and a valve seat are to different things.

You are missing the point completely. The accessories that get swapped for marine stuff ARE NOT part of the engine. The actual engine is NOT specific to a marine environment. The actual components of the engine including the block are car parts. No special valve seats or anything in the heads either.

The cam is made of the same metal as an automotive unit so how exactly is it more durable in a boat engine?

The way to successfully use an auto engine is to outfit it with marine ACCESSORIES to safely and legally operate it (marine alt, marine carb, marine starter etc etc). Sourcing an automotive block and adding marine accessories to it is the same way Merc did it from the factory.

Ive come to the conclusion that there ARE some differences in boats vs car motors....either way....they pump air/gas and make HP.....

I see this claim all the time but no one ever says what the differences were. So what were they?

 

[Philster]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

The typical Mercruiser (and others) marine engine is simply an off-the-rack GM/Chevy car engine, with the only changes being brass freeze plugs, non-corrosive head gasket, and a slightly different cam profile for a different power curve. There is no special coating in the block, and all of the internal components have GM part numbers stamped all over them that can be crossed right to regular car parts.

The others are also correct that the external components are different. The exhaust manifolds, carbs, fuel pump, starter, alternator and distributor are all coast guard approved (anti-spark, anti-fuel leak,etc) and designed to prevent an explosion from gas vapors and sparks.

I have personally seen 4 or 5 car/truck engines in boats, using the marine components I mentioned above, and they work fine. The marine engine manufacturers want you to think there is something special about their long block assemblies so that you come to them for parts, but you can buy a lot of stuff from NAPA, etc. Also, as mentioned, late model marine engines tend to be (Vortec) roller cam engines.

 

[QC]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

and a slightly different cam profile for a different power curve.

For clarity the other reason for the different profile is to prevent reversion which is the ingestion of water into the cylinder. Truck/RV cams match up well, car and high performance cams, not so much.


Edit: FWIW . . . I left this in the boat section as the discussion was about marine wear vs. automotive engine wear and seemed pretty generic . I note this only to clarify that we usually move engine related discussions out out of the Boat section, and this looks like a contradiction, which of course it is . . . Clear as mud?

 

[Philster]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

Marine cams were still produced with enough valve overlap to risk reversion, and some cam profiles used in boating are aggressive (as in cars). Reversion remains a problem in marine engines and exhaust manufacturers have been scrambling to create risers and headers that could minimize reversion.

This essential part of 'different' for the purposes of this discussion is to note that the cam profiles in marine engines are different, but materials remain the same.

 

[QC]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

Agreed.

 

[NSBCraig]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

I know I'm missing it all.

I thought the point was- "Boat motors seem like a great place to get a clean used long block for your next budget car project!"

And that just is not true.
Sorry but no dice!

 

[Bronc Rider]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

I know I'm missing it all.

I thought the point was- "Boat motors seem like a great place to get a clean used long block for your next budget car project!"

And that just is not true.
Sorry but no dice!

The original point is not what I was commenting on. I was commenting on this:

I've read in a lot of places about people trying to use car motors in boats and they don't work.

My point was that they do work because they are the same as boat engines.
If you bought a new truck engine from GM right now, it would be ready to bolt into a hull. The new engines come with brass core plugs, graphite headgasket and the truck cam is close enough in grind to use in a boat. Reversion shouldn't happen and the torque curve is similar to a boats, meaning most of the power is made down low. The only thing you would have to do is bolt on your marine accesories.
And yes, some people do rob their boats engine to put into cars. There was a thread in the I/O section not too long ago with someone wanting to do that (take the 350 from a boat to put in his camero).
Well cared for engines last a very long time. My dad has a 350 in his boat that has a little over 800 hours on it. Compression is barely different from when he bought it brand new. He takes very good care of his things. That 350 would still burn rubber if it was put in a car. Most of us wouldn't use boat engines in a car but you most definitely could find a good engine from a boat to put in a car.

 

[NSBCraig]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

Well cared for motors do last but that's not most boat motors so yes if you find a jewel it could be put in your car, but then odds are the boat it's in is a jewel too so unless your reusing your boat motor while repowering then the odds of finding a good budget car build motor in a boat is real slim.

Sure you can find cheap cars with small blocks worth throwing in your boat but decent boat motor are gonna cost you more then buying a car motor worth putting in your boat.

That was the point of the tread.... boat motors are hardly ever in better shape then car motors...... point is wrong.

So now your saying if you wanted to buy a gm crate motor you could bolt your marine accessories on it and you'd be better off then buying a marine engine or rebuilding your present motor?


Really???

 

[Bronc Rider]

Re: Boat motors, wear and tear = an Interesting 1/2 truth

Well cared for motors do last but that's not most boat motors so yes if you find a jewel it could be put in your car, but then odds are the boat it's in is a jewel too so unless your reusing your boat motor while repowering then the odds of finding a good budget car build motor in a boat is real slim.

I dont know why you think that, good used engines are very easy to find in my area. I prefer new or rebuilt but, I have successfully used trucks engines for boats. Local scrapyard will charge me $100 bucks for a used engine with a 30 day warranty. Some of these engines are simply taken out of service because the vehicle they were in was totaled. Plenty of these around so I have no idea what you are referring to.

you can find cheap cars with small blocks worth throwing in your boat but decent boat motor are gonna cost you more then buying a car motor worth putting in your boat.

Again, this is not true. I have bought engines for boats at auto machine shops with no price difference. All you have to do is tell them what cam you need. Most shops already use brass core plugs and graphite headgaskets anyway. If not tell them you want those too. There is no extra machining done to marine engines so there is no reason why it would cost more.

That was the point of the tread.... boat motors are hardly ever in better shape then car motors...... point is wrong.

I never implied or said that. Must be directed at someone else.

now your saying if you wanted to buy a gm crate motor you could bolt your marine accessories on it and you'd be better off then buying a marine engine or rebuilding your present motor?

I brought up the new engine only to show that you can get an auto (truck) engine and bolt it up with no changes. No changes required because they are the same. Boat or truck, the engine will not care.
The way to go is a new engine. I only made all these posts because you seem to think that boat engines are different than auto engines and its not the case. I'm not advocating everyone go to the scrapper for their engines but, you could do it successfully.

Really???

Yes!!!



EDIT: My first comment in this post makes no sense. I read it backwards, sorry.