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Old 24-04-2014, 07:52   #1
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Life of an engine A-4

How many hours before I rebuild this engine that purrs like a kitten.

Thanks
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Old 24-04-2014, 07:57   #2
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Re: Life of an engine A-4

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Originally Posted by bcsailorgirl View Post
How many hours before I rebuild this engine that purrs like a kitten.

Thanks
Depends on the engine, how it's used and how it's maintained. Not sure if your engine is an A-4 but I don't recognize the abbreviation.

GM 6-71 diesel which is a heavy duty, commercial grade engine, could easily give you 20,000 hours or more.

High compression, high power, gasoline engine might be good for 2,000.
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Old 24-04-2014, 08:03   #3
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Re: Life of an engine A-4

The OP is talking about the Atomic 4. Inline 4 cylinder flathead low compression gasoline engine that was found in a lot of boats from the 60s to 70s.

Try to ignore the gaso-phobes in the thread, but here's some opinions:

Lifespan of an Atomic 4

By the way here's where you get parts:
http://www.moyermarine.com/
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Old 24-04-2014, 08:41   #4
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Re: Life of an engine A-4

A couple of years ago I rebuilt an 1961 vintage Atomic 4. It developed a pinhole in the cylinder wall and was sucking water. Aside from pinhole, (that I suspect was a casting anomaly combined with seawater corrosion) the engine showed surprisingly low wear. The low compression ratio in this motor must contribute to the low cylinder wall and bearing wear.

We had the cylinder sleeved and put another 500 hours on her before we sold the boat. We would change the oil every 50 hours and kept the engine temp around 140 to prevent salt build up. If your boat engine is freshwater cooled and you keep after the oil changes you should be golden.
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Old 24-04-2014, 08:51   #5
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Re: Life of an engine A-4

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Originally Posted by cal40john View Post
The OP is talking about the Atomic 4. Inline 4 cylinder flathead low compression gasoline engine that was found in a lot of boats from the 60s to 70s.

Try to ignore the gaso-phobes in the thread, but here's some opinions:

Lifespan of an Atomic 4

By the way here's where you get parts:
Moyer Marine Atomic 4 Engine Rebuilding and Parts
Of course, A-4. Never owned one of my own so did not feel familiar enough to call the engine by its knickname. Have sailed boats with them, including one rented boat where the fuel line ruptured and dumped gas in the bilge. Even after that I'm no gasophobe but if I owned a sailboat withone I would look a little closer at the fuel system than the owner of the rental.

Also, did not know the Atomic was a flathead. Interesting.

So, based on my limited experience, a well cared for A-4 is good for at least a couple thousand hours. If you're worried, watch the oil pressure and run a compression check.
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Old 24-04-2014, 10:02   #6
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Re: Life of an engine A-4

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Originally Posted by bcsailorgirl View Post
How many hours before I rebuild this engine that purrs like a kitten.

Thanks
I don't think you can base a rebuild need by just hours. For example, the 40 year old A4 in my Tartan probably has a bazzilion hours on it, and to my knowledge it's never had a rebuild. But the boat spent it's entire life in the great lakes, sucking up fresh water and being hauled out and serviced every year, and the engine still purrs like new.

If all 4 cylinders are golden on compression, cooling water flows freely, engine temp stays steady, and there are no leaks or wierd noises, then just keep happily motoring and don't worry.

There are some things you can do to the A4 to increase it's longevity, like installing a secondary fresh water cooling system with raw water exchanger, doing occasional acid (or vinegar) soaks, electronic ignition etc. The Moyer Marine forum is an excellent source of info on all this and more.
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Old 24-04-2014, 10:29   #7
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Re: Life of an engine A-4

Moyer Marine is the place to go. I have installed the intake breather, new alternator and electronic ignition. I have this motor in a 62 Pearson Triton. Has been in the family all her life. I sail in the Great Lakes - fresh water all her life. If you are in salt water get the fresh water cooling kit from Moyers and install it. That's your best protection right there. You could also consider the oil filter kit from Moyer. I don't have it but may install. My engine doesn't get heavy use so I don't worry too much. After 50 years os smooth running with minimal oil consumption I think it will be OK. These motors are nearly bulletproof. Salt can corrode the block, tho. The crankshaft is not supported ideally but as long as you don't load her down too much it won't be a problem. The gasoline issue is bogus. Really, now, we all know how to be safe with propane fuel, the issue is not much different than with gasoline. Maintain your fuel system, install a sensor if it makes you feel safer and use the blower to ventilate the bilge. My strategy is to blow the bilge if I even think I may need the engine when in close quarters/busy seaway.
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Old 24-04-2014, 10:35   #8
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Re: Life of an engine A-4

Don't fix it if it ain't broke.

The a4 will go thousands of hours easy. And you'll know when you need to rebuild it. Low compression, water in the combustion, etc... All the typical gasser failures will tell you when/if it's done for. Then you can buy a NEW one for $4K and drop it in (moyer is casting new blocks/heads/etc...)

Electronic ignition is a good thing on this motor.
Electric fuel pump is a good thing too.

And yup - it's a teeny little flathead motor. Valve adjustment through the side of the block.
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Old 24-04-2014, 11:36   #9
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Re: Life of an engine A-4

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Originally Posted by jeepbluetj View Post
Don't fix it if it ain't broke.

The a4 will go thousands of hours easy. And you'll know when you need to rebuild it. Low compression, water in the combustion, etc... All the typical gasser failures will tell you when/if it's done for. Then you can buy a NEW one for $4K and drop it in (moyer is casting new blocks/heads/etc...)

Electronic ignition is a good thing on this motor.
Electric fuel pump is a good thing too.

And yup - it's a teeny little flathead motor. Valve adjustment through the side of the block.
New blocks? Wow that's good news. Everybody seems to have tons of crankshafts and rods and pistons and stuff.

OP, at this point it might be shutting the barn door after the cow got out, to convert to freshwater cooling. 40 years of seawater cooling will have done enough damage already. If you are already freshwater cooled, then that is a definite plus. One thing I do recommend though is replacing the mechanical fuel pump with an electric one. The diapghram can fail and send gasoline into the crankcase. That isn't good. Oh, and the Moyer Marine electronic ignition add-on is a good move. Definitely improves things. No more worries about damp points, etc.

Most Atomics out there have NEVER been rebuilt. They wear sowly. The most common atomic killer is the raw water cooling. Eventually corrosion eats into the block and you got water on the pistons or in the crankcase.

My A4 spent considerable time under water under previous ownership, post-katrina. This would be a death blow to most gasoline engines. After sitting unused for years, I bought the boat and the engine actually turned over with the starter, when I connected my pickup battery to it. That was the deal maker. I figured I could get it running if it wasn't solidly froze up, so I bought the boat. Took a while to get it actually running, though. Now, it runs, and yeah it is a little cranky sometimes, but the only reason I am fixing to get rid of it is my fuel tank has a hole in it and I can't get to it without pulling the engine, and I have been wanting to go electric for a long time anyway. After 40 years of hard use and harder neglect, it still runs and it could still replace a busted engine in a beat up old boat that you wouldn't want to put a new motor in. They are great, simple engines.

If your oil looks good and a magnet doesn't pick up any shavings and has no water or foam in it, and it starts and runs okay, and has good compression, I say don't worry about a rebuild, ever. You can get a compression gauge at autozone and do your own compression check. The gauge just screws into the spark plug holes. Record the pressure at idle and the 4 cylinders should be within about 20% of each other.

You do need to tune it up every year or so. If you have regular point type ignition, anyway. For that you COULD do it by ear, but you SHOULD use a timing light and tachometer. Cheap at autozone. Make sure it will work with a 4 cyl motor. Moyer Marine is a good source for the detailed how-to. If you have electronic ignition, just replace the plugs every 5 years or so. Serious. With electronic ignition it is set and forget.

Do you have a separate fuel filter / water trap? You really should. And check the engine mounted filter. In fact, replace it or remove it altogether if you have a proper filter setup down there.

Replace your belts and hoses, especially fuel lines, with good quality stuff, every few years. Make sure your fuel lines cant chafe on anything when stuff is getting all vibratey down there. A catastrophic fuel leak is a major problem with a gasoline boat. You really really need to have spare belts and filters.

Change the oil. There is no oil filter on an atomic so oil changes are very important.

If you decide you don't want gasoline on your boat, which is a legitimate concern, A Beta 10 is pretty much a drop-in replacement diesel. Very little to do beside simply replace the engine. You will need a return line to the fuel tank, freshwater cooling setup, thats about it. I am going electric, but that isn't for everybody. The Beta is cheap and for most parts you just go to a Kubota tractor dealer.

Good luck with the A4 and do visit Moyer Marine's website and get all the manuals and stuff, even if you elect not to go with the upgrades I mentioned. Unless the block gets ate up from the inside out from raw water cooling, they are really long legged engines with a long lifespan.
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Old 08-05-2014, 06:40   #10
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Re: Life of an engine A-4

A good recap of Atomic 4's. An outfit in Canada- Seacraft Publications, as I recall- used to publish a maintenance/repair/shop manual for the Atomic 4. If you can find one, you need it. The owners' manual published by Universal Medalist Motors is handy for tune-ups, light maintenace, winterizing, etc. and though helpful, is not as detailed as the Seacraft manual.
I once had one that had a leaking exhaust elbow. No big deal, just replace the black iron pipe. BUT I removed the manifold to do so. Major mistake. Just three bolts to get if off. This disturbed the rust, which then didn't secure so well when the manifold went back on. And the manifold is a combined exhaust-intake manifold. Everything was running fine, until the engine shut down, with seawater in the carburetor. Eventually helicoils fixed the problem, and the engine ran better than ever. Needless to say that A-4 was raw water cooled.
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Old 09-05-2014, 00:24   #11
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Re: Life of an engine A-4

Oh, one more upgrade suggestion. This one only costs a couple bucks. Extended mixture needle for the carb. The extra length and the knurled make carburetor adjustment a lot easier. Moyer Marine for that. It is really hard to get at the stock screw with a screwdriver on some boats.
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