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chtaylor 01-03-2009 06:12 PM

Replace vs Rebuild?
The Atomic 4 that came with my 1977 Ericson 32 has been a pain in the rear ever since I bought the boat 2 years ago. I contacted a local mechanic who quoted me $2500 to rebuild it. While talking with him, I mentioned that I would rather have a diesel, but can't afford it.

He told me that he has a used 2 cylinder 12 horsepower Yanmar diesel that he would swap out for the same price as the Atomic 4 rebuild.

Is 12 hp enough to replace the Atomic's 30 hp? Any thoughts on the pros and cons of rebuilding the Atomic vs. replacing it with the Yanmar would be greatly appreciated.

Charles Taylor

jaschrumpf 01-03-2009 06:43 PM

What kinds of problems are you having with the old girl? Have you done a compression check?

Mine is a vintage 1975, but it was rebuilt in 1994. I've since replaced the head gasket and the carb, among other smaller fixes. If you have a modicum of mechanical ability, they are easy engines to work on, assuming you have decent access.

Tell us more of your story.

Also stop over at the Moyer Marine site at Moyer Marine Atomic 4 Engine Rebuilding and Parts. It's a specialized forum for the A4 as well as a great site to get parts. A wealth of knowledge over there, there is!

CalebD 01-03-2009 07:04 PM

I am not a marine engineer but my guess is that a 12HP diesel would be fine in nice weather. I would want more HP for a 32' boat in any kind of snotty wind or seaway though. That said, the A4 is rated at 30 HP but probably delivers more like an effective 20+ HP.
I am with jaschrumpf on this. A4's need a bit of TLC and chances are there are some simple maintenance tasks you should do after 2 years of ownership. Tell us more about what the symptoms are and how you have been maintaining your engine.
Definitely stop in over at the Moyer forums as well. There are a lot of A4 owners who know their engines quite well and do most if not all of their maintenance themselves (saving some boat bucks at the same time).

SEMIJim 01-03-2009 08:38 PM


Originally Posted by chtaylor (Post 426738)
The Atomic 4 that came with my 1977 Ericson 32 has been a pain in the rear ever since I bought the boat 2 years ago.

Define "pain in the rear." Properly-maintained A4s that aren't sick in some way tend to be quite reliable. The A4 on our '76 Pearson 30 runs like a top. (Knock on wood!)


Originally Posted by chtaylor (Post 426738)
Any thoughts on the pros and cons of rebuilding the Atomic vs. replacing it with the Yanmar would be greatly appreciated.

Check this thread: for a similar discussion.

Personally, as I noted there, I'd prefer to keep the A4. I prefer gasoline-powered engines over diesel.


hellosailor 01-03-2009 08:41 PM

Charles, a used diesel that hasn't been rebuilt is still an unknown factor. How willing is the mechanic to warranty it? How available is he to come and work on it, if there is a problem?

It does seem marginal on the horsepower, but then again diesels and gas engines have different torque curves as well--so the hp isn't effectively the same. (Well, it is, but the torque makes a difference.) I'm not sure that you wouldn't also need to change the transmission in order to run the diesel at the right speed as well.

If fuel stowage and pricing isn't an issue, a properly rebuilt A4 should be a perfectly serviceable and good powerplant. It isn't unreliable because it is an A4, or because it is a gasoline engine. It is an OLD engine, and that's a problem no matter what the fuel is. Two grand wouldn't be bad, for a complete rebuild, if it was done properly with no corners cut.

chtaylor 01-04-2009 12:52 PM

Thanks for the responses. Here's a thread that explains SOME of the problems that I have been having with the engine:

At Wits' End - Moyer Marine Atomic 4 Community

Now, I have water in the oil. I checked the entire exhaust system for clogs and now suspect a blown head gasket.

At any rate, I'm tired of spending more time working on the engine than sailing and my disgust level has maxed out.

I understand that the Atomic 4 was, perhaps, a good engine it its day and that the engine is old; but THIS engine is a POS.

Charles Taylor

chtaylor 01-04-2009 02:50 PM

No wonder your handle is "cardiacpaul". You might want to calm down, take a tranqualizer or go sailing a bit before the big one hits you. Also, as I was seeking advice on a decision of whether to have the engine rebuilt or replaced, your insulting critique of my attempts at repairing the engine is irrelevant.

You make an unwarranted assumption that I have a "desire to work on my own stuff".
Nothing could be further from the truth. My only desire is to sail. But since I have not become wealthy in my lifetime, I'm forced to attempt to do my own work. Unfortunately, I was not born with your innate knowledge of internal combustion engines.

SEMIJim 01-04-2009 03:13 PM

I can just see CP sitting at his computer, gritting his teeth, vein popping-out on his forehead, the Cuban glancing at him worriedly--concerned he's gonna stroke out :D

The above is why I don't spend more time at the MM site. Beside the fact my mad IC engine skillz aren't what they used to be, I fear I'd too-often go ballistic over IC engine n00bs w/o a clue going in all the wrong directions, doing all the wrong things, reporting the wrong things, mis-reporting the things they do get right... Seen it many, many times, over there. Sometimes I read, shake my head, and think "That can't possibly be right."

Not trying to pick on you, chtaylor. You're having iron genny problems and haven't a clue about IC engines. Not your fault--exactly. But what you're going thru isn't your A4's fault, either.

Btw: Water in the oil. I suppose this has been asked, already, but I don't suppose you once-or-twice cranked too long w/o her starting, with the raw water intake open, did you? Check the MM site for how to check for water in the cylinders. It'll come into #4, first, then on to the others. If that's the problem, and it's not too bad, it's pretty easily fixed.

Tho "IC engine mechanic" wasn't on the list of skills at which you wished to become proficient when you got into sailing, that iron genoa is part of your boat, and, if you're like the rest of us, a pretty damn imporant part when you need it. So it would behoove you to become somewhat proficient at it, whether you really want to or not. Life will be easier. Or you could hire it done. Expensive, tho, and if you're out in the middle of nowhere and a minor problem crops up, well... (Not-to-mention that, once you know what you're about, you'll probably do a better job, anyway.)

The good news is it sounds like your A4 isn't in bad shape at all. Just needs the right fixes.

Good luck.


SEMIJim 01-04-2009 03:17 PM


Originally Posted by chtaylor (Post 427027)
No wonder your handle is "cardiacpaul". You might want to calm down a bit before the big one.

I think I begin to perceive the true nature of the problem...


hellosailor 01-04-2009 07:18 PM

Let's not forget the A4, like almost all gasoline engines of that vintage, uses a carburetor. Carbs need to be stripped down and rebuilt every 5 years in routine use, more often if fuel has been left in them without stabilant during the off-season. Carbs simply gum up from normal gasoline aging in them (less of a problem since gasoline was generally reformulated by the 90's) and thsat's one advantage of a diesel engine--no carb, fuel injection system instead. Of course when a diesel FI system has problems, they can be way more of a problem than a simple carb rebuild. Catch-22.

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