Catalina 30 A4 engine

dlochner · May 6, 2019

Could be rings, worn cylinders, or leaky valves.

For all things Atomic A4, check out https://moyermarine.com

Whatfiero1 · May 6, 2019

Usually they sit in easy access location so easy to rebuild in place. But I know of a boat that replaced with a 4 cylinder Perkins 50 hp and man that's boat flys under power.

Afrakes · May 6, 2019

If you do most of the labor yourself the investment can be only a couple of thousand. Swapping the A4 for a diesel will run many, many bucks.

sailnoproblem · May 6, 2019

I had a similar problem #1 had no compression. I rebuilt the head/pot (flat head) removed and replaced the valves, springs, also had the head machined to make sure it was flat. No problem ever since, had great help from Ken at Moyer.
The biggest problem with the A4 is carburation. If the engine is not seized as I assume yours is not, I am sure it is a valve problem. It is a lot cheaper then repower, and simple as it is a flat head motor. Good luck.

rgranger · May 6, 2019

Or... the Catalina 30 has a flat transom. You could just pull the engine, put an electric tilt mount for an O.B. on the transom.

Pirate Dave · May 6, 2019

Moyer marine is your best friend right now. I'm sure that question has already been answered on their website

DArcy · May 6, 2019

Moyer Marine is a great resource for the A4. I've rebuilt or replaced most parts you can bolt onto an A4: alternator, water pump, fuel pump, carburetor, exhaust, manifold, ignition. But I have not removed the head or bottom end. Mine is fresh water only and is running great after only 44 years of service. It only sees about 50 to 100 hours per year.
These engines are incredibly simple and very easy to work on. If you have swapped heads on engines before, you have more than enough skill to rebuild an A4. Contact Moyer and price out the parts for a head rebuild or a complete rebuild.

Roadking Larry · May 6, 2019

Get thee to the Moyer Marine forums!
It might be as simple as a bad head gasket and a stuck valve. (it wouldn't be for me of course).
Dead simple engine. If the boat itself is good it might well be a good deal.

Capt jgw · May 6, 2019

The A4 is commonly maligned just because it's gasoline. Actually they're great engines. Easily rebuilt and upgraded with electronic ignition. Many people would shun a gas engine but put a propane stove on the boat when propane is way more dangerous than gas. I wouldn't reject this boat just because of the A4, and as others have replied, Moyer is your best friend to get this engine running. If it's not seized it can be repaired at a fraction of the cost of a diesel.

DArcy · May 6, 2019

If you buy the boat you're gonna want this manual http://www.fdlaudubon.org/page19/assets/A4RepairMaint.pdf

DArcy · May 7, 2019

The Universal Atomic 4 went into a LOT of boats between 25 to 35 feet, even some up to 40 feet, from the 60's into the 80's. It is really too much engine for smaller boats like mine but it was cheap, reliable and easy to maintain so that's what everyone used even if it is not an efficient engine. There were some slight differences between early models and later models but they are the same basic engine. Moyer Marine has a discussion on the differences https://moyermarine.com/faqemorlm/

dlochner · May 7, 2019

In one of the photos just posted, there is a clear picture of the exhaust pipe from the exhaust manifold. There are a couple of issues I see there. First the the parts look to be off the shelf galvanized pipe connected to a black iron elbow with teflon tape used in the joints.

I'm not sure that galvanized pipe if the correct material. When I replaced a similar part on a diesel, it was made of black iron. Someone with a better understanding of the virtues of black iron and galvanized pipe might be able to weigh in with a more reasoned explanation about using galvanized or black iron. My inclination is to replace it all with black iron. The problem is the hot exhaust gasses what effect those gases might have on the pipe.

What I am sure of is the use of teflon tape and the lack of pipe insulation. The pipe threads should be coated with a high temperature pipe dope as the pipe will get very hot from the exhaust gas. Something like Bostik's Marine Never-Seez will work. (The link is to a large can, shop around it comes in smaller containers).

Next, the pipe will get exceptionally hot. It should be wrapped in a fiberglass insulation tape. Something like this tape: https://amzn.to/3034w4V It can also be found in local auto parts stores. In the old days, this part was wrapped in asbestos tape.

If you buy this boat, these should be corrected. The fix is pretty straightforward and not all that expensive.

DArcy · May 7, 2019

Based on the fuzz around the drain plug at the back of the manifold, it looks like there may be some corrosion going on. IF you have trouble with overheating or restricted water flow, check the pump first but if that looks ok then it is likely restrictions in the manifold due to corrosion. I was having overheating problems on mine and then one day found water in the carburetor. The water jacket in the manifold rotted through and it was leaking into the intake. The manifold is all in one, intake and exhaust plus it is water cooled. It is a really easy replacement if all the nuts and bolts aren't frozen. I got lucky, everything came out with generous application of liquid wrench. I rebuilt the carb while it was off.
I actually kind of like working on that engine. Don't judge me, I know it's a problem.

sailnoproblem · May 8, 2019

N

Newbie3 said:
Let's shift gears for a moment. Let's say that there is a diesel option for under $1000. Used but in good condition. And the same dimensions as the A4 except... the transmission has a 7* down tilt on it so it will require a bit of engine tilt with the mount. 1988 Volvo Penta 2002 Diesel

What are the barriers to a diesel conversation?

The fuel system should largely be the same, right? Tanks, fittings, and hoses.. drain it.. and pump some diesel through to clean out any gas residue.

Next, connect the exhaust.. and run the instrument panel/controls.

I'm just exploring options...

Not really on the fuel system, you need a return line, and I think you'll need different filters. Just food for thought.

Catalina 30 A4 engine

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