New life for an old beast

[DArcy]

A few weeks ago, heading home from a weekend at anchor, I started to have some engine trouble. The Atomic 4 was running rough and losing power. The wind picked up so I shut it down and we sailed but when we got to the harbour it just would not start. We sailed in with no drama and I poked around. The symptoms were either not getting enough fuel or a leak between carburetor and intake valve. The fuel filter was clear, and the fuel pump seemed to be working so I pulled off the carburetor and was very surprised to see water in the bottom of it.

I have been struggling with overheating for the past year and a couple of months ago I found the cooling jacket on the manifold had become blocked. I scraped it out the best I could and got much better water flowing. This is a combined intake and exhaust manifold with a cooling jacket. It turns out the scale build up in the cooling jacket was worse than I thought and it had rusted right through. I knew right away when I saw the water in the carb what had happened. This is a 43 year old engine but they still have a strong following so no problem ordering new manifold and gaskets. After a couple of weeks with frequent squirts from a can of Liquid Wrench, the nuts on the manifold studs came right off. Now she is up and running again... just in time for haulout.

 

[TomY]

Nice going, DArcy! I love to see good old stuff like an Atomic 4 fixed and functioning.

 

[Justin_NSA]

like the bumper sticker on an old Jag XKE said, "ahhhh but when it runs".
Good for you keeping 'er going and not scrapping it .

 

[sailnoproblem]

Nice job, I have one and they a tough. The flat head design is pretty simple. I totally rebuilt mine, several years ago. Other then a carb problem this past spring, she has been running great. You are right about the abundance of parts available.

 

[JimFacey]

Way to go, I had to replace my manifold on my A4 the first year I had it, mine is now 44 years old and was last rebuilt in 1989, but has run like a top since I bought the boat 12 years ago. In spite of being neglected by the previous owner, once I got over some sticky valve issues she has very few problems, it's been extremely reliable. I would not trade it for a diesel, when and if it goes, I will probably get one of those new Moyer Marine A4 blocks. I love the quiet, when I am in the dock at idle, people can't even tell I have the motor on. We can talk at normal voice levels on hte boat and be heard over the motor at cruising speed. Fuel economy is not what it might be for a diesel, but I don't have to bleed filters ever or worry about algae, though ethanol is an issue.

Looks like you have pretty good access, on my Ranger 29 it is much tougher to access the sides of the motor. My only issue this summer was a slippage in forward, but I just did the forward clutch adjustment and it was pretty easy.

 

[Todd D]

I am glad you were able to solve your problems. I have a slightly different view than the others so far in this thread. When I had gas engine woes with my powerboat I yanked the Chrysler Crown and dropped a new diesel in. End of gas engine issues.

 

[DArcy]

some sticky valve issues

@JimFacey I think I have a sticky valve issue. How did you diagnose and fix it?

Todd, I think the A4 is more of a cult icon than other gas engines. That probably has something to do with the tenacity with which us devotees cling to them.

 

[TomY]

Way to go, I had to replace my manifold on my A4 the first year I had it, mine is now 44 years old and was last rebuilt in 1989, but has run like a top since I bought the boat 12 years ago. In spite of being neglected by the previous owner, once I got over some sticky valve issues she has very few problems, it's been extremely reliable. I would not trade it for a diesel, when and if it goes, I will probably get one of those new Moyer Marine A4 blocks. I love the quiet, when I am in the dock at idle, people can't even tell I have the motor on. We can talk at normal voice levels on hte boat and be heard over the motor at cruising speed. Fuel economy is not what it might be for a diesel, but I don't have to bleed filters ever or worry about algae, though ethanol is an issue.

Looks like you have pretty good access, on my Ranger 29 it is much tougher to access the sides of the motor. My only issue this summer was a slippage in forward, but I just did the forward clutch adjustment and it was pretty easy.

Jim, I have the same manual transmission(paragon) on my boat. When I put a 'new' slightly used engine in a few years ago, it was the same as the old one so the transmission stayed as well. I thought I would replace it but I've changed my mind. Mine is a little tricky to get adjusted right so that you can stop the prop between forward and neutral. But I've gotten used to it. I guess the next guy will have to as well, or he/she can put a new one in.

 

[JimFacey]

@JimFacey I think I have a sticky valve issue. How did you diagnose and fix it?

Todd, I think the A4 is more of a cult icon than other gas engines. That probably has something to do with the tenacity with which us devotees cling to them.

On stuck valves, you can tell by loss of power, rough running and especially by a compression test.

 

[JimFacey]

D'Arcy - more on stuck valves, the first spring I had a stuck valve( #4 rearmost and lowest, and being a non mechanic a well versed friend help me get the cylinder head off and then work it free. You can try spraying in Kroil, or PB Blaster, lots of it, and turning over the engine, if that fails pour in several ounces of Marvel mystery oil and wait overnight then try it again.
If you can't t work them free, take the head off and you can carefully, manually work them up and down if they are not "too stuck". If this fails you will need a valve job to get them moving. Over the 2nd winter I had the boat my #3 and #4 stuck and eventually I had to get the valve job done by my friend, who is in his seventies and promptly retired from in-boat repairs.
Every fall now, after I fog for the winter layup, I will pour 2 or 3 ounces of Marvel into each cylinder and then turn over the motor by hand several times to try and coat things for the winter, its the inactvity that is the enemy of these motors. It has been working for the last decade, no valve issues.

 

[DArcy]

Thanks Jim, I first noticed it a month or two ago. It was running rough, not firing on all 4 cylinders. I pulled the plugs one by one and was getting a good spark on each one. After that I tried starting again and it ran smoothly. After it was sitting for a few weeks due to the rotted manifold, when I put the new manifold on it was doing the same thing, running rough, low power. After about 3 or 4 minutes it cleared up and was running smooth again. A friend suggested putting some diesel in the oil and letting it run for a few minutes before changing out the oil. Marvel would probably do the same thing and would be worth a try before pulling the head off.

 

[JimFacey]

You may have thought of it, but its a very good chance that your manifold led to the stuck valves, with mosture getting places it shouldn't be.

 

[Al Schober]

Hey Tom,
I've had a bit of experience with those Paragon transmissions. Can you send me a PM with your email? Perhaps I can give you some advice - rather not clutter up this BB.

 

[DArcy]

Yes, that thought crossed my mind. I just tried it this evening and it started right up. It is running smoothly at the moment with good temperature and oil pressure. I wanted to give it a bit of a run to burn out any moisture.

 

[nightowle]

Love the A-4. Had one for years. Take care of it, and it'll take care of you. A real workhorse and super easy to work on.