Diesel in a Cat 30?

Jimm · Nov 3, 2011

Diesel options

Inception said:
I have a Catalina 30,from around 1982, the old Atomic engine is blowing oil, and needs to be replaced! Will a Yanmar 22hp 3 cylinder engine fit? How about a 28HPVolvo?
Is it just a matter of getting the correct mounting plates?

Would seem a question for Catalina tech support -- I have a Universal (Kubota) 25hp, as do I think most of the later Cat30 models...

Stu Jackson · Nov 3, 2011

The M25XPB is still available, IIRC. Used in many C30s, pretty much the same size as the M25. 23 vs 21 hp. I'd stay away from Volvo, parts are way too expensive and hard to get. Yanmar make good engines and I think the C309 has them.

jsalley · Nov 3, 2011

Yep - C309 has Yanmar 3YM20, a very compact, smooth running diesel.

Old Skool Neil · Nov 3, 2011

Unless you are committed to going diesel, it will probably cost half as much or less to rebuild or replace the A-4.

A factor to consider is the shaft log and strut are at an angle determined by the A-4 configuration and you'll find it is unfriendly to other engines. The result is usually 4 or 5 inches of new engine sticking above the dinette seat when you're done.

Going diesel will mean a new fuel tank, new controls and cables, new control panel, new shaft and new prop, none of which is necessary staying with the gasser. It's usually more cost effective to replace the boat with one that already has a diesel if that's what you want.

A full array of A-4 parts and information can be found at Moyer Marine,
www.moyermarine.com

jrowan · Nov 3, 2011

I have to agree with Neil on this one. It is always more cost effective to rebuild an engine then to replace it, as long as the block & head are still good. The A4 gas model, although dated was a venerable, strong, & dependable motor when well maintained.
Although here is a question to Inception: you did not state whether your Universal engine was a diesel or reg. gas model? All of the engines still state they are "Atomic" in that era, the difference is whather it is a Universal Atomic A4 or 5411. By 1982 timeframe most C 30's were being ordered with the 5411 2 cylinder diesel engine. Although it has half the horse power rating of the A4, it was a very tough lil' engine. Mine is still going strong, knock on teak. There are still many rebuild parts available for both engines. Neil makes many good points for keeping the original, cost being the biggest benefit!

Old Skool Neil · Nov 3, 2011

WOW, it never occurred to me it might already be diesel. I saw Atomic and instantly thought gas. If it's already a diesel I retract about half of what I said.

Stu Jackson · Nov 4, 2011

Inception said:
...I used to pull apart old British motorbikes, cant be much diffferent!

Sure it will be. It will start, 'cuz it doesn't have a Lucas "starter."

Bold Rascal · Nov 10, 2011

Rebuilding that A4

Niel's advice is spot on.
My own experience with getting an old A4 back to life was a good experience. The folks at the moyermarine forum are a huge help and once you get into trouble shooting your engines problems you might find it easier and far less costly than you had expected. If you don't have one already, purchase yourself a copy of the Moyer Marine engine manual. It's extremely helpful and geared to those of us not so mechanically gifted.

Twice Around · Nov 17, 2011

I don't think you are doing yourself any favors with a second hand diesel. The motor itself may be cheap, but it will be a one-off installation with many unknowns. Even the 'known' switchovers (all detailed by Neil) are costly, so who knows what will happen if you try to shoehorn that Yanmar in there.

(sidebar) - My stepfather's Tartan 3000 has the 11HP Universal M-15 (basically the same motor as the 5411)...it says "Universal Atomic" all over it..:neutral:

Brad Woodward · Nov 24, 2011

If a rebuild is "the way to go" when your engine doesn't work any more, what is wrong with buying a rebuilt one to replace an older one. Catalina found the M 25 diesel was a solid engine and put it into their later models. I have one that worse great. Will push me into the harbor against a 2 kt current on a changing tide at 4.5 kts. Diesel is a lot safer than gas and diesel engines are designed to run at a constant speed all day long

jimgreen8c · Nov 28, 2011

I have a 77 and the last owner put in a Yanmar GM 20f two. It stands 4" higher and sticks out. We had to build a custom cover and it screws up the berth and seating. The old owner paid 7k for the engine and 7k for installation ...and it's stupid. They didn't even change the folding prop so it is way under pitched. A new folding prop is $1700. I'll replace the blades for $700.00 but still....

jrowan · Nov 29, 2011

That is a good point to make about the Yanmar diesel. I had one in my last boat, an
S 2 which was a tough engine, and it is compact in terms of its width and depth. But it is rather tall & with the central mounting of the engine, its crucial that the engine fits the confined space. The S 2 has the Yanmar mounted behind the rear bulkhead, below the companionway access steps. This gives the motor more room to spread out aft, under the cockpit sole. The Universal motor located under the galley is already loud as hell without the engine sticking out another 4 inches higher!

pencema · Dec 9, 2011

This summer I replaced a Yanmar YSE-12 in my 75 C-30 with a Beta 16 (Kubota) 2 cyl diesel. I built custom engine beds to align the new engine with the prop shaft and it fits completely inside the compartment - no dome, etc. Even the hi-rise exhaust manifold fit comfortably. With a 12x9 prop I reach the 3600 rpm "red line" and hit hull speed around 3000. It's a drastic improvement over the old Yanmar.