Boat Diesel vs Truck Diesel

[In Training]

Question: Putting together 3-4 year plan to Cruise. Diesel mechanic classes in Indiana assume you are preparing for a career as a truck diesel mechanic - not many boats here.

Are they similar enough that a class for truck diesel will prepare you to know what spare parts you need and how to replace them, minimal maintenance, oil etc.

I would have it hauled out for an overhaul, just want to do a good job with maintenance and not be stuck somewhere not knowing how to change or replace something. Also want to know what my husband is talking about when we have problems and not be so slow on the uptake.

Thank you for your feedback.

[sailorboy1]

I feel they are close enough. I you understand trucks it isn't much to learn about the dierences. I learned on large submarine diesels, was definitely close enough.

But really if you are mechanically inclined a diesel isn't that much to learn to start with as far as the basics.

[donradcliffe]

Boat diesels are the same as truck diesels except for the cooling and exhaust systems. The cooling system on a boat usually has a heat exchanger and two water pumps instead of one. The exhaust system usually has a water injection elbow after the exhaust manifold. Both of these systems requires periodic maintenance and spare parts, like impellers, zincs, and possibly the injection elbow itself.

Fuel and electric systems are essentially the same.

[Astrid]

It certainly would not hurt to take a class or two in diesel mechanics, even if aimed more at automotive rather than marine diesels. One just needs to remember that marine diesels work in a sometimes more hostile environment where condensation is the big enemy, resulting in shorter times between oil changes, and corrosion due to galvanic reaction runs a close second. Marine diesels also frequently have, or should have, more elaborate fuel filtration systems.

Finally, as Don says, there are differences in the cooling systems and exhaust systems.

[David M]

They are close enough where you would learn a lot and be able to tell hubby what kind of spark plugs the engine needs.

Kidding.

It's worth it.

[Tia Bu]

Truck diesel classes would be informative. A long time ago, a boat captain told me, "Diesels are easy. If they are getting fuel, they run. If they aren't getting fuel, they don't run." He was right.

Diesel mechanics is a lot easier than it seems. I applaud your interest in the subject. Working on the diesel has grown to be one of my favorite parts of boating, strangely enough. They're really cool machines.

[DeepFrz]

Just remember that on a cruising boat the operational characteristics are different. In trucks the fuel is, generally, turned over much more rapidly than in a boat. The main troubles with marine diesels are 1) fuel 2) cooling system (raw water pumps, heat exchangers, and injection elbows). Fuel tanks have to be cleaned periodically and the cooling system needs regular maintenance. Feed it "clean" fuel and keep the cooling system in good order, along with the other regular maintenance items and it will run well for a long time.

[djmarchand]

Log on and subscribe to boatdiesel.com. I have learned more about marine diesels on this site than anything else. And if you have a problem, the guys who hang out on this site will help with it.

David

[Seahunter]

Marine engines,in particular diesels are more similar to industrial engine rather than automotive type (EG BobCat etc). They're designed to run at constant engine speed for hours and are rated as Continuous Duty or Intermittent Duty and are subject to a time factor. IE, 3000 rpm @ 24 hours or 1800 rpm @ 10 hours. Automotive engines are rated as intermittent.
As noted there are differences in cooling and exhaust systems, however they are not necessary, (dry stack exhaust and raw water cooling).
Here's a good article explaining CD.
Seaboard Marine - Custom Marine Diesel Repower Specialists
MTU's CD chart.
Diesel engines for onboard power generation and diesel-electric drive: MTU Online

[S/V Alchemy]

The idea of understanding continuous duty is an important one. The way in which a boat diesel is run strongly affects its life cycle and maintainance needs. A few rules to follow:

1) Clean fuel is paramount. That requires vigilance at the deck fill (a Baja or similar filter to keep dirt out) and a decent fuel/water filtering setup prior to getting diesel to the engine's own fuel filter. In the broader sense, you need to keep your main tanks free of containments. Many long-term cruisers install a daytank that has nothing but post-filter fuel in it at any time, and therefore represents a "known to be clean" reserve, even if you have some sort of ingress and/or bad diesel.

2) Speaking of ingress, consider moving the tank vents off the side of the boat to someplace farther from the water.

3) Diesels will run optimally at a certain RPM. By optimal, I mean in terms of fuel economy, and in terms of running at 75-80% of rated output. They also like a certain amount of heat throughout the block, which is why truckers in cold climates leave their engines running, pollution be damned. Ideally, you want to switch on, run at 2,200 RPM (or whatever) for a few hours, and never touch the throttle. That heats the engine, makes the metal parts mate tightly and aids in proper lubrication. So I prefer to sail slowly at times rather than motor for 10 or 20 minutes, and I also in cold weather only gradually increase the throttle until my temps are nice and warm. The engine seems to like it better that way.

4) Cooling can be a black art. Most of my engine problems have been related to backpressure, little busted piston valve springs, and half-busted waterlift mufflers. The problem, of course, is that the engine cooling circuit is at or below the waterline, and the raw water (assuming you have a heat exchanger) is ultimately being pushed uphill to get, with the exhaust, out of the boat. That's a recipe for disaster unless it's fully understood. One of my decisions is to get rid of the siphon break and just to run a simple hose out to the deck. Easy for me: I have a steel pilothouse cutter with the exhaust going out one side. But the idea of having the fuel and water tank vents and the siphon break vent open and on the centerline near the "top" of the boat is not a bad one, and is worthy of consideration.

[Randyonr3]

went in to pick up a few parts for my 4-108 perkins a few months ago.. Was told that only about 7% of the 4-108 motors were used in Marine applications.. the rest were in stationary pumps, power generators, and in central america it seems, autos and small trucks.. looking over at the parts floor, they had 4 of the 104s on pallets waiting to go out for farm use..

[Seahunter]

The Perkins 4-107, 4-108, 4-154 and the 4-236 where and are the most commonly used engines for industrial use. The 107 and 104 are rated as intermittent duty, while the 154 and 236 are continuous duty. The 4-236 is and still is the best diesel engine ever built and was the key reason Cat bought bought Perkins. The 236 is Cats best industrial engine at this time in its Cat 4.4 name tag. The Perkins Sabre M92 is the 236 in a new wrapper. Both the 154 and 236 are CD engines rated at 3000 RPM (24-7) and that's hard to beat in a small engine.

[tropicalescape]

Originally Posted by David M

They are close enough where you would learn a lot and be able to tell hubby what kind of spark plugs the engine needs.

Kidding.

It's worth it.

And what type of gas to use..regular is not a good choice..high test(93 oct.) works best..

[Chuteman]

In Training:
Just in case you wander east,
Here's one option for marine diesel classes

Mack Boring & Parts Company - The Power Behind The Power

no connection, just an interest myself

[Bash]

Originally Posted by Chuteman

In Training:
Just in case you wander east,
Here's one option for marine diesel classes

Mack Boring & Parts Company - The Power Behind The Power

no connection, just an interest myself

the OP resides in Indiana. Anyone know of a marine diesel class anywhere close to that neighborhood?

You'll never learn how to change an impeller on a truck engine. Seems better to train on marine diesels if you can.