Diesel Maintenance

I have an '89 Carver 4207 with twin Cat 3208's (375 HP). We plan to take the boat every weekend once we get some repairs taken care of. How often should we be starting up the engines, how long should we run them for and at what RPM?

How often should we be starting up the engines, how long should we run them for and at what RPM?


Start the engines ONLY when you are taking a boat ride, and are about to depart.

Allow them to idle for about 1 min , should be smooth then , and get underway at perhaps 800RPM.

As the engine warms to say 120F , 1200 should do, then when above 140-150F increase the speed till normal cruise is reached.

Real simple , unloaded ideling is never good for a diesel, reaching operating temp with modest loading is the fastest way to warm up.

IF long ideling is required due to local circumstance change oil 2X as often as Da Book sez.

Buy the manuals.. CAT reccomends 10 min warm up. Best at 400 rpm below WOT. Idle aka Trolling is fine but run up to cruise speed every 3 hours.

FF is right on in my opinion been running a 3208 n.a. For years

Sd

Odd. Can we resolve the apparent contradiction?
FF says warm up at idle, commence operating at around 800rpm, increasing rpm as temps rise. That sounds about right to me, if only because it`s what I do.
Wzdr02 quotes CAT recommending warm up at 400rpm below WOT. Assuming WOT falls around 2500 that seems a fast warm up speed. Faster than cruise speed for my ancient Lehmans.

FF says warm up at idle, (only for 1 or 2 min till the idle is stable) commence operating at around 800rpm ( to begin the warm up period)

This is hardly a problem as it takes a while for most to exit a marina.

That 400rpm below WOT sounds like an earth moving warm up requirement , never seen it done on any vessel.

I recommend running at light load until temps are stable, thermostats cracking open. Then add load gradually to where you want to be. When slowing, if possible remove load gradually.

In my past life with very large and expensive machinery, heat up and cool down were strictly controlled to limit thermal stress. It applies to these little beasts, too.

I think my CAT manual and my truck engine manual basically said the same as many other manuals I have perused.

No wide open throttle till warmed up..past that...not very specific.

Guess the safety margin for normal operation is enough to get there pretty quick...just don't exceed for a bit.

That said...I too believe a little more gradual is probably better in the long run...just can't prove it and as long as it doesn't affect my operation, I wil, probably continue the step approach too.

The OP may have been asking about how often to start his engines for longer life while at the dock. Obviously if he goes out every week that is plenty.


There is much debate about starting a diesel just to loosen it up, charge the batteries, circulate lube oil, drive off volatiles in the oil and coolant, etc. One thing is for sure, if you don't warm it up to operating temps, don't bother. Even then once every month is plenty.


David

Get the manual. Do what the manual says. My way on all things mechanical. As to running between uses, I'd say yes if uses were going to be four to six months apart. But if you'll be back in six weeks not necessary.

nope

You got it wrong I wrote CAT says warm up for 10 minutes . Normal cruise rpm 400 below wot

Warm up at idle rpm.

I had a pair of 3208T 320hp cats.....used to start them up, cast off, idle out of marina and no wake zones....bring up to around a thousand for a few minutes till the temp gauge starts heading for 180 to 190 (normal temps at least for my old boat).....then feel free to run at 400 to 200 under max rpm.

Like what my manual said.....

Engines are still going strong at around 5000 hours and are 30 years old.

If all you do is idle...in cooler waters...good luck....mine never started the climb towards normal op temp.....

For any diesel I've been around, idling them at no load is one of the worst things you can do. I agree with others that, as usual, the best system is RTFM.

unless they have some load most diesels wont warm up at idle.


When I was unable to use my boat for an extended period I started the engines periodically, waited for oil pressure to be up then shut down. The idea was to keep everything lubed and close different valves but not carbon up everything.

If we do not actually take the boat out for a month we run the engines in the slip. We do each engine in turn. These are FL120s so perhaps the process for a modern turbocharged engine would be different.

We start the engine, let it run at fast idle (900-1000 rpm) for a minute or so, then pull them to idle, engage the transmission and ease the engine on up to about 1000 rpm again. When the coolant temperature starts coming up we take the engine to 1300-1400 rpm in gear and let it run for 20-30 minutes.

We then shut the engine down and do the same thing with the other engine.

When we first started doing this we would do both engines at the same time with one of them in reverse to "neutralize" the strain in the dock lines. However after talking to one of the local BW Velvet Drive experts in the area we stopped the practice of running one engine in reverse. Not wanting to run both engines in forward at 1400 rpm against the dock lines we do them one at a time.

As to warm-up times when we do take the boat out we follow the process described by FF. Get the boat ready to go, start the engines while one of us monitors the exhaust and let them idle at perhaps 800 rpm while we turn on the instrumentation and take in the dock lines. Then we drop back to idle, leave the slip and head out of the harbor. By the time we get outside the breakwater the engines are well on their way up to temperature.

Once outside the breakwater we advance power to 1200 rpm for about five minutes. There is no scientific reason for 1200; it's one of the rpm settings we use in the floatplane so it's sort of burned into our minds. After roughly five minutes at 1200 we increase power to 1400-1500 for five minutes or so. And finally we go on up to our cruise power of 1650.

Coming home or approaching our destination we reduce power to 1200 for the last quarter mile or so and then drop to idle entering the harbor or anchorage.

All of this is the procedure we were advised to use when we first bought the boat back in 1998. The advice came from our diesel shop and acquaintances in the marine propulsion and generator manufacturing industry. Like everything else to do with boating, there are a million ways to do everything, so other folks have other practices. As long as the engines are not run in such a way as to not reach operating temperature I suspect that most of the warm-up practices favored by boat owners are just fine.

Marin said:

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As to warm-up times when we do take the boat out we follow the process described by FF. Get the boat ready to go, start the engines while one of us monitors the exhaust and let them idle at perhaps 800 rpm while we turn on the instrumentation and take in the dock lines. Then we drop back to idle, leave the slip and head out of the harbor. By the time we get outside the breakwater the engines are well on their way up to temperature.

Once outside the breakwater we advance power to 1200 rpm for about five minutes. There is no scientific reason for 1200; it's one of the rpm settings we use in the floatplane so it's sort fo burned into our minds. After roughly five minutes at 1200 we increase power to 1400-1500 for five minutes or so. And finally we go on up to our cruise power of 1650.

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This is almost exactly the same routine we use on the JD normally-aspirated 4045 except: (1) engine isn't started until boat is ready except for casting off lines, assuring all systems are working, and (2) we finally go to cruise power of 1800 which takes 20 minutes or so of slowly increasing engine speed. When starting, run at 1100 for a few seconds and then turn down to idle of 750/800 once the engine has "caught its breath." Time between engine start-up and putting the engine in gear is less than five minutes. JD says not to idle without load for longer than five minutes at a time.

My procedure with my Volvo is to start the engine and let it idle (800-850 rpms) while I make sure I have raw water flow and get my dock lines in. I then back out of my slip and head out. I generally run out of the harbor at about 1,200 rpms. By the time I pass the entrance buoy for the harbor (a bit over a mile) the engine is up close to operating temperature and I go up to my normal cruise of 2,000 rpms. That brings the normal operating temp to 195 in about 1-2 minutes. While cruising I vary engine rpms up/down by about 200 every thirty minutes or so (i.e., up 200 for 30 minutes then down 200 for 30 minutes).

I only run the engine at the dock after I work on it (fuel filter changes, oil changes, tranny oil change, etc.) and then only for long enough to make sure everything is OK, say 3-4 minutes. The longest I have gone this season without running the engine was 7 days (I was out cruising on the other boat).

My engine sits unused for six and a half months every year. It starts right up in the Spring without any problems. I do change the oil immediately before haulout in the Fall so that the only time on the engine after the oil change is the run from the marina to the haulout (about 1/2 mile).