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Old 10-27-2011, 05:25 AM   #41
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RE: How do you start you boat?

Quote:
bobofthenorth wrote:
There's no chance I'll ever start any diesel anywhere past idle throttle.*
When your engine starts the fuel control is at full throttle every time. Until it starts, the power lever position means nothing.

The cold start feature on the Minimec provides extra fuel beyond what the governor full fuel setting normally delivers until the engine starts then it automatically resets.

When a manufacturer suggests putting the power lever at some point above idle it is normally to set the speeder spring to a point where the engine will idle smoothly until it warms up or to prevent the governor from reducing fuel too much too soon if the engine is only firing on a couple of cylinders but is turning fast enough to "actuate" the governor. Otherwise it can create the piston engine equivalent to a "hung start."
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Old 10-27-2011, 06:52 AM   #42
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RE: How do you start you boat?

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RickB wrote:
Until it starts, the power lever position means nothing.
Obviously.* But in the instant after it starts the lever position means a great deal.* And equally obviously if it doesn't idle smooth then you need to advance the lever.* But not anywhere near to 1/4 throttle.
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Old 10-27-2011, 07:20 AM   #43
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RE: How do you start you boat?

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bobofthenorth wrote:But not anywhere near to 1/4 throttle.
*Even if you left it there it wouldn't hurt anything.

The only problem is with the operator's perception.
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Old 10-27-2011, 07:41 AM   #44
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RE: How do you start you boat?

Extended cranking, with some designs, can allow water into engine since the exhaust pressure is too low to push it out the exhaust run.
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Old 10-27-2011, 07:58 AM   #45
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RE: How do you start you boat?

Prior to purchase when investigating the meaning of the oil samples results taken by the surveyor, the lab tech told me that my Cummins 6BT turbo diesels has minute gouges etched into the cylinder walls whose purpose is to trap oil. This traped oil lubricates the piston and cylinder walls prior to the next start, so you don't get a "dry" start. Since most diesel engines are designed for the automotive farming or trucking industries this concept seems to work. However in a boat when engines can go weeks and sometimes months between use, this traped oil is long gone.*

I've been told by what I consider some knowledageable people that dry cracking the engine a few turns before starting will lubricate the cylinder walls before start especially after a long down time. Apparently Cummins didn't think so because they made no allowances for this in my boat. I have a key start and would have to electrically disconnect the S/O solenoid to dry crank. I don't.

I've also read on boatdiesel.com by a very knowlegable moderator that dry cranking is a waste of time and only wears the starter.*

My only other experience with this was on my sailboat with a 2 cylinder Yanmar diesel. Everytime I started after a week long or more absence I could hear a pinging sound for a couple of seconds until oil pressure built up and then it disappeared.*

I always leave the blowers on while the engines are running and for about 20 minutes after shutdown. For cooling not fumes removal, I don't have fumes. Same thing for the generator. The only downside to this is that the blowers are so powerfull they suck all the airconditioned air out of the cabin.*
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Old 10-27-2011, 10:29 AM   #46
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RE: How do you start you boat?

Having a belly up starting motor can cause extreme hardship here in Alaska so I do'nt even think of putting any excess load on it by cranking or any other means. Took lots of cranking to get my old Perkins to start and that was one of the reasons I repowered. My Mitsubishi has "glow plugs" and starts basically instantly. I had a glitch in the glow plug system at first but that was soon fixed. I was still a bit unsettled about how long to heat the glow plugs before cranking so I took one out (it was about 1/8"x 1" ..looked like a small square bar) and turned the key to activate it. In 10 seconds it was very red hot. Also I noticed how easy it was to remove them. Do'nt cost much either. At that point I decided that if I was going to stress anything it would be the glow plugs and NOT the starter motor. The Mitsu starts as quickly as any of my cars and I have'nt had a glow plug out in 4 years. The Mitsu idles at 1050rpm during initial warm up and 950rpm when fully warm. I initially run the engine fast enough so it runs smoothly but an old truck driver instructed me to "just let her chug" to warm up. ??? At any rate I do'nt buy into any of this "dry start BS". If that were true engines would wear out promptly and they mostly last and last. It could happen though I suppose if one had chrome plated cylinder bores and left the engine sit for several years but I've only had one engine that had chrome bores ..small 2 stroke. I'm sure ther'es plenty of oil on the bores and rings. Also consider that in a rod or crank bearing oil would gravitate down but (for sure) puddle at the bottom of the bearing and get distributed around on the 1st revolution. I don't think the dry start theory is valid at all. But I'm a firm believer in a multi step and fairly slow warm up (10 min to cruise throttle) half that at shut down. And there I believe you can reduce wear.
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Old 10-27-2011, 11:33 AM   #47
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RE: How do you start you boat?

Quote:
nomadwilly wrote:
*At any rate I do'nt buy into any of this "dry start BS". If that were true engines would wear out promptly and they mostly last and last.*
*I know nothing of the possible wear on an engine due to a dry start, but it does sound like something that would happen if no oil is in the top part of the cylinder when it fires.*

Apparently Cummins recognizes this and has gone to some effort to minimize the effect by etching the cylinder walls to trap oil. Since most engines are used frequently especially in the automotive and ag insdustries that these engines were designed for, the oil trapped in the etchings is well positioned to lubricate the cylinder when it starts.*

However in a boat that sits for a prolonged period of time the oil trapped in the etching is gone. Remember most of these engines have been modified for marine use so they were not designed from the ground up for occasional use.*

However, as Eric mentioned, these engines last a long time and usually die of something other than dry starting.*

But an interesting discussion non the less.*
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Old 10-28-2011, 12:26 AM   #48
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RE: How do you start you boat?

However you start any internal combustion engine, the most wear is going to occur until it gets fully warm - water jackets and all. So the advice I have always thought made most sense is to get it started asap with minimal cranking, let it settle into an idle, and then get moving asap. You don't do it any favours idling away in the berth waiting for the water temp to come to normal. The slow passage out of the marina or anchorage under some load does the best possible job of warming the engine with minimal fuss, and minimal wear, (you can't escape some), and by the time you clear moored boats or the 4-6kn limit markers, she's ready to GO.....Once properly hot the wear is minimal - hence the longevity of taxi engines...
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Old 10-28-2011, 12:50 AM   #49
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How do you start you boat?

When turning off the diesel engine after it has achieved operating temperature, I've been told it is best to run at idle-neutral for five minutes to help in the cooling down of the engine.* Apparently, "fast" cooling is harmful to the engine.* What do you all say?


-- Edited by markpierce on Friday 28th of October 2011 12:51:55 AM
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Old 10-28-2011, 01:51 AM   #50
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RE: How do you start you boat?

"and by the time you clear moored boats or the 4-6kn limit markers, she's ready to GO"

Yep Peter, clear that pesky 6 knot zone, open up the old Lehman and let her rip, to.............7 .5 knots! (7.8 with the tide)

Heh, Heh an affectionate dig at the mighty FL120 (having had a single FL120 for 9 years I got a twin 5 years ago and still do 7.8knots) I think the FL120 is the one excetion to the law of physics, if you put four FL120's into your boat it still will do 7.8Knots

Sorry off subject, my appologies.
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Old 10-28-2011, 01:59 AM   #51
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RE: How do you start you boat?

That's ok Andy, never forget...it's all meant to be fun. The vision of how my boat might look with 4 x L120s in it was quite amusing. What a stern drag she'd have - what a wake...! I could get my own back on those pesky Riviera and Maritimo semi-planers who rock the s***t out of us when they go past....
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Old 10-28-2011, 03:23 AM   #52
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RE: How do you start you boat?

"Apparently Cummins recognizes this and has gone to some effort to minimize the effect by etching the cylinder walls to trap oil."

Cummins recognizes? You gotta be kidding,

Honeing cylinder walls , so the fine scratches hold oil is over a CENTURY old.

The long time between engine runs is why some folks avoid synthetic oil in their boat engines.

For old engines with crappy compression there are ether kits that can be installed to assist in a cold start.

I have often thought that with fogging oil instead of ether , a posh button short term layup setup might be a worth the effort.
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Old 10-28-2011, 12:36 PM   #53
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How do you start you boat?

Quote:
markpierce wrote:
When turning off the diesel engine after it has achieved operating temperature, I've been told it is best to run at idle-neutral for five minutes to help in the cooling down of the engine.
There may be something to notion of letting an engine cool down some from it's normal operating temperature, I don't know.* RickB would be the one to answer that one, i think. But if it's an advantage to let them cool down a bit, I suspect that the time from bringing the power back from cruise to idle or near idle to enter your marina, taxi to your slip, enter it, and get the boat tied up, will be sufficient to give you any benefit there might be from a cool-down period.


-- Edited by Marin on Friday 28th of October 2011 12:47:26 PM
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Old 10-28-2011, 01:30 PM   #54
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RE: How do you start you boat?

I was told one should let the engine idle maybe a minute or so to let the turbo slow down before stopping the engine which would cut off the oil flow to the turbo bearings. That was in the 70s, in the Caribbean where machinery operators had a bad habit pushing the throttle all the way forward then back fast and shut down immediately leaving the turbo whistling. I guess that sounded "cool" to them.
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Old 10-28-2011, 06:23 PM   #55
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RE: How do you start you boat?

Unless you approach the dock at maximum power and shut the engine down while the boat is still moving there really isn't much to worry about. A dedicated cool down period isn't necessary when the engine has operated at low power for a few minutes as in the case Marin described which is probably pretty much the norm for almost everyone operating a recreational trawler.

Allowing the turbo to cool after a sustained high power run is very important. If a turbocharged engine is operating under a high load the turbo is wound up and hot. Shutting down directly from that condition will lead to "coking" oil on the shaft between the compressor and the turbine and that leads to imbalance and rapid wear. Larger engines such as the EMDs on the smaller Alaska ferries and many of the coastal tugboats use an automatically activated "soak back" pump that turns on with a timer when the engine is shut down. It runs for about 10 minutes and supplies oil to the turbo bearings to cool it and prevent damage. The same pump turns on to prelube the turbo on startup until lube oil pressure is established.
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Old 10-28-2011, 06:24 PM   #56
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RE: How do you start you boat?

To this end I ramp down over the last 3 or 4 miles to the harbor from 2300 to 1900 to 1400 and to 1000rpm to effect a good slow cool down and then to "taxi" (as Marin says) to my fairway and ultimately my slip and to make a few lines fast finishes the cool down. I take about 6 miles to warm up through several stages of engine speed/load steps to get to cruise speed/load. At 2300 I think I'm about at a 60% load *...perhaps higher.*
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Old 10-28-2011, 06:28 PM   #57
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RE: How do you start you boat?

Quote:
RickB wrote:
Unless you approach the dock at maximum power and shut the engine down while the boat is still moving there really isn't much to worry about. A dedicated cool down period isn't necessary when the engine has operated at low power for a few minutes as in the case Marin described which is probably pretty much the norm for almost everyone operating a recreational trawler.

*Thanks.* That saves me five minutes of idling for every trip.
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Old 10-28-2011, 06:35 PM   #58
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How do you start you boat?

Quote:
RickB wrote:
Allowing the turbo to cool after a sustained high power run is very important.
*Rick---* Is this same cool-down process needed for an engine with a mechanical supercharger?* The reason I ask is that in talking to many WWII*PT vets, some of whom were motor macs, they never talked about idling or cooling the engines down when they came in and were tied up.* The 4M2500 Packard Marine Engine (V-12) used on the PTs was mechanically supercharged.

Of course these were gasoline engines, not diesels, so perhaps that makes it an apples and oranges situation.

And, with a few exceptions, the boats were not brought to their docks or raft-ups at high power settings.* So the engines would have been idled for a bit before being shut down.* The exceptions where hot-rod skippers who roared back into base and right up to the dock and then stopped the boat dead*with a huge burst of max power in reverse.* Very dramatic, I was told, when it worked.* Very loud sounds of splintering wood and cursing when it didn't.


-- Edited by Marin on Friday 28th of October 2011 06:39:04 PM
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Old 10-28-2011, 08:51 PM   #59
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RE: How do you start you boat?

Quote:
Marin wrote: Rick---* Is this same cool-down process needed for an engine with a mechanical supercharger?
*No. A mechanical supercharger doesn't need it because it stops as soon as the engine stops turning. A turbocharger keeps spinning for a bit and is also extremely hot after a high power run.

Gas or diesel it doesn't make much difference, it's kind of like not shutting down a recip aircraft engine immediately after a high power run, you need to let temperatures stabilize a bit to reduce the potential for damage caused by hot spots* and to let lube oil help remove heat from the pistons. And sort of like an aircraft engine, you want to provide for moderate rates of temperature change both heating up and cooling so close the cowl flaps on a descent, open them for taxi, and let it idle for a moment to let the turbo spin down before pulling the mix.
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Old 10-28-2011, 09:58 PM   #60
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RE: How do you start you boat?

Unload my dink from the back of the truck, install*the motor. Connect the gas line, open tank vent pump the priming ball twice. Pull the choke out half way and pull the starter rope. Idle the engine push in the choke and leave the dock.

*

Soon we will have something a little nicer to launch it from than the truck*

*

On a serious note though. I have not seen many mention venting the engine room. Should I assume it is because most of you do not have gas engines?

My education continues...
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