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Old 10-04-2012, 04:03   #16
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I'm curious, what type of boat do you have. Its just that running at 3000 continuously seems high and usually for very little gain. Joe
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Old 10-04-2012, 05:51   #17
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Re: Engine Stops at 3000 RPM

I agree that 3000 seems high. Manual says you can run steady at 3000. I have a 40 HP Volvo Penta on a 33 ft Storebro. I find that I run normally at 2000 RPM. The difference from 2 to 3 is nothing except more fuel used. I found the original problem when I was in some very bad current against the wind. Want to have the ability if I need it, although very seldom use it.
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Old 10-04-2012, 07:01   #18
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Re: Engine Stops at 3000 RPM

Quote:
Originally Posted by landonshaw View Post
sailed to Tobago Cays and all went well. Changed the filter and pre-fuel filter. The pre=fuel filter had stuff all over it. Ran the engine at 3000 RPM and it never hesitated once. I will change the pre-filter this week and see how it looks. So my problem was in one of the filters and I suspect the pre-filter.

I suggest you think this a little further. WHY did the filter get dirty? Did you forget to close your fuel access port and then a pelican flew by? Probably not.

Probably you have dirt in your fuel tank. It can form clumps that float at lower RPM's, but at higher RPMS get sucked to your fuel line. If there's a screen there, it can block the fuel flow enough.

Typical pattern for this is that it happens more at ... higher RPM's.

You may need to clean your tank.

Diesel does not turn to dirt all by itself. It's great that your filter caught it, but the fact that your filter was so dirty is telling you that you may not have found the whole problem.
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Old 10-04-2012, 10:51   #19
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Re: Engine Stops at 3000 RPM

I hadn't changed the pre-filter for some time and may have gotten a growth in the fuel (algae or fungal). I had in the past added an additive to reduce or eliminate this, I am hoping that this is not the case. I will be changing the pre-filter very regularly and monitor the filter. If the tank needs cleaned, then I will haul the boat earlier and have it done when I clean and paint the bottom.
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Old 10-04-2012, 11:49   #20
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Re: Engine Stops at 3000 RPM

Quote:
Originally Posted by joemac4sail View Post
I'm curious, what type of boat do you have. Its just that running at 3000 continuously seems high and usually for very little gain. Joe

I can tell you about my engine. It's a new diesel -- a Yanmar 3gm 20 hp.

The instructions (and the tech who installed it) BOTH say to break the engine in at HIGH RPM and to run it HIGH, not low. It's not good for diesels to run them below their optimal cruising RPM. For my engine, that IS ... 3000 RPM. If I'm running it all day I'm supposed to run it at 3200 for an hour or so. The manual couldn't be more clear.

However, because of a fouled tank, if I run it at 3000 RPM, the suction is enough to clog the screen. Then the engine dies. The last time I limped in, we sailed as far as we could, started the engine and ran her at 2000 RPM up to the bridge, and then goosed her up to 3000 to go under the bridge.

The engine died before we were completely through the bridge. We thought that might happen and someone was on the bow ready to drop anchor quickly.

We sat at anchor for a while, let the clump of whatever free itself from the screen, and then limped back to home at 2000 rpm.

The boat will not be used again until I have cleaned the tank, and then I will follow Yanmar's instructions and run that engine at 3000, and occasionally 3200, RPM.

I know someone who did a lot of damage to his diesel by idling it way too much. He would do this to charge his batteries when there wasn't enough sun for his solar panels to do the job. at 2 years 5 mo. the engine threw a rod. The mechanic/tech told him that the thrown rod was the LAST bit of damage done, that he almost certainly had a variety of other damage done to the engine including burnt rings and scored pistons.

I had lots of people tell me that I'm running my engine too high, but it's my warranty, not theirs. They all have older engines and probably haven't looked at the manual in years.

And, by the way, with the right prop, for me, there IS a significant gain in speed at 2500 compared to 3000.

One thing that I have noticed with my fuel problem is that I had less power at the lower RPM's as well since it developed. Unless you're being fanatical about paying attention to RPM to speed to conditions (wind on the nose, current with you or against you, etc.) these variances can be explained way and go unnoticed. "You had less speed? You *probably* had a current against you."

You can damage your engine without it overheating an without an oil pressure problem by running it too long, too slow.
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Old 10-04-2012, 11:52   #21
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Re: Engine Stops at 3000 RPM

Quote:
Originally Posted by landonshaw View Post
I hadn't changed the pre-filter for some time and may have gotten a growth in the fuel (algae or fungal). I had in the past added an additive to reduce or eliminate this, I am hoping that this is not the case. I will be changing the pre-filter very regularly and monitor the filter. If the tank needs cleaned, then I will haul the boat earlier and have it done when I clean and paint the bottom.

If I may make a suggestion, also monitor how much power you're getting from your engine at all RPM's. If you're going slower than you think you should with the wind on the nose, turn around for a minute and try it with the wind at your back. See if you can get the speeds you used to get at optimal conditions. If you don't, but you're not seeing smoke, temp rises or other indications of trouble, it's another sign that your fuel may be fouled.

Often you can deal with it yourself -- pump the fuel out into containers, remove the tank, and clean it. You can put an access port in the top, the direction I'm leaning in. I want to be sure I get ALL the grunge out.
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Old 10-04-2012, 20:27   #22
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Re: Engine Stops at 3000 RPM

About engine speed, I have a Yanmar 20, (18 Hp). Owners manual says 3400 rpm for an hour, 3200 continuous. Real world, I get a bit more than 5 kts at 3000 rpm, and a bit more than 5.5 kts at 3400 rpm. I use about .3 gals per hour at 3000 rpm. Since I don't run at 3400 rpm for any length of time, I have no idea what it would use. The extra 400 rpm is not worth it to me.
Hull speed should be about 7 kts, and I can get that with the sails.
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Old 10-04-2012, 21:32   #23
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Re: Engine Stops at 3000 RPM

Quote:
Originally Posted by nes View Post
About engine speed, I have a Yanmar 20, (18 Hp). Owners manual says 3400 rpm for an hour, 3200 continuous. Real world, I get a bit more than 5 kts at 3000 rpm, and a bit more than 5.5 kts at 3400 rpm. I use about .3 gals per hour at 3000 rpm. Since I don't run at 3400 rpm for any length of time, I have no idea what it would use. The extra 400 rpm is not worth it to me.
Hull speed should be about 7 kts, and I can get that with the sails.

But -- it isn't just about whether it's "worth it" to you -- it's about what the engine needs to operate at its best. It NEEDS to be run at 3400 sometimes, and it needs to be run at 3200 a lot. that's what's right for that engine.
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Old 23-04-2012, 05:33   #24
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Re: Engine Stops at 3000 RPM

Changed the pre-filter and it did not look bad. Did have a dark substance on it in places, but not totally covered. Since the pre-filter only takes about 10 minutes to change, I will continue to change it often and the main filter as maintenance describes. The pre-filter is a 2 micron.
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Old 23-04-2012, 06:25   #25
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Re: Engine Stops at 3000 RPM

What year is it?
Mack trucks...Volvo engines finally admitted they have a injector problem in the last 3 or so years.bad supplier.I dont know if they use the same supplier for marine engines but....
food for thought
Mark
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Old 24-04-2012, 05:49   #26
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Re: Engine Stops at 3000 RPM

We have a 2005 MD2040.
From an earlier response I looked at the operating manual and it states that the cruising speed should be between 300 and 500 rpm lower than the maximum rpm at WOT. WOT is 3,600 (Volvo Penta defined WOT) so for us that is around 3,100 rpm.
Generally I find not much difference in running at 2,300 RMP and 3,000. I will check my diesel consumption over the next few trips at 3,100 and see.
So, from the thread I read it is bad to not run a diesel at the prescribed RPM, a lower rpm may over time hurt the engine.
Did I interrupt this correctly?
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Old 25-04-2012, 19:23   #27
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Re: Engine Stops at 3000 RPM

Quote:
Originally Posted by landonshaw View Post
I have been having problem with my 40HP Volvo Penta engine. MD2040. I am suppose to run at around 3000 RPM, I have found that if I do, the engine will cut out after a little while. Maybe an hour or so. I can run all day at 2300. This past weekend I realized it was shutting down and quickly reduced the throttle to 2300 and the engine remained running. In the past, it would shut down but I could restart and leave at a lower RPM. I had changed the fuel filter at 1060 hours, I'm now at 1283 and will be doing that in the next week or so. Any ideas? I have thought that possible it is an air leak that at the higher rpm it is able to suck in enough air to stop the engines.
Any thoughts of what it might be and how to find, fix it? Thanks

I just went through something similar and the cause turned out to be a dirty fuel tank.
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