Ric
Well-Known Member
No, the PRV on my calorifier works on pressure and temperature.
Running a diesel at high revs?
- Thread starter ash2020
- Start date
No, the PRV on my calorifier works on pressure and temperature.
D
Deleted member 36384
Guest
What is the difference? Engines are turning when they are running.
Can you explain this please, do you mean that the mechanical hour meter only started counting at rated rpm and at lower or higher rpm the hour meter did not count up? That appears an odd way of working.
Surly oil is being subjected to work as soon as the engine is started and it picks up contaminants and degrades slightly whenever the engine is on. Just wondering!
Skylark
Well-Known Member
Hard carbon is unburned fuel (a hydrocarbon). It's entirely possible that the whole of the engine is coked.
The wastegate is normally closed at low speeds and loads and will progressively open as load/speed increases. It's purpose is to bypass excess exhaust gas. Without the wastegate, higher exhaust gas mass flow would choke the turbine volute and hence increased back pressure resulting in poor performance.
Neil
Well-Known Member
Given that the Beta10 and Beta14 are the same engines, differing only in that the former revs to 3000 and the latter 3600, I'm guessing that 3000 is an acceptable 'max' with which to go to to prevent carbonisation. I say this because I have a Beta14 in a Sadler 25, and I suspect that under normal circumstances, this is overpowered, such that anything above 3000 will attempt to push my boat over displacement speed. I'll give it a whack, next time I'm out, but I seem to remember that 3000 gave me 6+ kts.
theoldsalt
Well-Known Member
"......a function of revolutions turned rather than mere time running."
Seems obvious to me !! An engine running at 1000rpm does 1000 revs in a minute - at 2000rpm it does 2000 revs in a minute. Same run time but twice the revolutions. DOH !
Seems obvious to me !! An engine running at 1000rpm does 1000 revs in a minute - at 2000rpm it does 2000 revs in a minute. Same run time but twice the revolutions. DOH !
D
Deleted member 36384
Guest
Of course! Thanks.
gandy
Well-Known Member
Mechanical hour meters are geared off the rev counter drive cable, the same as an old style mileometer off the speedo. For example the meter on our digger is marked "Hours at 1540 rpm". Running for an hour at 1540rpm will advance the meter by one hour, running for an hour at 770 rpm would only advance by 1/2 an hour.
...Waves
New Member
I recently purchased a 37' sloop with a rebuilt 3GM30F (27 hp) with 975 hours. Just finished a 60 mile delivery to my home port today. Starts reliably with good oil pressure and no over hearing issues.
I am most concerned it would only reach 2100 rpm!
When attempted past that 2100 rpm it produced a stuttering (bogging down as if chocking), black smoke, AND the throttle appeared to have reached a stopping point and would return 'on it's own' when released to 2100 to 2000 rpm. This with an engine rated for 3400 to 3600 rpm!
Oil pressure remained constant at 40 and temperature at 170.
In a flat sea dead calm this yielded 4.6 knots in a vessel with a documented hull speed of 7.7 knots.
It has a 2 blade prop.
What to do?
I am most concerned it would only reach 2100 rpm!
When attempted past that 2100 rpm it produced a stuttering (bogging down as if chocking), black smoke, AND the throttle appeared to have reached a stopping point and would return 'on it's own' when released to 2100 to 2000 rpm. This with an engine rated for 3400 to 3600 rpm!
Oil pressure remained constant at 40 and temperature at 170.
In a flat sea dead calm this yielded 4.6 knots in a vessel with a documented hull speed of 7.7 knots.
It has a 2 blade prop.
What to do?
ash2020
Well-Known Member
Hi there. It may have nothing to do with it, but I had exactly the same symptoms in a Beneteau with a 2 cylinder Yanmar. Black smoke and only 3 knots at max revs. Strangely it turned out to be a fouled prop, weed, barnacles etc. It may be worth giving the prop a really good clean.
Cheers
Andrew
[70521]
Well-Known Member
Look at the hull and prop.
Same thing happened on my old boat, beached her and removed about 100 kg of mussels from the hull and prop. I had not been able to get down to the boat for six weeks boy do these things grow fast.
skyflyer
Well-Known Member
I had a similar problem that turned out to be a sticky valve. It ran fine on all 3 cylinders initially then when I throttled up i ended up with the sticky valve and that of course killed the compression on that cylinder, so all of a sudden it is rough running on two cylinders, producing two/thirds of the power and the fuel being injected into the dodgy cylinder just gets blown into the exhaust and creates a load of smoke!
When i throttle back it seemed to cure itself.
Spoke to my tame engine expert and he suggested it was probably a bit of crud that was trapped betwene the valve and the valve seat and to simply run the engine at the max revs at which it would run properly without problems for a good thirty minutes or so and aim to burn off the crud.
I did and it worked - but your problem may be totally different!
When i throttle back it seemed to cure itself.
Spoke to my tame engine expert and he suggested it was probably a bit of crud that was trapped betwene the valve and the valve seat and to simply run the engine at the max revs at which it would run properly without problems for a good thirty minutes or so and aim to burn off the crud.
I did and it worked - but your problem may be totally different!
lpdsn
Well-Known Member
It might be a wrongly sized prop, but it is much more likely that your hull etc is simply badly fouled. You'll need to anti-foul for the new season anyway, so arrange to lift out before making any big plans for a summer cruise (some people lift out in the winter but I prefer spring as it marginally reduces the risk of hypothermia whilst working on the hull).
Most yards normally insist on carrying out the pressure washing themselves.
Heckler
Well-Known Member
Ive unseized wastegates before now, bit of judicious tapping, wriggling, freeing oil, wd40 does it.Darglow Featherstream
Good question.
I am starting to ask a lot of questions about the installation and commissioning of the engine.
Starting with the incorrectly configured exhaust system and now this.
Spawn of the devil are turbos in boats, we never get to the sweet spot for long enough to clear carbon!
Stu
Beyondhelp
Well-Known Member
Sorry ,if this has been answered. But a big NO. Do NOT do this. Wastegates tend to stick shut, not open. Good chance you may end up running too much boost.