SC35
Well-Known Member
Volvo D4 / D6 have been around since 2005, so not exactly new.
And the block and heads are generally not the problem, it’s the marinized bits around them: heat exchangers, intercoolers, shift actuators etc.
They are NOT Volvo Pentas, not IPS
- Thread starter superheat6k
- Start date
Volvo D4 / D6 have been around since 2005, so not exactly new.
And the block and heads are generally not the problem, it’s the marinized bits around them: heat exchangers, intercoolers, shift actuators etc.
ChromeDome
Well-Known Member
...and electronics...
Still they're introduced for marine use not long after being presented for their primary use
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Bran
Well-Known Member
I had a 1970s Foden with 220hp 12.5 litre engine. Last truck I owned built 1992 had a 350hp Perkins engine, 12.5litres (based on same engine as the earlier truck).
Volvo D6 350hp is 5.5 litres, overstressed and only rated for leisure use so must impact reliability and life.
Volvo D6 350hp is 5.5 litres, overstressed and only rated for leisure use so must impact reliability and life.
Portofino
Well-Known Member
Marine Diesel life
Diesel engines are capable of having a long life when the power to displacement ratio is low. But when they start jacking up the power, beyond what the manufacturer originally intended, that benefit disappears. There is a very simple formula you can apply to estimate service life: simply multiply the cubic inch displacement of the engine times one. The result is the maximum amount of horse power you can have and still expect a reasonable service life. A 6V92 engine is 552 CID; at powers greater than 550, these engines don't last. At 450, they'll go 10 - 15 years easily.
. Now, an 8V71 has a 568 cubic inch displacement; the fact that these engines have a 0.56:1 power/displacement ratio explains why they could run so long.
Conversely, divide the CID by the horse power, and the greater the result UNDER the factor of one (1), the longer engine life you can expect. If you have an engine with an 0.70 CID/HP ratio, then you can expect greater than 3000 hours engine life.
Diesel engines are capable of having a long life when the power to displacement ratio is low. But when they start jacking up the power, beyond what the manufacturer originally intended, that benefit disappears. There is a very simple formula you can apply to estimate service life: simply multiply the cubic inch displacement of the engine times one. The result is the maximum amount of horse power you can have and still expect a reasonable service life. A 6V92 engine is 552 CID; at powers greater than 550, these engines don't last. At 450, they'll go 10 - 15 years easily.
. Now, an 8V71 has a 568 cubic inch displacement; the fact that these engines have a 0.56:1 power/displacement ratio explains why they could run so long.
Conversely, divide the CID by the horse power, and the greater the result UNDER the factor of one (1), the longer engine life you can expect. If you have an engine with an 0.70 CID/HP ratio, then you can expect greater than 3000 hours engine life.
julians
Well-Known Member
I don't think many diesel engines in leisure boats ever actually wear out, they usually suffer a catastrophic failure because some other ancillary part failed, for example over heat due to blocked heat exchanger , belt failure. Or water in cylinders due to corroded /failed other component etc etc. Ie nothing to do with how much power they put out relative to their capacity.
You're right in so much that the more power an engine has relative to its capacity the quicker it will wear out,but that's rarely the limiting factor in leisure boats, usually something else unrelated to the power/capacity fails first.
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Portofino
Well-Known Member
Was thinking older boats like what the Ops just gone and purchased.
The stuff you mentioned is in my book maintenance related .
Thats a two part story .First comply with the “ book ” ie throw away the inter coolers of a CAT powered boat every 7 yrs because CAT say so to protect themselves from another law suit due to leaks as you infer hydrolock.
Second don’t just leave them for months on end in the off season drying up , open valves rusting , injectors sticking on the gunk from excess hrs in the season under low loads etc ,and possibly the whole cooling system pickling in salt water .Although winterisation is part of 1 .
Poor maintenance and the subsequent early demise is optional .Agree it’s a rabbit hole a lot ( from reading this forum ) seem to drop into .So statistically you are correct a lot fail from sea water leaking ancillaries.I will add poor maintenance as well .
Another one .
Try and buy a boat with lower revving motors .Or avoid a lower displacement screamer .
Speaks for itself the distance , more like speed and thus lubricity the rings have to experience between oil changes .
A lot of builders cheap out esp with IPS fitting the throwaway blocks of the 5.5 L D 6 .Yes thats another subtle point - has it got replaceable drop in liners or not in Volvos D 6 case ?
New who cares I get that .
10 yr 1000 hr D 6 or with IPS will divide opinions on here .
20 yr old outdrives with D4 or D6 or D6 with IPS hovering on 1500 hrs = RUN .
Wonder who’s gonna tackle those throw away motors + propulsion systems .
Trev the O P hasn’t.
My MAN 20 year old 13 L s blocks modular construction, replaceable liners are on 1000 hrs I have put 500 + on .All original cooling parts .
Rebuilt the water pumps Jabsco actually and replaced one injector .Only because it housed a sensor in one unit .
1800 rpm gives 30 knots @ 80;% load .
Some ones already said if the base block is ex marine it’s better ie from a truck , rail car , coach , plant etc .
Another pointer is if they ( the motor builder ) do commercial variants , better still the leisure side is the smaller in terms of numbers than the commercial. Rationale is the marine bits you say that have a tendency pack up first in leisure don’t .They don’t because the commercial guys expect the materials and engineering to be best quality in terms of longevity in there ferries , tug boats etc , and use the said same spec coolers , pumps seawater contactable stuff in the leisure variants .
This ^^ knocks almost every VP motor with the exception of the D12/13 ( truck blocks ) into the throw away group I am afraid .
Bit like black cars , you only ever have one then realise what a pain they are to keep clean , You only ever should have one VP powered boat , it’s a right of passage , a well trodden path with endless newbies jumping in.Speaking from experience…..on both .
julians
Well-Known Member
Was thinking older boats like what the Ops just gone and purchased.
The stuff you mentioned is in my book maintenance related .
Thats a two part story .First comply with the “ book ” ie throw away the inter coolers of a CAT powered boat every 7 yrs because CAT say so to protect themselves from another law suit due to leaks as you infer hydrolock.
Second don’t just leave them for months on end in the off season drying up , open valves rusting , injectors sticking on the gunk from excess hrs in the season under low loads etc ,and possibly the whole cooling system pickling in salt water .Although winterisation is part of 1 .
Poor maintenance and the subsequent early demise is optional .Agree it’s a rabbit hole a lot ( from reading this forum ) seem to drop into .So statistically you are correct a lot fail from sea water leaking ancillaries.I will add poor maintenance as well .
Another one .
Try and buy a boat with lower revving motors .Or avoid a lower displacement screamer .
Speaks for itself the distance , more like speed and thus lubricity the rings have to experience between oil changes .
A lot of builders cheap out esp with IPS fitting the throwaway blocks of the 5.5 L D 6 .Yes thats another subtle point - has it got replaceable drop in liners or not in Volvos D 6 case ?
New who cares I get that .
10 yr 1000 hr D 6 or with IPS will divide opinions on here .
20 yr old outdrives with D4 or D6 or D6 with IPS hovering on 1500 hrs = RUN .
Wonder who’s gonna tackle those throw away motors + propulsion systems .
Trev the O P hasn’t.
My MAN 20 year old 13 L s blocks modular construction, replaceable liners are on 1000 hrs I have put 500 + on .All original cooling parts .
Rebuilt the water pumps Jabsco actually and replaced one injector .Only because it housed a sensor in one unit .
1800 rpm gives 30 knots @ 80;% load .
Some ones already said if the base block is ex marine it’s better ie from a truck , rail car , coach , plant etc .
Another pointer is if they ( the motor builder ) do commercial variants , better still the leisure side is the smaller in terms of numbers than the commercial. Rationale is the marine bits you say that have a tendency pack up first in leisure don’t .They don’t because the commercial guys expect the materials and engineering to be best quality in terms of longevity in there ferries , tug boats etc , and use the said same spec coolers , pumps seawater contactable stuff in the leisure variants .
This ^^ knocks almost every VP motor with the exception of the D12/13 ( truck blocks ) into the throw away group I am afraid .
Bit like black cars , you only ever have one then realise what a pain they are to keep clean , You only ever should have one VP powered boat , it’s a right of passage , a well trodden path with endless newbies jumping in.Speaking from experience…..on both .
True enough about black cars, I've had one,won't have another.
I've had one VP engined boat.....don't currently have a Vp engined boat. Can't say for sure I won't have another....suspect I won't have any choice at some point... It's all a compromise
superheat6k
Well-Known Member
I have bought direct from Aqualarm in the USA. They are due to arrive Monday.
I have also bought from Ebay a dual channel temperature controller so I can monitor the exhaust elbow temps with adjustable alarm settings that will feed into the Aqualarm annunciator panel via its alarm output contacts.
So the complete system consists of ...
2 of these ...
10334-barbed-water-flow-detector-for114-p-61.html
1 of these ...
https://aqualarm.net/cooling-water-flow-c-2/20359-water-flow-and-exhaust-panel-twin-12v-p-31.html
and 1 of these ...
STC-3008 Thermostat Dual LED & Probe Temperature Controller AC 12V | eBay
The whole lot less than £300 including UK VAT & duty to UPS. The temperature controller seems too cheap at less than £10, but I had similar on my Turbo 36 and they worked absolutely fine for the 2 years between fitting them and selling the boat.
SC35
Well-Known Member
In commercial use, a VP D6 might hit 2500-3000 hours before getting overhauled or replaced.
For a leisure boater doing 50 hours per year, that's 50-60 years ?
Clearly the power to displacement ratio is not an issue for leisure use, because the engines don't actually last 50 years - other factors come into play.
If you want a 250-400hp engine that doesn't weigh too much there isn't actually much choice.
If your boat is massive and on shafts, there is a lot more choice.
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Pleinmont
Well-Known Member
Interesting, how do you insert the temperature probes into the water flow?
Also where is the flow detector going? Before or after the Water Pump?
Thanks
superheat6k
Well-Known Member
The flow switches will be installed between the strainer and the pump, and in a horizontal section, although I'm not sure this matters.
The temperature is that of the injection bend. If the water fails it will be the first thing to heat up. I will use surface mounted temperature probes, set in heat conducting metal epoxy putty. These are around 40 - 50oC inn normal WOT operation of the engine and will rapidly reach say 100oC if the water flow stops, so I will set the alarm ~ 15oC above the established maximum normal working temperature of these probes - better to know early than late. If it is a transitional rise due to say warmer Summer weather it is simple to adjust the alarm threshold up a bit.
Pleinmont
Well-Known Member
Thanks - sounds good. I've been thinking about sorting out something similar.
superheat6k
Well-Known Member
The Aqualarm items arrived today, and although the alarm panel is a little basic - an engraved traffolyte plate with the four alarms, the piezo buzzer and a mute button, but looks neat enough, but I will need to make a suitable mounting plate to the dash panel.
Now just need to complete the purchase ...
Now just need to complete the purchase ...
harvey38
Well-Known Member
We're back down to the boat at the weekend for 10 days so I'll get the inlet pipe measurements and get the new remote strainers and Aqualarms ordered
