D3 160 Limp Mode

[Kingruar]

Well thats good!!

I was hoping for the same with my 'diesel man' although he and the engineer quickly steered me to the oem part and wouldn't even entertain making one. oh well.

I suspect mine too will probably show nothing wrong with it, although i would like the satisfaction of a crack.

I was also talking to a mate of mine this afternoon who happens to be a diesel mechanic and he reckons all it could boil down to is someone having given it a knock and the engine vibrated it loose. However, as i plan to use the boat this weekend, I figure having the part ordered will cover me both eventualities.

 

[Kingruar]

Also,

What are your thoughts on the cruising speed rpm? The boat really needs to be a tad over 3000rpm to be plaining nicely.

However, after reading the owners manual volvo state :

"Avoid operation at full throttle, for best fuel economy. We recommend a cruising speed which is at least 10% below the maximum engine speed at full speed (full throttle). The maximum engine speed will vary due to propeller choice, load and sea conditions, but it should be in the full throttle range.
Full throttle range:
D3-130A/160A/190A ............................. 3800–4100rpm
D3-130i/160i/190i ................................. 3800–4100rpm
D3-110i ................................................ 2700–3000rpm

Assuming 3800rpm would be my max rpm, 10% off that would take me to 3420rpm. Would I be safe then hovering around the 3200 / 3300 rpm range or just up to where plaining occurs?

I don't mine loosing speed as my trips are only around 30nm each leg so we are talking 10/15 minutes difference on arrival time which is definitely no biggie. Apart from fuel consumption what are your guys thoughts on a solid rpm range? These engines are new to me so I do appreciate your advice.

The only other thing I can see in favour of the higher rpm is keeping the vanes in the turbo moving (i.e hopefully prevent them seizing from carbon)

 

[[2068]]

The "10% off" is from whatever full throttle rpm you are getting.
3800-4100rpm is quite a wide range for Volvo to specify ... I'd be happier being able to hit the upper end of that range (4000rpm) rather than the lower.
If you can hit 4000rpm, then 10% off gives you 3500-3600rpm as an upper cruise speed.
Bear in mind that this might change as the season progresses with weed / fouling, so you might need to drop this figure down.

You don't have to worry too much about the vanes sticking if you are using the boat regularly at planing speeds.

.

 

[Kingruar]

Its more of reliability factor. I am not fussed about full speed but i am fussed about plaining at a semi solid speed.

Is full throttle a wise move? Just to see what it does or do i potentially risk making something go bang?

A diesel engine in my head at 4100rpm is bonkers but thats probably me thinking along the commercial diesel route rather than the 'car derrived engine' i have on my boat.

 

[[2068]]

Full throttle is a bit scary, but should be fine for a couple of minutes IF everything is working correctly AND you are in the recommended rpm zone.
If something is flaky, a full throttle run might flush that out for you, so to speak.
I'd be keeping a close eye on the temperature gauges during those couple of minutes.

If you can't get to 3800rpm then I would back off, because an overload is one of those things that could cause an expensive "bang" type event. Similarly, going much beyond 4100rpm is not a good idea.

But assuming you are in the rpm zone, bring up the trim tabs, trim out the drives to maybe +1 (try a few clicks either way) and see what speed / rpm you can manage

.

 

[Portofino]

It's difficult for you Volvo guys ,I know I had one .
Load is what you are talking about really not rpm per se .
Rpm only is a bit vague but in the absence of a "load" guage or EGT -exhaust gas temp .
The VP manual kops out by mentioning " propellor load and sea conditions "
3-3200 rpm in my view you should be ok .

Basic problem is this folks think diesels are just a much more fuel ,cheaper fuel version of an internal combustion engine instead of a petrol they think that's the only difference .Stuck in car petrol mind set at the pumps and mpg .
Petrols use a spark to ignite a volatile vapour .
Diesels are air pumps they heat air by super compression ,that compression alone produces vast quantities of heat squirt a little oil( little hence the mpg advantages) and it too ignites .
Needs a big pump and solid injector system to do that ,the speed is controlled by the pump on a diesel .
There s no throttle body ,choke or butterfly like on a petrol .
There's only one gear in a boat dictated by the prop pitch .
The prop moves the boat the diesel just turns the prop .
Drag and friction from the wetted area try to stop the prop moving the boat .
So if you ,let's return to the real world -have a boat " on the edge " whereby when new @ 1/2 load with two 8 stone testers ,a flat calm sea no cruising stores ,no head wind and a brand new UN antifouled bottom ,you can record what ever speed you think looks best in a mag to sell the boat .
Trial n error the prop pitch to suite @ engine max rpm that Vp ok -in this case 39-4000 .
Fast forward a few years ,add kg,s and then more Kg, a rough antifouled hull ,add some seasonal growth ,a few barnicle s on the props ,canopies up a head wind ,---now the brochure speed is just a dream .
But nether the less you try
"Push that hand fwd on those sticks " -- all you are doing is asking the pump to squirt more diesel in ,but it can not make WOT, or even get near ,all that excess fuel burns and adds allready more heat to a hot situation the EGT rises dangerously ,
You have no idea what harm you are doing .
It's does not labour lie a car in high gear ,it just suffers at 3400 rpm you think is ok because the book said 10% less than the WOT
First to go is actually your turbo the vane tips disappear in the excess EGT ,it looses boost --gradually ,too big a gap now .
valve stems /seals loose it ,burns oil -heating side struggles ,you rydlyme it or get the coolers done but strangly they are immaculate --nether the less "should be done" -you kid yourself as you hand over a few Thousend £ .

So without EGT or load guages in the real world I would ER on the side of caution 3-2000 rpm ish
I wonder if VP fitted these what % reduction in the parts side of the business there would be ,expensive parts @ that !
For them it's better you guys go arround exceeding EGT,s

 

[Portofino]

If you can't get to 3800rpm then I would back off, because an overload is one of those things that could cause an expensive "bang" type event.

.

There's no "bang "event excess EGT is cumulative ,over time .

Biggest marine diesel killer .
In a Volvo D12 powered cement mixer going up a hill ,it's got gears the driver changes down ,oh and when descending down , other side ,
Over runs ie the pump is cut back low --EGTs drop,

In an overloaded D12 powered VP - boat-( same block ) - it just suffers in silence ---who can tell ?
Owner does not know

One lasts 1000000 miles
Other does not make 1000 hrs

 

[Kingruar]

Amazing guys,

To be honest i think i'd be shitting bricks at 4000rpm, I'm pretty sure it would get there no probs. The boat goes real nice, around 23knts around 3200 / 3250rpm, so may keep it there. Good solid drive and engines sound sweet.

However, being one of those muppets who always has to push it and on the receiving end of the comment 'I told you so', I may venture to 3600 and not the 3800 / 4100 band. I do want to enjoy this rather than be on a mounting invoice list.

 

[[2068]]

There's no "bang "event excess EGT is cumulative over time .

As to "all that excess fuel burns and adds allready more heat to a hot situation the EGT rises dangerously, You have no idea what harm you are doing .

I stand by my advice to back off if you can't hit the recommended RPM at full throttle.

We can argue about exactly how long it takes for this situation to result in cooked turbo vanes / cooked valves / cooked exhaust manifold / bang event.
The point is, it's not a great place to be.

 

[Portofino]

I stand by my advice to back off if you can't hit the recommended RPM at full throttle.

We can argue about exactly how long it takes for this situation to result in cooked turbo vanes / cooked valves / cooked exhaust manifold / bang event.
The point is, it's not a great place to be.

I would be nice to know exactly where that place is .
It does vary .
After lift in with 1/4 or less tanks I can be doing 27 knots circa 1650 rpm ( wot 2150) with only 75 % load and EGt,s mid 500 degrees .
Add 3 tonnes of fuel and water next day -- same cleanliness -in other words add 3 tonnes which lowers the boat deeper in the water --more drag -same numbers -now the load is 85% up,10 and the EGt nearer 600 .

Fast fwd 4 months of Med growth ,or say 6 weeks of growth on the props 27 knots is now over 90'% f load .
A snorkel and scrape of the props it drops back to mid80 % -my confort zone .
I try and stay below 90 % and EGTs mid 500 ,s not over 600 ---- thing is --- I can that's the point .1750 /1800 out of 2150
But 1800 /1850 with dirty props= 100% -once @ 100 there's no 105 or 115 , its overloded the EGzt zooms up -harmful as said .

When it's clean and lightly loaded 2150 -2200 - makes 98 % load
But later in the season it's surprising how that load drops due to fouling 100 % comes up @ 1800rpm until props cleaned .
Without the guages I could hare arse about late season exceeding 100 % @ 1850 thinking I,am ok below 2150 .
That's why I Q the VP staement ,which actually is well written but tells you nothing re safe rpm .

 

[[2068]]

An EGT gauge would help assess which curve you are following.
It's surprising in some ways they are not fitted as standard by VolvoMort, but maybe they don't want to scare the end user who might not know how to interpret the readings.

.

 

[ari]

Trial n error the prop pitch to suite @ engine max rpm that Vp ok -in this case 39-4000 .
Fast forward a few years ,add kg,s and then more Kg, a rough antifouled hull ,add some seasonal growth ,a few barnicle s on the props ,canopies up a head wind ,---now the brochure speed is just a dream .
But nether the less you try
"Push that hand fwd on those sticks " -- all you are doing is asking the pump to squirt more diesel in ,but it can not make WOT, or even get near ,all that excess fuel burns and adds allready more heat to a hot situation the EGT rises dangerously ,
You have no idea what harm you are doing .
It's does not labour lie a car in high gear ,it just suffers at 3400 rpm you think is ok because the book said 10% less than the WOT

I'm a bit confused by this. If flat out you're only getting 3,400rpm then how can that also be 10% off WOT? If WOT = 3,400rpm then at cruise is 340rpm less = 3,060rpm.

You're not going to drive a boat at 3,400rpm with the throttles pinned because it's 3,900rpm in theory so that's okay then, you're going to take the max RPM you're getting (3,400rpm to use your example) and knock 10% off that aren't you?

Also, and I might be wrong here, but isn't the point of modern electronically controlled diesels that you can't 'over-fuel' them by pinning the throttles and supplying 3,400rpm with 3,800rpm worth of diesel? My understanding was that the electronic metering wouldn't let you do that, but as I say, I stand to be corrected.

 

[[2068]]

If the WOT rev range is 3800-4100rpm and you only hit 3400rpm, then even backing off 10% from this could still be in the overload zone with high EGT. You're just a little less overloaded.

VolvoPaul posted up some good words about how electronic diesels work. If I remember rightly, it's still possible that the engine tries to reach an rpm demand that it never quite makes, but not with the gross over fuelling of older systems.

 

[Portofino]

I'm a bit confused by this. If flat out you're only getting 3,400rpm then how can that also be 10% off WOT? If WOT = 3,400rpm then at cruise is 340rpm less = 3,060rpm.

You're not going to drive a boat at 3,400rpm with the throttles pinned because it's 3,900rpm in theory so that's okay then, you're going to take the max RPM you're getting (3,400rpm to use your example) and knock 10% off that aren't you?

Also, and I might be wrong here, but isn't the point of modern electronically controlled diesels that you can't 'over-fuel' them by pinning the throttles and supplying 3,400rpm with 3,800rpm worth of diesel? My understanding was that the electronic metering wouldn't let you do that, but as I say, I stand to be corrected.

If you look @ post # 30
Bottom para --you can see with dirty props I reach 100 % load at 1850 ish --but there's nothing stopping me reving it up to say 2000 -well into overload and watching EGTs soar .ok it may not reach wot the last 150 in this case .Any where between 1850 and 2100 is dangerous ---until the fouling is removed .
It's this bit the area before the apparent wot were the loads is exceeded 100'%

Nice to know where no go zone is ---- so you don,t inadvertantly stray into it.-- it does vary as explained .VP point that out .kop out imho.

How many do a wot test every time they go out ? Then set cruise ? In doing so they must exceed 100 % load or go into that zone ,paffing about .

Electronic metering is fooled by the propellor curve or demand ,the extra friction from too bigger pitch and /or fouling or extra drag by too manyKg,s
The engine does not know that it's trying to follow its prop demand curve .it just keeps pumping it in .
Fouled props demands more from the engines and they attemp to oblige -- EGTs rise .

They need to dig deep @ holeshot the prop demand is high ,any backing off via fuel metering and you will never get it up on the plane. Eventually the (clean ) props demands are met a certain rpm and the engines settle into a nice place 80-90'-% load all day -that's your cruise speed .For longevity sans rebuilds .

 

[Portofino]

There's quite a few articles if you google "marine diesel load "
A fouled prop is effectively a higher pitch ---until it's cleaned up .

https://www.sbmar.com/articles/engine-life-vs-engine-loading/

 

[Kingruar]

Hello,

So an update on the boat. Fuel lines were done.
The weather has been pretty crappy recently so had an opportunity to take it out this weekend. We did a 50nm round trip. The sea was not in a great state so the boat got a fair bit of tossing around however all was well and worked perfect.

I was a little apprehensive at first as the thought of the limp mode engaging in those seas was not going to be a nice one. So I took it easy until the swell levelled out a bit and gave it a few more revs where it performed perfectly. Hopefully out next weekend with a calmer sea so will be able to push it back up to speed.