D4 or KAD43?

[alt]

I have pretty much made up my mind as to what boat i'd like next.

The boat comes with either D4 or KAD43 options (granted the KAD boat would be older) 2nd hand.

The boat has enough power with KAD43 as i've spent many hours on a KAD43 version and no problems.

My only decision is; which to go for?

Heart says D4, newer engine, nicer to play with the fly-by-wire etc.

Head says KAD43 - Simple engines that just seem to work, less worry of electronic issues etc.

I just don't know?!

 

[KevB]

It has to be D4 doesn't it???

I have KAD43's with approaching 1000 hours and apart from general service haven't missed a beat.

I appriciate your dilemma but all things being equal I'd have to go for the newer engines.

Of course if there was a big enough price difference or the boat with the kads was in better condition... I'd have the Kads everytime.

 

[DAKA]

Any chance of a bit more information

Not just being nosey but a bit depends on single/twin and where you are cruising.


I wouldn't be keen to cruise across the Irish sea or English channel on a single D4 so I would opt for the KAD43 and put up with a bit of smoke and soot to clean off the stern/tender on arrival, but a Twin D4 to dash across from Lyminton to Yarmouth in company would be easier to live with and probably higher residuals.

 

[alt]

I should be more specific, sorry.

Leader 805, mainly cruising inland lake in Ireland with the odd coastal cruise (but in a sheltered bay with help close by if ever needed). Single engine.

My fear of the D4 is possible electronic/diagnostic faults. There's no Volvo dealer close-by, so any issues would mean i'd have to get an engineer from 120 miles away with a diagnostic. I'd consider the D4 if I was able to purchase the diagnostics too, but from what I know this isin't possible like it is with cars.

There is a bit of a price difference, but that's not much of a concern of mine.

I don't mind putting up with soot etc. as I tend to clean my boats every week anyhow. I'd love the D4 for the 'toy' aspect, but think deep down the KAD43 is less likely to crop up issues. I currently have a KAD32 (had a KAD32 on last boat too) and never missed a beat - I love them

 

[DAKA]

I should be more specific, sorry.



My fear of the D4 is possible electronic/diagnostic faults. There's no Volvo dealer close-by, so any issues would mean i'd have to get an engineer from 120 miles away with a diagnostic. I'd consider the D4 if I was able to purchase the diagnostics too, but from what I know this isin't possible like it is with cars.

Well thats both you and Kev that love the old style reliability, sorted

However I dont think you should base your decision on the lack of a diagnostic tool , I would be interested to hear what he experts say but its not really all its cracked up to be, you havent got one on the KAD32 !

If it wont start you check where the electric power is and trace a fault, hot wire it and put a relay on order for next weekend.

If its a fuel blockage you clear/bleed it and off you go.......

The electronic aids are so Volvo can employ kids fresh out of college who otherwise wouldnt have a clue where to start looking for faults.

If your stern is 1 foot lower than normal you dont need an electronic gizmo to tell you to lift the hatch to find it submerged as the end cap of the heat-exchanger has come off.

two weeks latter when your rev counter doesnt work you dont really need any gizmo's to tell you the alternator and starter has failed following the salt water submersion.

 

[David2452]

When we bought our boat new we had the option of both those engines with a longer wait and a price premium for the D4 , after sea trialling both we decided to wait and I’m very glad we did, for the first three or so years, like you we were based and cruised inland in the main with the odd coastal trip. The lower smoke levels and controllability were great with that cruising combination. Latterly we have been based coastal and all of our cruising is coastal with the odd trip across the North Sea on a single D4, the engine and fuel system is scrupulously maintained and monitored and we have not had one single issue with the thing from new bar a slight weep from the charge air cooler end cap. It’s quieter, vibrates less and is more economical. My experience with it has been nothing but good and even if the old technology were sill available on our next boat there is no way I would go back.

 

[Philiz]

I have pretty much made up my mind as to what boat i'd like next.

The boat comes with either D4 or KAD43 options (granted the KAD boat would be older) 2nd hand.

The boat has enough power with KAD43 as i've spent many hours on a KAD43 version and no problems.

My only decision is; which to go for?

Heart says D4, newer engine, nicer to play with the fly-by-wire etc.

Head says KAD43 - Simple engines that just seem to work, less worry of electronic issues etc.

I just don't know?!

Personally, I'd go with your heads choice.

 

[DAKA]

Personally, I'd go with your heads choice.

My RM69 (12 volt) chews it up and minces it nicely, bit loud at times though

 

[Philiz]

My RM69 (12 volt) chews it up and minces it nicely, bit loud at times though

. Not sure I needed to know that

 

[Nick_H]

I went for a KAD44 boat, and wish i'd opted for D4's, just because of the smoke and diesel smell you get with the KADs.

edit- Leader 805 is a lovely boat, nearly bough one ourselves a while back

 

[wakeup]

I went for a KAD44 boat, and wish i'd opted for D4's, just because of the smoke and diesel smell you get with the KADs.

edit- Leader 805 is a lovely boat, nearly bough one ourselves a while back

I'm biased as I have a D4 engined leader 805. Several volvo techs have driven this boat and they all say that the performance is impressive compared to the Kad 43 option. More space in the engine room as well apparently. I did have all the usual problems with the raw water filter leaking which took a while to sort but boat hasn't missed a beat since.

There are a bunch of mods I would recommend to this boat though that are non volvo related.

 

[DavidJ]

I had the choice back in 2002 for KAD43's or 44's for my Sealine S37. I do my own maintenance so went for the 43's (which were £8000 cheaper per pair as well!)
eg Half the valves to set and no common rail to pull apart to get to them.

The only problem I've had is with the tiny bit of electronics, the speed sensor for the supercharger, which gives me concern with engines with considerably more electronics.

I also have a thought that the lesser power of the 43 will put less stress on the drive unit so may in turn give that a longer life.

So you can guess where my vote goes.

Best of luck with whatever decision you make!

 

[ulyden]

My opinion is clear. But it depends on a lot. Priority.

D4 have a common rail injection and better performance on smoke at low load. D4 is a more modern engine with larger cylinder swept volume compared to KAD44 0.6 against 0.9l/cyl. This gives better fuel consumption.

If you compare D4 225hp and KAD43 the fuel consumption difference is almost 10%

A kad 43 uses 52l/h at full power 170kw which is almost 257g/kWh.
A D4 225hp engine has 46l/h at 165kw which is 235g/kWh

(At part load specific consumption is better. Only have maximum load figures on KAD43 so I can’t compare.)


If you were sure that noting goes wrong D4 is the best engine, no doubt.

But if you get a cylinder failure the difference occurs. On D4 no oversized piston is available. No dry liner is possible (I know people have tried). So if you get a failure on a cylinder you end up with a new engine block. This is expensive compared to Kad where on cylinder can be exchanged.

On KAD you only have a stop solenoid so normally you can run without any electronic sensors.

On D4 you have a common pipe for fuelling. If one injectors leaks the whole engine stops. Same goes for leakage or common components like rail pressure control or hp pump.

If one injector is leaking (Anybody seen a nozzle that are leaking during pressure test?) this fuel might detonate in compression stroke and cause tremendous force on components.

Bosch common rail system also has a need for very clean fuel. Some operators where I live have 6 separate fuel filters to be able to have some running hours on their nozzles.

D4 also suffer from some common failures that lead to seawater leaking into and over the engine. This is mainly a bad pressurised seawater filter, some covers on the heat exchangers that are leaking. The exhaust outlet also leaks on this. This is not good for the electric components and gives corrosion on the block surface.

The charge air cooler is making a lot of condense water that seams to accumulate in the cooler. The position of the cooler makes it possible for this water to enter the comb chamber.

A KAD have more developed marinization kit. No such issues. No brain that can fail. Not that sensitive fuel system, less parts, cheap nozzles, replaceable /repairable cylinders, no expensive sensors, easier trouble shouting and so on.

A typical marine engine last for 30years. In 10 years the D4 is as outdated as the KAD is today. Diesel development goes fast. Miller and to stage turbo charging will come reducing fuel consumption same amount that differs KAD and D4 today.

If your priority is cold start smoke, fuel consumption, and sound go for D4
If your priority is low maintenance cost, low repair cost, easy trouble shouting, less failure possibilities go for the KAD43.

An option is the kad 300 286hp witch have electronic fuel control, 4valves pr cylinder and two stage nozzles. Fuel consumption same as a D4 260hp. But reparable cylinders and nice 6 cyl sound.

 

[alt]

Hi folks,
Thanks for the info and advise.

All things considered, I think the KAD would be the better choice for me. I can deal with the soot on the transom. I would love the extra power from the D4 but I think for the sake of sacrificing a few knots i'd be better of with a more simple engine

 

[ulyden]

I’m not sure if you are loosing so much performance. If you compare a D4 225 and a KAD43!

The D4 have a maximum speed of 3500rpm but maximum cruising speed is 3150rpm. That means 10% down in engine speed and 25% down in engine power (2.7 factor). The kad43 have a maximum speed of 3900rpm and a cruising speed of 3700rpm. This is a reduction of 5% in engine speed and 12% in engine power.

This means that you can have the same maximum speed but the maximum cruising speed is higher on the KAD.

If soot is a problem you can underprop your engine. That means that you are not utilising maximum power at 3900rpm but maybe 90%. Then your propeller curve is shifted down.
This will cost 3% in top speed but still your cruising speed will still be higher than the D4.

To avoid smoke on this engines keep your fuel system 100% air sealed. If air is leaking into the fuel system you get a lot of wite smoke during startup. Lots of people forget the return leakage system from the nozzles.

If your smoke is constant at low load the fuel nozzles are ok, the fuel pump might have drifted giving delayed timing.There are trick you can du but best way is to recalibrate your pump.

Smoke from leaking cylinders, leaking valve sealing’s, crankcase ventilation, turbo end so on you don’t avoid by modern fuel system. But on a KAD this things are much cheaper to repair.

 

[wakeup]

I’m not sure if you are loosing so much performance. If you compare a D4 225 and a KAD43!

The D4 have a maximum speed of 3500rpm but maximum cruising speed is 3150rpm. That means 10% down in engine speed and 25% down in engine power (2.7 factor). The kad43 have a maximum speed of 3900rpm and a cruising speed of 3700rpm. This is a reduction of 5% in engine speed and 12% in engine power.

This means that you can have the same maximum speed but the maximum cruising speed is higher on the KAD.

If soot is a problem you can underprop your engine. That means that you are not utilising maximum power at 3900rpm but maybe 90%. Then your propeller curve is shifted down.
This will cost 3% in top speed but still your cruising speed will still be higher than the D4.

To avoid smoke on this engines keep your fuel system 100% air sealed. If air is leaking into the fuel system you get a lot of wite smoke during startup. Lots of people forget the return leakage system from the nozzles.

If your smoke is constant at low load the fuel nozzles are ok, the fuel pump might have drifted giving delayed timing.There are trick you can du but best way is to recalibrate your pump.

Smoke from leaking cylinders, leaking valve sealing’s, crankcase ventilation, turbo end so on you don’t avoid by modern fuel system. But on a KAD this things are much cheaper to repair.

I think Alt meant D4260hp versus the KAD43 230hp which are the engines that are fitted to the model of boat in question.

On the subject of the Voida tool the two set of engineer that have worked on my boat, all volvo qualified have never used the voida tool to diagnose any problems. In fact when I did have a problem it turned out with the electronic gear change the volvo engineer was going to use his voida tool but couldn't remember the password as he hadn't used it in ages so I am not sure that the perceived difficulty of maintaining these engines versus the KAD43 is in reality a problem but then again I don't do it my self nor am I remote from people who can. I think a comparison of the power curves might be more relevant because I think it might show a greater differential throughout the rev range due to differences in supercharger and turbo set up.

 

[alt]

ulyden - Wow, thats some very specific knowledge, thanks

wakeup is correct, I was comparing D4 260 with KAD43 230.

I know myself, that deep down, with the KAD43 I wouldn't be thinking 'When it this thing going to cause me trouble', whereas with the D4 I would.... that says it all for me really.

Again, the issue is that i'm in the West of Ireland hence no engineer with diagnostics etc. should I need them. At least with the KAD I can do most of the servicing myself (My friends and I re-build engines/play with mechanics in general for fun), the thing i'd let a pro do is re-build the gearbox etc. - Again i've never had an issue with the 290 duo-prop (i've had 2 boats with this) provided proper maintenance was adhered to.

 

[DavidJ]

Hi folks,
Thanks for the info and advise.

All things considered, I think the KAD would be the better choice for me. I can deal with the soot on the transom. I would love the extra power from the D4 but I think for the sake of sacrificing a few knots i'd be better of with a more simple engine

You need not necessarily get soot on the transom with kad 43's I don't find this with my Sealine S37.
With performance, I get 32knots from mine with a clean bum so I can't imagine you would get any more than a couple of knots more or so from the D4 and after blasting around when you first get the boat you will soon settle down to a more economical 22-25 knots.

Have fun!

 

[rule the waves]

I don't want to spoil the fun, but I have a brand new D4 since 2 years and here's the story: new cable from the throttle amplifier towards the leg, massive sea water filter leak (apparantly a known problem), small hole (!!) with oil spill in the middle of a steel tube on the turbo oil system - remains a mysterie..., bad firing with engine stall in mid-sea, apparantly due to humid coils (was solved with a special teflon-based spray), flipping EVC system (ghost alerts). Just bad luck ??
Just holding my breath for things to come this season....

 

[alt]

I don't want to spoil the fun, but I have a brand new D4 since 2 years and here's the story: new cable from the throttle amplifier towards the leg, massive sea water filter leak (apparantly a known problem), small hole (!!) with oil spill in the middle of a steel tube on the turbo oil system - remains a mysterie..., bad firing with engine stall in mid-sea, apparantly due to humid coils (was solved with a special teflon-based spray), flipping EVC system (ghost alerts). Just bad luck ??
Just holding my breath for things to come this season....

KAD43 it is then!!