KAD 42 - Speed Problem - Please Help.

Dear All,


I have 1995 Wellcraft Martinique 27 with single diesel Volvo Penta KAD 42.


Normally boat sails with 23-26 knots gps speed with 3000 - 3300 rpm with maximum speed of 33 knots at 3500 rpm.


Last week performance of the boat was very good but this week I faced with a strange problem.


At marina, in neutral (N) gear, when I give throttle, engine goes up to 3800 rpm which is quite good.


However, at the sailing, when I give full throttle engine stucks at 2000 rpm with 8.9 knots gps speed and never go more.


Also there is no any white or black smoke.


I have removed turbo, compressor, intercoller, injectors and cleaned them and connect again however nothing changed.


I checked the quality of the diesel also it was good.


I checked cable/wire of the throtte arm and it was also good and normal position.


What could be the problem ?


Where do I have to look and check ?


Waiting your helps and recommendations.


Kind Regards

Can you see, hear that the compressor kicks in?

martinhellstrom said:

Can you see, hear that the compressor kicks in?

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Martinhellstrom, I can easly hear that the compressor works as its usual sound.

Even you are 2 persons or 4 persons on boat, it is max. 2000 rpm with 8.6 knots gps speed.

Some possible thoughts -
Is the propeller dirty or damaged?
Have you checked the boost level with a gauge to make sure there is no leak in the intake side?
Have you changed all the fuel and air filters?
If boost etc is OK, and with everything you have done already, you need to check the injector pump.

It must be something with the air pressure, I assume you have checked that you have full trottle at the injector pump, check all the air hoses for leakage.

Forgot to ask, is it starting and idling as normal? Another possibility might be an air leak in the lift pump. Not uncommon in Volvos, but it would have to be pretty bad to cause the drop in performance you have.

I'm about to go crazy. There are no any air leaks, just changed injections and diesel filters all working good but still max.2000 rpm and 8.6 knots speed. Besides hull and prop. very clean.

Have you measured the boost? Did you compression test the engine compressions when you changed the injectors? The most likely problem is a lack of boost, so checking the boost pressures is where I would start. If it is turbo/supercharger engine then it won't be a bad turbo as the compressor should run you up past 2000rpm. If there isn't an air leak, your boost should be fine, but is a cheap thing to check compared to what else you may need to do next. The other possibility might be an oyster or similar blocking your exhaust. That depends on how well you have been cleaning the inside of the leg during servicing. We had an oyster in a leg juts recently that dropped the engines rpm's from 3800 to 3200 due to back pressure affecting the turbo performance. If boost and compressions are OK, then I would check the lift pump and throttle seal on the injector pump. Both can let air into the system. That would usually mean harder starting when cold as well.

Is the intake fuel line inside or outside of the fuel tank clear of partial obstruction?

Gents,

No more good news.

Turbo, Compressor, Intercooler, Dizel Pump, Injectors are all cleaned and installed again.

Aır, oil and dizel filters are fine.

There is no any air leak, hull and prop are all clean.

But still max. 2000 rpm and 8.6 knots speed with no any black or white smoke.

Than, where should ve check now ? Any ideas ?

Hi

I know, this thread is 4 years old. But today I got the exact same issue. port engine will not rev past 2000rpm. KAD300s. Did you fix the issue?`If so, what was the solution?

Best regards
Didrik

Didrik - first thing I would do is check your boost levels. It isn't uncommon for that generation of Volvo to have corrosion in the turbo exhaust housings and lose boost. In fact the turbo could be stuck so maybe first thing is to remove the piping at the intake to the turbo and reach in to check that the vanes are not stuck and move freely.

didrikbe said:

Hi

I know, this thread is 4 years old. But today I got the exact same issue. port engine will not rev past 2000rpm. KAD300s. Did you fix the issue?`If so, what was the solution?

Best regards
Didrik

Click to expand...

Hi didrikbe, had spent huge amounts o money but could not solve the problem. Then an old mechanic at around 60 years old came with a screwdriver and pliers and fixed the problem within 5 minutes time. He did not clearly explain me how he did it but as long as understand, there are two adjusting points on the fuel pump which adjusts fuel and air (I guess). My mechanic only told me that these two adjusting points have some special ratio between. Now my boat reaches 30-33 knots at around 3500 – 3600 rpm.

As your KAD300probably have EDC you must check on the diesel pump that you get fulltrottle, if not calibrate. Check the turbo so it does not stop theexhausts, check that the clutch on the compressor engages, you hear this,or just check on the engines and compare.