KAD 43 - Power problem

[volvojurg]

Hi all, I'm new to here.

So I have a problem with my starboard engine. Port engine is revving fine but starboard engine is lacking on revs. Revs picks up good until 2500 and will slow down up to 3000 and it will stay there. However when the port engine is revving 3500 the starboard engine goes up to 3100/3200. New fuel filters, new water seperator, new air cleaner, props have been swapped and still the same problem.

Port engine is boosting 0.9bar in 3k revs and the starboard engine is boosting 1.5bar in 3k revs. Looks like the engine is on load. To have 0.8bar boost on the starboard engine, the engine has to be around 2600/2700 revs.

We checked what happens with the supercharge off, and still it planes and 1.5bar at 3k revs. I noticed though the the port engine supercharger while coming off the plane the supercharger switches back on at around 2500/2600 while the starboard engine supercharger switches back on around 2300/2400 (according the the rev counter). Our next guess is checking the rev counter.

No smoke or anything. engines both run fine and sound healthy. Boat is not new to me but this is the first time happened. I don't know when because I usually drive at around 2900revs. But now it has been a month or so.

Any more ideas please?

 

[Portofino]

Turbos knackered.Replace both .

KAD 44 rpm surging

 

[DavidJ]

Agree

 

[volvojurg]

Turbos have been replaced last season.

can you please explaine why turbos are gone if they are shooting 1.5bar? And the other one 0.9bar as it should be?
Thanks

 

[Portofino]

1.5 bar is lowish .Both should be north of that running @ 3200 rpm cruising .
I see 1.9 bar running .

Where the turbos OEM , after market ,or remanufactured ?
Oil quality? It matters with turbo bearings .Fully warmed up ? They suggest jacket temp of 60 *c before letting rip spooling up .
Oil filters again OEM ? Seen Chinese cut open to find it’s just a can no paper element .

When coming off the plane they should get 10 mins low rpm / tick over marina manoeuvres to cool and lub the bearings .
Otherwise the oil bakes on the bearings shortening life .

 

[Mr Googler]

Could be an air leak after the turbo

 

[DavidJ]

Turbos have been replaced last season.

can you please explaine why turbos are gone if they are shooting 1.5bar? And the other one 0.9bar as it should be?
Thanks

I replaced mine on my KAD43’s and recorded both 2 bar. Check the graphs I think you will find yours are well out of spec. i would guess you have another turbo related problem.
spec is
115 kPa (16.6 psi) 145 kPa (21.0 psi) 175 kPa (25.3 psI) for 1800, 2500, 3800 rpm

 

[volvojurg]

According to two different approved volvo mechanics 1.5 bar is what the engine should make while doing 3500rpm and not 3000rpm. They both told me that they should read in the region of 0.8/0.9 bar at 3000rpm. ?

David can you tell me from where I can get the graphs? I’ve been trying to check online to see any graphs related to boost without any luck

 

[volvojurg]

1.5 bar is lowish .Both should be north of that running @ 3200 rpm cruising .
I see 1.9 bar running .

Where the turbos OEM , after market ,or remanufactured ?
Oil quality? It matters with turbo bearings .Fully warmed up ? They suggest jacket temp of 60 *c before letting rip spooling up .
Oil filters again OEM ? Seen Chinese cut open to find it’s just a can no paper element .

When coming off the plane they should get 10 mins low rpm / tick over marina manoeuvres to cool and lub the bearings .
Otherwise the oil bakes on the bearings shortening life .

They were remanufactured. Oil temp and engine temp were about 80degrees before planning. Oil filters OEM.

Yes I guess they get more than 10mins. Until I arrive at my slip and leave it at idle until everything is settled.I’ve been doing this every single time.

Do you have any graphs I can show to my mechanics please?

 

[DavidJ]

Here we go
It took me a while to get my head around it but if you took your reading at about 20 deg C then you are comparing directly with the spec
My 2 bar is a bit on the high side, could be instrument error but you should be seeing 1.75 bar with well refurbished units I would have thought

 

[Mr Googler]

They were remanufactured. Oil temp and engine temp were about 80degrees before planning. Oil filters OEM.

Yes I guess they get more than 10mins. Until I arrive at my slip and leave it at idle until everything is settled.I’ve been doing this every single time.

Do you have any graphs I can show to my mechanics please?

Unless the exhaust housing was changed…..waste of time.

id be checking for air leaks first though. At idle…..use a screwdriver to activate the super charger kick down magnetic switch. Running s/c helps find air leaks after the turbo

intercooler been cleaned?

 

[volvojurg]

Here we go
It took me a while to get my head around it but if you took your reading at about 20 deg C then you are comparing directly with the spec
My 2 bar is a bit on the high side, could be instrument error but you should be seeing 1.75 bar with well refurbished units I would have thought

Thanks alot

 

[volvojurg]

Unless the exhaust housing was changed…..waste of time.

id be checking for air leaks first though. At idle…..use a screwdriver to activate the super charger kick down magnetic switch. Running s/c helps find air leaks after the turbo

intercooler been cleaned?

Will have a look at this one. Thanks.

no i dont think that the intercooler has been cleaned

 

[volvojurg]

Unless the exhaust housing was changed…..waste of time.

id be checking for air leaks first though. At idle…..use a screwdriver to activate the super charger kick down magnetic switch. Running s/c helps find air leaks after the turbo

intercooler been cleaned?

Is it something you can do while the boat is in the water (cleaning the intercooler)

 

[Mr Googler]

Is it something you can do while the boat is in the water (cleaning the intercooler)

Yes

 

[volvojurg]

Yes

Ok thanks and have a look

 

[volvojurg]

My only concern is this... I am still managing to do 25knots while both engines are at 3k. According to the boat specs and since the first time I bought it (2019) the crusing speed is 25knots. It’s a 2003 Cranchi Zaffiro 34. Having one at around 0.9bar and the other at 1.5bar. To match the boost i need the strbrd engine to be at around 2800. Now if I have low boost, the speed should decrease no?

i still need to discus thiss with my mechanics

 

[Mr Googler]

The higher boosting engine is compensating….working harder

 

[volvojurg]

The higher boosting engine is compensating….working harder

yes its working harder. Can a leaking injector (on the same high boost engine) cause this?

 

[volvojurg]

I’

Here we go
It took me a while to get my head around it but if you took your reading at about 20 deg C then you are comparing directly with the spec
My 2 bar is a bit on the high side, could be instrument error but you should be seeing 1.75 bar with well refurbished units I would have thought

I’m studying this data and noticed that the ambient temperature effects the boost pressure.. right now temperature is around 36degrees celcius. Will this effect my readings compred to the date sheet shown above?