KAD 32 - breathing 'fairly' heavy

[Bbroomlea]

Just had a survey on a boat with KAD32's

Report says that the engines were breathing fairly heavily - so I am guessing blow by. I saw a bit of smoke coming out of the crankcase breathers after the sea trial but not a lot, although there was a faint smell of oil. What should be normal as I have conflicting information on how much? Some say none at all others say unless the engine bay is murky with smoke dont worry. Hours are 895 and 910.

Engines need a good service - oil is a couple of years old although only done 40-50 hours at a guess.

Engines started fine from cold but fairly smokey (grey/white not blue and diesel is at least 2-3 years old), no smoke on sea trial under load but did come back a little bit on tickover after run.

Engines wouldnt make full revs - both would not go over 3500 but again new fuel and air filters are needed.

Prior to last owner who hasnt serviced engines or used it much I have every receipt from the last 10 years showing annual services to manufacturers guidelines.

Both engines have had new turbo's and superchargers

Am i worrying unnecessarily?

 

[jrudge]

Get the vendor to service it so you can confirm full revs. ( but it is more likely to be fouled hull / props).

 

[Bbroomlea]

Get the vendor to service it so you can confirm full revs. ( but it is more likely to be fouled hull / props).

It had new props fitted on the survey lift (new J4's) and the hull washed. 1/4 fuel in each tank, 3/4 water and 4 on-board for the trial so not too heavily laden.

If we get engines to full rpm I am still concerned on the surveyors comments about the engines breathing heavy

 

[volvopaul]

First question, who was your surveyor ? Is he conversant with volvos because some breath more than others .
Did they start from cold straight away and run evenly ?
What make and model of boat ?
You can answer via pm if you wish .
I’ve had follow up engine surveys in the past where there was nothing wrong.

 

[jrudge]

It had new props fitted on the survey lift (new J4's) and the hull washed. 1/4 fuel in each tank, 3/4 water and 4 on-board for the trial so not too heavily laden.

If we get engines to full rpm I am still concerned on the surveyors comments about the engines breathing heavy

Were the correct props fitted?

Why did it need new props? Did it hit something?

 

[Bbroomlea]

Were the correct props fitted?

Why did it need new props? Did it hit something?

They were not in good shape and thin. Also one of the duo props had turned itself into a single prop. The dealer fitted new ones regardless as it needed them.

 

[Bbroomlea]

First question, who was your surveyor ? Is he conversant with volvos because some breath more than others .
Did they start from cold straight away and run evenly ?
What make and model of boat ?
You can answer via pm if you wish .
I’ve had follow up engine surveys in the past where there was nothing wrong.

Hi Volvo Paul - I'll PM you more info - however

Both engines started well from cold. Oil pressure was 60psi on cold and 35ish when hot. They were smoky though on cold start. No rough or uneven running. In fact they sounded as smooth as the ones in my S28 currently.

Boat is a Sealine S34.

 

[Greg2]

Having just bought an S34 with KAD32's I would be interested to hear how this pans out if you feel able to post details. Might be worth looking at my posts on here and on the Sealine Forum

http://www.ybw.com/forums/showthread.php?505274-Duo-prop-size-Sealine-S34
http://sealineforum.co.uk/t13644-s34-prop-size-kad-32

Our issue was that the boat was apparently not making max RPM - should be between 3,700 and 3,900 but showing 3,300 at WOT but we were making 27 knots, which is the max you are likely to get on those boast with A4 props (switching to J series has led to speed loss in some cases).

Long story short fuel -pre-filters replaced as the ones on there apparently had insufficient flow rate and tachometers not reading accurately. On the latter point people tend to think that they can't both be out but in my experience they can!

 

[Bbroomlea]

I have been following your threads - hoping we had a better outcome on the initial sea trial!

Brand new J4 props were fitted - max speed at 3450rpm was 21kts. It would do no more. However fuel filters are 3 years old etc. so they need changing and fuel lines were not good.

I dont think the tacho's are wrong given the kts are down. I would think with J props 25Kts is about all it will do. Those extra 350rpm should get it there. My own experience of changing from A's to J's on my S28 was reduction in top speed but increase in acceleration.

I'll keep you updated on progress 'if' we get to full revs and there are no wear issues on the engines.

If we dont then plan B - spend more money on a S34 with D4's!!

 

[jrudge]

Don’t make excuses for the vendor. Fuel filters. Maybe. But maybe not. Tell him to solve it.

 

[Bbroomlea]

you are right it could be something else entirely. The engines need to pull to max revs and speed simple as that - whatever the issue may be!

 

[Momac]

You know what kad32's should be like as you already have them .
A few wisps of smoke on start up or if idling a while and that's it.
Sound like the J4's are a bit under propped which means it should easily reach full revs.

 

[Greg2]

I have been following your threads - hoping we had a better outcome on the initial sea trial!

Brand new J4 props were fitted - max speed at 3450rpm was 21kts. It would do no more. However fuel filters are 3 years old etc. so they need changing and fuel lines were not good.

I dont think the tacho's are wrong given the kts are down. I would think with J props 25Kts is about all it will do. Those extra 350rpm should get it there. My own experience of changing from A's to J's on my S28 was reduction in top speed but increase in acceleration.

I'll keep you updated on progress 'if' we get to full revs and there are no wear issues on the engines.

If we dont then plan B - spend more money on a S34 with D4's!!

Sorry, yes of course you have. We have ‘spoken’ - didn’t click - bit of a senior moment and posted in haste

 

[QBhoy]

Grey or white smoke would suggest air to fuel mix is rich on the air side. Suggesting a lack of fuel maybe. Filters would be a start. If she smoking anything else like a whispy colour after being out for a run and totally warmed up...check for signs of oil or diesel surfacing out the exhaust on drive. Be a sure sign of an injector problem.

 

[aquatom]

When selecting the new J series props was the Volvo prop calculation software used to determine the correct ones? A4 is not necessarily replaced by J4. From experience the Volvo software is very accurate in calculating the correct props and predicting the top speed of the boat. You do need to know an accurate weight of the boat, water line length, drive gear ratios and engine power.

 

[Momac]

A4 is not necessarily replaced by J4.

A straight swap a4 to j4 mostly seems to result in reduced top speed according to reading forums.
Is the calculation freely available?

 

[Boat2016]

A straight swap a4 to j4 mostly seems to result in reduced top speed according to reading forums.
Is the calculation freely available?

I would perhaps ask the supplying dealer ?