Big Yanmar Engine trouble, smoke and loss of power

[Perudo]

This is a long one - sorry but am a bit desperate!

We were out today in our Trader 575 with 2xYanmar 500’s and ran the boat at about 2000 revs for about three hours with no issues. We were a bit late coming back so just pushed on a bit to around 2600 revs, temp and pressures were bang on on both engines but suddenly there was a drop in power on the starboard engine so I backed off but throttle response was way off and something clearly not right although the gauges were all still bang on. I then noticed that thick blue smoke was pouring out of the right hand exhaust so I quickly shut the starboard engine down and went to the engine room. It was a bit smoky in there but not too bad and no sign of damage. I left the engine off until we got to port and then started it for the close manoeuvres and immediately had a huge cloud of smoke again so shut off and managed to park with one engine.

Any ideas, is there anything that I can/should do to diagnose the problem further?

 

[Portofino]

It’s likely to be burning oil .
1- Blown oil seal in a turbo - hence loss of power “gauges normal “ but have you got a boost pressure gauge ?
Oil hits the hot air on the exhaust side , engine runs but the boat / car turns into what resembles a WW 2 destroyer emitting smoke .
It doesn’t take much oil and the level seems normal .= rebuilding the turbo or replace ?

2- I,am not familiar with the details of Yanmar but faulty Exhaust Gas Recirculating valve on cars can give blue smoke , but the thing runs normally with normal power so probably not that if it’s got a similar system ?
That the cheapest fix btw .

3- Two much diesel has got past the rings and diluted the sump oil ( level again seems normal ) as any burnt is diluted down .A or some faulty injectors due to overloading and excessive EGTs .Exhaust Gas Temps .
The injector tips let go ends get burnt off and they don’t close off properly. Removal will revel and testing .

4- The rapid change of piston crown temp can crack a piston or and a ring and oil enters the chamber .
A simple diagnostic test is to start up and remove the oil filler cap ( do both sides ) .With the caps off at tick over place the palm of your hand over the filler hole and feel any pressure difference .You will see excess fumes coming out as well .” Smokey “
Ask somebody to rev it up to say 1000 rpm unless it’s obvious the bad engine will have blow by .
Compression is getting past a piston(s) and oil the other way and burning = blue smoke .
I guess they will pull the injectors first and examine then borescope through the hole to examine further while they are out .
If that draws a blank then ......

5- Excess EGT from overloading your running fast may have destroyed a exhaust valve stem seal and oil is getting in from there again put your hand over the open oil filler cap when running to feel the pressure .

How clean is the stern gear ,how many hrs on them , and when was the last full service - like time ago ?

 

[Perudo]

This is very useful, thanks for your time and effort with such a detailed response. I suspect the turbo, we had some issues with exhaust gas getting pushed back into the engine room on our very first run of the season which was blamed on the turbo not kicking in after the winter shut down. Once it did, we had no further issues but it feels like the blame could lie there! Stern gear isn’t perfect after winter in the water but not bad, we had a diver do a once over.
Thanks again.

 

[mcanderson]

Could you have caught a rope which is now causing significant additional loading on the engine and therefore overheating and poor fuel burn?

 

[volvopaul]

It’s likely to be burning oil .
1- Blown oil seal in a turbo - hence loss of power “gauges normal “ but have you got a boost pressure gauge ?
Oil hits the hot air on the exhaust side , engine runs but the boat / car turns into what resembles a WW 2 destroyer emitting smoke .
It doesn’t take much oil and the level seems normal .= rebuilding the turbo or replace ?

2- I,am not familiar with the details of Yanmar but faulty Exhaust Gas Recirculating valve on cars can give blue smoke , but the thing runs normally with normal power so probably not that if it’s got a similar system ?
That the cheapest fix btw .

3- Two much diesel has got past the rings and diluted the sump oil ( level again seems normal ) as any burnt is diluted down .A or some faulty injectors due to overloading and excessive EGTs .Exhaust Gas Temps .
The injector tips let go ends get burnt off and they don’t close off properly. Removal will revel and testing .

4- The rapid change of piston crown temp can crack a piston or and a ring and oil enters the chamber .
A simple diagnostic test is to start up and remove the oil filler cap ( do both sides ) .With the caps off at tick over place the palm of your hand over the filler hole and feel any pressure difference .You will see excess fumes coming out as well .” Smokey “
Ask somebody to rev it up to say 1000 rpm unless it’s obvious the bad engine will have blow by .
Compression is getting past a piston(s) and oil the other way and burning = blue smoke .
I guess they will pull the injectors first and examine then borescope through the hole to examine further while they are out .
If that draws a blank then ......

5- Excess EGT from overloading your running fast may have destroyed a exhaust valve stem seal and oil is getting in from there again put your hand over the open oil filler cap when running to feel the pressure .

How clean is the stern gear ,how many hrs on them , and when was the last full service - like time ago ?

Engine is a Scania base unit not yanmars own as far as I’m aware , I’d have to see engine numbers.
Not many around,
NoEGR system so don’t go there .
First thing to do is check the oil level , if it’s gone down it’s the turbo shaft seal, if it’s good then it’s fuel un burnt , could be damaged injector .
Run engine with oil filler cap removed , do you get excess pressure from crank case , if ok it’s not piston blow by so that’s good.

Have a look in air filter you might see oil, if so it’s possibly turbo which is a fairly easy fix.

 

[Mr Googler]

Engine is a Scania base unit not yanmars own as far as I’m aware , I’d have to see engine numbers.
Not many around,
NoEGR system so don’t go there .
First thing to do is check the oil level , if it’s gone down it’s the turbo shaft seal, if it’s good then it’s fuel un burnt , could be damaged injector .
Run engine with oil filler cap removed , do you get excess pressure from crank case , if ok it’s not piston blow by so that’s good.

Have a look in air filter you might see oil, if so it’s possibly turbo which is a fairly easy fix.

Easy to spot the expert in this thread!

 

[Perudo]

Everything is pointing to turbo - oil level slightly down, spray on turbo side and some in the bilge.

Oil pressure and temp on engine were both fine when we first noticed that we were the source of some major air pollution!

Engine is a Yanmar 6CXM - GTE2 with Holset HX50 turbo, I think full model number is HX500X9T but hard to be 100% sure.

Thanks for the advice!

 

[omega2]

Another possible? is the intercooler clean, a mate of mine had his blocked with all kinds of muck, caused by the breather pipe injecting blow by straight back into air cleaner, took a while to find it after chasing turbo, compression, injectors, pump. solution remove the intercooler then extract the core and steam clean.

 

[kashurst]

If the turbo seals have gone and the engine has been sucking in engine oil, it would be well worth cleaning out the charge air cooler and associated pipes.

 

[Perudo]

Thanks for the assistance everyone, some very impressive knowledge which puts me to shaame. Sadly it turns out it is not the turbo, but it is a piston related issue so its one engine for the rest of this trip and let the engineers have a thorough look when they are gone. In the end got Offshore Marine to help after trying everyone, the office is run by Adrienne who is super-helpful and the boss is Stephane who came in person and was great. Next step, remove the injectors and see how bad the damage is - ouch!!

 

[Portofino]

Easy to spot the expert in this thread!

You might want to revise this post now .
Refer to 4 of my post .

 

[Perudo]

Yes - that was spot on sadly! Please note that the comment above didn't come from me! I don't believe I can delete other users comments.

 

[Mr Googler]

You might want to revise this post now .
Refer to 4 of my post .

A machine gun will hit the bullseye once or twice

 

[Portofino]

A machine gun will hit the bullseye once or twice

Many years and decades ago when I was in the Parachute Regiment we had a “sustained firing device “ for the GPMG , ( general purpose machine gun ) it was a very heavy looked like a road man hole cover .
The bipod was mounted on this base , it’s stopped bounce and we could direct fire with Uber accuracy .
We won competitions with this and with the LMG aka the Bren gun.
I vaguely recall hitting targets from 1000;m out in another life with “machine guns “.

Wasn’t luck you know !
So no I don’t agree with your inferred inaccuracies re “ machine guns “

 

[MrB]

You might want to revise this post now .
Refer to 4 of my post .

VP said the same thing Porto and he is a VERY well renowned expert on these forums, he just gets to the point quicker!!

 

[Mr Googler]

Many years and decades ago when I was in the Parachute Regiment we had a “sustained firing device “ for the GPMG , ( general purpose machine gun ) it was a very heavy looked like a road man hole cover .
The bipod was mounted on this base , it’s stopped bounce and we could direct fire with Uber accuracy .
We won competitions with this and with the LMG aka the Bren gun.
I vaguely recall hitting targets from 1000;m out in another life with “machine guns “.

Wasn’t luck you know !
So no I don’t agree with your inferred inaccuracies re “ machine guns “

To quote Mrs Brown......”that’s nice”

 

[MrB]

To quote Mrs Brown......”that’s nice”

PMSL

 

[Portofino]

VP said the same thing Porto and he is a VERY well renowned expert on these forums, he just gets to the point quicker!!

Agree the posts where there a-bouts more or less the same , and i,am not anywhere near the hands on level of experience of VP , but thought I had a bit to contribute in a diagnostic tree from the top down given the info supplied.

So why the dig ? and further a none contributor to the actual issue .

How was that gonna advance the poor guys predicament?
At least I inferred / told him ( the OP ) “ they all busy “ - an ounce of local knowledge, which turn outs spot on as well .
It’s not good for the forum toxicity of this sort just kills folks with thinner skins posting .

Idea is to advance the OP,s topic / problem from a varied wealth of knowledge/ experience.

Or is it just a have a go shop ?

 

[volvopaul]

Now now boys , play nicely .
Engines not stripped yet , let’s see the scope results .
I’d be very surprised if the base units failed from design fault , I’d think it’s possibly an ancillary part failure thats lead to the failure .
An example would be a leaking intercooler , plenty of D6 trashed that way .
Remember the D6 base unit design and manufacture is Deutz.

 

[Machaseo]

Or blocked piston cooling nozzle, seen 2 D6’s with this failure, both with what looks suspiciously like Factory Volvo orange sealant in the nozzle and the strainer. Volvo warranty response in both cases was that it was not possible, sealants were dispensed in computer controlled quantities. Despite CSI style forensic strip downs with every step photographed. Volvo answered we’ll give you a new short motor at a discounted price of 12k.