Any Perkins M90 or engine diesel mechs to advise ?

[Gallant Spirit]

Hi Folks

I have issues with some white smoke in my exhaust, I had this checked before leaving the canaries at Pasito Blanco, I asked them to check compression etc and re tip the injectors as that was my thoughts on the isssue, they replaced the nozzles but also sent my fuel injection pump away for a costly overhaul, there has been no issues running or starting the engine at any time before or after , it looked ok in harbour tests but re appeared 30 mins into my trip to Maderia, called them up and pulled in to las palmas for a further check
they changed my fuel filter ( I thought this had been done already but waiting on itemised bill still )
and said will be fine
same issue again when having to motor 2 days to Maderia, they suspect old diesel but I topped up my tanks there , the diesel is clean I have a water separator and a MFP 100 purifier, my current thought after getting to Maderia is that I have a very slight leak on the cyl head gasket as I had to top up the coolant after it cooled with only a small cup of water, the oil is good with no contamination anyone with similar issues in the past or advice before the warranty mechanic appears on monday hopefully?

 

[RichardS]

White smoke is usually unburned diesel fuel. Water entering the combustion space causes steam which looks very similar but usually disperses and vanishes within a foot or two of the exhaust. Genuine white smoke will still be visible a metre or two away and can be caused by several things.

Richard

 

[Bobc]

If it isn't there when the engine is cold, but only starts appearing when the engine is hot and under load, it could be steam caused by your engine running too hot. Check that you have a good flow of water through the engine, and put an infra read temperature guage on the engine to see how hot it is getting.

 

[Gallant Spirit]

Hi Folks
It turned out to be an exhaust valve not sealing properly on one cylinder , giving over pressure in the header tank as well
at least it will be ready for next months trip to the Azores or Lisbon depending on weather
cheers
Robbie

 

[Heckler]

Hi Folks
It turned out to be an exhaust valve not sealing properly on one cylinder , giving over pressure in the header tank as well
at least it will be ready for next months trip to the Azores or Lisbon depending on weather
cheers
Robbie

Im curious as to how a non sealing exhaust valve causes overpressure in the header tank?

 

[AndrewB]

White smoke is usually caused by water. Most likely sources are from:

(i) condensation in the cylinders, which results in white smoke on startup which quickly clears.
(ii) water in the fuel tanks, perhaps getting mixed with the fuel during a vigorous sail, which will show as water in the primary fuel filter/water separator (from which it should be drained).
(iii) a blown head gasket, in which case there will be loss of coolant (in a heat exchange system), without necessarily much sign of external leakage.

From what you say, the head gasket must be strong suspect. Specially if the engine power seems down a bit - you are needing a little more throttle to get the same revs. If there are signs of leakage around the top of the engine block, that makes it a cert.

As RichardS implies, one can mistake white and black smoke. Black smoke is the result of unburnt fuel, and has entirely different causes. You can tell by dipping an oar briefly into the exhaust, if it is unburnt fuel there will be specks of black carbon.

 

[Heckler]

White smoke is usually caused by water. Most likely sources are from:

(i) condensation in the cylinders, which results in white smoke on startup which quickly clears.
(ii) water in the fuel tanks, perhaps getting mixed with the fuel during a vigorous sail, which will show as water in the primary fuel filter/water separator (from which it should be drained).
(iii) a blown head gasket, in which case there will be loss of coolant (in a heat exchange system), without necessarily much sign of external leakage.

From what you say, the head gasket must be strong suspect. Specially if the engine power seems down a bit - you are needing a little more throttle to get the same revs. If there are signs of leakage around the top of the engine block, that makes it a cert.

As RichardS implies, one can mistake white and black smoke. Black smoke is the result of unburnt fuel, and has entirely different causes. You can tell by dipping an oar briefly into the exhaust, if it is unburnt fuel there will be specks of black carbon.

He said it was a stuck exhaust valve which I am curious about

 

[AndrewB]

He said it was a stuck exhaust valve which I am curious about

Sorry, I should have read down the thread. A stuck exhaust valve would mean unburnt fuel and black exhaust.

 

[Heckler]

Sorry, I should have read down the thread. A stuck exhaust valve would mean unburnt fuel and black exhaust.

Im curious though as to why he has been told that it caused over pressure of the header tank.

 

[Gallant Spirit]

I am back at work in China, the mechanics in Maderia are doing a lot of tests and have not stripped the head down yet, will add more info when I get it from them , I still firmly think it is the gasket but they told me they will photograph the stripdown

 

[Andy Cox]

I'm curious how they've diagnosed a non sealing exhaust valve before stripping or removing the head . In your first post you say you asked them to do a compression test - what was the result of that? A valve not sealing would show as low compression on that cylinder.
As with Heckler, I'm also curious as to how this would over pressure the header tank?

Andy

 

[Gallant Spirit]

Finally back on boat , the compression tests were good, the work i had done in the canaries on the injectors was shoddy and was redone in Maderia, the main issue was blocking on the cooling system , heat exchanger etc this was cured by chemical cleaning of sea water circuit ( RYDLYME ) and at the same time a full backflush on the FW circuit, sea trial was yesterday over 1.5 hrs at 2100 rpm boat doing 7.5kts and every temperature was correct no more steam in the exhaust
well done to Neptune Pirate in Maderia and their perkins mechanic for sorting it all out at a very reasonable cost.

 

[Bobc]

Finally back on boat , the compression tests were good, the work i had done in the canaries on the injectors was shoddy and was redone in Maderia, the main issue was blocking on the cooling system , heat exchanger etc this was cured by chemical cleaning of sea water circuit ( RYDLYME ) and at the same time a full backflush on the FW circuit, sea trial was yesterday over 1.5 hrs at 2100 rpm boat doing 7.5kts and every temperature was correct no more steam in the exhaust
well done to Neptune Pirate in Maderia and their perkins mechanic for sorting it all out at a very reasonable cost.

So it was steam then. Almost always is.

 

[Mr Cassandra]

So it was steam then. Almost always is.

probably condensate, steam is invisible to the eye

 

[Gallant Spirit]

yup Steam (saturated lol ), have done a 500m trip with engine as a test to Lisbon no issues at all and my fuel economy is also a lot better

 

[Bobc]

probably condensate, steam is invisible to the eye

Pedant alert!

 

[Mr Cassandra]

Pedant alert!

 

[Bilgediver]

Im curious as to how a non sealing exhaust valve causes overpressure in the header tank?

Me too! So often steam is mistaken for smoke especially on a cold humid night when it can look frighteningly dense .