Dieselly question

[Bergman]

Afraid its a motor not the boat.

Mitsubishi 2.8 turbo.

If you open the throttle at low revs the engine makes a noise like "pinking" and kicks out cloud of black smoke

Open the throttle very slowly and its ok.

When running at mid revs its fine and seems to perform as good as ever.

Not been used much for last few months but is overdue for a service.

Anyone got any ideas?

 

[savageseadog]

I think you will find the timing has shifted. I's probably too far advanced, I don't know how the timing's done on your engine but if it's belt timed it may have jumped a tooth or two, if you aren't careful it will go completely and that will be the end of the engine or the head at least. Running it too advanced that might erode the head as well.

 

[oldharry]

Not been used much for last few months but is overdue for a service

I think you just answered your question.

While timing belt failure is always expensive, another reason for not neglecting servicing, retarded injection timing results in a softer ignition sound and major power loss every time I have met it. Over advanced tiing makes more noise and again less power, and both will make for difficult starting.

Sounds to me more like injector knock because of a duff injector(s) which is over fuelling its cylinder on pick-up causing the black smoke and noise. Easily enough sorted by an injection specialist, but not a good idea to ignore it.

 

[boatmike]

Agree the first thing to do is whip the injectors out and get them cleaned and reset by a specialist. Not expensive and well worth while. If a diesel has not been used for a while the components of the fuel system (injectors and pump) can build up a hard lacquer which needs cleaning off. I doubt if your timing is out if it runs OK when at working revs.

 

[Bergman]

Thanks guys

A service is booked for next week

The injectors are coming out after that and going to diesel specialist in York

Cheers

 

[savageseadog]

Speaking for myself, do as little as you can. I'd make sure the timing is ok, check the timing belt (if it has one), then give it an extended run at high revs as long as the smoke and noise are ok. This will unstick most things in the fuel delivery system and elsewhere. In my experience running an engine, preferably regularly, keeps it happy. Diesel specialists will check your injectors for free usually but you would need to replace the washers/seals.

 

[Bilgediver]

This sounds like detonation .. The combustion process taking place too early. This can happen due to timing problems or possibly if the fuel is not right. Is there any chance something was tipped in the fuel tank which has contaminated the diesel.Did you refill with diesel from a different source before this happened????


John