help needed "Erratic Main Engine Cylinder Exhaust Temperature"

[donkey131]

hello to all, im new to this forum, but i need some help from you good people out there
can any one help on some information, procdure and regulations on "Erratic Main Engine Cylinder Exhaust Temperature"

officer of the watch-:

information?
What to do?
cause of problem?
risks?
etc

as im not able to find much in my books

Get on BoatDiesel, http://boatdiesel.com/ now, and ask for Paul Fouston (He's in UK, and SUPER knowledgable) or just a general inquiry and pay attention to Tony, Ski, Paul, Mike.

[gonzo]

Are you qouteing correctly? It should be either cylinder temperature or exhaust.

[donkey131]

Yes thats correct "Erratic Main Engine Cylinder or Exhaust Temperatures" as i'm not sure what would be the procedure would be? or what would cause it?

1. i think a scavenger fire would cause erratic temps, then i guess you would slow the engine down or stop, if the fire was too great.

[gonzo]

If there is an "or" then it makes sense.

[gonzo]

What kind of engine?

[donkey131]

I dont have a specific kind of engine in mind, its just a general question on what to do if you get erratic temperature readings for cylinder or exhaust. as if your the engineer on watch in the engine control room. plus the action to be taken and the cause of the problem.
Engine type would be marine diesel 4-stroke and the large 2-stokes that you get on container ships

[Landlubber]

...the cylinders are individually fed from their own injector and their own injector pump. Erratic temperatures would indicate that the cylinder in question has an erratic fuel feed, so most likely the injector has been damaged (or the supply pump). The weak cylinder will be the only one affected heavily, but the other cylinders will also show minor temperature alteration as they are part of the system that has a lazy cylinder.
Diesel engines have no air throttle, the air suppy is wide open always, the fuel injected is what allows the cylinder to work harder. Balancing the engine via the exhaust temperatures is the best way to even the loads on all cylinders, so that they are working evenly, the temperatures of the exhaust reflect the amount of work that they are doing.


Hope this helps a bit....

[gonzo]

It could also be a bad water pump or cavitation in areas of the water jacket.

[Landlubber]

....yep gonzo, but not cavitation cos that would involve high velocity water flow, and the water pumps deliver high volume, not velocity, but yes, water of course is the cooling agent for the engine, individual cylinders would only be affected if there was some sort of blockage....broken water pump impellors can cause local conditions as the pesky little varmits can block flows if they are large enough.

[gonzo]

There can be cavitation in small spots where there is a sharp turn. If there is a restriction, the water flow increases. It may create a small hot spot.
One of the things to check if the gauges have erratic readings, is that they are working properly. Check the actual temperature with a contact thermometer or a infrared.

[Frosty]

A badly designed water cooled exhaust system. It will also cause improper Turbo function.

[michael pierzga]

Fuel combustion and cooling water flow are high on the list of suspects. Also consider the effects of the propeller and shaft system. Addition friction such as a rope in the prop , fouling on boat or prop or a propeller adjusted with too much pitch will overheat the engine

[gonzo]

Would an intermittently cavitating propeller (adjusted with too much pitch) cause erratic readings?

[rayman]

DONKEY, service your injectors-fuel valves or sprayers, whatever you want to call them. They are dribbling and not spraying correctly that will have your cylinder cover water temps going crazy and same with the ex. temps. After that attend to the suction and delivery valves in the fuel pumps. You are going to have no playtime at your next port of call, believe me.