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hauguelpa
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Join Date: Jan 2012
Posts: 34

Exhaust Temperature MTU 12V4000M71

08/03/2013 4:36 PM

hello,

on a high speed craft we have 4 diesel engines MTU 12V4000M71 for propulsion with waterjets.

We run these engines at 1950rpm (MTU advise).

Because of high temp exhaust gas after T/C (730°C) we have to reduce speed to 1830rpm.

We send parameters to MTU but we get no answer.

I heared about somebody who has exactly the same problems with the same engines.

Do somebody have the same problem with these engines?

do you have a solution?

thanks for help

pa
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Tornado
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#1

Re: exhaust temperature MTU 12V4000M71

08/03/2013 4:52 PM

One possibility could be a slight mismatch between the engines and the waterjets, with the engines a bit underpowered. With a standard propeller, this could be fixed by repitching the prop; I don't know if a similar scheme would work for your case.

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lyn
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#2

Re: exhaust temperature MTU 12V4000M71

08/03/2013 5:30 PM

Why not ask the person you heard this from?

Also, depending on the age of the old tub maybe it's time to scuttle her.

Till then, run at 1,800 RPM and have no issues. Just assume that MTU was wrong and 1,800 RPM is ideal.

Or, take it to the shop>>>>>>>>>>>>>>>>>>
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JWthetech
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#3

Re: exhaust temperature MTU 12V4000M71

08/03/2013 6:24 PM

I live on the East side of P.R. I strongly suggest you bring it around to verify your findings.
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dvmdsc
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#4

Re: exhaust temperature MTU 12V4000M71

08/03/2013 6:37 PM

Be very careful. These engines, together with MAN are known to have a very good HP/weight figure. But that makes them also a very critical engine. When the cooling pumps wear out or the filters get clogged, the temperature raises quickly, destroying your exhaust cooling heat exchanger manifolds. They expand and crack. I have 2 here.

You definitely need higher water flow, bigger raw water pumps if this is a new project. In case the installation is old and worked well before, it is 5 to 12 to clean out the heat exchangers.

The impellers of the Raw water pumps might be damaged (happens fast with running dry).

The weed filters partially clogged or the intakes might be placed in a wrong place or positioned wrongly so that not enough water is enabled to enter the raw water pump system.

Under no circumstance this should happen, just because of the water jets. Power is power and RPM is RPM, be it to feed a propeller, jet, hydraulic pump or generator.

Before you take everything apart: where exactly do you measure that temperature? What point of the engine? And how?

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SolarEagle
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#5

Re: Exhaust Temperature MTU 12V4000M71

08/03/2013 9:34 PM

Sounds like water flow is restricted....Have you checked volume of flow?

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hauguelpa
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#6

Re: Exhaust Temperature MTU 12V4000M71

08/04/2013 2:28 AM

thanks a lot for helping.

In fact all parameters (pressures and temperatures) are OK except exhaust outlet TC.

MTU analysed the parameters but cannot give us a beginning of solution.

The purpose of my message is only to find somebody having the same engines.

thanks again

pa
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dvmdsc
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#7
In reply to #6

Re: Exhaust Temperature MTU 12V4000M71

08/04/2013 2:43 AM

Have 2 of the MAN version. Have the same body.

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dvmdsc
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#8

Re: Exhaust Temperature MTU 12V4000M71

08/04/2013 2:47 AM

How and where do you measure this exhaust temperature? Where do you use these engines and what are the diesel fuel specs of the diesel you are using?

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hauguelpa
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#9

Re: Exhaust Temperature MTU 12V4000M71

08/04/2013 5:01 PM

hi,

Temperature sensor for exhaust are on outlet pipe TC.

engine are run 1950rpm and around 90% injection quantity.

we use: ultra low sulphur automotive diesel fuel (10ppm S)

thanks for help

pa
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dvmdsc (3); hauguelpa (2); JWthetech (1); lyn (1); SolarEagle (1); Tornado (1)

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