dd 6-71 turbo without max rpm

[robymayway]

hallo to all.
The boat near mine is a bertram with the same engines of mine. DD325hp 6-71 turbo. (around 1900 hours )
He is a real good friend and he bought the boat on 1982.
By now, we have the same mechanic and last month when I had some problem of over heating, he help me giving an hand with great attention.
Now he has a problem but he doesn't know this forum so he asked me to place a new thread to all of you for your great experience:

the problem is that right side engine lose power and doesn't arrive at 2300 rpm but only 1900 ( 14/15 knts)
He notice this problem before changing primary Racor1000 and secondary fuel filter to both engines and he tought to fix probelm changing filter.
Left side engines return to run regulary but right following in the problem.

This moorning we have go out and after 30 minutes with engines enough warm , we have placed engines on neutral position and we have opened all accelerator for few second at maximun power.
Left side engine arrived around 2700 rpm but right side just only at 2100 rpm.

We have done this experiment to understand if the problem could be about the uncleaned hull or about the engine.
Now we can say that that is a problem of engine and not of hull !

What you suggest?
a) diesel in the tank is cleaned and also the racor changed were enough cleaned.
b) no black smoke
c) all pipes and faucet well opened
d) we have checked the cable of accelerator and everything looks to be correct.

answer:
may be fuel pump? iniectors? turbo? how we can determinate the fisrt thing to do?

I know there are a lot of possible replies , but probably ther are someone in this forum that had the same problem in the past and may help us to resolve this problem.

please notice that engines sound correctly at 6 cylynder. the only problem is that it doesn't arrive to max rpm and

thanks to all!

 

[Avenger]

First, verify that the tachometers are accurate using a hand held or photo-tach. If they are in fact reading correctly re-check your no-load RPM by operating the engine throttle lever manually. If the engine still fails to reach rated RPM you should probably do a fuel pressure check before attempting to reset the high idle RPM on the governor. It is unusual for governor settings to suddenly change by themselves. Has any other work been done that may have caused a change?

 

[Genesis]

First things first - make sure the throttle lever is going all the way to the "full" stop, and that the RPM being registered is accurate (use a phototach - do not trust the tach on the bridge)

The odds against the governor high idle "changing itself" are astronomical as that is set by shims in the governor cup.

Fuel restriction and/or flow problems are POSSIBLE but are not the first place to start when the problem manifests itself at high idle (no load); start with making sure the throttle lever really is going to the "full throttle" stop and that the engine RPM really is what you think it is.

That much difference in actual RPM should be readily audible as well.

 

[robymayway]

Hallo Genesis and Scrod.

Exactly!!!
The odds against the governor moves setting around of 1 centimetres!!

Now is all perfect!

thanks friends!

 

[REBrueckner]

so did a control cable fitting come loose???

 

[robymayway]

so did a control cable fitting come loose???

Yes It did.
Both cables ( fly and second pilot station) are fixed onto a metal tube by a plate fixed with two screws. We noticed that both screws were not perfectly closed. So the plate moves for one centimetres and didn't permit to cables to open correctly the accelerator. Really easy !!!
thanks to all

 

[Genesis]

Excellent!