Twin diesels - unequal power

[Carioca]

Pneumatic-type boost gauges on instrument panel driven off intake manifolds.
Right you are, 1bar (for all practical purposes) = 1 unit of atmospheric pressure = 14,7 psi.
More confident now to tackle eventual replacement/refit of waste-gate mechanism.
Thanks

<hr width=100% size=1>

 

[Piers]

Three main problems with waste-gates. Ruptured diaphragm, sticking actuator rod, or bend mounting brackets.

The results can either be too much or too little boost, with an appropriate engine performance.

Removal of the wastegate usually requires a regulated air pressure supply so the actuator rod can be removed.

It's important to ensure you check for damage to the mounting brackets and rod. If anything looks bent, or not smooth in operation, replace it.

Next is a pressure test to verify the actiating rod's movement. Again, not only is the amount of movement checked against specific pressures, but the smoothness of travel as well.

As your advisors say, it is a specialist job, but if not done correctly, incorrect boost will occur, with the ensuing lack of performance.

<hr width=100% size=1>Piers du Pré
http://www.dupre.co.uk

 

[Carioca]

I was told that:

1. It is the diaphragm within the actuator bulb that dictates the pressure at which the rod just starts moving. Changing diaphragms will allow for major alterations to max boost pressure.

2. In turn, the adjusting nut on the rod, controls the amount of rod movement / valve seating.It is the latter adjustment (milimetric) - and consequently the degree of seating imposed on the valve - that is a specialist job. If not done right, will produce erroneous boost and hamper engine performance.

Is this so ?

<hr width=100% size=1>

 

[Piers]

In answer to your points,

1 Yes. But bear in mind that the bulb can fracture or rupture (the same thing), either so it doesn't work at all, or, in the case of small puncture, cause the arm to start moving at the wrong time, and prevent full movement. Hence, wrong boost pressure at the wrong time, with full boost and power not being achieved. A specialist job.

2 Yes. Hence, needs checking. A specialist job.

Don't foget, as well, to check the assembly is not bent, and is not impeding the free movement of the arm. This is not a specialist job, but if you are having the other two looked at, this should be checked at the same time.

In other words, it can all be done on the boat, given the specialist has the correct gear with him.

Given your loss of boost and the checks you have done to date to ensure no leaky gaskets, etc, I would have the waste gate checked. A small item, but one which can cause so much hassle. At the very least, it would eliminate it as a problem source.

<hr width=100% size=1>Piers du Pré
http://www.dupre.co.uk

 

[Carioca]

Many thanks.
Yes, it would be expedient to eliminate this potential problem source.


<hr width=100% size=1>

 

[Piers]

Please let me know the outcome.

<hr width=100% size=1>Piers du Pré
http://www.dupre.co.uk

 

[oldharry]

If you suspect the turbo is at fault - how easy is it to swap them over to see if you get the same problem running it on the good engine?

Just a money-saving thought.....

<hr width=100% size=1>