Turbo Pressure

[Ole Hank]

I have twin D300 Volvo engines. The turbo pressure used to be the same for both. Recently I have noticed the pressures vary about 8% between the engines. Is this an indication of problems?

 

[BruceK]

You might want to look at this:http://www.trawlerforum.com/forums/s60/beneteau-st-44-potential-sea-water-intrusion-35913.html

 

[Lepke]

You could have an exhaust or air leak, or build up in the passages to (or from) the turbos that are thicker in one side, restricting flow. An early sign of a bad turbo bearing is the slowing of the blade and lower boost. There could be some other restriction in the exhaust after the turbo or in water cooled exhaust, too much water in one side.

 

[smitty477]

Or ... your props could be unbalanced either by a hit or by one prop with barnacles or a line wrapped around the hub. It takes very little to cause an imbalance.
How fast did this come up?
Any other symptoms?
Boat has been sitting maybe?

 

[Ole Hank]

The problem just started. One other symptom is I hear a high pitched noise, faint but its there. Occurs when running the engines at high RPM. Another thing that happened, I am not sure if related or not. I was running wide open for a short period and one of the engines temperature climbed, when I slowed it came down. Later I was running fast when the temperature climbed again on the one engine, slowed and it came down. When I arrived in the Bahamas I changed out the impeller. Have not had a chance to run fast to test if it changed anything with the temperature climbing.

 

[smitty477]

Were both engines able to reach rated WOT rpm as a brief test?
Is one engine making smoke or soot? Which one?
Have you checked the flexible hose connections from the turbo outlet to the engine carefully for broken clamps or slits in the hose at the clamps? (very hard to detect).

 

[Barabus]

Check for air leaks with soapy water

 

[Ole Hank]

no problem reaching rated rpm, both engines run the same.

 

[Xsbank]

Look at the wheels first, simplest solution first.

 

[Ole Hank]

not sure I am following you?

 

[Ski in NC]

What is exact rpm at full power, off sync. A small difference there can carry down to cruise.

Post full power rpm, boost, gph, %load.

Those data can help sort this.

Also, a boost variation of 8% is sort of in the "noise". Curse of the twin engine boat, they are never exactly the same on the numbers.

 

[Tom.B]

not sure I am following you?

He is saying to check the props for growth. More growth (barnacles specifically) will make a huge difference in performance. And while a little more complicated than this: Twins are a "lowest common denominator" thing. One will kinda drag down the other to it's performance level. <-- preparing for a lot of crap regarding that statement Anyway, as new members of the "High Performance Twin Turbo Engine Owners Club" we recently discovered that getting the best (or even adequate) performance is going to not only require our diver to be on the top of his game, but at the very least, annual haul-outs for running gear cleaning. It's just the cross we must bare... or is it bear?

 

[North Baltic sea]

no problem reaching rated rpm, both engines run the same.

Hi,

can I make sure you have the two engines synced off?


I was thinking how the engine where turbo -8% can give the same rmp / power out, the reason might be synchronizing on.
In general, sync is switched on, so engines automatically run the same rmp.


The difference can also be due to sensor / wire coupling oxide. Does your VP EDC have given a bug code to the issue under pressure? Maybe you should call Mr Volvo and his VODIA device that can see the pressure or cause of the problem or the sensor interference


NBs

 

[Ole Hank]

No error codes, I will be taking her for a run today and get some additional info based on everyones suggestions.