Re: Volvo RPM issue


 

Doug,

Maybe this helps and maybe it will make sense to those Amel owners who have not experienced vacuum controls on a diesel engine. On older diesel engines for boats, there was no vacuum. The D3 might have been the game-changer for this.  Full Disclosure: The reason I know a little about this is that I own a 1985 MBZ diesel which has 2 electric vacuum pumps and one mechanical vacuum pump. I believe the only way to get vacuum on most diesel engines is to "pump it" with a pump, electric or mechanical.

I think this is what Mark is referring to and how to check it. Unlike most diesel engines prior to the D3, the D3 has vacuum-operated systems. You'll need a hand vacuum pump with a gauge that you can buy online from auto parts suppliers. I doubt the mechanical vacuum pump is defective, but trace that vacuum line looking for loose connections, cracks, or breaks.
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CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
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On Sat, Oct 30, 2021 at 10:26 AM Mark & Debbie Mueller <brass.ring@...> wrote:

Hi Doug,

Checking wide-open throttle at the dock may not necessarily reflect what you see underway.  The vacuum pressure in the engine is usually dramatically different under full load conditions versus no load.

There is a vacuum operated device on the turbo I have always heard called a waste gate, Volvo calls it a turbo actuator.  This device is a valve that controls the flow of exhaust gases to the turbine wheel.  If the vacuum pressure is not correct the turbo will never develop full boost pressure.  I am not sure of the D3 spec on vacuum but it might be worthwhile to try and measure it if the following does not work.  You may have a vacuum leak somewhere in the system. 

Take a look at the OEM Fault Codes shown on the Volvo multifunction display; see the attached PDF on how to retrieve those fault codes to see if any refer to the turbo.  Next, take a look at the Volvo service bulletin regarding the turbo actuator – be sure to click on the “Comments” at the top of your PDF reader for additional information.  It does take a little bit of effort to push the linkage causing the vacuum actuator and wastegate to operate manually.

Forgot the attachments in the earlier message.

Good luck!!


--
Mark Mueller
Brass Ring  A54

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