Volvo D4 320hp- lack of power.

G

GarryH

Well-known member
Joined
Jan 15, 2019
Messages
65
Fluid Motion Model
C-30 CB
Hull Identification Number
FMLT2932D121
Vessel Name
Miss Starr
MMSI Number
368228190
After sitting in a marina slip for a month while we were on board, we left for the next port. After leaving the channel I opened the throttle to reach a cruising speed of 3180 rpm. The engine would only go to 2850rpm. Engine has only 90hrs. Engine worked fine going into marina31 days ago. Now speed only 8-11mph. Any suggestions? Thank you.
 
My first suggestion is either put a mask on and check the bottom. Or just call a diver and have the bottom cleaned. What type of bottom paint is applied ? One month in Florida waters can be enough to get some growth on the bottom. Growth on the bottom will slow you down. If the bottom is clean at least you checked that box off. Proceed further with more troubleshooting. I think you will find you have a dirty bottom.
 
Your turbocharger is likely not fully spinning up. My D4-300 had the same issue a few months ago when I got it back from the engine shop for unrelated issues (FOBs and software). After launching, I pushed the throttle to full power - I only got 1700 RPM. Turbochargers work by having the exhaust from the engine spinning an air compressor for the intake. If the exhaust port gets too much soot and/or flakes of whatever - it won't spin. Thus, full throttle becomes very disappointing...

The fix is fairly simple. There is a large steel "exhaust/raw water mixer" coming off the starboard side of the engine - it is also attached to a large exhaust hose going to the large "wet muffler" aft of the engine. There is a silver clamp that holds the mixer to the engine. Loosen the nut for that clamp so you can pull the mixer away from the engine. The hoses are flexible, and you should be able to push it down away from the exhaust port of the engine. The spinning wheel for the turbocharger can now be seen. A small shop vacuum is useful to suck out any flake of "stuff". Also spin the wheel with your finger - and use a lubricant like WD-40. Someone told me that oven cleaner is also useful for removing built up soot.

My mechanic told me that there are issues with some of the raw water that cools the exhaust getting back up to the turbo charger - especially if you are trailering and getting raw salt water to slosh back toward the engine. Part of the reason I built myself a fresh water flush system to remove salt from the chemical equation.

Finally, it actually took me about three tries to clean my turbo - the last time I did it at anchor so I could instantly go to turbo without idling for 10 minutes through no-wake zones. It worked. Occasionally, the turbo takes a few seconds to spin up - but then it kicks in and I'm off and running...
 
The Volvos have a variable vane turbo - you have to run them hard to keep them from shooting up - it’s advisable to treat the fuel too


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I would not discard theses suggestions but I would still check the bottom before removing the exhaust elbow. Normally if the Turbine side of the turbo is stuck it will not push boost pressure from the compressor side and to the engine induction which really shuts down power. It will only turn 1500 rpm to about 2000rpm. Your post indicated two RPM's 3180 and 2850 RPM. I'm not sure If one was WOT and the other was cruise but if you are able to turn 2850 rpm you are getting boost. I would still check the bottom, and prop for fouling. Then proceed with more advanced troubleshooting as suggested by previous post. ( turbo inspections)

tranmkp":r2tnlhj7 said:
The Volvos have a variable vane turbo - you have to run them hard to keep them from shooting up - it’s advisable to treat the fuel too


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Click to expand...

The D4 Volvos are not equipped Variable geometry turbo's. They do not have waste gates either. The turbo's are simple turbine /compressor type turbo's that do commonly foul if not cleaned out regularly by spinning them up. I do believe the low engine installation in the Tugs and Cuts can contribute to some sea water back up under some conditions but that is only my own speculation or opinion.
 
tranmkp":34rav5x8 said:
Well hell, I stand corrected on that VGT issue BB - D4s and higher dont have them. My Bad. I did find this earlier discussion though...

http://www.tugnuts.com/viewtopic.php?t=13999&start=0
Click to expand...

This is from that post. Which I stated this:

Exception"if the engine is equipped with a VGT turbo periodic WOT and higher rpm operation is desirable to exercise the turbines vane plate.
D4 compare your running results to the graph https://pubs.volvopenta.com/ProdDocs/Ho ... ng=en-USD3

D3. https://pubs.volvopenta.com/ProdDocs/Ho ... lang=en-US


Volvo D3 have a VGT, D4 Volvos I believe use a waste gate. ( My believe was incorrect the D4 does not have a waste gate.)
 
Brian, looks like the links you embedded to the Volvo docs aren't complete. Try again?

And as long as I have your ear, a quick question. I don't need to remove my exhaust elbow -- at least not anytime soon -- but if I ever do, is there any kind of gasket or other material that will need to be placed on the connection when it goes back on? When I've looked at Volvo schematics, nothing is shown. I wasn't expecting bare metal to bare metal, but maybe that's what it is. Thanks for any info, Brian.

Gini
 
The Volvo Docs were copy and pasted from an old post that Tranmkp was referring to that I posted in a different thread.

There is a V-band clamp that connects the turbo to the exhaust elbow. I am not aware of a seal or sealant in this area. The exhaust is sealed by the clamp. This type of seal rely's on good clean mating surfaces and proper installation of the V-band. Actually a simple task.
 
Thought I would provide one follow up to my post from April 2022 - the turbocharger remained problematic. I was certainly tired of pulling off the exhaust hose clamp just to clean it out and squirt fluid. Then one day while the turbo charger was kicking in (you can hear it start winding up) -- it suddenly stopped spinning. This time a vane in the turbocharger failed and was bent out of shape. So, I replaced the turbocharger, and it has been problem free ever since. It was a $4K part, but worth it for getting reliability back into my engine.
 
Thank you for the posting. Wasn’t that turbo replacement covered under warranty?
 
Brian, Didn't you find the manufacturer for the Volvo turbos and they were willing to sell direct to you? Or maybe I'm just imagining this.....or maybe Ive read way too many of your posts here on TugNuts?
Thanks for your expertise on all things marine!
Terry
 
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