Significant Drop Off in Top Speed

Status
Not open for further replies.
I have changed filters, tuned prop, cleaned bottom, cleaned air filter and several other things. One thing I did notice this weekend was, I have a scan tool that I used and ran the boat with it hooked up. I noticed that the Yanmar display was saying that I was getting 29 psi of boost from the turbo, but the scan tool indicates only 22. I have find out which is wrong. 22 psi would explain my issue for sure.
 
Had Steve, from Steve's Marine, come over today.....They are a Volvo Diesel authorized repair/service provider on Long Island.......No error codes, filters were clean....(We changed them anyway)......Checked the vanes on the turbo.....nothing.....Checked the whole fuel system.....Steve took it out with my wife and drove the boat with the diagnostic computer hooked up to the engine.....Something is definitely wrong......It is down to 13 to 14 knots at 3000 RPM......Steve is coming back with a 10 gallon fuel container with known clean fuel....He is going to bypass directly to the fuel rail to eliminate that as a cause.....
 
Please keep us posted as to the results of what you find. I have not called a yanmar guy out as of yet, but feel that I may have to. Really tired of this at this point.
 
Saw the note about the R 31 drop off in speed. On mine, full fuel, full water and 3 people aboard I show 21 Kts GPS against a 2 kt current and 3400 RPM - did not push to the full 3600 RPM since the engine was new. After break in (100 hours) I can run 19 kts at 3000 RPM but the fuel burn is painful at 1.4 NMPG 😀
 
A dirty fuel filter caused this on our boat. Ran fine at the lower RPMs but we couldn't get above 2900 RPM. Performance was as you described. I vote for dirty fuel filter. How low did you run your first tank? I don't go below 50% any more.
 
Still had 45 gallons left when I filled it up.....swapped out pre-filter without any benefit ...Volvo mechanics supposedly looked at today, but no word back yet....

A little frustrating as the boat only had 20 hrs on it before the problems started and it is a brand new boat.......We are scheduled to go to the Mystic CT Cutwater/Ranger gather next week....followed by another week cruising to Block Island and other ports on LI Sound....

Not looking good........
 
Have you been in contact with your dealer on this issue. They should be notified so they can help with the issue. It the dealer needs assistance they will contact us to help. Here is something I would check on the fuel system. Pull the fuel pick up out of the tank and check the screen on the bottom of the pickup.

Thanks
Ronnie Gonzales
Cutwater/ Ranger Customer Service
425-220-3932
ronniegonzales@cutwaterboats.com
 
We checked the pickup, its clean, just changed the filters, added fresh fuel with treatment, ran the boat from mystic to block island, no change for us
 
Seems odd it's happening on Yanmars and Volvos. Must be a fuel delivery issue. I have the same use on a VW TDI when the fuel filter gets clogged.
 
Sorry to be hung up on possible air supply to the engine but for both engine manufactures experiencing similar problems I think we need to look at things in common to both. I have a small and older Yanmar so I don't have the problem and I don't know your boats. However....

Air.
Has anyone run their engine and experienced the problem when the engine hatch is open?
Is it possible that there is not enough air intake area for the demands of these turbo charged engines.
Is stored equipment or supplies blocking any air inlets to the engine compartment.

fuel
Is it possible that that the fuel supply hoses on the suction side of things is collapsing internally and causing a restriction?
Is the hose diameter large enough?
Is the hose made for suction duty or did someone get a bad batch of hose?
My two cents,
Don
 
I have a gut suspicion that the Volvo D3 in my R27 is starving under load. I suspect it is starving for fuel, cooling water, ventilation/combustion air, or all three. As to the engine compartment's air supply, it's not obvious to me what openings are available and whether they are adequate. As to fuel and cooling water, I can think of several seasonal environmental factors that could restrict their flow. Marine growth has repeatedly blocked the probably-undersized cooling water through-hull on my boat to the extent that the raw water strainer looks dry when the engine runs above 2000 RPM. Water temperatures here on the Chesapeake Bay are in the low 80s right now, which must reduce the effectiveness of whatever cooling water actually reaches the engine. On several occasions, fuel tank vents on some of my machinery/vehicles that are idle for extended periods have been plugged up by mud wasp nests, to the extent in one case that the plastic fuel tank collapsed from the vacuum pulled by the engine before it stopped. A Caterpillar guide to engine room design states that "Approximate consumption of combustion air for a diesel engine is 0.1 m3 of air/min/brake kW (2.5 ft3 of air/min/bhp) produced." I wonder if my D3 gets that much at high RPMs and what I could do to give it more.
 
Did you try running with the hatch open to see if there was a significant change in performance? That may be a rudimentary way of seeing if your suspicions are correct.
 
There is a Volvo marine diesel installation guide that sets forth very specific requirements for supplying water, fuel, and air to a model I am unfamiliar with, but I assume the same principles apply. It's at http://boatinfo.no/lib/volvo/manuals/41install.html#/0
I am particularly impressed by the effect that combustion air temp above 77F has on engine power (see page 104).
 
knotflying":39yqmd92 said:
Did you try running with the hatch open to see if there was a significant change in performance? That may be a rudimentary way of seeing if your suspicions are correct.
Click to expand...
That's the next step I'll take. I'm also trying to devise a way to temporarily bypass the raw water seacock to give the engine as much water as it wants.
 
In order to reduce one of the possibilities, my wife and I spent saturday afternoon swimming in the potomac river to scrub off the layer of growth on the bottom of our R-31. There was not a giant amount of growth on the ablative paint. After hours of scrubbing, we gave another full speed run. Two POB a nearly full water tank and 156 gals of diesel, empty waste tank. The best we could manage was just under 19kts. We were about 3100rpm at WOT. This is better than we achieved prior to scrubbing off the bottom but still less than the over 23kts. It is disconcerting to have lost speed without identifiable cause.

Corey Chamness
 
After another 5 hour service attempt today to solve the problem, it appears to be the turbo. Checked everything else....Even bypassed the fuel system with a separate fuel cell.....Lifted the boat out of the water....

It appears the unit is making materially less boost than the factory specs....Oddly, the first 20 hours had the boat with nice speed.....I am now up to 39 engine hours after about 6 hours of that from the three test runs out with the Volvo techs.....

After almost three weeks of diagnostic servicing, I will have to wait again for Volvo to approve a new turbo.....I had planned an 8-day trip with the Mystic NE Rendezvous this week as part of the trip.....All this from a brand new boat.....
 
I will contact Volvo tonight and make sure that a new turbo is approved right away. Working with Volvo in the past, I'm confident it has already been approved if the servicing dealer involved has contacted them. I'll just make sure that has happened and we don't allow you to lose the 8 days on the water you had planned for.

The thing that everyone needs to know is every engine we install has been certified by the engine manufacturers directly. Whether it is a Yanmar, Cummins or Volvo, I have personally invested many hours on the water with these manufacturers making sure everything we install falls under their requirements.

Andrew Custis
 
I suppose I will just call the yanmar guy out and have a look at the boat then.
 
Hmm, perhaps I need to contact a Volvo tech too - but it costs almost $200 in transit time for them to even come over. Am I the only R-31 that can't get past 19kts? At my original sea trial the Volvo tech thought either my engine "might" be not making enough power or there might be too much pitch in my prop since we couldn't spin quite the RPMs he was expecting.

Corey
 
Status
Not open for further replies.

  • Tugnuts.com is the community hub for Ranger Tug, Cutwater, and Solara owners. Since its inception in 2008, the Tugnuts forum has grown into an active and thriving community of more than 9,000 members. It serves as both a meeting place for the best boating community online, and an invaluable archive of information.

  • User menu
Back
Top