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Post by gofast24 on Sept 7, 2020 10:44:32 GMT -5
Yes, it’s mph, I believe that’s what I had in my post. As our boat doesnt have a spedo (MPH) gauge we use our GPS nav or smart phone with GPS to determine speed. As the GPS is a marine program it indicates knots, not MPH? You indicated your surveyor reported 24.6 knots, how did he measure that? Also, with the condition of your props (bad) you would certainly see much higher engine RPM's (4800 a little high) with them in that condition vs new correctly sized props? RPM higher as bad props slipping/cavatating like one blade missing? |
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Post by hawker63 on Sept 7, 2020 10:59:22 GMT -5
They got the speed from the Garmin chart plotter.
With the work they did on engine and new props, I could understand losing some rpm as you say, there’s more surface area, but makes no sense to loss speed so I think I’ll have the injectors pulled and ultrasonically cleaned to see if that helps. Everything else (fuel pressure, new plugs, new wires, throttle body fully opens, air filters clean) looks fine so slowly isolating why we can’t achieve either rpm or speed.
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Post by gofast24 on Sept 9, 2020 10:30:45 GMT -5
2007 4460 with basically the same engines as our 2001 VP 8.1GSiI -A engines(420 BHP each) and with the same props we have you should be able to do around 30 MPH (26 knots or so) , depending on loads= passengers/ black and fresh water tanks level, and fuel levels ? Are you sure you actually lost speed, not just RPM's? With your new props (compared to the ones you had that were really bad) you should loose RPM's but pick up speed? If it was me, I would have a dealer/mechanic check engine RPM's at WOT any fault code stored on ECM using a OBDM connected to engines ECM to see what the actual RPM's are! Also, sorry if I have asked this already, how many hours on engines? kindly add your vessels info to a salutation in your posts.
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Post by hawker63 on Sept 10, 2020 7:49:53 GMT -5
Engines have about 300 hrs on them. When we purchased boar in March, Merc tech pulled motor history to confirm hours. Over 80% of the hours were less than 1000 rpm. Compression on all cylinders was good. The marina we are at doesn’t have equipment to connect to the engines so he want to confirm the rpm with a hand tach on the flywheel which well do in a few weeks. Our next plan is to have the local Merc guy come and connect to the engines and see if they see anything. Last option, is well pull the fuel injectors and have them ultrasonically cleaned as I don’t want to replace without some confidence on what the root cause is.
Thanks to everyone for ideas and feedback.
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Post by gofast24 on Sept 10, 2020 10:56:19 GMT -5
980 hours on our VP 8.1 GSiI-a's. No problems with anything . Forget about a guy going into your engine room with a hand tach at WOT to measure engine RPM's. I believe you will have the front crank mounted sea water pumps as we have, no way to check RPM without a connection directly to crank shaft in that case? Get the MERC mechanic that can connect to ECM to measure actual RPM at WOT! 80% below 1000 RPM'S ?? Something wrong here unless previous owner trolled forever at idle while fishing?
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Post by hawker63 on Sept 26, 2020 9:32:58 GMT -5
We were able to measure the rpm without connecting to the engines. Taxis are accurate so I am leaning to the injectors. I plan to have them pulled and ultrasonically cleaned as I am not anxious to replace 32 injectors at a cost of over $100 each
As to the feedback about the engine history, I don’t think there’s an error. The previous owner had a 42’ Scout and a 65’ Cruiser so for the last 4 years, the only use of the boat was a captain to come down, start the engines weekly and let them idle. That’s why the history shows so much time below 1000 rpm. We find even our use on the ICW is around 1500 rpm as we enjoy just puttering and looking at the shoreline and I am not in a hurry to spend $5/mile to cruise (boat gets 0.6 mpg).
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Post by gofast24 on Sept 27, 2020 12:23:56 GMT -5
We were able to measure the rpm without connecting to the engines. Taxis are accurate so I am leaning to the injectors. I plan to have them pulled and ultrasonically cleaned as I am not anxious to replace 32 injectors at a cost of over $100 each As to the feedback about the engine history, I don’t think there’s an error. The previous owner had a 42’ Scout and a 65’ Cruiser so for the last 4 years, the only use of the boat was a captain to come down, start the engines weekly and let them idle. That’s why the history shows so much time below 1000 rpm. We find even our use on the ICW is around 1500 rpm as we enjoy just puttering and looking at the shoreline and I am not in a hurry to spend $5/mile to cruise (boat gets 0.6 mpg). Idling any engine for that long is the worse thing for a engine, more so a diesel! Carbon build up, piston rings sticking, engine lube oil not coming up to temp (combustion by products (acid) staying in in oil), etc. Still dont know where your located, wet or dry docked (assume wet docked year round if in the south or pull out for winter if in the North ) with that size vessel) . Also, assume with two V-8 engines you only need 16 fuel injectors? As you indicated a MERC mechanic coming to pull codes and check RPM's at WOT that is best course of action. I would recommend you wait until any results from codes pulled from engines before pulling injectors. Good luck and let us know what you find out! |
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Post by hawker63 on Sept 27, 2020 15:15:17 GMT -5
Boat is Regal 4460, docked in Charleston South Carolina. Motors are Merc gas, 8.1L. Wet docked
When we had survey done, engine compression looked good. Oil was changed regularly according to the boats captain. Merc tech that did the engine survey said they looked good. Plugs were pretty clean but we changed plugs and wires when we bought the boat.
Yes, sorry, 16 injectors.
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Post by gofast24 on Oct 5, 2020 10:16:32 GMT -5
Boat is Regal 4460, docked in Charleston South Carolina. Motors are Merc gas, 8.1L. Wet docked When we had survey done, engine compression looked good. Oil was changed regularly according to the boats captain. Merc tech that did the engine survey said they looked good. Plugs were pretty clean but we changed plugs and wires when we bought the boat. Yes, sorry, 16 injectors. Dont need to be sorry, just my usual self asking for clarification on something. And, apologize, you do indicate your boat/engine info in your salutation! Good luck and let us know what Merc mechanic finds out after connecting to engines ECM's and pulling any codes or the actual engine RPM's at WOT at sea! ! |
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