Transmission wow's

That's weird. I'm wondering what they will change on the programming to take care of a knock like that?

Doug
 
Hans took the boat back to his marina yesterday. The vibration has been removed as our marina here had the props sent out. The noise is still there but greatly reduced. The mechanics here are all leaning towards a miss firing cylinder at the low RPM’s and possibly a fuel injector issue.

The knocking sound got better just by running some fuel treatment through it. They gave him the OK to take the boat out, which he is doing this week. Hopefully running a load of fresh gas and fuel treatment will help.

I wonder as I read other threads here with engine knocking problems on the new boats, is the ethanol damaging fuel injectors? :huh:
 
When I bought my boat I nixed the “Passport” warranty as I thought there would be too many reasons for them not to honor it. I did however extend my Mercruiser warranty for the engines. I must say that every issue I have had with the engines has be covered to my satisfaction by the warranty.

Being a close personal friend of Hans and boating up and down the Chesapeake Bay with him I have been almost as close to his problem here as he. Now I think I can safely say I made a wise choice in not buying the “Passport” warranty. Any future boat purchases I will not even consider the “Passport Warranty”.

When I have a problem with my boat, unless it is something I know I can fix myself, I take it to the shop and expect them to fix it. I don’t really care how they fix it, I just want it fixed and completed when I pick it up. Now if the shop is guessing at the problem and keeps trying different things that is not my problem, but theirs. I am paying a hundred plus dollars an hour because they are supposed to know! I don’t want to pay for “this and that” they replaced if “this and that” was not the problem and did not fix it. I realize that sometimes problems can be very illusive, but at some point in time the manufacture must step up to the plate and bring in the big guns to fix it. After all they made it, who would know more?

I hate to see anyone, especially a close friend strung along like this. The only thing I am sure of is he is in good hands now. Hans is taking the boat to St Michaels this week, which is a little over 2 hours each way. I guess it will either run correctly or break all the way….. I hope for the “run correctly” part!

Good luck Hans,
Bill
 
Sorry for the delay on my posts. Well put Bill. We had a great cruise to St. Michaels. As Bill mentioned the vibration is gone. Still some noise backing into the slip at 650rpm. MarineMax will continue work when we get back. 7 weeks without a boat is unbelievable. As much trouble as we had this season, I still assisted MarineMax in the sail of a new 38. Got a call while underway from the Northeast sale rep asking fuel usage figures. I gladley gave info to him. Stilling here on deck at St. Michaels this morning make me realize that we are really hooked. This is a great life style.
 
Interesting fix so far. I'm still a little perplexed exactly how they solved the issue though? Fuel injector cleaner? Did they pick up the misfiring cylinder with a scanner or O-scope?

Doug
 
Hans:

http://www.motorboating.com/articleHtml.jsp?ID=1000084813

You mentioned you keep fuel data. Just wondering how you compare to this article, with the HO's. I kept data this summer using smartcraft (verified by gallons filled). I am close, but in running between 3500 and 3900, I was at 0.69 + / - everytime. The lake was dead calm one day and I did WOT and got 4640 on both engines and about 34.2 MPH. She might have done more, but I was only at WOT for a few seconds. I'm thinking things seem normal per the article, but always am wondering about the guys who say they get over 1.0 mpg on 8.1's.

I'm thinking I was heavy being on vacation, load with food, drink, grill, clothes, water tank half full, etc.
 
Brutus C Paw said:
Hans:

http://www.motorboating.com/articleHtml.jsp?ID=1000084813

You mentioned you keep fuel data. Just wondering how you compare to this article, with the HO's. I kept data this summer using smartcraft (verified by gallons filled). I am close, but in running between 3500 and 3900, I was at 0.69 + / - everytime. The lake was dead calm one day and I did WOT and got 4640 on both engines and about 34.2 MPH. She might have done more, but I was only at WOT for a few seconds. I'm thinking things seem normal per the article, but always am wondering about the guys who say they get over 1.0 mpg on 8.1's.

I'm thinking I was heavy being on vacation, load with food, drink, grill, clothes, water tank half full, etc.
Click to expand...


I think your numbers appear spot on from what I've read. 7.4/8.1 liter engines all seem to get around 0.7 mpg in boats around 34' - 40'. Whoever says they get over 1.0 mpg on a 38' boat with 8.1's is not at cruise speed. I would venture to say people who quote those numbers are calculating overall tank figures which include a bunch of hull speed runs.

Doug
 
Sorry to hear of your ongoing issues with your boat. After reading the thread, I decided to chime in & share a story which may be helpful to you or others, & there is a remote possibility it might apply to your current situation.

I recently witnessed a strikingly similar vibration/noise problem on a PCM inboard which was driving a good friend / tech that was hired to service it mad.

The tech who is quite reputable & has years of training & experience was spinning his wheels to the point he lost touch with his usual logic, and proceeded to replace just about every electrical item on the engine, changed the fuel filter multiple times, ran remote fuel feed, dropped the belts, flushed the injection circuit, inspected the running gear, sent the prop out to be balanced & trued & spent countless hours testing new theories and still had an unusual vibration most noticeable at idle in reverse, and under initial fwd acceleration.

He shared his story with me, indicating he was out of ideas, & had basically given up
frustrated, and upset along with the boat owner that the problem persisted.

I suggested a fresh look, starting from scratch & taking a systematic approach with no assumptions , back to bare basics. He agreed to give it a shot, and together we went to the boat & began troubleshooting. He supplied the effort, I brought he patience.

To make a long story short, during a compression check, I noted that all but 2 cyls showed +/- 138psi but #4 was 133 & #6 was 129. While the actual numbers may differ from gauge to gauge, the fact that 2 "adjoining" cylinders differed (albeit slightly) from the rest, drew my focus, though I didn't rule out a more obvious cause, as I have seen many motors with worse readings run without issue. Sticking to basics, I decided to address the issue before going any further. A leakdown test provided no conclusive info, though I had hoped it would help pinpoint the area of loss.


Off come the heads, & after a dockside inspection, we sent them off to the machine shop . The heads tested fine, but we had them magnafluxed, surfaced & serviced the valves for good measure.

The real culprit was a barely detectable breach of the head gasket between 2 cyls which did not compromise oil or cooling passages, just compression. Evidenced by a lightened portion of the gaskets contact "print" on the surface of the block.

The tech then admitted that he never gave compression a second thought during his initial diagnosis as he considered any discrepency between cylinders of less than 10% acceptable, or at least unlikely to factor in as the root cause of a vibration, seemingly mechanical in noise & nature , and since all 8 cylinders were " really close" he crossed compression off as a likely cause.



In the end, once it went back together, freshened up heads, square decks, & new gaskets in place, compression returned with less than 1psi difference across the board, & the vibration is gone.

I felt I would share this, as it is quite simple to re-check compression, and look for subtleties which may have gone undetected initially.

Silver bullet? probably not, but what an albatross it was to the poor tech, who now has an arsenal of high priced spare electrics to supplement his test kit. I'm relieved that I didn't get the initial service call, or I might have made the same oversight & I would be the one holding the bag of spares.....;-)


Best of luck with getting your boat back to 100%
 
yaraesRNFsearay said:
The tech then admitted that he never gave compression a second thought during his initial diagnosis as he considered any discrepency between cylinders of less than 10% acceptable, or at least unlikely to factor in as the root cause of a vibration, seemingly mechanical in noise & nature , and since all 8 cylinders were " really close" he crossed compression off as a likely cause.
Click to expand...

I definitely would not have given it any more though with those cylinders at around 5% difference. I'm really surprised that would cause an issue.

Doug
 
Brutus C Paw said:
Hans:

http://www.motorboating.com/articleHtml.jsp?ID=1000084813

You mentioned you keep fuel data. Just wondering how you compare to this article, with the HO's. I kept data this summer using smartcraft (verified by gallons filled). I am close, but in running between 3500 and 3900, I was at 0.69 + / - everytime. The lake was dead calm one day and I did WOT and got 4640 on both engines and about 34.2 MPH. She might have done more, but I was only at WOT for a few seconds. I'm thinking things seem normal per the article, but always am wondering about the guys who say they get over 1.0 mpg on 8.1's.

I'm thinking I was heavy being on vacation, load with food, drink, grill, clothes, water tank half full, etc.
Click to expand...

Just returned from a trip to St. Michaels, Maryland. With all the work that has been done on the port engine I found that I burned a little under a quarter tank less than the starboard engine. I am a believer in tuneups.
 
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