Re: Really Bad Constant Vibration Problem New Install HELP!
Hi Lenny,
It has to be aligned in the correct position. The way its drilled I don't think you can bolt it up any other way.
If it was possible to bolt it up in a different position, than yes it would knock it out of balance.
I just re-read your 1st post, why is this the 3rd attempt to get it rebuilt?
This rebuild shop, they rebuilt the entire engine or just freshened it? Last question, is the shop acknowledging there is a problem? If its not from a misfire, or bad cyl, did the mechanic perform a cylinder balance test to make sure she is firing right on all 8 ?
Did it ever vibrate before the rebuild, are there any flat spots in acceleration, is your tach jumping?
IMO I would check everything to make sure and if it is a problem with a cyl & not balance , narrow it down. Then pull the engine, check the flywheel & balancer if they are correct, tear it back down and play forensic mechanic.
I will try to keep in same order as above.
The flywheel issue has been a confusing one due to all the opposing information I have seen and heard. With the machine shop, mechanic, and local mercruiser dealer all having different opinions on if it has to be installed in a specific location on the crank, or if it can even be installed in more than one location.
From looking at pics I could find online of a 454 crank it looks like it may be possible to install it 180 deg out, or even backwards, but without having one in hand it is hard to be sure of anything.
Third attempt, well third attempt to get this repower done. It started in 2005 (there is an old post here someplace in the archives) when a family member ran her aground during my vacation, and upon return the old 7.4 was locked up and full of seawater and sand. After having it towed to the closest shop to where it was towed after grounding) a rebuilt 454 from Hesco manufacturing was installed, but sadly was not running correctly, and sounded more like a diesel than a gas engine, and the installer would not do anything except partially sink the boat during a fall storm and hold the whole thing hostage.
Warranty was not honored (think this story is long lol) other local marina was used to evaluate problem and check valves etc, but was in contact with original installer, and stole $600 for doing nothing for 3 months and advising that motor needed a new starter due to being underwater (oh, and I know they were talking because I saw a copy of my bill from the orig guy on the seconds desk). I never ran it at this time.
Skipped 06 season due to time and other personal reasons, and then in 07 when some down time was available to do it the engine was removed, most all accessories replaced due to corrosion, the valves were adjusted, and the engine installed. It ran but would not rev up beyond 3k rpm, and had some problems that were found earlier this year when it was "freshened up" with new rings, valves, cam, all bearings, and much of a normal rebuild except for the bottom end due to not showing any wear (had approx 1-2 hours on it at most)\.
It was found that the rev problem most likely was related to the impressions on the pistons from the valves, and yes though no serious damage to the pistons there was issues with the valves.
Rebuild shop is acknowledging a problem, and is different people from the mechanic who did the install (another long story, but I guess he helped with the install as it was his equipment, he did some of the installations like flywheel and coupler, and he set the timing, and some other stuff) but like yourself is advising to check the other potential causes before moving on to pulling the engine etc. He has been helpful, and is someone I have used for small engine (atv bikes etc)projects that I have worked on in the past (all good experiences, and one of the few local shops who would actually size things to my spec and not what he thought it should be etc), but he is also the guy my mechanic uses as well, so we both wanted to bring it to the same people.
I am working on checking over all potential causes for misfire etc (about the third time), and the mechanic is supposed to come for a ride tomorrow (most likely will be a no show as he is over booked again) but far as I know he has not done a balance test.
Oddly I have been back and forth to the parts store many times, but somehow they seem to keep supplying me with the wrong plug wires, and until I can get the right ones they are still suspect in my mind. I did not find any difference when removing the wires when running, but still want to change anything that could be a problem.
Previous vibes were of no comparison. Prior to 05 it had really small amounts during hard turning (old drive had worn u-joints, and leaking transom assy ate up gimbal brgs), and after the new rebuild was re installed in 07 it ran so poorly and backfired so loudly you did not really notice much else, but I do not remember anything near this, and it was only upon acceleration, and turning.
I have not really run it enough to feel for any flat spots, but I found the rpm to be steady.
I guess where I am now is on par with your suggestion to check over everything to narrow it down to a rotational balance problem, but I also wanted to cover the obvious or most potential causes as the vibe really does not feel like a miss problem, and is unlike any previous vibes in this boat.
Back to the flywheel for a moment. I have received so much opposing information on if this can be installed in the wrong position, and that it needs to be installed in a specific location. Even the rep at Mercruiser CS advised that "this flywheel just bolts on any way" so they were little help.
Thanks again to everyone for your help, and let me know if you find new info on the potential for installing the flywheel wrong, and I will update as things progress as well.
