Discussion in 'Engines' started by cleanslate, Apr 19, 2021.
I'll have to repost #9....
If you have a leaking injector, it ends up putting more fuel in ONE cylinder than the others and can cause vibration (and torsional stress) regardless of being in neutral or in gear. If you put your hand on the engine, do you feel the vibration one location more than another? Is the engine smoke darker, or oil sheen visible?
Cleanslate, here's your post #9:
"I've asked them all, but will try at the commercial docks. I'm at Utsch's, for 5 years now. It's a dying / retiring breed...good DD mechanics around hear. My good one I've used is just getting to old and not wanting to do the work any more. Which I understand. He was a long time J & T mechanic in the shop dyno guy and in the field during the 70s and 80s. He knew his 71's and even was involved with my 471s , J & T so he told me called them "CAT Killers'' being my , 471s were going to put a hurting on the Caterpillar 3208s. At least that was what J & T had in mind back in early 80s.
Before him, which was only for a short time cause I only used him the past year or so, I used a not so good mechanic which I learned over time that he was not so good. I am not the best when it comes to motors( such as pulling heads, pistons etc..), but I'm slowly getting there.
Anyway, almost two years ago. Right before winter time and winterization I had the bad mechanic work on my governor , he replaced it with a new one I got from J & T.
Soon after I went to start the engine and it ran away at the dock. Vroom...up to 3000 or so Rpms before I pulled the emergency shut down knob.
Turned out to be a broken blower drive gear?..if I recall. I was never around when the bad mechanic did the work, cause I had to work ! So he replace that and all was good. I know he had the blower off and some other things in that specific area.
When he put it back together , I did not buy any gaskets for the reassembly. And I'm sure he did not. He was a big RTV user..which I'm finding out know from other work that he did.
My point is, the shake gradually started after the drive gear was replaced. Could I be sucking in or is air escaping from the blower or the blower area due to old gaskets leaking? What about connecting parts going to the blower? Would this cause a shake? Any hoses I should know about that work with the blower that could cause and air problem?
I really do not think it's my motor mounts...Original, clean not cracked Ocean Yachts paint still on the mounting base and bolts where it meets the hull engine beds. All looks good."
Hey leeky ! Thanks .
As most can tell Cleanslate and computers do not mix .
No smoke , no oil sheen , no fluctuations in the gauges.
I’ll be on the boat later this week and will do a thorough observation of things. With hatches up so I can see all around the motor.
Here is a photo of the gauges this past weekend this photo was taken with approximately two hours time on them add 2000 or so RPM everything was stationary sea water temperature 48°.
Starboard voltmeter gauge is broken ignore that please!
You'll do better down with the motors where you can put a palm on each cylinder and each motor mount to locate the source of the vibration. So bring ear muffs.
Well, things seem to be much better after I tightened many loose items my past mechanics left behind, Prop suckers....;
4 loose bolts ; that hold the square to round elbow that rests on top of the blower and houses the emergency shut down damper.
Newly installed governor , five or six? loose bolts that go into the blower.
Upper governor body that houses the spring, buffer screw/idle screw, two bolts not tight that go into the head I think ? After all was snugged up it change my idle some and created ''hunting'' which I had to adjust.
Loose, but not leaking oil, engine block/cylinder? inspection plates which face outward side of hull next to fuel tank. All loose.
Newly installed turbo and S/S exhaust elbow, rubber hoses all clamps not snug.
Can not remember if there was anything else loose, think I lost count.
ALL motor mount good and snug. None loose, broke, etc.
No back pressure or air pressure coming out of the oil fill.
After all this collective @#$% was done, by me , the 40 year old motor is running much better, shake is mostly gone. I'm happy.
Will be running it this week for a few days and will see how things go underload.
Thank You All for your input.
Wow- hard to imagine that many loose items. Do you think they were all left loose or became loose due to excessive vibration? I guess if this has remedied your situation they must have been loose to begin with. But, if this is the case, why wasn’t the vibration there since the work was done originally?
Thanks for sharing your update. It amazes me how often we learn something new here.
I think it came loose from vibration in some cases most of it was more than finger tight.
I was ignoring the vibration for a little bit being a “DIY” owner I always have so much stuff on my list of things to do on the boat I just chalked it up to 40 year old engines as long as the temperatures and pressures were good I just let it be and try not to run at those RPMs that made it shake.
As I said on a whim I went over everything that the mechanics worked on it’s just a genuine lack of care I guess.
You mentioned that RTV was used everywhere.
In correctly using gasket sealant, the nuts / bolts are not usually tightened down till after the RTV sets a while.
Did your techs get distracted from or thought they were returning to the job maybe?
Or, was SFB syndrome involved?
I did not notice any RTV sealant on the work that was recently done I know he used it on my after coolers or whatever they are back by the turbo and they leaked
Hi every one. Just joined this forum a few mins ago. I had a vibration on one of my 671 Detroit's a while back when in neutral at the dock, and it was the front engine damper.
In my case (Viking 43 DC) the engine had to be lifted at the front to replace the damper, but did not take to long to do. You can see it wobble if that is the case.
What’s the front engine damper ?
What’s the damper ? And it’s purpose?
Anyway, welcome to the forum. Enjoy !
My shake is doing much better , see my post above .
NOW, same motor , belt driven water pump took a poo! Coming home from Annapolis...
I’ll start a new post on this one ...
I’ve got new questions and Concerns.
Shake is old news .
It is a large heavy disc on the front of the engine. It is called a crankshaft vibration damper I think. When mine went bad, it shook the whole boat at certain RPMs. When the mechanic found the problem, he had me look at it and it was going around in a kind of an elliptical orbit, rather than turning smoothly. May not be your issue, but I wanted to mention it.
All the best.
Mod edit: link removed.
The harmonic balancer I had mentioned earlier.
12-71ta besides vibration, what other visual inspections are recommended for general analysis. I.e. smoking after 5-10 seconds, vibration? We are buying a large hatteras and engine inspection.. Curious what others definition of “Engines running as they should”. What is considered in marine/engine as “working as they should”. Small vibration, leakage, ? Thanks and big step for us on a asis- where is vessel.. Any input is appreciated.. thanks.
It cannot be described. If you know Detroits, you know how one should start and run. Hire an engine surveyor. It's worth it's wait in gold.