Re-power help

Hi, again.

Looks like, "we" forgot to to ask NEWBEE a couple of questions...

1. Is there any lub oil consumption ? Do You have to add oil sometimes ?
2. Where You got information that "propulsion is at last legs" ?
3. What are total rhrs ? Not since last overhaul, just total.

But, ok.

Regarding price for overhaul kit of spares. In Europe it's appx. the same for this size of engine. But labour excluded.

Regarding crankshaft. Yes, be careful. Pay attention to K1W1 last post.
My experience with this:
When rhrs are lower than 30 000-40 000, normally it's NOT necessary to grind off, even to first repairing size. Again, depends on engine / oil / etc.

So, if (after dismantling) they tell "have to grind, but better if You purchase new crankshaft, new camshaft, bla, bla, bla ...." Be careful... Ask to prove it.
In such cases I took my micrometer and went to workshop...
And sometimes I marked crankshaft in hidden places, luckly , otherwise would get some piece of xxxx instead.

What is "dangerous" ? That You can get essentional parts, what are even worse...

If You decide to do overhaul, ask them to measure all parts according to manufacturer / common-known specifications.

Of course, try to get references abt workshop.

And as K1W1 mentioned, be ready to replace some extras.

If any further advise / help needed, please post.
If necessary, will provide with weardown limits, etc.

Regards,

Andrei

Tri Star,

I was neither testing nor teasing you.

I was simply after someone else's views/experiences on what the advantages are of Counter Rotating Engines.

I was taught that C.R Engines are actually more efficient by a marginal percentage when the input shaft of the gear box turns opposite to the output shaft. I don't know if this is a completely accurate statement or not but I have been on quite a few boats that were fitted with a pair of inboard turning engines and the shafts turned outboard when going ahead.

Counter Rotation is only really required these days when using a CPP Setup.

Not all the manufacturers who used to do them still offer them. 2 Yrs ago I worked on a deal for a pair of Cat 3516 B Series 2 Engines for a client (One is my Avtar) and found that these engines are not offered as C.R Engines any more.

With the Cats I have seen as C.R. Engines I have not seen any that were specifically arranged to have the Oil Fillers etc on a particular side as most of them were Vee configuration and the Oil filler etc was in the middle or in one of the Valve Covers. The pumps on the C.R Engines were different to the other one. I have seen the dip sticks and gauge panels facing each other , I have this on the current Std Rotation engines today

The only engines I remember off the top of my head being available "handed" were the Detroits 6-71's. I can't recall if these were C.R. or not.

I hope this has put your mind at rest and answered your questions.

To KIWI,

pardon my paranoia. Obviously, you are a gentleman. With an honest interest, in getting to the truth of things.
Although, sometimes people in these forums
- can be a little pernickety and petty.
Anyway...
I'm also, curious, as you are - re: counter rotating things.
It's not a suprise, to hear "...are more efficient by a marginal percentage...."
However, if it's already part of the package, maybe it's worth keeping ?

Because, we design mostly narrow boats, like cats - Inline engines, are the
ones I tend to deal with. And people, such as Cummings - are happy to swich things, back and forth.
To my point of view, this is a simple way to improve reliabiliy. As by putting dip sticks, gauges and so on - in opposition - with easy access.
Then one engine will be less likely to be " forgotten".

Where, in my view, counter rotation may have the:
" best return on investment " is at the prop.
As in theory, I repeat theory....speed may improve, or conversely
directional stabiliy will increase - depending on the direction of rotation.

With a serious accident, with the 100 mph off-shore racers, being caused by intentionaly having the props counter rotate, the " wrong way ".
I suspect that, at 15 knots, this may be not have the same potential drama....
And that the major manufacturerers, are not focusing as much on this, at lower hp ratings, as they used too. Except, perhaps, for people like Volvo.

However, as indicated, if gains due to counter rotation are already in place.
Then maintaining them may serve the project.

Do you - or others out there - have some difinitive data.
One way or the other on what goes on with counter rotating propellers ?

Cheers !

Tri Star,

Thank you for the compliment.

Don't get confused between Counter Rotating Engines and Counter Rotating Props.

If you didn't have counter rotating props in a twin engine installation you would have a nightmare to handle. It would also tend to crab along as the stern was trying to walk one way all the time, the opposite rotation of two props normally negates this.

As I said above I have sailed with C.R. Engines where the engines rotated inboard and the shafts rotated outboard. This is easy to achieve with the use of a gearbox.

The project I am involved in now has two Standard Rotation engines, this means that one shaft will rotate when going ahead in the same direction as the engines crankshaft and the other will be opposite. During tank testing it became apparent that there was a difference in fuel consumption and performance when the shafts on the model were set to rotate inboard. I opted to have this on the vessel itself. Inboard turning wheels make for a whole new set of parameters for manoeuvring especially when up against a bulkhead.

I am reliably informed by a colleague who has driven a number of yachts with them turning in both directions that once you get used to them going that way it is not much different. He told me on the second yacht we sailed on together that when he joined he asked the departing Captain about the direction of shaft rotation before having his first attempt at driving and was told he didn't know. It turned out that they were inboard turning with C.R Engines. The departing Captain is one of the big players in the industry today and an excellent boat handler.

Newbee-

If you have the engine out and don't intend to strip it at all ask your mechanic to remove the sump and a couple of Rod Bearings plus one main bearing for examination. You can get a special strip that is called Plastigage (http://www.hastingsmfg.com/Tools/plastigage.htm) that can be put between the bearing and shaft the caps tightened and it will give you the clearance. When the rods are disconnected it is also possible to push the disconnected rod all the way up the bore and look up the liner from underneath. This isn't going to show you the whole picture because the upper part will be covered by the piston but it will allow you to see any water marks or scores in the liner. If the bearing clearances are within tolerance and I think they will be if the Lube Oil pressure is good and no Liner damage is visible and there is still some good cross hatching then the engine is probably fine and dandy to go again.

CR -High Speed Concerns

To KIWI,

well stated.
I'm a great beliver in; imperical, in the field, feedback.So I appreciate the added data. Especially, re: the experienced Capt.

Who does need to remain nameless. As obviously, his innocence of things mechanical, did not overly effect his performance in handling a vessel.
Instinctively - compensating for any abberations in what ever boat was handed to him - no doubt.
Proberly, his passengers were, in fact, safer with him. Than a Capt. who needs to analyze matters for too long, during an emergency situation. Before taking action.

Re: High Speed Concerns.

With jet drives, often there is no gearbox involved. As conveniently, the water flow, is in effect, neutral in it's rotation.
With prop driven vessels, at displ. speed, avoiding crabing has got to be one of the major advantages of going to the trouble of CR.
And you add support, to my presumption - that in practice, slower speed yachts will come with props rotating in either direction, to each other.
Also, in operations, it is not even considered of note, by many people.

Your tank tests, indicate that clockwise or anti - clockwise rotation of the props, to each other, has a measureable and useful effect.
Also, below say 25 knots, ones options re: rotation - are somewhat to the designer's and /or engineer's descretion.

However, a little food for thought.
If intended speeds will exceed 40 knots......

On a tunnel hull cat, the helmsman will sense 3 distinct zones of operation.
Marked when planning is achieved and past 40 - when the craft will " break loose ". Attaining " flight ".
Not so well understood, is that monohull vessels are also receiving significant lift from Surface Effect, above these elevated velocities.

Not to get into, the wisdom of rushing about, jumping waves. Or which generic hull form is best for this......
The important consideration is: That with all vessels, the hull's effect on directional stability is Decreasing, as the propellers effect is Increasing - as speed goes up. - And especially, when aerodynamic lift starts to exceed that, from hydrodynamic forces.

And especialy, when the dreaded: " chine walking " sets in.
Even, at relatively slow speed, in bad weather, a similer dynamic can occur.
Due to wave action, or said ".....walking" - if one prop stays immersed and sinks lower - and the other is grabbing air.....
The desire for the sunken prop to push the craft sideways to the direction of travel - as well as forward. No longer has any opposition.

To make matters even more interesting...This torque thrust will also be doing it's best to roll the vessel. At this point, the direction of shaft rotation becomes of increasing concern.
As: sideways thrust in one direction will increase the amplitude of the roll
and the degee of repeated ossilations!
Whereas: if this same thrust, is in opposition to the direction of roll, it will help to right the vessel. And also dampen the amount of - and degree, of said occilations.
{A prize for any one, defining which is the " wrong " way for CR props to rotate on a 75 knot boat ?!}

It's also interesting to note: that it's becoming de riguer, with the 1/4 mile hot rod set, to use twin props now.
(With a Single Engine.) Over just one propeller. As was previous practice.
I'm not sure which way they rotate.
As I only watch these monsters, from far away....!

I know this is all becoming somewhat removed from the original question.
re: Re-building.
However, the vessel concerned, has the wise redundancy of twin engines.
As a lot of dockside wisedom, being stated about twin drive trains these days can run; " counter " to scientific observation.
Perhaps, it serves, to present data gathered from various sources. To support the continued use of the vessel concerned.

Cheers All !

Hi,

I appreciate your input Tri Star but think we have sort of hijacked the original thread subject.

Carl, Would you like to spin this of into a separate thread and extract the C.R and associated stuff so we don't confuse YF Member Newbees original questions and answers?

Hi,

TAD seems to have reasonabvle prices indeed from what you are quoting here.

Before stumping up for a new Inj. Pump ask your mechanic to take it off the Port engine and have it and the injectors bench tested by a Diesel shop locally.

If the engine is out it should be no more than a couple of hours max to remove the Pump and Injectors, similar to refit. You will be up for this labour charge even if you just decide to change them out. The Pumps are master splined so it is almost impossible to get the timing wrong ( saying this there is a mark on the pump body and flat surface where it mounts. A reference of where these marks are in relation to each other should be made and the pump reinstalled as close as possible to this , a photo is the best way to record this one).

Hi,

1. 1600 rhrs is almost nothing. Do minor overhaul.
2. Turbo can be rebuilt if casing / diffusor / shaft / wheels are not damaged / corroded.
Overhaul kits are available (seals, slide bearings).
It takes 2-3 hrs to replace everything.
What they offer as "rebuilt turbo for exchage" ? What parts are replaced ?
3. Injection pump rebuilt for 2019 $. If I compare to prices in my place, then, I would assume that it was rebuilt.
And again. What they can offer for 1000 $ rebuilt ? All plungers / bearings / pushrods renewed ?

4. Performance can be affected by a lot of things ... everything is important.

5. Don't forget cylinder heads. Ask the workshop to dismantle one or two and take measurements. Look at condition of valves / guides.

6. Again, I remind, that You face situation "low rhrs, but overhaul long time ago". I would suggest follow scenario: dismantle 1 cyliner unit - check/measure - replace parts if necessary. If some replacements were necessary - overhaul next cylinder. (but, all piston rings have to be replaced for sure).

rgds,

Andrei

Agreed KIWI

Looks like you dropped a valve.

Hi,

Thanks for posting the photo.

If a whole valve had been dropped there would also be damage in the combustion chamber of the piston which in this photo looks relatively unscathed and the valve itself may have been smashed through the cylinder head if the whole thing ended up in the cylinder.

Broken Rings or foreign body entry to the cylinder leaps to mind, what ever was going around on the top of the piston wasn't very big but it was obviously very hard.

How badly damaged is the cylinder head face on that Cylinder?

Do you have a picture of it?

Hi,

It happens.

1. Check the camshaft's cams surfaces. Very important.
2. Cyl. block's geometry has to be checked. I hope, it's ok.
3. Are pushrods dented ?
4. Check the conrod's geometry.
5. Replace all defective parts.
6. It could be worse... lucky You.

Such things happen.

It could be a valve complete or a part of it, or a piston ring, or liner's piece... whatever... has to be fixed anyway now.

Stay strong, we are with You.

Sorry for being so far away, otherwise would help myself...

Regards,

Andrei

Hi,

I am pleased to read that you seem to have everything under control.

I would like to thank you on behalf of myself and other YF members for continuing to post your news keeping us updated as to how it's all going.