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Old 27-01-2010, 19:26   #106
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The turbo has no separate thermostat or such for coolant delivery. The coolant runs into it from a large tap off the main heat exchanger and it returns via a line back to the front of the heat exchanger. The engine run temp is normal.

We inspected the valve gear closely and found nothing of note. Everything seemed to operate normally and turning the engine slowly by hand gave no indications of leakage past any valves and compression seemed consistent. Also, if you remove the breather line from the valve cover with the engine running and put your finger over it you feel no pulsing or other indication of any blow by or pressurization of the crankcase at all.

The engine idles smoothly and starts immediatly. It would seem that if we were dragging a cylinder this would not be the case. Also, if dragging a cylinder would I get 4,000rpm in neutral?

As for ruling out exhaust back pressure.... I have not ruled out anything including alien intervention at this point. But it seems unlikely and I have no means of testing it. Trying to rig something up to a 6" diameter irregularly shaped hole at the waterline in the transom that is spitting both large quantities of water and exhaust gases and get a meaningful and repeatable reading on pressures seems like a MASSIVE project all by itself and of course I would have no idea what the readings meant if I could get them given no readings from when the engine was running correctly.

I will ask the Yanmar guys if they have any ideas on getting such a reading.

Chief: I believe we got about 6 knots.... but I am not positive and I am unsure if that was SOG or in the water as I do not know what the current was at the time. We did not spend much time sea trialing... the engine was at normal temp, we raon out about 1/4 mile and tried various rpm's and all indications were of the exact same problem with the new turbo making no difference at all so we came back.

When things used to operate normally, we tended to get just over 6 knots at 2400rpm and that is where we cruised. We would see right around 8 knots or just under at 3400rpm but we almost never did that as the fuel consumption was much higher for the small gain in speed plus it seemed the engine was working much harder for no purpose.



Terry
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Old 27-01-2010, 19:27   #107
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I'll repeat myself for clarity.

check the pitch. if that's true to the notes and PYI's set up. You need to do a compression test.

you have no fuel issue mater of fact the engine is getting too much fuel and can't burn it all off. This is know as overloading the engine. The prop is the prime culprit here.
If the prop is good, you don't have the compression to make the power to burn the fuel you are getting. This reduced exhaust volume and pressure will cause the turbo to spin slower, not pressurizing the intake to the numbers you want.

in regards to boost. The value is linear climbing from 0 to your spec of 15 at 3600 RPM. SO, naturally at a reduced RPM of 2950, the boost is going to be lower....
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Old 27-01-2010, 19:44   #108
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Never Monday....

That is my plan, get hauled out and check/reset the prop pitch.

It makes me very angry that the Yanmar techs here who have been working on this did not do a compression test when they had the injectors out. I asked about this specifically and they said they didnt need too as it was obvious that the compression was good based on how the engine started and no obvious pressurization of the crankcase. To me however... not checking the compression seems like a case of being lazy. I would have checked it myself if I had a mechanical compression guage that would work on this engine.

Terry
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Old 27-01-2010, 19:55   #109
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Terry.

Do not lose heart over this......once you are underway...free from the bonds of Florida.....take comfort in the fact that you now know more about diesel engines than most....this adventure in troubleshooting will be valuable to you and others whom you will meet along the way.

As far as the compression test that NM mentioned, I have one thing to say
L-A-Z-Y. or they don't have the proper tool. It IS time consuming. Thank your lucky stars it isn't a Detroit Diesel.

Keep us posted my friend
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Old 27-01-2010, 20:02   #110
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Terry,

If you're overloading the engine at 2950 rpm that means you're getting more than 65hp out of it. If you were getting 65 hp to the prop, over pitched or not, you would be going more that 6 knots, it's probably more like 20-25 hp to do 6 knots. So if the engine is oveloaded there must be some other drag on it, really dirty bottom, tight stuffing box, something wrapped around shaft, gear problem? If it was stuffing box or gear, wasting 40 hp would generate a lot of heat which you probably would have noticed, can't believe that the bottom could be that dirty. So it's got to be either something wrapped around the shaft, a fuel problem or an air problem.

Doug
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Old 27-01-2010, 20:06   #111
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Originally Posted by s/v Thea View Post
Terry,

If you're overloading the engine at 2950 rpm that means you're getting more than 65hp out of it. If you were getting 65 hp to the prop, over pitched or not, you would be going more that 6 knots, it's probably more like 20-25 hp to do 6 knots. So if the engine is oveloaded there must be some other drag on it, really dirty bottom, tight stuffing box, something wrapped around shaft, gear problem? If it was stuffing box or gear, wasting 40 hp would generate a lot of heat which you probably would have noticed, can't believe that the bottom could be that dirty. So it's got to be either something wrapped around the shaft, a fuel problem or an air problem.

Doug
If the blades do not rotate to the proper stops then they would act as paddles rather then a screw.

Terry,
One test I've heard about is to push the throttle to full while at a dead stop. If the motor bogs down then there is too much pitch.
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Old 27-01-2010, 21:43   #112
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Terry,
Really feel for you!
As Chief Engineer said "Do not lose heart over this......once you are underway...free from the bonds of Florida.....take comfort in the fact that you now know more about diesel engines than most."

Elsewhere it was mentioned that a turbo is not a stand-alone piece of equipment - it depends on many other components working to spec.

The quote from post # 106 "The turbo has no separate thermostat or such for coolant delivery. The coolant runs into it from a large tap off the main heat exchanger and it returns via a line back to the front of the heat exchanger. The engine run temp is normal."
The cooling that the Turbo needs is dependent on the fresh water pump, the raw water pump, the heat exchanger, the thermostat, the delivery cooled water pipelines. All of which must operate at specified temperatures. The engine temperature gauge may show a normal operating range, but what temperature is the water when it reaches the turbo? The thermostat should be taken out every 500 hours, checked and tested, if it doesn't conform to spec, change it. The fresh water pump and it 's impeller should be checked for wear and delivery.
The service manual for this very engine requires a thermostat to be replaced every year or sooner if malfunctioning ( in this case it would have been replaced 28 times!)
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Old 27-01-2010, 22:10   #113
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My Yanmar smokes a kinda blue steam but I run the Sh** out of it and can only get 3000 RPM's at max throttle, At 3000 rpm's I'm at 7.2 knots and the engine never overheats I have over 400 knots of motoring under this blue smoke condition and the motor still gets me home, I would much rather have black smoke than blue smoke. Have you ever been behind a greyhound bus at a stop light and when the light turns green the bus takes off with black smoke from hell and that diesel engines runs for a million miles without a wink.
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Old 27-01-2010, 23:59   #114
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Hi Terry:

Read thru your posts and just want to wish you good luck. I know this engine part sucks but it will pass. when I have major problems on my boat i try to set the family up with something fun to do. this usually gets them in a better mood and then I can think more clearly aobut how I am going to solve the problem. On that note I was looking at Caulders book today trying to resolve a problem with my generator when I saw a picture on page 404 of a simple homemade manoneter to check exhaust back pressure. . . . if the manifold has no suitable outlet to make the connection (manonemeter) drill an 11/32 inch hole, tap this for a 1/8" pipe fitting (standard pipe thread) and crew in an appropriate sized fitting. When finished remove the fitting and fit a 1/8" pipe plug" If I was home I would scan and send you the proper page. I'll see if I can find a scanner here in Mexico and send you a copy of the page.
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Old 28-01-2010, 07:15   #115
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Charlie, I have the Calder book and read that portion. He also says to do this at least 12" downstream from a turbo. On my boat the mixing elbow connects directly to the turbo and from there all the way out the system has no metal parts, it is all the reinforced rubber exhaust hose and the fiberglass waterlift muffler and vented loop. There is no place to drill and tap for any fittings to test with.

I guess it is possible that the added weight to the boat has lowered the waterline some and that could increase back pressure to raise the exhaust/water from the muffler through the vented loop and out the back but the waterline when looking at it from the dock really appears unchanged.

I am very sceptical that the issue is the prop pitch, but what else to try I do not know.


Terry
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Old 28-01-2010, 07:22   #116
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Terry I figured you had the book. I just thought I would throw it out there. have you asked the Max Prop guys if there was someone they would recommend that could change the settings on the prop without hauling the boat. I looked into this because when I changed the settings on my prop the boat is now slower and consumes more fuel. Max prop had a list of people that they felt were qualified to do the work. I was looking in SF Bay Area don't know about your area. I guess one downside is that you won't be able to tell if there is something wrong with the cutlass bearing if you do it in the water. Good luck with it I hope all works out well.
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Old 28-01-2010, 07:31   #117
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Hi Terry,

Found this a little late (have been writing on Sailnet).

Since the engine performed properly and nothing was changed I too find it hard to believe dat the pitch would have something to do with it. I am familiar with Gori folding props (they either work or break). If yours is a folding prop does it unfold properly?

I do not think the injector pump is the issue (you get more than enough fuel); are you sure the nozzles (your own spares I read) that were installed are of the right type. Even with too big nozzles you can get them to pop at the right pressure but they would not work properly since the amount of fuel injected is too small to vaporize correctly. Test pumps deliver more fuel than your injector pump would and might (if the mechanic doesn't pay attention) indicate the injectors are set up correctly.

Good luck with your ordeal and try to see it from the bright side: I bet you learned a lot about your engine this week.

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Old 28-01-2010, 07:41   #118
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Using a diver, or a haulout, I would NOT have them check the pitch. I would have them De-pitch it by a couple of inches. If this does not allow you to hit a higher rpm, then pitch was not the issue.

If you simply check the pitch, that will not determine whether you have too much pitch, based on your current weight.

Some may say that it is all about waterline / hull speed, but you can't tell me it takes the same force to push a very light / empty boat through the water, as it does to push a heavily loaded boat (likely riding a couple of inches lower, therefore displacing more heavy water out of it's way as it moves). If it akes more force, the engine won't rev as high, which results in less horsepower, at the lower rpm, thus overworking the engine.
200 lbs may not make a difference, but 2000lbs might, especially if you were slightly overpropped / overpitched to start with.
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Old 28-01-2010, 07:49   #119
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My max prop is an older model, you cannot change the pitch in the water as the prop has to be disassembled and you have to clean off the grease to see all the tiny markings inside the prop. To change pitch it has to be hauled.

I have been pouring over the all the maintenance notes on the prop and speaking with the max prop guys. If the notes are correct and the prop is pitched as they indicate then the issue is not the prop. le

EDIT: Northeaster.... all my maintenance notes and notes in the max prop manual I have show that the prop is 20" diameter and the blade angle is 18 degrees giving a prop pitch of 12.1 degrees. There is however some confusion as there are also some marks next to a blade angle of 20 degrees which would give a prop pitch of 13.7 degrees. The max prop guys say either of those should allow us to reach much higher and correct rpm's than we are seeing. There is of course no way to be sure that my actual pitch matches these notes without hauling out and checking to make sure. If these notes are accurate however and my pitch is in the 12-14 degree range then reducing the pitch further is not a great idea according to max prop as they pitch will be so thin as to limit power.

I have spoken more with the Yanmar dealer I have been working with through all this and I indicated in no uncertain terms my disappointment and dismay that they never did a compression test when they had the injectors out. It turns out they do not have the correct tool to do this on my engine, that is why they did not do it. The injectors on my engine do not screw in, they are held in place with a small metal strap that goes over two studs and tightens down with two nuts.

He said he would try to find a compression tester that would work so we can test compression. He also said we could test exhaust back pressure by drilling a tiny hole in the exhaust hose down from the elbow and inserting a bastketball type needle that connects to a testing device and then when done use some 5200 or such and a clamp to repair the small hole. Sounts mickey-mouse to me but what do I know.

If there is a problem with the exhaust, that may be worse than needing a new engine as removing and replacing the giant hose would be pretty much impossible without massive cutting and disassembly of the boat. Even getting the fiberglass water-lift muffler out would require removal of the shaft and transmission and maybe even the turbo and all parts on the aft of the engine it appears.


Terry
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Old 28-01-2010, 08:11   #120
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Hi Terry,

I am not suggesting that you permanently depitch by a certain amount! Of course, there would be a point where you would have too little pitch to be efficient.

What I am saying is that I would depitch temporarily, by a decent amount, like 2", so that you will either see an immediate increase in rpms, and decrease in smoke, if pitch was the problem. If it doesn't help, then you have ruled out the prop.

OK, so it is hard to change the pitch - haulout required. What about hauling, or having a diver take the prop off, and temporaily installing a borrowed prop - any fixed or folding prop, with way too liitle pitch. Even if you borrowed a 16" x 10" prop, you may only do 3 knots, but if you can hit 3600 rpm (or 4000, whatever max is, without smoking, then you know that the prop was the problem, and you can have it looked at / depitched.
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