Yanmar problem

[Tropic Cat]

I was asked to post this in the appropriate forem. I hope I've got this in the right place!!

I own a catamaran which has twin diesels.

I've had quite a bit of trouble with the Starboard engine. First off these are 20 year old Yanmar 1GM10's which are raw water cooled. When I bought the boat I did have an oil analysis done and it came back OK. Cooling water flow is very good, however, symptom number 1 was that I had to bleed the fuel system repeatively whenever I tried to start the engine. I read that this is typical of air in the fuel line so I've replaced both primary and secondary fuel filters a couple of weeks ago as well as the starboard fuel line which I found a whole in. It helped quite a bit as now this engine cold starts in 3-5 seconds. I've read that this indicates that the engine compression isn't terrible.

This is about the limit of my experience/ability/reading. The next symptom is that when the engine is running in neutral it isn't acheiving it's max revs. I don't have a tach but compared the the port engine I'd say that this one isn't reving past 2000 rpm in neutral. When the throttle is advanced it hesitates and is accompanied by a lot of black/dark grey smoke before steadying up at the higher rpm where smoke is white.

I'm wondering if I should inspect the exhaust mixing elbow as I've read that this is a normal maintenance part. Somewhere I read that if it's bad, there could be a carbon build up around the exhaust valve blocking gas flow. Should this be the next place I look?

The boat history is that I bought her from a family who had the boat since new. The fella past away in 2004 and I bought the boat from his widow who had no knowledge of engine maintenance. In searching the boat I came across receipts for 2 new engine heads and some other items installed in 1995. I figure the last few years the boat wasn't used very much because of the husband's health problems.

Thanks

Rick in Florida

[never monday]

Couple of quick questions, please. Do both engines share the fuel tank? Is the port engine also smoking white?
The 1GM typicly doesn't have the problem exhaust elbow, but could have an accumulation causing a problem similar to what you are describing.

[Tropic Cat]

No, separate 10 gallon black metal tanks

[never monday]

Rick,
I'm leaning tword water contamination in the starboard fuel tank.

[Tropic Cat]

I have a water separator on both engines as part of the filtering. I'll crawl down there and have a look at the glass bowl, but I seem to remember glancing at it when I changed the fuel line and it didn't seem to contain any water.

Thanks

Rick in Florida

Originally Posted by never monday

Rick,
I'm leaning tword water contamination in the starboard fuel tank.

[Alan Wheeler]

Check you have a clear unrestricted air intake. If you have an air filter, ensure it isn't dirty nor damp. A damp filter will easily restrict air.
It is possible that injectors and pump need looking at. It is easy to remove and have the injectors tested. Infact, you can even remove and reconnect them to the fuel lines. Turn the engine over and look for a fine spray pattern from each. If it is a squirt or none at all, then they need looking at.
Next possibility is the fuel pump. It is possible that something in the rack/governor is not working properly.
This is a little more difficult to remove and you need a little competence to remove and replace to ensure timing remains correct.
They are the simple projects. Next is a leakdown test to obtain compression and possible leaks. It is easy to do, but you also need a level of competence to be able to accurately interpret the results.
I would start with the easy part. The injectors. They aren't expensive to do. And should you have ever suspected a possibility of water in the fuel at any stage in the past, then the injectors should be considered suspect. A droplet of water reaching the tip of a very hot injector literaly explodes and will chip the end of the injector. It also corrodes the internals very quickly and can cause blockages and sticky needle valves.

As a point of interest to others, a sticky needle seat on an injector can cause it to squirt out a dribble of fuel. For an engine that has glow plugs, this can cause an engine to struggle to start when hot, but be starting just fine when cold. When cold, the fuel is vaporised by the glow plugs and the engine starts with no hassle. When hot, the glow pulug is not going, so the fuel squirts into the cylinder and vertually floods the engine and stops it from starting.

[Tropic Cat]

Alan,

It seems both you and Pat are leaning towards a fuel generated problem. You both could be right. When I bought this boat, the yard she was in didn't have fuel pumps and I had to use what was on board. The fuel was contaminated both with water and bugs. After running the engines for a couple of hours the starboard primary fuel filter was totally clogged and there was water in the glass bowl of the filter at that time. As you can imagine that little engine shook and rattled. I limped to the closest marina and added fuel additives and fresh fuel. This was about 10 months ago.

The starboard engine never was as strong as the port engine, yet worked well enough for me to get out of my berth and get my sails up. Over time it then began getting steadily worse as I mentioned in my original post.

So, the water in that load of fuel could have damaged the injectors, right?
Guys, I have the engine service manual. Do you advise an amateur disassemble the injector and bring it to a Yanmar shop for testing?

Thanks

Rick in Florida

[Tropic Cat]

I should mention that I sat down and estimated how many hours I've put on the engines since I've owned her. My best guess is 50 hours, as I hardly run the engines at all. The hour meters were disconnected / disabled when I purchased the boat. I really am in the dark here.

Rick in Florida

[never monday]

Rick,
Before you start taing things apart, go motor at near full throttle for about 2 hours then let it rest a day and start over. Oh, this is after pumping out that tank and getting new fuel in there.

[Tropic Cat]

Pat,

I had to smile at your post!! I just love it when an expert zeros in a problem!!

I have 4 gallons of fuel in the starboard tank. I will pump it into a gas can and refill at the marina this weekend.

Rick in Florida

[Alan Wheeler]

See told ya it was worth posting eh!
Rick is suggesting you go give her a good hard run for several reasons. Let us know what you find as a result.

Just as an answer to a question you posed above, yes it is easy to remove an injector. It's kinda like a spark plug. You can take them out and take the set along to a Deisel guy and have them cleaned and calibrated.

But do not try pulling the injector apart. It has a strong spring that is on a calibration thread. This is calibrated on a test rig. There is a series of seals and then the valve and seat. Not a lot you can do with any of it, unless you know what you are doing. Easy to damage the highly accurate seating assembly. Best to leave it all together as one.

[Tropic Cat]

Alan,

You were right about posting. The reason I asked about disassembling the injector is that it seems to have a lot of parts!!

[never monday]

Originally Posted by rickm505

Alan,

You were right about posting. The reason I asked about disassembling the injector is that it seems to have a lot of parts!!

Actualu everything from the heat shield up will come out as an assembly. Like Whees said, don't try to disassemble the injector! Between the small and calibrated parts in there something will get messed up.

If your addimate about testing it. Get a soup can and re attach the injector to the fuel pipe so it points into the can and turn the engine over by hand with the seacock closed. Watch the injector to verify the spray patern is even and a mist like spray. You don't want a garden hose, a drip, or a one sided spray. ***MANDATORY SAFETY NOTE*** Don't let your hand get in the spray path there is enough force to cut your skin open with just the fuel flow.

[Tropic Cat]

Pat, I'll just do the fuel replacement first and see if that fixes it. Testing the injector is plan B

Rick in Florida

[Tropic Cat]

Just a follow on to my original post. Although the starboard engine ran a bit smoother, new marina fuel didn't quite do the trick. So, I bought some diesel injector cleaner and tossed it into the new fuel.

Yesterday, I motored for about an hour and 1/2, running both engines at full speed. It wasn't hard to tell if there was improvement as I motored into a 20 knot head wind (with a catamaran) at 6.5 mph, which is as good as the boat has ever done, since I've owned her.

I've decided not to test the injectors myself. I ran into the local diesel expert at a pub Friday night and he gave me the phone number of a regional diesel injector rebuilding outfit. He said that it's up to me to remove/install the injectors, but I send them to this outfit and they do the reconditioning.

Would you fellas agree, that this would be a reasonable thing to do? I mean, it can't hurt, right?

Rick in Florida