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Talbot · 08-05-2006, 09:41

A trick I was taught some time ago when you really suspect an injector, is to drain down your main fuel filter and fill it with injector cleaner. bleed the system, then start the engine. The engine will get a blast of neat cleaner and will start and run on this for a few moments, this should make a fair difference to the clogged injector!

I use it as a means of getting my diesel car emmissions down low enough to pass our car tests.
If you regularly run your diesel fuel with "Fuel Set" or "Soltron" in it, it will keep the injector much cleaner and more efficient, it will also much reduce the probability of fuel problems

DeepFrz · 08-05-2006, 09:53

Rick, you mention adding injector cleaner, but you didn't mention that you cleaned the tanks. If you had contamination in the fuel then you really should clean the tanks and fuel lines to the filters and then replace the filter elements again. You might also want to read up on fuel "polishing". There was a fellow from Australia that posted here about a fuel polishing system he built that looked easy and cheap.

Phil.

Edit: It would be worth cleaning the tank and lines before going to the trouble of sending your injectors in.

Tropic Cat · 08-05-2006, 13:10

Talbot .... would there be any downside to using a few ounces of pure injector cleaner?

Phil ... you're right of course. I didn't clean the fuel tank. But wouldn't you argee that having two filters on that fuel line would take care of anything in the fuel? I have a large primary and small secondary filter on each fuel line, recently replaced.

Another update to the engine problem. My boat is scheduled to go on the hard a week from today. I have noted a significant vibration in one of the drive trains. Recently a small crack in the gel coat developed on the starboard side (the weak engine we've been discussing) between the shaft seal (stern gland) and the P-bracket bolts. After discussing this with Talbot, we've come to the conclusion that this probably indicates a bent propellor shaft. I've come to the conclusion that I bought the boat this way. This shaft and propeller were heavily encrusted with barnacles, which I had removed. However, the vibration remained and the gel coat crack got longer, so I have to deal with this immediately.

Isn't it a coincidence that all my drive train problems are on the starboard drivetrain?

Rick in Florida

Talbot · 08-05-2006, 14:31

No downside to the injector cleaner other than a very smokey exhaust for a short while! and keep the revs up once the engine fires! (good idea to warn people round you, in case they think you have caught fire)

Fuel set or soltron will do a good job on cleaning up your fuel .

I actually filter all the fuel going into my tanks using a smart funnel - this filters and stops any water entering the tank. I then add fuel set. My fuel is incredibly clean because I run by espar from the main fuel tank and want to ensure that I dont have any problems with that.

DeepFrz · 08-05-2006, 20:09

Quote:

Phil ... you're right of course. I didn't clean the fuel tank. But wouldn't you argee that having two filters on that fuel line would take care of anything in the fuel?

Hmmm, maybe... But then you might get out in some rough water someplace off the North West end of Cuba (or somewhere else) and get into some rough water and all of a sudden all that black s..t gets ta pluggin up your fuel lines and filters... maybe

Phil

**Alan Wheeler** · 09-05-2006, 01:02

Believe it or not, this is the third time I am attempting to write and post this. I typed for ages this morning and upon htiing Submit, something went wrong my end and I lost it all. I came home this evening and did it all again. This time, something else hapend and I lost it all again. OK, third time lucky, or no one will ever see this, and of course, you will never even know.

OK, firstly Rick, the best thing you can do is to get those things serviced. Well worth the effort. Here's some info that will explain why and hopefully help some others in diagnostics.

An injector is a high precision piece of engineering, being asked to operate in an extremely harsh environment. They have a duty cycle that requires them to be serviced once in awhile. This is ruffly every 1000hrs. Although they will often work just fine for many tens of thousands of hrs with seemingly no adverse effects. Seemingly!
How it all works. Well it's reletively simple actually. The injector comprises of a needle valve and a seat. Both highly precision ground and polished. Behind those is a spring. The injector pump provides a metered dose of fuel at a substantial pressure to the injector. As the pressure reaches a threshold, the pressure overcomes the force of the spring and the needle is lifted and the dose of fuel is sprayed into the cylinder.
Because of heat and the fact that the spring is always under tension, the spring slowly looses strength and this is mainly what needs to be adjusted every 1000hrs or so.
The needle and seat can be damaged very easily. Water is the biggest enemy of these two. The main way water damages an injector, is corrosion and contaminants being left behind in the internals as the water boils away. The seat is higly polished and very precise and corrosion on the seat surface effectively destroys it's ability to work as it should. The other major danger, is the fact that water will instantly expand to 700 times it volume when boiled. As soon as it reaches the tip, the extreme temperature causes it to explode and it can damage and even chip the nozzle tip.

At this point, I want to bring in some info on fuel additives. Be careful what is in them. The Base products of some are nothing more than Kerosene. Kero is a very good cleaner but it has a very major negative. It is very abrasive. It does not lubricate metal parts very well. So be very careful at what you run through the fuel system in any concentrated form. The other point with additives, is the way in which they handle contaminants in the fuel system. There appears to be two basic ways of doing the job. One is to mix water with the fuel so as it burns away and the other is to seperate any water and moisture out of the fule so as it can be trapped in the filter system.
The ones that emulsify and mix the water in, need to be viewed with caution. You CAN NOT turn water into fuel. Trust me, many have tried, no one has found that holy grail yet and the one that does, will be a rich man indeed. So water, in what ever form, entering the injector, can cause damage. In saying that, I do use a product Talbot described, called Fuelset. I watch my seperators on a regular basis to check for water, but I also use the fuelset in a "in case of" situation. Remember, when it goes wrong, it is going to be a very inopportune moment and I would rather have an injector damaged and get safely out of trouble, than to worry about an engine shutting down right when I don't want it to.

Now on to what to look for. Well, this part is a little tricky. It's easy to say, "Oh if you see such and such colour of smoke, this is the problem", but it isn't always as simple as that. So the following are some guide lines that hopefully could help.
To correctly diagnose an engine, there are some basic principles to use. This is befor you start ripping things apart and/or connecting up expensive test equipment.
What is the complaint, what are the symptoms, what do you see and what do you hear.
The last two are VERY important. What is happening with the exhaust smoke. Do you see anything unusual. Remember, just because it has smoke, doesn't mean it has a fault, it could be a Volvo eh darryl

.
If it's your engine and you know it well, has the sound changed.
OK, before I go further, to follow on from the description at the begining of how things work, well take the stroy back up. The needle is lifted by the pump pressure and as it lifts, the fine hole and shape of the seat, causes the fuel to atomise and spray out in a pattern. This pattern actually has the cylinder designed around it. You don't want fuel igniting on hot parts of the engine. It will eventually burn those parts out, like pistons and valves etc. So if that spray pattern has been altered in anway due to a damaged seat, then it will not burn correctly. If the fule does not burn correctly, it will cause all sorts of issues in the engine.
A totaly blocked injector, will of course mean that that cylinder is not firing at all. Easy to spot so you would think. But because a diesel tends to run ruff, sometimes it is not so easy to spot. So you run down the injectors and lightly crack the fule rail nut on each top. This will drop the pressure enough to stop an injector from working if it was working to begine with. Listen for a change in the tuning condition of the engine.
A stuck open injector, never allows the fule pressure to rise enough to cause it to atomise. It squirts out in a jet and will can cause several problems. A common sign for this, is the engine will start fine cold, but be difficult to start hot. Normally seen when the engine is using a heat source like glow plugs. The heat source vaporises the fule at it starts fine and will run fine. Once the engine is hot, the heat source is no longer used and the squirt of fuel will not ignite when you try and start the engine. This can also be very bad, as it is washing oil from the cyclinder walls and diluting the engine lubricant in the sump.
A damaged seat can cause the burn pattern to change. The burn pattern is important for two major reasons. the main benifit of diesel is the enormuse Torgue they can produce. This is from the slow rate the fuel burns at. It produces a long power period over the length of the stroke. If the burn pattern is changed, so can the burn period or just simply, the power that should be gained fromt he way the burn takes place, could be substantialy reduced.
The other issue is, the spray pattern ignites on hot components such as say an exhaust valve and can cause improper detonation timing, plus heat damage to those components.
To sum up, the major beuty of a Diesel is it's simplicity of operation and the fact that they are very reliable. The major disadvantage is, they are precision machines of extremely high tolerances.

Hope this wasnt a bore.

Talbot · 09-05-2006, 01:52

Wheels a nice explanation.

For your info, my diesel is very different. It has the normal lift pump providing low pressure fuel for use or return, but then it gets different. The low pressure fuel goes directly to the injectors, and they are a combined high pressure pump/injector. Thus the only bleeding required is on the low pressure side, and is carried out at the two filters (one on the engine, the other a racor filter/seperator near the fuel tank)

The downside is that these injector pumps are V. expensive and are not much enamoured of water (3 x £300 each - 10 years ago when I discovered the hard way about water in diesel). Hence the use of fuel set , a water seperator, and the "smart" funnel.

Tropic Cat · 09-05-2006, 05:11

After running the engines hard for 90 minutes at full speed with the injector cleaner. I tried to analyse the color of the smoke.

At 100% throttle small amounts of dark gray/black smoke, and raw water exhaust turned dark and cloudy. At 90% throttle, small amounts of white smoke, and the exhaust water is clear.

Rick in Florida

Talbot · 09-05-2006, 05:45

100% throttle with the small amounts of dark gray/black smoke, and raw water exhaust turned dark and cloudy, would be pretty normal for a slightly overpropped engine, or a fouled bottom.

The white at lower revs could be a bit of steam from a very hot engine after running at full throttle.