BoatU.S Magazine Diesel Engine Myth #2

[rardiH36]

The current issue of BoatU.S. magazine has a very informative article about diesel fuel injectors. A side bar to the piece cites three diesel engine myths. Myth #2 is that its OK for a diesel to shake and rock at idle as long as things smooth out when in gear. Instead, shaking and idle clatter may caused by faulty injector timing and much of the condition can be improved by proper adjustment.

Maybe this myth buster advice applies more towards larger power boat diesels, but it got me to thinking how frequently do conscientious sailboat owners check (or have checked) their injector timing (and injectors)? Posing the question in an inverse way, has anybody ever found that their injector timing has been off? My Seloc manual for the Yanmar series QM's, GM's and 4J's of the end 70's/80's cites injector timing and inspection be performed every 500 hours. Checking the timing seems doable by a DIY home mechanic. However, if the timing is off, shims need to changed. I would think that just like the shims that set the valve clearances in cars these days, its going to take a lot more time than every few hundred hours to make a difference in shim wearing/timing.

My 2QM is performing fine. Starts quickly, never smokes, doesn't need oil between changes and reaches the rated rpm. But it does shake. I've always attributed that affliction two it's 2-cylinder nature.

rardi

 

[Ed Schenck]

Geez Rardi, just when I think I am catching up here is something else to worry about. And I forgot to write down the engine hours yesterday when I took the log off of the boat. I don't remember my original 2QM20 shaking much except at very low idle. Motor mounts can also be a source of shake, rattle, and roll.

 

[Johnb]

So how would a DIY owner check the injection timing?

 

[rardiH36]

Dear Johnb:

Its in the Yanmar service manual and also Seloc. Sorry, I'm running off soon and not enough time to try and write it out.

 

[Texas Lake Sailor]

I have not messed with the timing but have removed and had my injectors rebuilt. then reinstalled. It made a big differance in performance. Started easier, runs smoother (less rattle)more power.

 

[jibes138]

Natural frequencies

Mechanical systems have natural frequencies where they will resonate, as you increase your rpm's do it slowly and note the rpm's where you seem to get extra vibration. these are likely the natural frequency speeds as you increase the speed a little more it will often smooth right out. Stay away from operating at a natural frequency. If it vibrates all the time regardless of speed something else is the problem.

 

[Newbie]

More then likely if you have never touched your injector pump the timing is still close enough to factory specs not to have to worry about it.I would however recommend getting a injector cleaner through a company that rebuilds injector pumps. They have a great cleaner that mixes with the fuel and one bottle can be run through many gallons of diesel fuel. This tends to be the best place to start.
Also always mark where your pump is fitted to the casing with punch marks before you remove it. that way you just line it back up when reinstalling the pump. It just saves you time.

 

[rardiH36]

Injector Timing Must Be A Non-Issue

Newbie: You must be post "newbie" regarding engines. I'll look into injector cleaning additive for the fuel. Must be the equivalent of Chevron's Techron for gas engines -- they add to the gas to keep injectors and valves from deposit build-ups. Or buy a bottle to add to a tank to do a deep cleaning. Whether it really works or not?

With over 430 views to the original post, but not one person responding that their injector timing has been off, or has ever been adjusted on their engines, seems that its something that rarely comes up in small sailboat diesels ... notwithstanding the BoatU.S. article. I'll leave well enough alone.

rardi

 

[foustjl]

How to check your injector timing

So how would a DIY owner check the injection timing?

I took a great class in diesel mechanics in Annapolis this last spring and we checked the injector timing on a couple of engines during the adavanced class. I totally recommend these guys.

http://www.annapolisschoolofseamanship.com/diesel.html

1. First, you have to remove the high pressure fuel lines from the injector pump. Then wipe off excess fuel from the fuel pump.

2 With the transmission in neutral, rotate the flywheel by hand (using a ratchet and socket) until #1 cylinder is coming on to its compression stroke. On some engines, there are numbers etched into the flywheel to indicate which cylinder is coming onto its compression stroke. If yours doesn't, you will have to remove your valve cover to watch for the intake valve to open.

3. Now carefully and very slowly turn the flywheel until you see the first hint of fuel movement in the output port of the fuel pump. It won't be much, and if you miss it, you have to wipe the excess fuel off again, rotate the engine through the power and exhaust strokes to come back around to the compression stroke. It takes a steady hand and eye to stop just as the bubble of fuel moves on the fuel pump. It took me four attempts to coordinate the hand with the eye. The movement in the fuel is slight and easy to miss.

4. When you finally do it just right, you have to look for the timing mark inspection port on the flywheel. Depending on the make, there is some sort of a line and a marker. If the mark is more than 3/16" above or below the line, you need to add or remove shims to the injector. Repeat for all the rest of the cylinders. Like I say, the hard part is catching the just the first hint of fuel movement out of the pump.

5. The instructor said there is a chart for converting degrees into shim thickness, but we didn't look at that.

This was hard enough doing it on a engine on a bench. I can only imaging the difficulties doing it "in situ".

Hope this answers your question. Here is a link for timing a Universal engine.

http://www.marinedieseldirect.com/u...rsal-owners-manual-fuel-injection-timing.html

 

[rardiH36]

This was hard enough doing it on a engine on a bench. I can only imaging the difficulties doing it "in situ".

http://www.marinedieseldirect.com/u...rsal-owners-manual-fuel-injection-timing.html

Thanks for the tips. I've probably got one of those rare boats where the engine is very accessable. For the fuel lines, and injectors, and putting the manual start crank wrench on the crankshaft bolt, the orientation is almost as good as being on a workbench.

Thanks for the tips. The manual says something about putting on an inspection pipe on the high pressure outlet tube. Somewhere else I've seen a reference to pressing some clear plastic tubing over the opening and observe the fuel rise through that. Seems that your description is easier. My manual does have a chart for shim thickness.

 

[Stu Jackson]

I'll look into injector cleaning additive for the fuel. Must be the equivalent of Chevron's Techron for gas engines --

Next time you change your primary diesel filter, just use the injector cleaner to fill up the fuel filter instead of diesel.

 

[kenn]

Before getting too worried about shake at idle, be sure your diesel engine is not idling too slow.