How to fix a vibrating engine

[youngsalty]

Hey guys,

The engine is a diesel Westerbeke 50.

Part 1 of my problem- when I start the engine it vibrates bad. Still in neutral, I turn up the throttle the vibrating stops. When I pull back on the throttle, the vibrating kicks back in before the shifter is in twelve position.
Part 2, I have a dripless stuffing box, though while running the boat in gear I have to pump the bilge out about every three hours, salt water is coming off the the rotating shaft, stuffing box is no longer dripless. The engine does not vibrate while in gear.

I have tighten the motor mounts (not that) and am thinking my next step is to check the alignment. I need some help where to start and how.

Its summer and I want to sail but apprehensive about using the boat in its current condition. Open to ideas.

thanks

[a64pilot]

If its vibrating when the shaft is not spinning, it's not from alignment. It may be from bad mounts though, or possibly a misfiring cylinder from any number of reasons, but I'd suspect injector first, or maybe valves was out of adjustment. (too tight)

[ontherocks83]

Pick up a cheap laser temp gun at sears for 20$. When the engine is vibrating check the temp of each exhaust manifold port and see if one is cooler then the rest. If one is lower, then bring up the idle and see if they even out. If they do then you could be looking at a partially clogged injector or possibly lower compression in the "dead cylinder" (although this is less likely.)

[a64pilot]

I've done the laser temp thing on other engine before and it works well, but will it work on a water cooled manifold?

[donradcliffe]

Crack the nut on the injector input pipe (not the return pipe) to each injector in turn--if the engine slows/runs rougher, then its not that cylinder. If the engine stays the same, you have found your bad cylinder. The first and cheapest thing to do is to pull that injector and take it to an injector shop for testing/replacement.

[ontherocks83]

Originally Posted by a64pilot

I've done the laser temp thing on other engine before and it works well, but will it work on a water cooled manifold?

Good point. Theoretically there should still be a big enough difference to tell but who knows.

[Stu Jackson]

1. Rough idling: What is your low idle rpm? Consider increasing the low idle rpm. Many skippers et theirs to 800 and complain about rough idling. Most Hurth transmissions state they will operate up to 1100 to 1200 rpm. Move it up to 1000 and see if that helps.

2. Dripless box: you haven't told us what kind you have. PSS or standard stuffing box? Which one?

3. Mounts: Tightened motor mounts? What does this mean? Did you just tighten the top nuts or did you end up moving the mounts vertically? Unless you explain this, all the answers are speculative.

[gjordan]

With the lazer temp guage, you should also check the temperature of the injectors after it has been running for 10 or 15 minutes. Aim at the same general spot on each one, and if there is a significant difference, you are close to finding your problem. It can be amazing how smooth a 4 cylinder engine can run with a dead cylinder once you get the RPMs up. ____Good Luck. ______Grant.

[youngsalty]

Thanks everybody.

After reading the post several times here is what I have gathered information wise. The leak filling the bilge from the shaft is its own problem, not related to the vibrating engine. The engine vibrating while idling has a good chance of being cause from a bad fuel injector or a slight chance from the rubber feet on the motor mount being worn out. I suppose first I will look at the rubber feet, easiest first and then try to find the bad injector next as mention how from above.

Another question, is the engine usable while in this condition. Meaning is it ok to run an engine on only 3 cylinders?

Thanks again for the help.

[a64pilot]

You won't kill it right away, but it's better that it runs on all four.
I believe though if it's what I think it may be, that under a load it's running on all four.
I think it's an injector, but that is purely a guess. If it's an injector it will take all of about two min to find out which one by loosening the lines.

[gjordan]

Just as a side note, check your engine oil for fuel contamination. The smell test works OK. Running on 3 cylinders can have unburned fuel leaking past the rings, which could possibly lead to a runaway diesel. A good injector puts an even spray of fuel into the combustian chamber, but a bad one can put no fuel, or the correct amount, but as a stream instead of a spray, or an uncontrolled volume of fuel which will not ignite. Cracking the injector nuts one at a time is the best way to isolate the bad cylinder, but then you need to take the injector to a shop and get it POP TESTED, to determine if the injector is the problem. If the injector tests good, then you have a much more serious problem(rings or valves) ______Good Luck with it. _____Grant.

[youngsalty]

Tomorrow is the day I will test for a bad injector, just want to be sure I know what I am doing.

Quick questions; by cracking the fuel injector nut, will diesel fuel spray everywhere, should I place a rag on top while loosening the nut? Also what sound or sign will tell me it's a bad injector? Should I crack the nut when the engine is vibrating all over the place (could be hard to get a wrench on it) or idle it higher to calm the engine down then do it.
Also when you say take it to an injector shop, is this a marine boat shop or do I need to send it away to a special diesel engine repair shop? My apologies for all the question, just want to do it right and not make things any worse.

Thanks again for all the help, I think I can fix this.

[ontherocks83]

Originally Posted by youngsalty

Tomorrow is the day I will test for a bad injector, just want to be sure I know what I am doing.

Quick questions; by cracking the fuel injector nut, will diesel fuel spray everywhere, should I place a rag on top while loosening the nut? Also what sound or sign will tell me it's a bad injector? Should I crack the nut when the engine is vibrating all over the place (could be hard to get a wrench on it) or idle it higher to calm the engine down then do it.
Also when you say take it to an injector shop, is this a marine boat shop or do I need to send it away to a special diesel engine repair shop? My apologies for all the question, just want to do it right and not make things any worse.

Thanks again for all the help, I think I can fix this.

You would need to do it when the engine is running rough. If the problem gets worse when you open the first injector then that one is good. Eventually you will crack one and there will be no change at all, that is the bad one.

If you were to do it while it is running smoothly most likely you won't get a correct test result.

[a64pilot]

Some fuel will spray, less than you would think but a rag is not a bad idea.
If you find a bad injector my opinion is avoid a marine repair shop and go to the Diesel shop the truckers and farmers go to. Unless of course you have a good relationship with a marine Diesel shop.


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[a64pilot]

If it is a bad injector you may want to invest in a new one. Have your old one fixed and keep it as a spare. Injector problems are common enough to warrant having a spare in my opinion


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