Engine making "clackity clack" noises

[macbeth]

I'm just about to change the engine oil at the end of this summer season in my 15 year old Universal 25 HP diesel 3 cylinder engine. About 1500 hours on it.

When I took the cover off, I could distinctly hear a "clackity clack" noise. Fairly consistent at any rev speed.

Any suggestions as to what this might be ? Thanks. If you need more details, please respond. Could I record the noise and put it on this forum somehow ?

[chris95040]

Originally Posted by macbeth

I'm just about to change the engine oil at the end of this summer season in my 15 year old Universal 25 HP diesel 3 cylinder engine. About 1500 hours on it.

When I took the cover off, I could distinctly hear a "clackity clack" noise. Fairly consistent at any rev speed.

Any suggestions as to what this might be ? Thanks. If you need more details, please respond. Could I record the noise and put it on this forum somehow ?

You say "consistent at any rev", but it does change in repetition rate as a function of RPM, yeah?

Better equipped folks will come along and ask to describe that clackity clack, but first question: Are you sure it's abnormal?

Coming from a small gas engine background, diesels always sound scary and broken to me up close. But thusfar, they haven't been.

[Cheechako]

Could be valve adjustment. Could be nothing. With hours of motoring I have often been fooled by sounds I think I hear in the diesel. Worrying, wondering why it sounds different.
You mean when you take the engine cover off... just curious why the engine is running when you do that...? Anyway, it will sound different with the cover off.
Sorry I'm not much help, but diesel noises have driven me crazy for decades with no ill effect. But it's good you are listening, cause often things will complain to you before they have a problem. Maybe someone else has a suggestion.

[MarkSF]

Originally Posted by macbeth

Could I record the noise and put it on this forum somehow ?

You could take a video (including sound), upload it to Youtube, and then post the link here.

[atoll]

1500 hours,time to check those valve,tappet clearances,easy to do with a screw driver,spanner and feeler guage.also worth getting the injectors tested at 1500-2000 hrs

[model 10]

Unfortunately valves tend to get tight not loose. While there is wear on the valve stem tips, rockers, lifters and cam, most often it's the valve seat and face that wear, causing the valve to sink in the head and reducing clearance.

[a64pilot]

Originally Posted by Guy

Unfortunately valves tend to get tight not loose. While there is wear on the valve stem tips, rockers, lifters and cam, most often it's the valve seat and face that wear, causing the valve to sink in the head and reducing clearance.

That is exactly correct, and unfortunately they get quiet too when they are too tight, eventually they get so tight they leak, and burn and you need a valve job then.

Bet your noise is dirty injectors, but valve clearance is so easy to check and adjust you need to do that anyway, even if it was done recently, they may be too loose as they were adjusted loose.

[a64pilot]

Loose valves usually "tick" and are usually very well timed the "clackity clack" is usually dirty injectors and is sort of a sporadic sound, old Redneck way to clean up injectors was automatic transmission fluid in the fuel, it's a high detergent oil, but best is to remove and have tested

[macbeth]

Originally Posted by atoll

1500 hours,time to check those valve,tappet clearances,easy to do with a screw driver,spanner and feeler guage.also worth getting the injectors tested at 1500-2000 hrs

I had the injectors cleaned by a professional firm 2 years ago, so it should not be those.

Could be tappet clearance. But other posters are confusing me ! Some saying they loosen, some saying they tighten ! What is the TRUTH ?!

In either case, are they fixable ?

I'll try making a recording !

[a64pilot]

Injectors can varnish up rather quickly enough to mess up the spray pattern, and that will cause a clackity clack noise especially at idle, worse when engine is cold, doesn't cause any harm though and are easily cleaned, even dumping a can of Sea Foam or your favorite brand of snake oil in the fuel may do the trick.
Valves wear tight, if they are loosening, you have another problem like a worn camshaft or something.
Don't get overly concerned though, it could literally be as simple as Summer is over and Diesels are noisier in colder weather is all.

Valve clearance is easily fixable, about a two beer job, assuming good engine access it's easy. I enjoy adjusting valves, easy to do and rewarding, makes you feel like you got something done without all the swearing and bleeding usually associated with boat maintenance.

[darylat8750]

First do a good visual and hands on inspection looking for anything loose. Then check the valves. Typically valves do tend to get tighter with hours used but that is not a hard and fast rule. Some engines do tend to open with use. Modern motorcycles have worked out the wear rates in the valve train to the point that they can go many times longer without needing adjustment than their older cousins. Also it is possible that it is not a wear issue but than something in the valve train has gotten loose for whatever reason. Take a long screw driver and put the metal end on one end of the head and put your ear against the handle. It will amaze you how noisy it is! Work your way to the other end of the head and note if the noises stay consistent.

[Kayoko Monk 33]

Originally Posted by macbeth

I'm just about to change the engine oil at the end of this summer season in my 15 year old Universal 25 HP diesel 3 cylinder engine. About 1500 hours on it.

When I took the cover off, I could distinctly hear a "clackity clack" noise. Fairly consistent at any rev speed.

Any suggestions as to what this might be ? Thanks. If you need more details, please respond. Could I record the noise and put it on this forum somehow ?

Consider this: Diesels actually begin to inject fuel on the UPSTROKE, called timing, as the injection begins and the fuel is sprayed in atomized form in a specific pattern, the fires may begin in many locations due to the heat of compression and these multiple fires and pressure actually run into each other making the rattle or metallic sound diesels make as the pressures become pretty serious and sound runs into itself. Very destructive in a gasser known as predetonation, it happens when compressing gas/air mixture and it compression lights. Once the piston goes over top dead center the expanding gasses push the piston down and the spray continues, duration, pressures are less and piston driven downward by expanding gasses. Maybe you are hearing that normal audible click, maybe an injector pattern is off if its a "new" sound, maybe fuel is too volatile (gas in fuel), maybe piston slap, maybe bearing noise? Have to hear it.

[Cadence]

Just a side thought. I agree with starting by eliminating valve clearance. I would suggest doing that at operating temp. not stone cold. Probably add to skinned knuckles and the swearing.

[hamburking]

Originally Posted by Cheechako

Could be valve adjustment. Could be nothing. With hours of motoring I have often been fooled by sounds I think I hear in the diesel. Worrying, wondering why it sounds different.

I thought I was the only one who listened to his diesel and heard all sorts of imaginary clanks, clunks, moans and thuds. What a relief.

Look for anything loose in a nearby locker.

[a64pilot]

Originally Posted by Cadence

Just a side thought. I agree with starting by eliminating valve clearance. I would suggest doing that at operating temp. not stone cold. Probably add to skinned knuckles and the swearing.

Only issue is if clearances are specified as cold, if so and you adjust on a warm engine, the clearance won't be correct

Sometimes there are two specs, cold and hot, then of course use the hot spec and your fine