Engine transmission makes noise after about 1 hour of running

[ndutton]

After re-reading your post I now see it was diagnostic, sorry. Seems all of the suggestions have been diagnostic.

[JOHN COOKSON]

A Slight Digression

t how many times have we experienced members presenting a problem and during the discussion we hear "the timing is correct", "I set it at TDC", "firing order is correct", "fuel supply is good" or the all encompassing "I know that is not the problem" only to find out otherwise a couple of weeks later? Hypotheses are good places to start but solid troubleshooting tests them before moving on.

My favorite one is "I just fixed\replaced the _______________ (you fill in he blank) so I know that is not the problem."
I try to pay attention to a description of the problem and what has been done to fix it not the stated conclusion.
Also, especially for engines that have not been run for awhile, there may be more than one problem.

TRUE GRIT

[Nicholasmiller]

Thanks very much everybody for all of your responses and advice!

When you are in the boat, the sound is very much like when you change gear in a car and mis-time the clutch and the gears grind. It is actually quite a bit louder than the sound of the engine running and this does not really come across in the audio recording. I checked the cutlass bearing when I had the boat out of the water at the beginning of the season and there was essentially no play when trying to move the prop up and down or from side to side. Also, I re-checked the play at the engine coupling and there is no play in any direction except for maybe 1 or 2 degrees of play when you rotate the coupling in a clockwise/anti-clockwise fashion when the transmission is in forward. My boat has no support bearing on the prop shaft, so there is just the coupling (which I think is a Federal flexible coupling, which I have checked and appears to be OK), and the cutlass bearing supporting the shaft with the PSS in between. Because of the nature of the sound, I am virtually positive that it is transmission related.

I appreciate the comments about ruling out the driveline as a suspect and I have not tried disconnecting the coupling from the engine when the problem occurs because it only occurs at sea after about an hour of running, and leaning over a hot engine to do this at sea when the problem happens is not really feasible! - Plus, it seems to me that the coupling, PSS or cutlass bearing could not cause the sort of noise I am hearing - which in any event seems to be coming from the engine compartment. If I could replicate the problem at the dock, I would definitely give this a try just to absolutely rule out the PSS and the cutlass, but I have never been able to get the problem to happen at the dock and it would also introduce another variable as the engine would not be under load.

The problem only occurs after 1-7 hours of running, although after it occurred the first time on our recent cruise after 7 hours of running, it occurred consistently and repeatedly after about 1 - 1 1/2 hours of running. The problem has never occurred immediately after start-up when the engine is cold, but sometimes reoccurs almost immediately on a re-start if the engine is hot, particularly if the engine is under high load (i.e. in rough weather, exactly when you need it most!).

When the grinding noise happens, it goes away instantly if you shift into neutral but sometimes starts again if you shift into reverse (that is why I have ruled out the accessory drive).

Definitely not seaweed, as the noise has more of a sharp grinding mechanical sound to it rather than the thump thump thump of seaweed - we have a lot of kelp around here so I have lots of seaweed experience!

I think my next step is to remove the reversing gear from the engine and take a look at it. Does anyone know if you can do this with the boat in the water without removing the engine? If this is not feasible, I will pull the engine and put the whole works on the bench over the winter for further investigation!

Thanks Ed for your comments and a link to Al's diagram!

Cheers,

Nick

[Nicholasmiller]

BTW - I have been using Castrol 10/40 four-stroke motorcycle oil for quite a few years to mitigate the wet clutch issue.

[ndutton]

BTW - I have been using Castrol 10/40 four-stroke motorcycle oil for quite a few years to mitigate the wet clutch issue.

OK, I'll bite. WHAT wet clutch issue? There's an issue that needs mitigating??

[Nicholasmiller]

Some years ago some people advocated using motorcycle (crankcase) oil, because motorcycles have a wet clutch (clutch is in the oil unlike a car where it is dry), as motorcycle oil was designed to be used with wet clutches and so did not contain some of the additives that are in normal motor oil these days. Some people reasoned that these "slippery" additives in modern motor oil were increasing the likelihood of clutch slip on the A4. I started using Castrol 10/40 motorcycle oil to eliminate the clutch slip that I was having, and it seemed to be beneficial.
Pretty sure there are some other threads on this on the forum about this.
Cheers,
Nick

[tenders]

As I recall, the advice on this site for "my clutch is slipping" is "adjust clutch so it does not slip, using the Moyer part with more teeth on it if you need to get a finer adjustment than the stock part allows."

I would not use motorcycle oil in my engine unless I were dissatisfied with its performance doing wheelies. Which, for the record, I am not.

Nor am I an expert on clutch issues as I have never had any with my engine. But is it possible that your clutch is now slipping again, noisily?

[ndutton]

Sounds like a solution looking for a problem. I, like most of us, use standard non-synthetic oil as specified by our engine manufacturer with excellent results.

[Nicholasmiller]

Here is one of the original threads on the subject of oil if anyone is interested:

http://www.moyermarine.com/forums/showthread.php?t=7663

ndutton you were in it !

I discounted clutch slip some time ago for a variety of reasons: the noise is too loud; I had the forward adjustment up to the point where it was hard to change gear; + it did not feel there was clutch slip - but who knows - maybe? In any event if it is clutch slip, which I doubt, I have done everything possible to fix it short of pulling the reversing gear and inspecting it for something broken or worn.

[Nicholasmiller]

Incidentally, Robert Hess, who ndutton cited, was the one who recommended me to change to motorcycle oil in the first place, and Don is on record as suggesting it as a potential fix for clutch slip!
Nick

[ndutton]

Back to the earlier question, did you have a slippage issue that needed mitigating by oil type rather than adjustment? Not sure how this applies to the reported noise which is the subject of this thread.

and BTW, I post an awful lot, maybe too much.

It seems pretty clear you've decided the reversing gear must be removed.

[Nicholasmiller]

Yes, at the time I was not able to resolve the slippage by adjustment, so Robert Hess, who looked at my engine at the time, recommended that I switch to motorcycle oil as an experiment. We all concluded at the time that this had resolved the problem. However, my current issue could very well be a recurrence of the original problem which was perhaps never really fixed in the first place and has just got steadily worse. I am currently thinking that I am going to try to remove the reversing gear with the engine in the boat and take a look at it. If I can't get it out, I will pull the engine in the fall when the season is over.
Cheers,
Nick

[BunnyPlanet169]

My apologies ( can of worms )

In hindsight, my thread does seem like an indulgent navel-gazing exercise.

My bad. I was younger then. I simply had no idea just how epic oil threads could be....

I think the ideas are not bad - new oils are not the same as older formulations.

Heavy duty diesel service or wet clutch high performance motorcycle oil have the best combination of engineering specs.

MMI still recommends straight 30 weight, a factory recommendation that dates to the 1950's.

Either will work, and we simply don't have control groups over long periods of time to definitively suggest one is better than the other.