Gordon: have also posted this is the Props and drive train forum.. '91 Catalina 34, Universal M35 30HP diesel, Hurth BW100 transmission with PSS dripless shaft seal. When motoring, occasionaly get a loud, vibrating/grinding noise from the drive train. No consistency at all, happens at all rpms, may motor for hours with not happening or may happen 10 minutes from the slip. Back off the throttle and noise stops. Go right back on the throttle and all is ok until ?? Have talked to several Hurth/Universal mechanics and none have ever heard of this, particularly the inconsistency of it. Have found 2 other Catalina owners who have experienced this and they havent been able to figure out the cause either. The only thing in common was the PSS dripless seal. Is there anything you are aware of re: the PSS seal that could cause this? or any ideas as to what it might be? thanks
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R
R. Palaia
Is the noise a metallic tap,tap,tap??
Can you try to describe what the noise sounds like??(I know it's hard putting it into words). I have the same set up as you and also have grinding noises with the inconsistency you describe. Do you see a black stripe from spray coming from PSS seal?? When at idle speed, in forward, do you hear alot of damper plate chatter, goes away when given a little bit of throttle?? Roc
Can you try to describe what the noise sounds like??(I know it's hard putting it into words). I have the same set up as you and also have grinding noises with the inconsistency you describe. Do you see a black stripe from spray coming from PSS seal?? When at idle speed, in forward, do you hear alot of damper plate chatter, goes away when given a little bit of throttle?? Roc
J
j. mansfield
response to roc
roc: the noise best described as a 1/2 grinding 1/2 vibration. i really cant think of any similar noise other than maybe trying to put an old column shift standard transmission into 3rd gear without putting in the clutch. at first i thought it might be the cutlass bearing seizing. and yes, the PSS shaft throws a black line when this happens. I havent really noticed any damper plate chatter at idle in gear but there could be some. However, one Universal/Hurth mechanic told me the noise made by a bad damper plate was nothing like what i described . it seems odd that the few who experienced this all have PSS shaft seals?? Jack
roc: the noise best described as a 1/2 grinding 1/2 vibration. i really cant think of any similar noise other than maybe trying to put an old column shift standard transmission into 3rd gear without putting in the clutch. at first i thought it might be the cutlass bearing seizing. and yes, the PSS shaft throws a black line when this happens. I havent really noticed any damper plate chatter at idle in gear but there could be some. However, one Universal/Hurth mechanic told me the noise made by a bad damper plate was nothing like what i described . it seems odd that the few who experienced this all have PSS shaft seals?? Jack
R
R. Palaia
I think some is the PSS seal
J.M. If you have the black stripe, what's happening is the carbon ring (clamped to the bellows) starts chattering against the stainless rotor (screwed to the shaft). As the rotor turns, the carbon ring is actually coming off, throwing bits of dust mixed with water out the sides. This sound is a very rapid metallic sound, which I have from time to time. Also, I notice an underlying 'grinding' noise that is inconsistent. And sometimes, even after motoring for hours as smooth as silk, a noticable vibration happens (I dove under the boat, no barnicles, clean shaft and prop). I called PYI, and they told me to move the rotor back to pre-load the bellows. That didn't do anything, still chatters, still have more black dust. I think the bronze shaft tends to 'whip' because it only supported at the skeg and the trans. There is no stuffing box supporting it in the center. So when it whips, it throws the contact on the rotor off. This might also explain the vibration. The grinding I was told could be the shaft hitting the stern tube ever so slightly so the sound reverberates through the hull. I don't know if all this makes sense, but I'm not that happy with the whole set up. My plan is to get rid of the PSS (get a refund), put a traditional stuffing box with the dripless packing (packing about $50), install an aquamet shaft (stiffer than bronze) and a Vetus flexible coupling between the shaft and trans. I have information from other C34 owners with the Vetus and the dripless packing and have great performance. You can ask a million people what all these things could be and drive yourself crazy to get the right answer. Rather than doing things piece meal, I'll take care of this over the winter and hopefully get rid of this once and for all. Roc
J.M. If you have the black stripe, what's happening is the carbon ring (clamped to the bellows) starts chattering against the stainless rotor (screwed to the shaft). As the rotor turns, the carbon ring is actually coming off, throwing bits of dust mixed with water out the sides. This sound is a very rapid metallic sound, which I have from time to time. Also, I notice an underlying 'grinding' noise that is inconsistent. And sometimes, even after motoring for hours as smooth as silk, a noticable vibration happens (I dove under the boat, no barnicles, clean shaft and prop). I called PYI, and they told me to move the rotor back to pre-load the bellows. That didn't do anything, still chatters, still have more black dust. I think the bronze shaft tends to 'whip' because it only supported at the skeg and the trans. There is no stuffing box supporting it in the center. So when it whips, it throws the contact on the rotor off. This might also explain the vibration. The grinding I was told could be the shaft hitting the stern tube ever so slightly so the sound reverberates through the hull. I don't know if all this makes sense, but I'm not that happy with the whole set up. My plan is to get rid of the PSS (get a refund), put a traditional stuffing box with the dripless packing (packing about $50), install an aquamet shaft (stiffer than bronze) and a Vetus flexible coupling between the shaft and trans. I have information from other C34 owners with the Vetus and the dripless packing and have great performance. You can ask a million people what all these things could be and drive yourself crazy to get the right answer. Rather than doing things piece meal, I'll take care of this over the winter and hopefully get rid of this once and for all. Roc
J
j. mansfield
makes sense to me
Roc: That all actually makes sense to me. I may try moving the rotor back a bit to see if it makes any difference. If not, i may go back to the stuffing box. I dont know if there is any chance of the dripless seal eventually failing or not but the noise is very irritating and when other people are on board they are about ready to abandon ship it it happens. thanks Jack
Roc: That all actually makes sense to me. I may try moving the rotor back a bit to see if it makes any difference. If not, i may go back to the stuffing box. I dont know if there is any chance of the dripless seal eventually failing or not but the noise is very irritating and when other people are on board they are about ready to abandon ship it it happens. thanks Jack
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Gene Barton s/v Paradigm
Check Cutless Bearing
It sounds like your cutless bearing is worn. The old stuffing box was probably providing support in lieu of the cutless bearing. Now that you have the PSS, the worn cutless might be allowing the shaft to wobble.. Combine that with a vibrating engine, and the problem you describe could occur. The PSS might be just where it's showing up, not necessarily the cause. I see you have a '91 boat. When did you last replace the cutless bearing?
It sounds like your cutless bearing is worn. The old stuffing box was probably providing support in lieu of the cutless bearing. Now that you have the PSS, the worn cutless might be allowing the shaft to wobble.. Combine that with a vibrating engine, and the problem you describe could occur. The PSS might be just where it's showing up, not necessarily the cause. I see you have a '91 boat. When did you last replace the cutless bearing?
J
j. mansfield
Gene: the cutlass bearing was replaced in '96 during the survey and when the boat was last hauled 2+ years ago was ok. plan to haul for a bottom job in Feb, Mar and will check the bearing again. thanks for your response. Jack
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