Water under engine while motoring — shaft seal leak? [Photos attached]

[testingthewaters91]

Hi all,

I’ve got a new old sailboat (1981 Hunter 30) and I’m trying to diagnose some water I’m finding under my engine after running under power.

Details:
The shaft seal system was completely rebuilt two summers ago.

The water doesn’t go into my main bilge—it collects under the engine.

I cleaned it up, and it only seems to appear when the engine is running and the shaft is spinning.

I’m afraid of the risk of sinking if this worsens.

I’m attaching photos of my shaft coupling and what I think is the stuffing box (or possibly a dripless seal?).

Questions:
1. Can anyone confirm what type of seal this is in my photos? Stuffing box or dripless?

2. Is this amount of water normal “drip” or does it mean something is wrong?

3. Should I tighten anything, or is it time to repack or service it?

4. Is there an immediate risk of sinking if I keep running it like this?

5. Any advice on next steps?

Thanks a ton for any insight! Trying to stay safe and keep the boat dry.

 

[garymalmgren]

RE, 1. Can anyone confirm what type of seal this is in my photos? Stuffing box or dripless?
This is a dripless shaftseal. I don't know the brand.

2. Is this amount of water normal “drip” or does it mean something is wrong?
A drippless seal should let no water in. Something is wrong.

3. Should I tighten anything, or is it time to repack or service it?
Identify the brand of seal and try to find a manual for correct procedures.
Do you have a manual amongst the documents aboard?
I have a feeling that you have come to the right place and a knowledgeable person will be along soon.
It could be as simple as moving the propeller shaft seal ring 1/16 inch closer to the rubber bellows seal ring.
Are there any small cracks in the bellows?
That will give you some indication of the age of the unit and how hard it has worked.

4. Is there an immediate risk of sinking if I keep running it like this?
Hard to answer that one remotely. I would say no, not immediately. But that means nothing.
Is the seal leaking when the shaft is not rotating?

5. Any advice on next steps?
Stay tuned here for some solid advice.

gary

 

[sailcapt340]

Where does the hose in your photo that is attached to the seal end? Is the end higher than the motor? Does the water appear in forward or reverse gear or both? On my shaft seal that hose runs UP the back wall of the engine compartment. Mine will show “some” water coming out the end when I am motoring in reverse, not forward. Not enough though to create a flood, as you show. I have mine empty into an overflow canister, above the motor, to catch any water that may come out. Basically to eliminate any rusting that could occur.
My feeling is your hose is not higher than the motor causing water to empty out under it into the pan. I could be completely off but it is worth a look.

 

[dlochner]

The shaft seal is a PSS Shaftseal

In normal use it should not drip. It may not be installed correctly, it may be old and leaking, the engine may not be aligned correctly. All of these can produce drips. It is recommended by the manufacturer to replace the bellows every 5 or 6 years.

There is nothing to repack or service, just replace the bellows every 5 or 6 years.

It is only leaking when running, so it won't sink at the dock. Take a look at it while running to determine how bad the leak is. If the engine is out of alignment it will leak when running and possibly not at other times.

Check engine alignment. Replace bellows. Consider another brand of dripless seal.

 

[Davidasailor26]

It’s definitely a dripless seal. Looks like a PSS or similar. If “rebuilt” means it was replaced two years ago then it really shouldn’t be due for replacement yet, but it shouldn’t be dripping.

One possibility is that the collar wasn’t properly secured and has slipped up the shaft, reducing the compression of the bellows. If that’s the case you’ll need to order new grub screws (don’t reuse them), compress the bellows again, and tighten it back down with the new screws. On the other hand you don’t want to tighten it down more if it’s already where it should be and there’s a different source of the leak. Can you tell where exactly the water is coming from? Maybe by putting a paper towel under it to narrow down the source of the leak? If the bellows compression in the issue the water would be coming from the interface between the collars.

If it does come to replacing the seal @Scott T-Bird just went through that at Shaft Seal (almost a fail)

 

[testingthewaters91]

Thanks so much for all the responses so far!

I’m leaning toward thinking it’s a PSS dripless seal (or something similar), but I’m still not completely sure. I haven’t been able to pinpoint the exact source of the water yet.

Here’s what I’ve observed:

The water only shows up under the engine after motoring or certain times under sail.

The area under the engine is not connected to the bilge, so it just pools there and I usually shop-vac it out.

I’ve noticed water under the engine three separate times so far:

1. After a recent haul-out.

2. Right after putting the boat back in the water.

3. When I took the boat out today for a sail/motor.

Interestingly, when I took it out for a short sail the other day, using the motor for a bit and not heeling much, there was no leak at all and it stayed completely dry underneath afterward.

So I’m wondering:

Could this be related to how the boat heels under sail?

Or to forward vs. reverse motion under power?

Or maybe something with the re-launch after haul-out?

My plan is to run the motor while tied up at the dock tomorrow, in forward and reverse, and observe closely around the seal to see if I can spot the leak directly.

I’m also planning to go in and take more pictures tonight and tomorrow, and I’ll post them here in this thread.

Questions for the group:
1. Does it make sense that a PSS seal might leak only intermittently—depending on load, alignment, or heel angle?

2. Could anything about the recent haul-out/relaunch have disturbed the seal?

3. Is there anything specific I should look for while running the engine in gear at the dock?

4. Is it normal for there to be zero leaks sometimes, then some water other times, especially with a dripless seal?

5. Any tips for inspecting the PSS seal more closely?

Thanks again for all the advice—it’s been super helpful, and I appreciate everyone’s insights immensely!

 

[testingthewaters91]

I’m definitely planning to run the engine at the dock tomorrow, both forward and reverse, to see if I can spot exactly where the water is coming from. The idea of using a paper towel under the seal is great—I’ll try that to pinpoint the leak.

I’m also going to check:

Whether the PSS seal collar has slipped on the shaft.

The bellows for any cracks or signs of wear, even though it’s only two years old.

The hose routing, to see if it might be dumping water into the pan instead of running higher up into an overflow or safe discharge point.

Possible engine misalignment.

I’ll get more photos tonight and tomorrow and will post them here once I have them.

Thanks again—I appreciate everyone’s insights immensely!

 

[jssailem]

1. Can anyone confirm what type of seal this is in my photos? Stuffing box or dripless?

It looks exactly like a PSS type A dripless seal.

here is the manual with troubleshooting information.

https://www.shaftseal.com/downloads/pss-type-a-pro-seal-instructions.pdf

Questions:

2. Is this amount of water normal “drip” or does it mean something is wrong?

Answer . When the shaft is turning there can be some spray. Can happen if dirt gets between the graphite and steel collars. Can happen if there is not enough compression of the bellows. See the instructions in the chart. Compression is based on the shaft size.

3. Should I tighten anything, or is it time to repack or service it?
Answer. No packing. Follow the instructions found in the above link.
4. Is there an immediate risk of sinking if I keep running it like this?
Answer. No water coming in when standing still? Then not likely are you going to sink. Check out trouble shooting instructions. It may be that the two collars have not yet fully seated.
5. Any advice on next steps?
Answer. Read the manual. Follow the directions.

The hose was mentioned. The instructions say you can have it open as long as the open end is secure above the water line. Or you can attach it to the HE and let water flow out of it.

Where is the smaller black hose going?

 

[colemj]

Have you ruled out a bad water seal on the raw water pump? That also would only leak when running. Look/touch at the bottom of it and see if it is wet.

Mark

 

[smokey73]

Have you ruled out a bad water seal on the raw water pump? That also would only leak when running. Look/touch at the bottom of it and see if it is wet.

Mark

The cover plate for the raw water pump might be leaking, especially if it has been removed and replaced recently. You could also have leaks where the raw water supply hose attaches to the pump are even leaking from a degraded hose.

Are you having to replenish coolant in the overflow tank periodically? Should be easy to tell if it is coming from the internal engine cooling water system because it would need to be replenished periodically or you will overheat plus it should smell like antifreeze.

You should be able to tell if it is coming from the PSS shaft seal. When the shaft is turning, if it is not compressed correctly, there will be mist (or maybe even spray) coming from the place where the graphite ring rotates against the stainless steel collar. The same may be true if there is debris in joint. Note that there may be mist when you first break in the new seal but that should stop after it breaks in if it is installed correctlly.

Finally, but it may be just lighting or something else but the graphite ring and stainless steel ring both look brand new. The bellows don't look as new as the graphite ring? Who replaced your PSS shaft seal? Are you sure they replaced the bellows too? You have a "secondary" clamp ring in front of the stainless steel ring which is a very good thing. It should have kept the stainless ring from sliding up and releasing the bellows compression.

 

[dmax]

Your bellows don't look compressed enough - they are supposed to be compressed 3/4" for a 1" shaft. When compressed, the ribs of the bellows should be touching and tight. If this is the case, then it could easily be the source of the leak as the seal requires pressure to work.

 

[testingthewaters91]

Quick follow-up to my earlier posts:

When I first checked the dipstick, the oil had kind of a grey color. I checked it again later, and it looked more like typical dark oil, but I’m still a bit concerned about that initial grey color.

Could that grey color have been from water getting into the oil? Or is it normal if the engine hasn’t run in a while?

Thanks again for all the help—this forum has been amazing.

 

[smokey73]

@dmax That is true and only a little less than the 3/4" will make a big difference. HOWEVER, the leak will be evident as either a mist or a spray when underway.

@testingthewaters91 Just as out of the box thinking. How old are your motor mounts and what condition are they in? Especially if the leak is more when heeling and/or when you are at higher RPM. Remember, the way the motor drives the hull through the water is (like the ankle bone song)
The Prop turns in forward
The forward thrust wants to move the boat shaft forward
The forward motion of the shaft is transmitted to the transmission
The forward motion of the transmission is transmitted to the engine
The forward motion of the engine is transmitted to the engine mounts
The forward motion of the engine mounts is transmitted to the rubber isolator of the engine mount
The forward motion of the rubber isolator is transmitted to the bottom plate on the motor mount
The forward motion of the bottom plate is transmitted to the hull
The hull moves forward

If those motor mount rubbers are bad or something else is wrong, the shaft moves forward more than designed and the bellows relax, possibly leading to a leak. It doesn't take much motion of the shaft forward to relax the bellows just a bit. Have someone looking at the shaft when the engine is running at different RPM and see if the leak appears when in forward or gets worse as the rpm increases. Also, just inspect the motor mounts, they may need replacement anyway.

 

[smokey73]

Quick follow-up to my earlier posts:

When I first checked the dipstick, the oil had kind of a grey color. I checked it again later, and it looked more like typical dark oil, but I’m still a bit concerned about that initial grey color.

Could that grey color have been from water getting into the oil? Or is it normal if the engine hasn’t run in a while?

Thanks again for all the help—this forum has been amazing.

Grey color in the oil is never a good sign. It is not normal for the oil to be grey even if the boat has sat for a long time unless water got in the oil. In any case, change the oil if you don't know when the last time it was changed and keep checking your fresh water cooling system (should have an overflow tank just like your car) and see if it is going down.

 

[dmax]

There is evidence of some spray (dirty) from the seal under it on the gelcoat - mine was perfectly clean. I would compress the bellows properly regardless, they are not installed correctly.

 

[smokey73]

If it is a new carbon and stainless ring it will Mist a little when brand new until it breaks in. It is easy to tell, just hold your hand a few inches above the "joint" the carbon and stainless make and feel. It it gets damp, it is misting. If so, compress the bellows more and check again. It says that in the installation manual I believe. BE SURE TO USE NEW SET SCREWS!

 

[testingthewaters91]

There is evidence of some spray (dirty) from the seal under it on the gelcoat - mine was perfectly clean. I would compress the bellows properly regardless, they are not installed correctly.

Is this something I can do while the boat is still in the water? I plan to go through the manual later.

I’m going to haul out to a DIY yard soon to install proper seacocks and also tackle some remediation on the pedestal under the compression post.

 

[dlochner]

Your bellows don't look compressed enough - they are supposed to be compressed 3/4" for a 1" shaft. When compressed, the ribs of the bellows should be touching and tight. If this is the case, then it could easily be the source of the leak as the seal requires pressure to work.

The SS collar compressing the bellows is held in place by 4 cup point set screws. Do not reuse these screws. ONLY use brand new set screws. Once use the cup point is dull and will not grip the shaft which will allow the collar to move. Each of the two holes gets 2 set screws, the first coated with Blue Loctite (or equivalent) holds the collar in place, the second on top of the first prevents the first screw from loosening.

Many PSS owners back up the first collar with an additional collar to keep the collar tight, some use hose clamps, others use shaft anodes, and others use a SS split collar, which is the best and most expensive. I use a split collar.

The set screws are 316 SS ⅜" x ¼ -20 cup point set screws. I ordered mine from McMaster Carrr. Order a bunch to keep on hand, you'll never know when you might need them again. I also ordered the back up split collar from McMaster.

 

[testingthewaters91]

If it is a new carbon and stainless ring it will Mist a little when brand new until it breaks in. It is easy to tell, just hold your hand a few inches above the "joint" the carbon and stainless make and feel. It it gets damp, it is misting. If so, compress the bellows more and check again. It says that in the installation manual I believe. BE SURE TO USE NEW SET SCREWS!

I was told the engine has “about five hours” on it since it was newly installed.

Here’s a picture of it:

 

[smokey73]

I can see a "peek" at the port forward motor mount. Outward appearance isn't too bad, but it is the condition of the rubber portion that really matters for the discussion of excessive mount movement under power.

I also notice that you do not have a hose hooked up to the heat exchanger tank (cap like on a car in the second picture.) That means you do not have an overflow tank either. Have you checked the level of water in your coolant tank under that cap? No really a likely source of enough water in the bilge to be "noticeable" but still something you should keep an eye on. Only remove that cap when the engine is cold, just like on a car! You'd probably smell antifreeze if it was a leak from the coolant system so I don't think it is a source of the water you describe but could be a source of the grey oil.

I notice you have a split collar on your shaft so you can loosen the set screws in the SS ring, move the ring back a little to compress the bellows, replace the setscrews in the SS ring as @dlochner describes. Then you can loosen the split collar an move it snug up onto the SS ring. This can easily be done while in the water, especially with the split collar still installed since it will keep the SS ring from moving too far forward.