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

[colemj]

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?

If it is not showing gray or looking strange anymore, then unlikely you have water in the oil. It's possible if it sat for a long time that the dipstick tube had some condensation in it that mixed with the oil as you pulled the dipstick out. Particularly if there were some large temperature changes during that layup time.

If the oil hasn't turned obviously black, I've often found the color of the oil looks a bit different in different light and light levels. Maybe it was just that. If I am questioning the color, I blot it on some paper towel and my finger and go look at it in a more controlled light environment. Engine room lighting can be frustrating.

Mark

 

[smokey73]

How long is "it hasn't run in awhile." Are we talking a few years, a few months, a few weeks etc. If its a few weeks or even a couple of months I would not expect water in the oil from condensation from the dipstick. I live in a very humid area and I have never seen "grey oil". Did you notice the grey oil after it had been run for awhile or was it before you started it up for the first time? What is the color of the oil now? If it were me I'd change the oil just in case. Really, an oil change doesn't cost that much.

 

[testingthewaters91]

Hey everyone,

Did an oil change today on my boat. The old oil came out black with a milky layer on top. After changing it, the new oil looks good so far — no milky film anymore. I’ll check it again later to be sure.

While I was at the dock, I ran the engine for about 15 minutes in neutral, then put it in gear (both forward and reverse). I saw the prop shaft spinning fine. No obvious water ingress or leaks during this short test (maybe around 10 minutes total).

I’ve attached photos showing what I found.

Any thoughts on what might have caused the milky layer initially? Or anything else I should check next?

Thanks!

 

[smokey73]

There should not be a "milky" layer on top. That is emulsified oil (water in the oil mixes with the oil and get kind of "frothy".) Was it just a few mm of milky layer or much more? When you changed the oil, had you just run the engine to heat up the oil (that is what I do). Did you happen to take a picture?

I don't really think the water under the engine is coming directly from the PSS seal. A video of the shaft turning would be useful to see if there is an alignment issue. Also a picture of all four engine mounts, as best you can, showing the rubber portion would be helpful. Even if it is not associated with the leak you should inspect these periodically. Since this is a "new boat" to you, knowing as much as you can about condition of critical components and equipment is important.

A sea story follows: I once had a mooring mate that was confused by the "milky stuff" in his bilge and thought it might be "sediment we call pluff mud here" and I told him that is not likely as the water is 20 deep where his mooring sits. He said if feels "slick" and I knew immediately it was emulsified oil. He said "Oh" that makes since because he had a major oil leak that emptied his engine oil on a short 2 mile trip from his mooring to a dock We then went out to his boat for a "look around" and he did not know where all his through-hulls were located, how many there were, and if they were closed or open . Some doors where they might be were "stuck" or screwed shut and could not be opened without tools. I am not saying that you are in that state of knowledge but you need to crawl all over you boat and into every cranny and crack where you can stick your head and see what is there. You'd be surprised. I found a good 3 bladed prop stuck in a cranny that the PO had put there when he installed a MaxProp. Sold it to someone on the site here and he was pleased as punch.

 

[dlochner]

Hey everyone,

Did an oil change today on my boat. The old oil came out black with a milky layer on top. After changing it, the new oil looks good so far — no milky film anymore. I’ll check it again later to be sure.

While I was at the dock, I ran the engine for about 15 minutes in neutral, then put it in gear (both forward and reverse). I saw the prop shaft spinning fine. No obvious water ingress or leaks during this short test (maybe around 10 minutes total).

I’ve attached photos showing what I found.

Any thoughts on what might have caused the milky layer initially? Or anything else I should check next?

Thanks!

The black streak under the shaft seal is probably carbon coming off of the seal as the graphite collar and the SS collar mated. Some water would have sprayed out as this happened, but that would have occurred right after the new seal was installed.

 

[sailcapt340]

On my 340 there is a weep hole in the stringer that is just behind the engine compartment.
This is 1 1/2” high and isolates the pan under the engine, keeping any liquids that may leak or spill contained, under the engine.
Any water that may spray from the PSS or leak from the engine thru hull will find its way into the bilge.
This is what lead me to believe it was the hose you have attached, as I do, to the PSS, that may be the cause of the water you show “under” the engine.
If you have ruled that out and If you do not have this weep hole in your boat, or its covered over or plugged, then does any water that may appear in that area, stay under the engine compartment, until you manually pump it out?

 

[JoeWhite]

I am not sure what engine we are dealing with but on my Universal engine the heat exchanger has end caps on both ends. They were leaking evidenced by salt deposit. I discovered one cap was cracked due to overtightening. Replacing them and with new pads stopped the leaks.
Spray from this cap may enter the engine oil through the dip stick entry.

 

[testingthewaters91]

Hey everyone,

First off, it’s great learning this engine build with all of you. I really appreciate the advice and read every post carefully.

Quick update: I’ve checked all my pictures around the prop shaft and don’t see any weep hole. Access isn’t great, but nothing obvious so far.

I also noticed a cutaway in the fiberglass right below the bellows of the PSS shaft seal. Water doesn't seem to fall into that cutaway. It falls somewhere and pools forward because the compartment slopes down (not into the bildge). I’ve never seen water directly under the seal itself. Not sure if that’s normal or a clue.

Another detail: there’s a hose attached to the top of the carbon graphite rotor on the PSS seal. It runs straight up above the engine compartment and I assume it’s an air vent. My hull speed is about 6.8 knots.

I’ll get more pictures, maybe a video of the shaft in gear, and lay paper towels next time to trace any drips.

Is that cutaway normal? And should I definitely see a weep hole somewhere?

Thanks again for all the help!

 

[testingthewaters91]

I am not sure what engine we are dealing with but on my Universal engine the heat exchanger has end caps on both ends. They were leaking evidenced by salt deposit. I discovered one cap was cracked due to overtightening. Replacing them and with new pads stopped the leaks.
Spray from this cap may enter the engine oil through the dip stick entry.

This is a Yanmar 2GM20F. I apologize if I failed to mention it earlier.

 

[dlochner]

Another detail: there’s a hose attached to the top of the carbon graphite rotor on the PSS seal. It runs straight up above the engine compartment and I assume it’s an air vent. My hull speed is about 6.8 knots.

Yes, it is a vent. Without the vent the seal needs to be burped by separating the graphite collar from the SS collar. If it is not burped there is no water in the seal to cool the bearing surfaces.

Normally, water rises up in the hose to the waterline. When moving forward the water level may drop a bit. In reverse water may rise, how far really depends on how fast the prop is spinning in reverse. In reverse water goes up the shaft log to seal and then up hose, run hard enough water can come out of the hose. Some people put a catchment system in to collect the water, others just let it drip out. In salt or brackish water it is probably best to collect the water in a catchment system or use a Hy-Vent (Amazon Link). PSS also sells them for a much higher price.

Hy-Vent

The Taco Hy-vent for sailboats and other low-speed watercraft. This product is a great option to maintain an air-free system and ensure the engine room stays dry in the event of backflow (from prop wash, unusual external pressure, backing down, etc)

pssseal.store

 

[smokey73]

I use the Hy-Vent. I used to just run the tube up high but when I backed down hard, I noticed water was coming out of the tube so I shifted to a collection bottle that I had to empty ever once in a while. I decided to shift to the Hy-Vent and don't have any water entering when backing down now. I forgot about that detail. Thanks @dlochner for the reminder. I'll bet that is his source of the water.

 

[jssailem]

Another detail: there’s a hose attached to the top of the carbon graphite rotor on the PSS seal. It runs straight up above the engine compartment and I assume it’s an air vent.

That is correct. It allows any air that gets trapped around you shaft to vent keeping the PSS cool.

 

[BAD ORCA]

Is it just me? That shaft seal looks WAY too compressed. I have never seen a properly compressed bellows all scrunched up like that. I wonder if the black carbon splashing is from too much pressure between the carbon stator and the stainless collar? It almost looks like the forward clamp nearest the bellows is in danger of wearing into the rubber of the bellows. I know the PSS has a bit of a gap there when normally compressed, but as that bellows ages I would worry it may push/fold forward and start to make contact that forward clamp. Hard to tell from the pics but the bellows are clearly distorted and in one pic it looks like the edge of the clamp is already making contact with the rubber of the bellows.

 

[testingthewaters91]

Yes, it is a vent. Without the vent the seal needs to be burped by separating the graphite collar from the SS collar. If it is not burped there is no water in the seal to cool the bearing surfaces.

Normally, water rises up in the hose to the waterline. When moving forward the water level may drop a bit. In reverse water may rise, how far really depends on how fast the prop is spinning in reverse. In reverse water goes up the shaft log to seal and then up hose, run hard enough water can come out of the hose. Some people put a catchment system in to collect the water, others just let it drip out. In salt or brackish water it is probably best to collect the water in a catchment system or use a Hy-Vent (Amazon Link). PSS also sells them for a much higher price.

Hy-Vent

The Taco Hy-vent for sailboats and other low-speed watercraft. This product is a great option to maintain an air-free system and ensure the engine room stays dry in the event of backflow (from prop wash, unusual external pressure, backing down, etc)

pssseal.store

Ah, I see. The Hy-Vent is an excellent idea — I didn’t know about that, and I find it interesting that there’s yet another component they can sell based on the construction of this PSS dripless seal. I’m surprised that there needs to be a ~$50 add-on to something already so engineered, but the strange, intermittent occurrence of water in the engine compartment might have something to do with backing up and the water running up that hose, possibly spilling out and maybe even landing on top of the engine. That could have led to water ingress into the engine and the white milky film on the oil I saw before. They may all be related. I should consider getting a Hy-Vent. I’m not even sure where that hose runs to on my boat — I’ll have to double-check the very top of the hose. I’d consider installing a Hy-Vent if it works well for others. My boat is currently in brackish water.


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I use the Hy-Vent. I used to just run the tube up high but when I backed down hard, I noticed water was coming out of the tube so I shifted to a collection bottle that I had to empty every once in a while. I decided to shift to the Hy-Vent and don't have any water entering when backing down now. I forgot about that detail. Thanks @dlochner for the reminder. I'll bet that is his source of the water.

I’ve never noticed water coming out of my vent line, but I’d probably need to get a friend to help me test that. It definitely makes sense, though.


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That is correct. It allows any air that gets trapped around your shaft to vent keeping the PSS cool.

I’ve never had any overheating issues with my PSS seal so far.


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Is it just me? That shaft seal looks WAY too compressed. I have never seen a properly compressed bellows all scrunched up like that. I wonder if the black carbon splashing is from too much pressure between the carbon stator and the stainless collar? It almost looks like the forward clamp nearest the bellows is in danger of wearing into the rubber of the bellows. I know the PSS has a bit of a gap there when normally compressed, but as that bellows ages I would worry it may push/fold forward and start to make contact with that forward clamp. Hard to tell from the pics but the bellows are clearly distorted and in one pic it looks like the edge of the clamp is already making contact with the rubber of the bellows.

That’s an interesting observation. Some folks were saying earlier that it wasn’t quite compressed enough, so I’d love to hear more opinions about whether my bellows is compressed properly. I’ve uploaded some more detailed images and I’ll try to attach them in this post as well so people can see. So far, when the engine is just spinning at the dock — not at high RPM and not with much water motion — I haven’t noticed any water, which leads me to believe this might be related to the air vent and water running up when I’m in reverse or something like that. But I definitely want this PSS seal to last and stay in great condition, since it’s relatively new and I’m trying to treat my boat carefully.

 

[colemj]

I’m surprised that there needs to be a ~$50 add-on to something already so engineered,

Check out the Amazon link @dlochner posted. It is kind of buried in the text, so you might have missed it. These are common vents and can be bought for $15.

Mark

 

[sailme88]

Check the gaskets on the heat exchanger,,, Also, there should be a hose from the nipple at the thermostat to an expansion tank.

 

[dlochner]

Ah, I see. The Hy-Vent is an excellent idea — I didn’t know about that, and I find it interesting that there’s yet another component they can sell based on the construction of this PSS dripless seal. I’m surprised that there needs to be a ~$50 add-on to something already so engineered, but the strange, intermittent occurrence of water in the engine compartment might have something to do with backing up and the water running up that hose, possibly spilling out and maybe even landing on top of the engine. That could have led to water ingress into the engine and the white milky film on the oil I saw before. They may all be related. I should consider getting a Hy-Vent. I’m not even sure where that hose runs to on my boat — I’ll have to double-check the very top of the hose. I’d consider installing a Hy-Vent if it works well for others. My boat is currently in brackish water.

Product evolution. In the beginning there were 2 types of PSS seals, one for high speed power boats and one for low speed sailboats. The Powerboat model needed to have the vent tube and some use the vent tube to force water into the seal for cooling. Sailboats didn't need the forced cooling water, so no vent was needed. But sailors had to burp the seal after each time the boat was hauled and launched. For some boats this was extremely difficult, some people forgot, and if not done correctly the graphic collar could be damaged. Eventually, some one at PYI figured out that making 2 of the same things with only one difference was unnecessary and sailors would like not having to burp their seals. Thus the unvented seal was dropped from the product line.

As more sailors used the vented seal it became apparent that under certain conditions water could back up and out of the vent. Not a big problem in freshwater, however in salt water engines were getting sprayed and salt would build up. Solutions evolved including adding a home built catchment system. Eventually someone figured out that a Hy-Vent would solve the problem.

PSS sells a basic Taco Hy-Vent at a premium price, adding in a couple clamps, those clamp protectors, and the fitting for the hose. You could assemble the same kit for a little less money shopping at Amazon and the local hardware store. The clamps are high quality SS, better and more expensive than HW store clamps.

I can't remember if I bought mine from Amazon or PSS. Regardless, I would not buy a knock off from Amazon, only a Taco Hy-Vent and I only use 316 SS clamps with a solid band.

 

[dlochner]

Check out the Amazon link @dlochner posted. It is kind of buried in the text, so you might have missed it. These are common vents and can be bought for $15.

Mark

I wanted to highlight the endorsement from PSS for the HY-Vent, so I included the Amazon link in the text and highlighted the PSS link. The PSS kit can be easily replicated at the HW store and Amazon, except for the clamp jackets the 316 SS clamps for less money and more effort.

 

[BAD ORCA]

That’s an interesting observation. Some folks were saying earlier that it wasn’t quite compressed enough, so I’d love to hear more opinions about whether my bellows is compressed properly. I’ve uploaded some more detailed images and I’ll try to attach them in this post as well so people can see. So far, when the engine is just spinning at the dock — not at high RPM and not with much water motion — I haven’t noticed any water, which leads me to believe this might be related to the air vent and water running up when I’m in reverse or something like that. But I definitely want this PSS seal to last and stay in great condition, since it’s relatively new and I’m trying to treat my boat carefully.

I think they might have been thinking if its dripping then this is usually the case, that the seal is under compressed, however i think maybe those comments might have been made generally and without considering the pictures first? I'm not sure, maybe someone will confirm. When mine is properly compressed, I can still clearly see all the low channels/folds of the bellows. I would send a photo and email to PSS maybe and ask them their opinion. I have only had two of them so could be perfectly normal the way yours is compressed. I'm looking at pics on google and see other boats look similar so maybe fine. It might be my boat for whatever reason does not require highly compressed seal.

 

[jssailem]

The instructions were provided in an earlier post. The PSS has a different compression for each shaft size. I believe the 1” shaft is 3/4”compression from a static state when installed.

here is the link to the manual. They are a pretty handy tool. Try page 3. Less need to guess.

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