Water in oil again & exchange Jabsco pump

[single]

I had water in the oil about a year ago so i changed the seals on the raw water pump.All has been good until i checked it today and i have water in the oil again. I pumped the oil out and rather than 4.5lts i removed about 7lts. There is no fresh water coolant loss, no oil cooler fitted and the exhaust has a Vetus anti-syphon valve which seems to work. This to me suggests it must be salt water getting past the Jabsco raw water pump seals? Any other ideas? Also ,i'm sure i saw somewhere a company that takes the old jabsco pump part-ex for a new one? Engine is a Thornycroft T-95 (Mitsubishi)

 

[Pords]

I've just had same problem but all of my own doing. Have you though about head gasket might have blown I replaced the seals on my pump thinking the seals had failed but it turns out I was pressurising the system by gravity feeding the water pump when running up for launch day. Water backfilled into exhaust and into engine which is now undergoing major overhaul.

 

[single]

I've just had same problem but all of my own doing. Have you though about head gasket might have blown I replaced the seals on my pump thinking the seals had failed but it turns out I was pressurising the system by gravity feeding the water pump when running up for launch day. Water backfilled into exhaust and into engine which is now undergoing major overhaul.

But if it was head gasket, i would be losing fresh water/coolant?

 

[RichardS]

I had water in the oil about a year ago so i changed the seals on the raw water pump.All has been good until i checked it today and i have water in the oil again. I pumped the oil out and rather than 4.5lts i removed about 7lts. There is no fresh water coolant loss, no oil cooler fitted and the exhaust has a Vetus anti-syphon valve which seems to work. This to me suggests it must be salt water getting past the Jabsco raw water pump seals? Any other ideas? Also ,i'm sure i saw somewhere a company that takes the old jabsco pump part-ex for a new one? Engine is a Thornycroft T-95 (Mitsubishi)

Is that 7 litres of oil or 7 litres of mayonnaise? If it looks like oil the water would have to show up as a separate layer as it can't be emulsified, and even if it was emulsified it would separate out quickly if it really was 4.5l of oil and 2.5l of water.

Once it separates out a quick taste will tell where it came from.

Richard

 

[knuterikt]

What did the shaft look like when you replaced the seal?

 

[single]

The stuff i drained out was 7ltr of light grey emulsion. Its in a drum onboard so i'll poor some into a glass container tomorrow.
The water pump shaft must have looked good or i would have questioned it at the time.

 

[PaulRainbow]

The stuff i drained out was 7ltr of light grey emulsion. Its in a drum onboard so i'll poor some into a glass container tomorrow.
The water pump shaft must have looked good or i would have questioned it at the time.

Did you use the correct seals, or some that matched the original dimensions ?

"Normal" seals usually have mild steel springs, which rust and break in a year or less (ask me how i know).

 

[single]

Did you use the correct seals, or some that matched the original dimensions ?

"Normal" seals usually have mild steel springs, which rust and break in a year or less (ask me how i know).

I bought them from ASAP so i assume they were genuine.

 

[PaulRainbow]

I bought them from ASAP so i assume they were genuine.

I'd assume so too.

I'd say you need a new pump. I'd also say the design of the pump is less than ideal if it lets water into the oil. Does it only have a single seal ? Be better if it had two, one to keep the oil in the engine and one to keep the water in the pump, with an air gap between the two to prevent the two getting mixed up.

 

[single]

I'd assume so too.

I'd say you need a new pump. I'd also say the design of the pump is less than ideal if it lets water into the oil. Does it only have a single seal ? Be better if it had two, one to keep the oil in the engine and one to keep the water in the pump, with an air gap between the two to prevent the two getting mixed up.

It had two seals but only one separated the oil if i remember correctly

Here it is- https://www.jabscoshop.com/jabscoshop-spare-parts/29450-1231-pump-20mm-brz-20-flange.htm

so seal 12 & 20 would have to fail but even then seawater should drip into the bilge, not along the shaft?

 

[single]

Another possibility is the exhaust, so what is the difference in meaning between these two paragraphs?



Mine has a gooseneck at the stern , a Vetus water trap and a Vetus anti-syphon valve running from the exhaust elbow.

 

[Tranona]

Another possibility is the exhaust, so what is the difference in meaning between these two paragraphs?

View attachment 64016View attachment 64017

Mine has a gooseneck at the stern , a Vetus water trap and a Vetus anti-syphon valve running from the exhaust elbow.

the difference is that the one on the left is describing a loop in the exhaust at the transom before it exits and the one on the right is describing the anti syphon valve which you have. You don't need the vent in the loop if you have an anti syphon valve as they both perform the same function.

 

[single]

Or.........is it possible it could be diesel getting into the oil? Would that make a thin grey emulsion?

 

[PaulRainbow]

Or.........is it possible it could be diesel getting into the oil? Would that make a thin grey emulsion?

No, diesel will mix with oil. You would just have thin oil that smells of diesel.

Looking at the diagram of your pump, there are indeed two seals and an O-ring. I see from the lower left diagram, showing the pump dimensions, that your pump does have two seals and they are separated by an air gap, where the O-ring, part #18, is situated. There is no way the failure of the water pump seal can allow water to get into the oil.

You need to look elsewhere. If you are sure that there is no loss of freshwater coolant then the water in the oil must be saltwater. I'm not familiar with your particular engine, but a quick Google suggests it's normally aspirated and as you say it has no oil coolers there aren't many places seawater can get in.

If the system is as basic as seawater coming to the pump > the heat exchanger > to the exhaust, it's hard so imagine the ingress can be from anywhere other than the exhaust.

 

[RichardS]

There is no way the failure of the water pump seal can allow water to get into the oil.

I'm surprised that you're so definitive about that.

It's a rotating shaft water pump which passes through 2 lip seals and an O-ring. If the seals and O-ring are worn badly, for whatever reason, then unless there is a continuous pressure differential between both ends of the shaft opposing any water flow I can't see why failure of those water pump seals would not allow water to enter the crankcase.

Richard

 

[PaulRainbow]

I'm surprised that you're so definitive about that.

I'm 200% certain.

It's a rotating shaft water pump which passes through 2 lip seals and an O-ring. If the seals and O-ring are worn badly, for whatever reason, then unless there is a continuous pressure differential between both ends of the shaft opposing any water flow I can't see why failure of those water pump seals would not allow water to enter the crankcase. Richard

Look closely at the pictures the OP linked to, bottom left pic, showing pump dimentions. The seal behind he impellor is fitted from inside the pump and the oil seal from the engine side. Between those two seals there is an O-ring. The section of shaft between the two seals, where the O-ring is situated, is exposed.

If the water pump seal leaks, water drips off th shaft at the O-ring. If the other seal leaks oil drips into the engine compartment. If both seals failed, water and oil would both leak out.

If both seals failed, there is no way water would leak out of the seal and travel along the shaft, past the O-ring and then through the other seal into the engine.

Without the air gap at the O-ring it would be a different story, hence my earlier comment that if the water could get into the oil it was a badly designed pump.

This might help you picture it Richard :

http://i493.photobucket.com/albums/rr300/haines35/18052010040.jpg

 

[VicS]

No, diesel will mix with oil. You would just have thin oil that smells of diesel.

Looking at the diagram of your pump, there are indeed two seals and an O-ring. I see from the lower left diagram, showing the pump dimensions, that your pump does have two seals and they are separated by an air gap, where the O-ring, part #18, is situated. There is no way the failure of the water pump seal can allow water to get into the oil.

You need to look elsewhere. If you are sure that there is no loss of freshwater coolant then the water in the oil must be saltwater. I'm not familiar with your particular engine, but a quick Google suggests it's normally aspirated and as you say it has no oil coolers there aren't many places seawater can get in.

If the system is as basic as seawater coming to the pump > the heat exchanger > to the exhaust, it's hard so imagine the ingress can be from anywhere other than the exhaust.

I'm surprised that you're so definitive about that.

It's a rotating shaft water pump which passes through 2 lip seals and an O-ring. If the seals and O-ring are worn badly, for whatever reason, then unless there is a continuous pressure differential between both ends of the shaft opposing any water flow I can't see why failure of those water pump seals would not allow water to enter the crankcase.

Richard

Just what can and does happen with a directly driven raw water pump.

The seals should be fitted so that the spring side of the water seal faces the pump and the spring side of the oil seal faces the engine

One will then prevent water leaking out of the pump while the other prevents oil leaking from the engine. Neither seal will work well in the opposite direction, meaning that if the water seal fails badly water leaking from it can overwhelm the oil seal and enter the sump.

However a leaking water seal should be made obvious by water leaking from the drain hole in the pump body between the seals long before it becomes so bad that water enters the engine. provided of course nothing is blocking the drain hole!

I would definitely check on the water pump, especially checking for shaft wear, correct installation of the seals , correct spring material and that the drain hole is not blocked ( VP, I seem to remember recommend removal of the O ring with some of their pumps as this, presumably, has been found to obstruct the drain hole!)

My smart money however would be on a defective or incorrectly installed antisyphon loop and vacuum valve on the seawater system.

 

[RichardS]

This might help you picture it Richard :

http://i493.photobucket.com/albums/rr300/haines35/18052010040.jpg

Indeed, that is helpful. Those are very large cut-outs so I see where you're coming from. Whilst Vic and I are correct that all the seals could fail and water entering the oil system is certainly possible, with that design it would have to be a very large water flow to pass over those gaps or a huge amount of dirt blocking them, so it is very unlikely.

Richard

 

[PaulRainbow]

Just what can and does happen with a directly driven raw water pump.

Not all pumps can do this, see the diagram to OP posted and the pic i posted.

The seals should be fitted so that the spring side of the water seal faces the pump and the spring side of the oil seal faces the engine

Better yet, upgrade to double lip seals (if they are not fitted as standard).

provided of course nothing is blocking the drain hole!

I would definitely check on the water pump, especially checking for shaft wear, correct installation of the seals , correct spring material and that the drain hole is not blockedhas been found to obstruct the drain hole!)

Again, check the images Vic. The OPs pump doesn't have a drain "hole".

My last boat had a very similar pump to the OPs and i had a seal fail badly. The engine compartment took on a lot of water from the leak, nothing got into the oil. The spining shaft and the large air gap between the seals forced the water to be sprayed into the engine compartment.

My smart money however would be on a defective or incorrectly installed antisyphon loop and vacuum valve on the seawater system.

I'll put my money with yours then

 

[VicS]

Not all pumps can do this, see the diagram to OP posted and the pic i posted.


Better yet, upgrade to double lip seals (if they are not fitted as standard).


Again, check the images Vic. The OPs pump doesn't have a drain "hole".

My last boat had a very similar pump to the OPs and i had a seal fail badly. The engine compartment took on a lot of water from the leak, nothing got into the oil. The spining shaft and the large air gap between the seals forced the water to be sprayed into the engine compartment.



I'll put my money with yours then

Odd then if the OP's pump has a open bodied design like the one in your picture that changing the seals previously solved the water ingress problem.

It didn't I suppose, just a coincidence