Johnson raw water pump leak

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Insequent

Insequent

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Insequent
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Ocean Alexander 50 Mk I
I have just replaced the raw water pump on my stbd engine with a spare. It was in a John Deere box, but the pump is a Johnson marked F7B-9. Other codes are 10-24753-01. The spare was US$495, so I suspect it is a similar pump that often gets retro-fitted to Lehman's.

What kind of life do you normally get from these things? At just 375 hours I am thinking that a seal failure is a little premature.

It will be no doubt 'interesting' trying to get a replacement or rebuild in Brisbane now the A$ has tanked big time.
 
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Insequent said:
I have just replaced the raw water pump on my stbd engine with a spare. It was in a John Deere box, but the pump is a Johnson marked F7B-9. Other codes are 10-24753-01. The spare was US$495, so I suspect it is a similar pump that often gets retro-fitted to Lehman's.

What kind of life do you normally get from these things? At just 375 hours I am thinking that a seal failure is a little premature.

It will be no doubt 'interesting' trying to get a replacement or rebuild in Brisbane now the A$ has tanked big time.
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My $495 US(AUD $900 landed) AD L120 replacement pumps are on the boat so I can`t check model nos. The Johnson pump itself is from Sweden. The reason to update is the drive connection on the original can fail unexpectedly,it`s not the pump itself.
When I bought my boat the RW pumps were leaking, and were rebuilt, I`d say that`s the way to go.
 
Local dealer has one for about $850. I found another supplier online, free deliveries anywhere in Australia and they wanted $1724 for the same thing. USA prices seem to be about $500-600, with major rebuild kits (bearing and seal) for $350. I don't have a press so a rebuild kit is not convenient right now.

I will take the old one out to the dealer's warehouse in the next day or so to confirm the one they have in stock has the same outlets. Apparently there there is an upgraded pump with slightly different outlets requiring pipe/hose changes as well.

Still looking for feedback on service life of these things.
 
Greetings,
Mr. I. The Johnson pumps on our Lehmans have 1200hrs+ (WAG) on them and short of impeller changes have worked flawlessly. I tend to agree with you that @ 375hrs, a seal failure seems premature. The only thing I could imagine affecting the life of said seal is very silty waters although that would also be reflected in accelerated wear on the pump body itself.
 
I would think 5000 hours might be possible, 3000 probable and if I didn't get 1500 out of a diesel raw water pump I would be flabbergasted.
 
Brian, if it helps,we would have done about 450 hours on ours since rebuild.
The $850 replacement sounds good, and you can take the old one in and compare it. A mechanic told me he could get me a pump locally for about $1000, I preferred getting them fully built up from AD. They came with a new hose, part of the redesign.
 
RTF
When I first noticed the leak I thought it was just the front cover plate. So I removed it, cleaned the O-ring and cleaned the surfaces and re-assembled. There was gritty material on the O-ring and mating faces, so your guess about silty waters could well be correct. When I reassembled, I had no leak at idle. But a few hours run produced about 10 gallons of water into the engine tray so obviously the seal was shot. Hence the replacement. I think I'll buy the local pump but perhaps also import a rebuild kit. It would be about A$500 landed I think. With time I can find someone to do the rebuild for me.
 
My leak was minor compared to the severity of yours. Your two pronged solution sounds ideal. The only problem with rebuilding the old one as backup will be if the new pump has been changed and requires different hoses etc, guess you just keep the old hoses with the rebuilt spare.
 
psneeld said:
I would think 5000 hours might be possible, 3000 probable and if I didn't get 1500 out of a diesel raw water pump I would be flabbergasted.
Click to expand...

Thanks, I thought there ought to be longer life than what I experienced.
 
Insequent said:
Thanks, I thought there ought to be longer life than what I experienced.
Click to expand...

In very silty waters...you could halve those numbers...but it would have to be just about a sand slurry....which I do operate a gasser in and get over 800 hours on a pump regularly.
 
psneeld said:
In very silty waters...you could halve those numbers...but it would have to be just about a sand slurry....which I do operate a gasser in and get over 800 hours on a pump regularly.
Click to expand...

ive a raw water pump for a lehman 120 that needs a rebuild for sale, a rebuild kit from smith is 40$ so they tell me
 
Well I just bought a replacement pump from the John Deere dealer, A$847. It is the same pump, so no need for pipe or hose changes. Just put it back into the spares inventory. The guy said the mechanical seal replacement is about $130 and that the bearings are usually fine, so I'm getting them to rebuild it for me rather than importing the full major overhaul kit.

He also said two interesting things. First, folks in the river, like me, have more issues than others. Second, the commercial users hardly ever have issues. So although the silty river water is an issue, so is just sitting there unused. The message is clear - get out and do a lot more hours!
 
Insequent said:
Well I just bought a replacement pump from the John Deere dealer, A$847. It is the same pump, so no need for pipe or hose changes. Just put it back into the spares inventory. The guy said the mechanical seal replacement is about $130 and that the bearings are usually fine, so I'm getting them to rebuild it...
Click to expand...
That worked out well, much easier than getting them in from the USA.
 
Insequent said:
The message is clear - get out and do a lot more hours!
Click to expand...

:thumb:

The same can be said with so many components on a marine diesel engine.

It is elapsed time more than engine hours that causes the wear. I have seen very low hour diesels with the main bearings badly etched because they hadn't been turned over for long periods of time. Chemical reactions occur damaging the bearing material while it is sitting idle. Sometimes it is due to galvanic corrosion; sometimes an acidic reaction occurs.

Use it or lose it.
 
AusCan said:
:thumb:

... I have seen very low hour diesels with the main bearings badly etched because they hadn't been turned over for long periods of time. Chemical reactions occur damaging the bearing material while it is sitting idle. Sometimes it is due to galvanic corrosion; sometimes an acidic reaction occurs...
Click to expand...
Thanks for that. Years ago, we used to mess with cars, rebuilding rally cars mainly, we`d buy something to get a low km engine that had been sitting a while, engine would run fine at first but soon begin to burn oil. Happened a few times,I came to expect it, now I know why.
 
Sorry - late to this thread. My TAMD41A's run Johnstone pumps. I dealt with a catastrophic failure of both shaft seals (age unknown) on my port motors pump. No indication of any problems before journey (bundaberg -> lady musgrave) - only found the water on checking motors before shutting down on reaching Musgrave. As you can imagine - total soupy mess inside the motor. All good after flushing/running/flushing several (5 from memory) times. And liberal use of a shop vac to vacuume the goop out of the rockers after each run.

Anyhoos... I ended up buying a bearing press from supercheaop auto (~$100) and I bought 3 sets of bearings and seals from CBC bearings. Cost $72 for all three sets. (I think Volvo wanted ~$200 for the rebuild kit). I just took the old bearings and seals in, and they measured and handed over the new ones. They alsop gave me rubber o-rings to replace the springs inside the shaft seals - apparently the most common point of failure in saltwater pump seals. I know insequent has already sorted it (sorry I got here late) but thought it worth mentioning for any future forum members searching fro salt water pump help..

Oh - the actual rebuild (using the bearing press) was a peice of the proverbial. Even a numpty like me could (and did) it.
 
shufti said:
Sorry - late to this thread. My TAMD41A's run Johnstone pumps. I dealt with a catastrophic failure of both shaft seals (age unknown) on my port motors pump. No indication of any problems before journey (bundaberg -> lady musgrave) - only found the water on checking motors before shutting down on reaching Musgrave. As you can imagine - total soupy mess inside the motor. All good after flushing/running/flushing several (5 from memory) times. And liberal use of a shop vac to vacuume the goop out of the rockers after each run.

Anyhoos... I ended up buying a bearing press from supercheaop auto (~$100) and I bought 3 sets of bearings and seals from CBC bearings. Cost $72 for all three sets. (I think Volvo wanted ~$200 for the rebuild kit). I just took the old bearings and seals in, and they measured and handed over the new ones. They alsop gave me rubber o-rings to replace the springs inside the shaft seals - apparently the most common point of failure in saltwater pump seals. I know insequent has already sorted it (sorry I got here late) but thought it worth mentioning for any future forum members searching fro salt water pump help..

Oh - the actual rebuild (using the bearing press) was a peice of the proverbial. Even a numpty like me could (and did) it.
Click to expand...

Still good info, never too late! If my starboard engine's pump fails soon then I'll be following your solution for sure.

It was by chance I found the tray below the engine half full of water, investigated and addressed it before failure. I was still getting good flow out of wet exhaust. There was a tell-tale green discolouration of part of the pump, between where the seal is located and the bearing assembly. The green of course was salt water reacting to copper in the bronze casting over a period of time from a small leak. I'll be watching both pumps closely from now onwards.
 
The water from mine was pouring out the tell-tale in the pump hiousing. Squirting strait through the dead seals into the motor. Joy. Made me sick to the stomach (litterally - came close to hurling) when I looked into the engine bay and saw it. Visions of 2 figure boat dollars dancing through my brain.

For what it;s worth - that was about an 8hr steam at ~7knt (~2100 rpm) with a 5 minute squirt to get through the musgrave entrance on an outgoing tide. Motor didn;t miss a beat the whole trip. Temp and oil pressure remained rock-steady at their normal levels. The olny indication of the failure I had was when I actually saw the water.
 
Just as a side note, I have heard of people blocking the telltale hole in the pump housing to stop the leak.


Not a good idea. The raw water can then be forced past the oil seal and into the engine crankcase. Best to put up the seawater leaking into your bilge until it can be repaired.
 
I picked up the rebuilt pump earlier today. All up it was $362, including a new impellor ($75) and $120 in labour. I'm happy. Replaced was a mechanical seal, 2 bearings and a seal. I also got a new mounting gasket.

The ceramic seal had for some reason bound up to its mating surface, the spring then tore up the rubber seal. Seems it was some kind of mechanical failure rather than from just silty water. I now have two spare complete pumps and also two spare impellor kits.

My spare pump did not have the impellor inside, I assume to prevent memory of the vanes that are bent over near the outlet. I intend to store both spare pumps with the impellor removed as well. The parts guy did not seem to think it was all that important to do this. He said to just make sure that I have the appropriate lubricant on the impellor when I do install them and start to use the pump, because it is dry start-up of the impellor that does the most damage to it.

For those with spare pumps, do you store them without impellor's inside?
 
Yes, definitely leave the impeller out of the pump.

Case in point - just got my 4.4m side console fishing boat going again after ~18months with practically no use (coincidentally I bought Wine Down ~18months ago as well... do the maths :)) The 40hp 4strk yammi had been fully serviced 12months ago as per it's usual yearly service which included a new impeller. So 12months since new impeller and NO use whatsoever. On servicing it last week - the unused impeller (basically a teenier version of the impellers in my Johnson pumps) was seen to have definite creases in several of the veins which my mechanic was adamant would cause failure at some point soon. I totally agreed with his assessment and a new impeller was sub $20 so it was no decision whatsoever to replace.

So long story short - yes, keep the impellers out until needed. And use glycerol as the lubricant (at least, that's what the volvo replacement impeller kit includes).
 
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To prevent a dry start damaging the impeller use liquid dishwashing detergent. It will do a fine job of lubrication untill the water reaches the pump. In addition it will help seal so the pump draws better.
 
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