superboots
Well-Known Member
According to jabsco this pump is only available through VP with consequent markup........... is there no alternative?
engine sea water pump not priming
- Thread starter superboots
- Start date
rogerthebodger
Well-Known Member
Typical that why I would never install a Volvo engine.
Its probably only the pulley and bracket that makes it exclusive VP . Dont know where you are but what I would do is tale the pump off, remove the pulley and bracket and visit Jabscoshop in person. The other thing is to rebuild the pump from spares that are available from jabscoshop.
Aquafax do johnson pumps.
http://www.aquafax.co.uk/html/products.asp?ID=197
Sherwood also do engine cooling pumps
http://www.sherwoodpumps.com/en-us/Products/Engine+Cooling+Pumps/VolvoPenta/
kieronriley
Well-Known Member
kieronriley
Well-Known Member
I had the same problem I first had the face plate re ground as it was well worn and a small amount of improvement, then I got a new back plate this again seemed to improve flow a bit, but still well short of the flow before the problem became really apparent I then put a new cam plate in the pump and ???? it has worked like a new pump ever since.
when I look back now and think hard about the pumps performance it had over a long period just worked less and less efficiently ,so if you are going to attempt to repair your pump replace all the parts that I have mentioned and I hope you have the same outcome as I did. Kieron
when I look back now and think hard about the pumps performance it had over a long period just worked less and less efficiently ,so if you are going to attempt to repair your pump replace all the parts that I have mentioned and I hope you have the same outcome as I did. Kieron
superboots
Well-Known Member
Its temping to replace just the can plate and go for sureseal cover plate if I can get a friend to bring them out to turkey as no parts or pump in stock here.
charles_reed
Well-Known Member
There can be so many reasons for your problem.
I suspect the most sensible answer to it is to have the pump rebuilt with bearing, seals and re-machined cover plate.
On my last two engines I've always carried a spare pump, far easier and quicker to change the whole thing over than to faddhl through all the suggestions.
Rebuilding the pump, in Chios town cost me €24, a new raw water pump from the negine manufacturers was £149 (and they're not quite as greedy as Volvo) and a complete pump excluding the body, in pieces from Johnson cost me £16.96 (the pressed pulley was valued @ £69 by the distributors, but I got one off a ditched pump. The body incidentally was £26.
Some get you home suggestions:-
1. If the cover plate is scored turn it round (after scraping off those sticky labels).
My current pump does about 800 hours on an impeller and about 1200hrs before needing new bearing and seals. 2. So it's quite easy to set up a preventative maintenance schedule. I've only had to replace am=n impeller once, on passage, since setting it up.
Clean the filter basket every 20-30 hrs . When you replace the lid a thin spread of silicon grease on the cleaned O-ring. Do it up sympathetically and firmly, not in the spirit of "now leak you bastard". More filter lids are cracked by over-enthusiastic owners than anything else.
Which brings me to the crewed-for-chrter French boat which came in with great anxiety, on one of the Dodecanese, waving ropes and spreading terror and claiming an overheated motor.
The "engineer" who claimed to clean the filter every day had crossed the thread, putting it back on again!!!
You certainly should NOT consider changing from the manufacturer-fitted pump for any with greater capacity - heat exchangers are very leak-prone with any over-pressure.
I suspect the most sensible answer to it is to have the pump rebuilt with bearing, seals and re-machined cover plate.
On my last two engines I've always carried a spare pump, far easier and quicker to change the whole thing over than to faddhl through all the suggestions.
Rebuilding the pump, in Chios town cost me €24, a new raw water pump from the negine manufacturers was £149 (and they're not quite as greedy as Volvo) and a complete pump excluding the body, in pieces from Johnson cost me £16.96 (the pressed pulley was valued @ £69 by the distributors, but I got one off a ditched pump. The body incidentally was £26.
Some get you home suggestions:-
1. If the cover plate is scored turn it round (after scraping off those sticky labels).
My current pump does about 800 hours on an impeller and about 1200hrs before needing new bearing and seals. 2. So it's quite easy to set up a preventative maintenance schedule. I've only had to replace am=n impeller once, on passage, since setting it up.
Clean the filter basket every 20-30 hrs . When you replace the lid a thin spread of silicon grease on the cleaned O-ring. Do it up sympathetically and firmly, not in the spirit of "now leak you bastard". More filter lids are cracked by over-enthusiastic owners than anything else.
Which brings me to the crewed-for-chrter French boat which came in with great anxiety, on one of the Dodecanese, waving ropes and spreading terror and claiming an overheated motor.
The "engineer" who claimed to clean the filter every day had crossed the thread, putting it back on again!!!
You certainly should NOT consider changing from the manufacturer-fitted pump for any with greater capacity - heat exchangers are very leak-prone with any over-pressure.
Last edited:
superboots
Well-Known Member
Thanks for the advice. I've ordered a new pump and will change the plate and cam on the old one. It will be a spare. I'm surprised at the wear given the few hours of use -could be due to grit or salt crystals. Will also grease strainer lid.
DannyB
Well-Known Member
Is the inlet clear ? There could be fouling before the seacock. Apologies if this has already been suggested.
superboots
Well-Known Member
Changed seacock and skin fitting from 1.25 inch to 1.5 inch so should be better flow than before - pipes through remain 35 mm- needed a bit of heat to get the hose onto the bigger fitting.
charles_reed
Well-Known Member
If you operate in estuarine waters with strong tidal streams then raw-water pump wear is grossly accelerated.
I've only once had to change the cam on a raw-water pump, when operating out of the Dyfi (8 knots on spring ebb).
In any case it's only possible on the Jabsco pump.
I've found the Johnson pump far more reliable than Jabsco, and spares are more reasonably priced and widely available world-wide.
lw395
Well-Known Member
That sounds big.
You may have created your priming problem.
How worn is your pump?
If the impeller is touching all round and getting squeezed a bit by the ramp, it should work.
But these things do not work well with air. Because air compresses, the pump tends to just circulate air around in the pump if there is any back pressure.
So if the back pressure builds up before water reaches the pump, it may never prime.
A high volume strainer, a tall anti-syphon loop and big bore plumbing can all conspire to stop the thing priming.
Throw in a little bit of leakage around the impeller and it's all over.
Yet, once primed it will deliver 99% of the designed flow.
So if it is a priming issue just prime the damned thing manually!
IF the problem is scoring in the body or cam/ramp plate, you might get away with an epoxy repair.
You can get bronze loaded epoxy or ceramic loaded for such jobs. Needs to be done well under good conditions though. (RTFM!)
It's not rocket science to get a new ramp made and have the body machined.
RichardS
N/A
Wny would a larger seacock and through-hull affect the self-priming ability of the pump?
Richard
superboots
Well-Known Member
Spares will arrive in a couple of weeks so will see what's the result. Will post it.
chewi
Well-Known Member
Wny would a larger seacock and through-hull affect the self-priming ability of the pump?
Richard
It has to displace more air before any water gets to the vanes.
If a back pressure is built up on the way the pump will not get there.
Think of the oversize pipe as a large tank of air between pump and water. Would you expect the pump to deal with that?..
I made the same mistake with the diesel supply to my eberspacher. The pump timed out before it lifted any fuel to the heater, so I had to give it several false starts to get it to work. Once I reduced the dia of some of the supply pipe it worked OK, cos the pump could cope.
RichardS
N/A
I just can't see that I'm afraid. I could understand why a much larger vertical volume of water before the pump in a system which has an air leak would be counterproductive as the weight of the column of water above sea level would tend to draw in more air ..... but when all the piping is exactly the same size and the only bit that has changed is below sea level it doesn't make sense. Surely?
Richard
chewi
Well-Known Member
If the air volume & head hasn't increased from water level to pump inlet as you say I don't see it would make any difference to the pump.I just can't see that I'm afraid. I could understand why a much larger vertical volume of water before the pump in a system which has an air leak would be counterproductive as the weight of the column of water above sea level would tend to draw in more air ..... but when all the piping is exactly the same size and the only bit that has changed is below sea level it doesn't make sense. Surely?
Richard
but the pipe diameter was increased to > 30mm, at least at the seacock end,
so all the piping is not the same size.
If that was carried all the way to the pump it could contribute to the OP's problem,
RichardS
N/A
The OP says that he "changed seacock and skin fitting from 1.25 inch to 1.5 inch so should be better flow than before - pipes through remain 35 mm- needed a bit of heat to get the hose onto the bigger fitting". Since both the seacock and skin fitting are below the water level I remain confused.
Richard