Volvo penta 2002 raw water flow problem

[brale]

Hi everyone.
I keep having an annoying problem on my Volvo 2002 MD on my sailboat.
About a month ago I noticed that after some time of motoring there was no water flow on the exhaust. I immediately stopped the engine and first thing I did was change the impeller although the old one didnt look bad.
It solved the problem but only until my next trip when the problem repeated.This time, after sailing for a while and starting the motor - again no waterflow.
Since then I did all of these things:
checked all seawater pipes and found a small piece of impeller in one,
tested the thermostat (OK opening on different temps) and changed its gasket,
flushed the whole seawater system with HCL acid - many nasty water came out,
put off and cleaned the exhaust elbow (was dirty but not fully clogged),
made a partial rebuild of my raw water pump because of little oil leaking (new shaft kit, orings and gaskets)
When motor starts cold the water flow is good, after driving for a while or more hours and restarting it is also good, but after sailing and then restarting it sometimes (not always) doesn't flow out on the exhaust.
Except the first time, I am pretty sure that this happens only after sailing. Then I have to restart my engine once or twice and then it starts flowing out again.
Water inlet on the sail drive leg ic clean.
What to do next - I am thinking of removing head and mecanical clenaing of all water passages) (not sure if that is necessary), or buying completely new water pump.
Can it be the plastic gooseneck after the exaust elbow which blocks water?
Any other ideas?

 

[glsg91]

Hi everyone.
When motor starts cold the water flow is good, after driving for a while or more hours and restarting it is also good, but after sailing and then restarting it sometimes (not always) doesn't flow out on the exhaust.
Except the first time, I am pretty sure that this happens only after sailing. Then I have to restart my engine once or twice and then it starts flowing out again.
Any other ideas?

I have the same engine and similar problem. Indeed after sailing starting the engine , no water. Then stop engine and start again, I have water.
In my case I think it has something to do with a new impeller.
2,5 years ago I replaced the impeller. After replacing I had this problem. I did put the old one in again, no problem. At the end I did put the new one in again and had the problem again. After a few months the problem was gone.
Early this year I did put in a new impeller again, same problem again. At this moment I don't have the problem anymore.
I also don't understand how this can occur.
I only had this problem the first start after sailing.

 

[owen-cox]

I wonder if you did nit change the cam in the pump at the time you changed the impeller asi used to use those engines a lot with sunsail. After sailing it is likely that the pump had become un primed after heeling and needs more suction than when it is primed. the cams often wear as do the pump bodies and so ifa new cam doesnt solve it then it may need to be new pump.possibly installing a non return valve in the intake line by the skin fitting will help too.

 

[glsg91]

I wonder if you did nit change the cam in the pump at the time you changed the impeller asi used to use those engines a lot with sunsail. After sailing it is likely that the pump had become un primed after heeling and needs more suction than when it is primed. the cams often wear as do the pump bodies and so ifa new cam doesnt solve it then it may need to be new pump.possibly installing a non return valve in the intake line by the skin fitting will help too.

I never replaced the cam. A month ago I "discovered" the cam can have wear and can be replaced. I planned to replace it (if necessary) this winter. But a the moment I don't have this problem anymore. So time solves it for me.

 

[Bilgediver]

I never replaced the cam. A month ago I "discovered" the cam can have wear and can be replaced. I planned to replace it (if necessary) this winter. But a the moment I don't have this problem anymore. So time solves it for me.

Is the end cover of the pump grooved or the internal side wall in the body....After a few weeks running the impeller may wear to settle into the grooves ad so handle air better which comes in while sailing.

 

[VicMallows]

Not sure what pump the Volvo uses, but had similar problem on my BUKH a few weeks back. Not priming. Fortunately I remembered that a worn cover plate is often the cause .... and that on many Johnson pumps it can simply be reversed. Sure enough it now works fine. The wear on the 'used' side can be quite easily felt, but I was still surprised how abruptly the 'failure' occurred. Thinking about it, I suppose the pump either 'just' manages to prime .....or does not! . Easy enough to skim the worn side ..... but if one side has lasted 28years I don't think I'll both

 

[glsg91]

Is the end cover of the pump grooved or the internal side wall in the body....After a few weeks running the impeller may wear to settle into the grooves ad so handle air better which comes in while sailing.

I'am almost sure the end cover is grooved or has wear in my case, not the internal side wall. I also planned to reverse the end cover.

 

[Bilgediver]

I'am almost sure the end cover is grooved or has wear in my case, not the internal side wall. I also planned to reverse the end cover.

You could consider the opportunity to fit one of these covers...Makes life easier


http://www.speedseal.com/speedseal.html

 

[brale]

Is the end cover of the pump grooved or the internal side wall in the body....After a few weeks running the impeller may wear to settle into the grooves ad so handle air better which comes in while sailing.

are you sure that it is possible for the air to come in the pump while sailing.
In my case, raw water intake is on the saildrive leg and am pretty sure that the leg never rises above the waterline no matter how closehauled sailing it is

 

[glsg91]

are you sure that it is possible for the air to come in the pump while sailing.
In my case, raw water intake is on the saildrive leg and am pretty sure that the leg never rises above the waterline no matter how closehauled sailing it is

I also have the water intake on the saildrive.
On another forum I also see this problem and people report back it is solved after they have revised or replaced there waterpump.
I also don't understand how this can happen with a saildrive water intake. I cannot try until I have a new impeller.

 

[brale]

I also have the water intake on the saildrive.
On another forum I also see this problem and people report back it is solved after they have revised or replaced there waterpump.
I also don't understand how this can happen with a saildrive water intake. I cannot try until I have a new impeller.

Maybe I should try with changing the pump cam, cap and wear washer.
After that the only solution is buying a new pump. But it aint cheap, haven't found it (in Europe) for less than 500 EUR

 

[Albert Ross]

I had identical problems in past. Wear on inside of front cover of water pump causes failure to prime when you are sailing or if the boat is heeled over at all. Generally still primes OK if you are upright and not moving. As soon as the water pump is primed it will run Ok till you next stop.
Remedy: New face plate
or apparently you can just put the old worn plate on the other way up (I've not tried this)
or replace with a Speed Seal

 

[concentrik]

We had endless problems like this until we checked the actual waterflow at various points and found that the oil cooler matrix was partially blocked with detritus - impellor bits, a grubscrew, bits of silicone etc. Symptoms? Sometimes it would be absolutely fine for hours, sometimes it overheated within 30 mins. Thought it was to do with heeling angle/blocked intake/pump wear.... and other things.

One odd thing that confused us a lot - sometimes the raw water strainer would be empty after an overheat. I can only guess that this was something to do with the pump churning away but unable to force the water through the oil cooler. The intermittent aspect was almost certainly due to bits of detritus changing position as the boat moved around.

SO..... can I recommend that you check the output from the pump by taking the hose off; then if it's OK (it should pump great gushes) start pulling off hoses to see where the cooling water reduces (as mine had) to a trickle. It's tempting to blame the pump - give it a try as above first. I don't think they fail suddenly unless it's an impellor!

 

[PabloPicasso]

Yes check for air leaks anywhere in the system as well. Thermostat could also be suspect even though yea checked it. Could run with no thermostat for awhile to check

 

[brale]

SO..... can I recommend that you check the output from the pump by taking the hose off; then if it's OK (it should pump great gushes) start pulling off hoses to see where the cooling water reduces (as mine had) to a trickle. It's tempting to blame the pump - give it a try as above first. I don't think they fail suddenly unless it's an impellor!

There is no oil cooler nor strainer on my setup.
The motor also doesn't overheat at any time (when cooling sea water flows), checked with a laser thermometer on various points on motor.
When water flows everything is OK. I tried the thing with taking the hose off on the pump exit and watching for water flow - haven't tried that after sailing when no water flow occurs.
So the problem is when the pump does not prime after sailing

 

[vyv_cox]

I also don't understand how this can happen with a saildrive water intake. I cannot try until I have a new impeller.

Siphon break? Could let air in at the highest point, allowing water to drain past a worn pump. The pump could then well fail to prime. As said, wear can occur at the front plate, cam and back plate, but worn seals will also allow air into the pump, which of course the others will not. My seals failed totally and leaked water out, replacing them fixed a long-term priming problem.

 

[brale]

Siphon break? Could let air in at the highest point, allowing water to drain past a worn pump. The pump could then well fail to prime. As said, wear can occur at the front plate, cam and back plate, but worn seals will also allow air into the pump, which of course the others will not. My seals failed totally and leaked water out, replacing them fixed a long-term priming problem.

I already changed the seals. I am gonna change front plate, cam and back plate, although they don't look like worn.
What do you mean by the siphon break. Looking from the other side, rom the water outlet goes the exhaust hose and enters the Vetus gooseneck and then the exhaust hose to the exhaust elbow. Where should be the siphon break?

 

[vyv_cox]

A siphon break can be either between the water pump and the injection point into the engine or between the engine and the point where water is injected into the exhaust manifold. It allows air into the water side when the engine stops to prevent back-filling of the exhaust system and flooding of the engine. Not all systems have one, dependent upon engine height above the water line.

 

[DJE]

Does the priming problem only occur on saildrive installations? Mine is a traditional shaft drive with the raw water pump below water line and I have never had priming problems even after drying the boat out.

 

[vyv_cox]

Does the priming problem only occur on saildrive installations? Mine is a traditional shaft drive with the raw water pump below water line and I have never had priming problems even after drying the boat out.

No, mine has a conventional shaft drive. We had a Bukh 20, replaced by a Yanmar 3GM30F. Both have suffered prime failures occasionally, mostly after sailing in choppy conditions.