VP 2003 Overheating

[West Coast]

Hi all, away cruising, but engine playing up. Engine is VP 2003, fresh water cooled,

Engine overheated 3 days ago, problem traced to failed FW pump. The pump bearings had failed. I sourced a spares kit which included new shaft, bearing, water seal and impeller. On dismantling the pump, I noticed the impeller had badly scored the inner face of the casing. However, the marine engineer thought it should still work ok with the new parts.

Salt water cooling circuit was checked, all seemed ok. I also dismantled and checked the heat exchanger, all ok.

Repaired pump refitted, engine run under load on the pontoon, all seemed ok. Small amount of water was noticed to be dripping from the header tank cap relief valve, but this wasputndown to overfilled tank. As engine temp built, the FW cooling pipes heated up, signalling the thermostat was ok. So all assumed ok.

However, later on the engine overheated again, after say 30 mins at moderate revs 2000 rpm. FW system had emptied again under the engine. No sign of leak except again water had been coming out of the heade tank.

Any pointers? Could there be a blockage caused by debris from the scored pump? Or if the pump is not working properly ? Wild either of these cause the FW to empty itself in this way?

 

[cryan]

I'm going to ruin your day by saying that gas coming back through the header tank and blowing the water out the relief valve sounds a bity like a blown cylinder head gasket?
If a centrifugal pump impellor is on the wrong way round (If its even possible to fit the wrong way round) then it won't pump and just spin in the volute casing. I would not have thought a scored volute casing would do much harm unless it is scored on a running surface under the impellor.
Have you made sure there is no air in the pump casing as if so the pump will not pump.
Is the Sea water flowing ok?
Check the simple stuff first but water blowing out of tank sounds like a head gasket.

 

[West Coast]

If I have blown the head gasket, would the engine still easily start? Have no experience of this.

When I previously drained the FW system, did not have to bleed it, so dd not bleed it the time either. If the pump had air, so the FW water boiled, could this force the water to come out under the pressure?

 

[uxb]

If I have blown the head gasket, would the engine still easily start? Have no experience of this.

When I previously drained the FW system, did not have to bleed it, so dd not bleed it the time either. If the pump had air, so the FW water boiled, could this force the water to come out under the pressure?

If the cylinder head gasket has blown there will be either/or/ both water in the oil( milky substance in the oil with increased level in the sump) or lots of white smoke from exhaust.

I'm no expert but have had a blown cylinder head on a Yanmar and got both symptoms and the engine was slow and difficult to start.

 

[superheat6k]

Blowing out of the cap is exactly what happened when my seawater / fresh water heat exchanger breached last year. Not cheap, but better than a failed head gasket. If you fill an inch or so below the cap and it then overflows this extra water can only come from the seawater system.

If this is the case the water level will remain high after the engine as stopped and cooled a bit. If it is a blown head gasket you will have less water after as it will be gas pressure from the cylinders pushing the water out.

 

[joha]

also check the pipe that goes to the thermostat runs from the turbo, and undo it push a bit of wire into the housing as it sometimes gets blocked with crud this stops the flow to the thermostat and causes an overheat and dumps cooling from the header tank. This has happened to me and once done have had no problems since!

J

 

[superheat6k]

Blowing out of the cap is exactly what happened when my seawater / fresh water heat exchanger breached last year. Not cheap, but better than a failed head gasket. If you fill an inch or so below the cap and it then overflows this extra water can only come from the seawater system.

If this is the case the water level will remain high after the engine as stopped and cooled a bit. If it is a blown head gasket you will have less water after as it will be gas pressure from the cylinders pushing the water out.

NB seawater entering the freshwater system won't do any harm in the short term, just flush the system thoroughly as part of the repairs.

 

[Jcorstorphine]

Hi.

I have looked at the engine manual for the 2000 series engines and they have core plugs so it may be worth checking to see if any of these have corroded through.

One thing I notice about the cooling system is that there are quite a number of smallish pipes and it does look as if filling it without getting airlocks may be a challenge. Can you be sure you have filled the system 100%. Perhaps breaking open some of the pipes may prove that the engine is filled completely.

It may be worth looking at a get you home solution of the following.

Remove the thermostat (I know the engine will run cold but it is overheating just now) as this will give you more circulation.

Run without the header tank cap fully closed so that the engine does not develop any pressure.

Tie the boat solidly to the pontoon and run under load for 1 hour and watch for signs of overheating all round the engine block as it may have a hot spot due to corrosion build up in the jackets.

Check for signs of water in the oil.

Check for signs of steam in the exhaust (may not show if the seawater is fairly cold coming out)

I have trawled the net and found numerous posting on forums regarding overheating problems on these engines which may help.

http://www.marineengine.com/boat-fo...ng-problem-on-Volvo-Penta-2003-closed-cooling

http://www.cruisersforum.com/forums...-flow-specs-28hp-volvo-help-needed-33915.html

http://www.ybw.com/forums/showthread.php?171943-Volvo-penta-2001-overheating-alarm

http://www.bluemoment.com/manuals/volvo_penta_2002_worksh.pdf

http://www.cruisersforum.com/forums/f54/overheating-volvo-penta-102202.html

 

[Heat Exchanger Guy]

I think Jcorstorphine has pretty much covered it with the last post, if all of the usual components have been checked such as the heat exchanger, thermostat and pumps then it could be an air lock if you're lucky, this happened to me once on a Mini engine and they can be a bit hard to find at first. I really hope it isn't a head gasket issue!

 

[West Coast]

Thanks all, all advice much appreciated.

No steam or emulsified oil etc so suspect not a blown head gasket. No leaking hoses. On cold start up, idling, no load (ie low heat), all seems ok. However, under load, engine soon heats up at which point the FW header tank level begins to steadily rise until it overflows through the header tank vent. No steam, the water is cold. Engine soon overheats.

I suspect the FW circuit is blocked somehow, so more extensive investigation needed. But puzzling!

But refused to let the problem get in the way of the cruise - sailed from Oban to Melfort today, tacking down the sound of Kerrera against the tide was interesting!

 

[whiteoaks7]

Mine overheated too and the fresh water level increased. I traced this to the heat exchanger which had a leak between salt and freash sides. The thing which baffled me was that the pressure gradient was wrong - the almost atmospheric pressure of the salt water somehow pushed against the 10 psi or so of the fresh water. However, I proved the HE was leaking so replaced it anyway. Then I started the engine up and did my first seatrial within five mins of > 1500 r/m the alarms went off and I limped back to the jetty where I sat and thought for a long time. I finally came to the conclusion that the HE had not filled properly so disconnected a few pipes which (a) bled a substantial amount of air out and (b) confirmed my diagnosis. So from there I had to find why the beast had not bled properly, this I traced to the silly little bleed vent that someone else has mentioned which on our version is in the thermostat housing (it feeds into the small pipe that goes to the header and on some versions runs from the turbo). The bleed was blocked so I cleared it with a 2mm drill and now check the small pipe each time I run for a while (though, now the thing is bled properly I can't see that this pipe has anything left to contribute).

Coincidentally I was moored alongside another boat that had had exactly the same pair of problems - a leak in the HE which increased his coolant level and a blocked bleed which he now clears on a regular basis with a toothpick. Anyone else with these symptoms.

However - I note you've checked the HE pipework and the temperatures seem to be correct for a unit without an airlock.

I hope when you solve your problem you'll share it with us.

... bemused 2003 owner ...

Dave Berry

 

[uxb]

But refused to let the problem get in the way of the cruise - sailed from Oban to Melfort today, tacking down the sound of Kerrera against the tide was interesting!

That must have been fun in the light winds and wall to wall sunshine today!

When are you heading for the Dorus? I might come to watch

 

[West Coast]

Thanks all.

The plot thickens. The engineer at Kilmelfort Yacht Haven ran the engine this morning to see the problem for himself. The engine ran fine under load at 2000 rpm (on the pontoon) for over 30 mins, and no overheating. He stopped it, let it cool and then tried again later. The overheat problem returned as usual on the second trial run.

Debris in the FW system? Maybe temporarily dislodged when we sailed the boat from Oban to Melfort, then stuck again?

 

[West Coast]

Mine overheated too and the fresh water level increased. I traced this to the heat exchanger which had a leak between salt and freash sides. The thing which baffled me was that the pressure gradient was wrong - the almost atmospheric pressure of the salt water somehow pushed against the 10 psi or so of the fresh water. However, I proved the HE was leaking so replaced it anyway. Then I started the engine up and did my first seatrial within five mins of > 1500 r/m the alarms went off and I limped back to the jetty where I sat and thought for a long time. I finally came to the conclusion that the HE had not filled properly so disconnected a few pipes which (a) bled a substantial amount of air out and (b) confirmed my diagnosis. So from there I had to find why the beast had not bled properly, this I traced to the silly little bleed vent that someone else has mentioned which on our version is in the thermostat housing (it feeds into the small pipe that goes to the header and on some versions runs from the turbo). The bleed was blocked so I cleared it with a 2mm drill and now check the small pipe each time I run for a while (though, now the thing is bled properly I can't see that this pipe has anything left to contribute).

Coincidentally I was moored alongside another boat that had had exactly the same pair of problems - a leak in the HE which increased his coolant level and a blocked bleed which he now clears on a regular basis with a toothpick. Anyone else with these symptoms.

However - I note you've checked the HE pipework and the temperatures seem to be correct for a unit without an airlock.

I hope when you solve your problem you'll share it with us.

... bemused 2003 owner ...

Dave Berry

Thanks Dave - You were spot on - problem now solved!

Issue was indeed an airlock in the FW circuit. On the thermostat housing, there is a small connection for the overflow/breather pipe (back to the header tank). This has a very small hole which had blocked. Hence the airlock; this must have blocked recently, hence why this has not occurred in the past when I had drained the FW circuit to overhaul the heat exchanger.

 

[West Coast]

also check the pipe that goes to the thermostat runs from the turbo, and undo it push a bit of wire into the housing as it sometimes gets blocked with crud this stops the flow to the thermostat and causes an overheat and dumps cooling from the header tank. This has happened to me and once done have had no problems since!

J

J - thanks also, your diagnosis, like Dave's, was correct