Overheating Volvo Challenge

[kalanka]

Volvo 2003, freshwater cooled in Sadler 34

Whilst on passage off Canna overheating alarm went off. Cleared some weed from water intake. Not cured. Checked impeller - it had lost a blade - replaced. Looked carefully for this fragment but not found. But raw water flow is now good.

Problem persisted. Back to mooring under sail alone.

Engine overheats to 100 degrees after 8-10 min running under modest load (2000 rpm in reverse on mooring. It is real overheating - not just an instrument problem.

Have checked everything I can think of:

Sea cock/inlet fine.
Strong flow of raw water through system
Heat exchanger dismantled - no damage, corrosion or obstruction
Freshwater in and out on HE are different temperatures
Injection elbow removed - heavily clogged up and corroded - replaced with new item
Circulation pump dismantled, checked - all seems fine
Freshwater system drained and treated with Radflush and Fernox - little effect, very little grot flushed out
Temp gauge checked against lab thermometer - spot on
All accessible pipes are clear and in good shape
Thermostat replaced with new item
Ran without thermostat - still overheating
Am currently attempting to eliminate possible air locks in freshwater system - have already removed calorifier from circuit with this purpose - no effect.
Oil clean and at level - no water in it. Old oil drained - no mayonnaise etc
No gas, fumes or muck in header tank
Engine starts well, runs smoothly, nothing unusual until it gets hot
Belt tension fine

Overheating unchanged after all this. I am beginning to fear some serious blockage in head or block. If so is there any cure for this? Any reliable diagnosis?
Anything else to investigate?
Is it new engine time?

Your suggestions would be welcome.....

Thanks

 

[savageseadog]

The overheating might have blown the head gasket?

 

[AntarcticPilot]

Volvo 2003, freshwater cooled in Sadler 34

Whilst on passage off Canna overheating alarm went off. Cleared some weed from water intake. Not cured. Checked impeller - it had lost a blade - replaced. Looked carefully for this fragment but not found. But raw water flow is now good.

Problem persisted. Back to mooring under sail alone.

Engine overheats to 100 degrees after 8-10 min running under modest load (2000 rpm in reverse on mooring. It is real overheating - not just an instrument problem.

Have checked everything I can think of:

Sea cock/inlet fine.
Strong flow of raw water through system
Heat exchanger dismantled - no damage, corrosion or obstruction
Freshwater in and out on HE are different temperatures
Injection elbow removed - heavily clogged up and corroded - replaced with new item
Circulation pump dismantled, checked - all seems fine
Freshwater system drained and treated with Radflush and Fernox - little effect, very little grot flushed out
Temp gauge checked against lab thermometer - spot on
All accessible pipes are clear and in good shape
Thermostat replaced with new item
Ran without thermostat - still overheating
Am currently attempting to eliminate possible air locks in freshwater system - have already removed calorifier from circuit with this purpose - no effect.
Oil clean and at level - no water in it. Old oil drained - no mayonnaise etc
No gas, fumes or muck in header tank
Engine starts well, runs smoothly, nothing unusual until it gets hot
Belt tension fine

Overheating unchanged after all this. I am beginning to fear some serious blockage in head or block. If so is there any cure for this? Any reliable diagnosis?
Anything else to investigate?
Is it new engine time?

Your suggestions would be welcome.....

Thanks

I recently had the head of my Volvo 2003 off, for other reasons - it wasn't overheating. But inside the head, the cooling water is carried by a pipe pierced at intervals within the block. Many of the holes in this pipe were blocked on mine, a quick broddle with a screw-driver sorted it. But perhaps if all the holes were blocked - and they are quite small hoes, 2-3 mm across - then that might cause your problem, and be relatively easy to sort. As other people have suggested the head gasket needs checking, this is something else to look at at the same time.

Otherwise, I'm as stumped as you are!

 

[Sammy Lou]

overheating

Is water coming out of the exhaust OK?
How does the exhaust 'note' sound?
Possibility of collapse exhaust pipe.

 

[jpd85]

I recently had the head of my Volvo 2003 off, for other reasons - it wasn't overheating. But inside the head, the cooling water is carried by a pipe pierced at intervals within the block. Many of the holes in this pipe were blocked on mine, a quick broddle with a screw-driver sorted it. But perhaps if all the holes were blocked - and they are quite small hoes, 2-3 mm across - then that might cause your problem, and be relatively easy to sort. As other people have suggested the head gasket needs checking, this is something else to look at at the same time.

Otherwise, I'm as stumped as you are!

The pipe pierced with holes getting blocked is a common problem and cause of overheating with 200x engines. Some people drill these holes larger to prevent overheating bt the first step would be to check it and unblock the holes.

 

[Red Admiral]

I recently had the head of my Volvo 2003 off, for other reasons - it wasn't overheating. But inside the head, the cooling water is carried by a pipe pierced at intervals within the block. Many of the holes in this pipe were blocked on mine, a quick broddle with a screw-driver sorted it. But perhaps if all the holes were blocked - and they are quite small hoes, 2-3 mm across - then that might cause your problem, and be relatively easy to sort. As other people have suggested the head gasket needs checking, this is something else to look at at the same time.

Otherwise, I'm as stumped as you are!

Kalanka's engine is fresh water cooled. There is no tube through the cylinder head; the water from the raw sea water pump goes straight to the heat exchanger and then to the exhaust mixer. My guess would be a problem on the fresh water side if, as you say, the flow of water from exhaust is OK. Possibilities are the circulating pump (belt driven), restricted flow in block or, most likely, scaling on the salt water side of the heat exchanger. Of course there is the possibility of head gasket problems as others have suggested but I would have a good look at fresh water circulating pump and heat exchanger first.

 

[mattnj]

IR Thermometer needed.

I would suggest an IR thermometer, run it up to overheat (ish) temperature then wave it around, you will get an instant reading of which bits are hot (or not), for example is the heat exchange seeing 100deg water on the input and still coming out at 100deg (or near) if so, then its HE, or maybe the thermostat is not opening/head is blocked, in which case the lower components, pump etc may be cold.

They are cheapish to buy, think mine was £15 on eBay or Maplin sells them.

 

[Pagetslady]

Hi have you checked the small hole in the thermostat housing which has a small rubber pie going back to the header tank its very small can get blocked easily but once cleared out with a small wire or drill all will be ok, I havnt had time to read all the post so sorry if I am repeating regards Mike

 

[alan]

Overheating Volvo

I had this on 2020; it was caused by a fouled prop. Does it overheat if run in neutral? Does it overheat at all rev ranges when in gear? Usually with a fouled prop it only happens when you open the throttle ..... say above 1800 ...... depending on how bad fouling is!!

Just a thought.

Alan.

 

[Topcat47]

Do you have a FW header tank? If you have a blown head gasket, you should be loosing coolant. Air locks in pipework or a collapsed hose would be my best bet if it's not the head gasket. Checking the hole in the thermostat, a nice cheap check, too.

 

[kalanka]

Thanks for the suggestions. Problem continues but have now taken out and checked the water distribution pipe - no obstructions. It is aligned as indicated in the workshop manual.

Thermostat chamber hole is clear, exhaust is unimpeded and engine runs fine.

Prop appears clear but I haven't dived to check!

I have tended to discount the head gasket because no gas in header tank, no water in oil no loss of coolant - is this a reasonable deduction?

Have dismantled circulation pump - all seems solid and functional.

Rechecked heat exchanger today - all OK

Somebody must know the answer!

 

[vyv_cox]

Overheating with the thermostat removed indicates a serious circulation problem, which seems to be on the fresh water side according to your posts. If the pump and drive are OK I would suspect blockage of internal coolant passageways. I would try a proprietary flushing additive. I realise you have tried Radflush but there are more effective ones, as used by the motor trade. Last resort would seem to be removal of the head.

 

[Red Admiral]

Second Go

I still think it's the heat exchanger. My 3 year old Peugeot diesel car developed overheating problems under load and I tried everything including flushing etc. The radiator looked fine but, finally, in desperation I fitted a replacement radiator and the problem was solved. Cost me about £100 15 years ago but saved a lot of heartache.

 

[kalanka]

A diagnosis?

I think I have found the problem and am now engaged with solving it - hopefully the easier part.

The posted advice to get an IR thermometer was really useful and using this quickly confirmed that the freshwater circulation pump was still the prime suspect, despite my having checked it before.

Dismantled again and looked more critically. Found that the impeller rotated on the shaft. This was slight when cold and dry, but very free when wet and at normal running temperature.

Annoyingly, the pump failed very obviously six months ago, just before lay up, and the rebuild kit was installed by the main VP dealer, who do not seem to have done a good job.....

Thanks for the help - an excellent education in cooling systems!