Lots of white smoke...

[Aeolus]

Good flow of water out of the exhaust but lots of white smoke and the engine overheating. Volvo Penta MD7a. What could be causing this?

Stopped me reaching Bexhill so I couldn't anchor there (as per my prev post) :-(

 

[Ludd]

Good flow of water out of the exhaust but lots of white smoke and the engine overheating. Volvo Penta MD7a. What could be causing this?

Stopped me reaching Bexhill so I couldn't anchor there (as per my prev post) :-(

If fresh water cooled, possibly sticking thermostat.

 

[Aeolus]

Seawater cooled - very old engine

 

[gljnr1983]

Sounds like a head gasket but im not clued up on the deisels.How does the oil look is it milky?

 

[theoldsalt]

Are you sure it is smoke and not steam.

It may be a blocked water gallery causing a local hot spot, or a blown head gasket.

 

[Aeolus]

Could well have been steam, will have to check the oil tomorrow - if milky, would that indicate a head gasket?

 

[gljnr1983]

Could well have been steam, will have to check the oil tomorrow - if milky, would that indicate a head gasket?

It would indicate a head gasket the other way i know that water can enter the oil and cause milkyness is if your water pump is driven off of the cam shaft and the pump seal blows this is usualy recognised in a drip from the hole under the pump housing.If not that i would try theoldsalts idea of restricted waterflow causing boiling which give you lots of steam out the exhaust.If it has a thermostat i would test it or replace it also.

 

[Bilgediver]

Good flow of water out of the exhaust but lots of white smoke and the engine overheating. Volvo Penta MD7a. What could be causing this?

Stopped me reaching Bexhill so I couldn't anchor there (as per my prev post) :-(

These volvo engines have two cooling paths. This would indicate the thermostat is stuck closed and water is only flowing through the thermostat housing by pass to keep the exhaust cool. Easy enough to check the thermostat by putting it in a saucepan of boiling water and checking it functions. New one will cost two arms and four legs!

 

[Ludd]

One other possibility I can think of is a cracked injector sleeve or it's seal gone..don't know if it's applicable to that particular engine,though.

 

[VicS]

If the engine is overheating there is inadequate water flow through it, or the thermostat is faulty ( amounts to much the same thing!).

Check inlet, strainer, all hoses, pump impeller and the water injection into the exhaust as well as thermostat . The thermostat should just start to open at 60C and be fully open at 74C. Check with a thermometer.. just tossing it in a pan of boiling water may not be good enough. Even a dodgy one might open at 100C.

Water passages in the engine could be blocked.

If there really is a good flow of water from the exhaust I'd not expect to see any steam even if the engine itself is over heating. I suspect therefore the water flow may not be as good as you think!

If you check the engine oil and find that it is milky then possibly the head gasket is defective.

White smoke, as opposed to steam, would indicate a fuel ( injection) problem probably or very poor compression. I think you would notice a lack of power.

 

[Aeolus]

Thanks everyone for your suggestions and comments. Down to the boat shortly to check the oil and water flows.

 

[VicS]

Add to the list of things to check for obstrucing the water flow: gearbox cooler ... assuming a water cooled gearbox is fitted.

 

[Billjratt]

You haven't mentioned any smell, so I assume it's not unignited fuel - which smells a bit like paraffin from a blowlamp that's just gone wrong (flame gone out but still hissing) . That could indicate a broken injector tip, which in turn could have been caused by fuel contamination.
Was this smoke accompanied by a distinct loss of power?

 

[Terra-Loon]

I had exactly these 'symptoms' on Sunday, motoring back from Dittisham.

Lots of white smoke and loss of revs.

After 40 mins or so the smoke died down and the revs increased.

At first I thought it might have been due to moisture in the exhaust thanks to the thick mist that we woke to find ourselves engulfed in.