Yanmar 1GM10 - white smoke and louder

[Captain Max]

Hi

I had to make a sharp turn to avoid a motor boat and I fell onto the throttle which reacted but reffing a lot ( which it should do ) but at this time the noise from the exhaust increased - additionally I now have white smoke, possibly steam , coming out the exhaust port .

it doesn’t seem to effect the running of the engine

it starts easily and water feeds out the exhaust too

what should I inv3stigate as being the problem?

 

[Slowboat35]

Well, smoke or steam? Which is it? Steam disappears quickly, smoke lingers.

If the engine is now louder I'd suspect something has affected the exhaust system, and combined with white vapour that suggests, water output notwithstanding, a lack of cooling water-flow. Unburned fuel would normally be accompanied with reduced power and poorer starting.

First check the seawater strainer for blockages, then every inch of the intake hose/s between the water pump and the intake seacock (higher revs = more suction and possibly a semi-collapsed intake hose) and finally the impellor. If all well there examine the other end - the exhaust elbow for partial blockage.
My money is on a damaged impellor or collapsed hose.

 

[Captain Max]

its all good at the front end - new impeller and intake pipe so i guess i will have to check the exhaust elbow - can i attach video here ?? - it seems not

 

[Tranona]

Exhaust elbow is first thing to check. If the inner is perforated then replace with an aftermarket one, not the original Yanmar. Also check that the water trap/muffler and exhaust pipe is not damaged.

 

[Slowboat35]

But have you checked the impellor and intake pipes since the problem arose? There's nothing to say new ones can't fail/collapse. These are the easiest things to check so do them first- then go on to less accessible items like the mixer elbow.
Also verify whether this is steam or fuel vapour or you may be barking up the wrong tree.

 

[Captain Max]

im thinking the water trap / muffler could be where the problem lies - i know nothing about what it does how it works - i have a box with a screw top on it - should this have water in it - does it muffle the sound of the exhaust ??

 

[Tranona]

Does not sound like a water trap, but more like the water filter on the cooling water intake between the seacock and the pump. The water trap is in the exhaust just - usually about 2-3 feet down from the the exhaust elbow. Probably plastic. See here for typical exhaust installations vetus.com/media/magentominds/sasdocument/20190621081849_0.pdf

 

[Spirit (of Glenans)]

im thinking the water trap / muffler could be where the problem lies - i know nothing about what it does how it works - i have a box with a screw top on it - should this have water in it - does it muffle the sound of the exhaust ??

The water and exhaust gas come in at the front end through a intake placed as high as possible, the water lies in the bottom. covering the outlet. When the back pressure builds enough it expels a gout of water into the after part of the exhaust pipe. The sound is muffled in the process, and the water appears to exit in pulses. If the water is slow in accumulating in the muffler/water-trap, the sound of the exhaust will be louder, but water will still exit in pulses. White 'smoke' in the circumstances described, is usually steam, which increases in volume as the engine comes to full temperature.; slow running on the pontoon will not achieve this, but i fit is used to motor against a foul tide for a couple of hours, the overheat alarm will be sounding. The lack of water is caused by either a leak into the bilges or an attenuation of the raw water supply; 'less water in-less water out'.
The OP should check that the vapour is steam by holding something cold, like a frozen ice-pack, close to the exhaust outlet to see if condensation forms on it. If steam is confirmed he should check whether or not the skin fitting of the raw water supply is blocked, by a plastic bag or similar. In most raw water installations it's possible to 'rod' it directly, with a length of wire coat-hanger for instance, or use air pressure, from a dinghy pump, or his own lungs, to blow out the obstruction. A length of hose on the seacock, , enough to end above the waterline, will enable this operation to be done without allowing any seawater to enter.
I experienced similar baffling symptoms on my boat and eventually found that in clearing molluscs out of the water galleries of my saildrive with a length of steel rod, I had invertently rammed some mussel shell or bits of barnacle up into the seacock which is integrated into the saildrive.

 

[Captain Max]

The water and exhaust gas come in at the front end through a intake placed as high as possible, the water lies in the bottom. covering the outlet. When the back pressure builds enough it expels a gout of water into the after part of the exhaust pipe. The sound is muffled in the process, and the water appears to exit in pulses. If the water is slow in accumulating in the muffler/water-trap, the sound of the exhaust will be louder, but water will still exit in pulses. White 'smoke' in the circumstances described, is usually steam, which increases in volume as the engine comes to full temperature.; slow running on the pontoon will not achieve this, but i fit is used to motor against a foul tide for a couple of hours, the overheat alarm will be sounding. The lack of water is caused by either a leak into the bilges or an attenuation of the raw water supply; 'less water in-less water out'.
The OP should check that the vapour is steam by holding something cold, like a frozen ice-pack, close to the exhaust outlet to see if condensation forms on it. If steam is confirmed he should check whether or not the skin fitting of the raw water supply is blocked, by a plastic bag or similar. In most raw water installations it's possible to 'rod' it directly, with a length of wire coat-hanger for instance, or use air pressure, from a dinghy pump, or his own lungs, to blow out the obstruction. A length of hose on the seacock, , enough to end above the waterline, will enable this operation to be done without allowing any seawater to enter.
I experienced similar baffling symptoms on my boat and eventually found that in clearing molluscs out of the water galleries of my saildrive with a length of steel rod, I had invertently rammed some mussel shell or bits of barnacle up into the seacock which is integrated into the saildrive.

wow - many thanks for your in depth reply .... i will try to push a wire coat hanger through the water intake - there's a lot of mussels growing - i had hundreds growing on the underside of my dinghy

 

[Slowboat35]

" white vapour that suggests, water output notwithstanding, a lack of cooling water-flow."

Mussels quite likely to be involved in that - but then they weren't mentioned at the time...

 

[Captain Max]

The water and exhaust gas come in at the front end through a intake placed as high as possible, the water lies in the bottom. covering the outlet. When the back pressure builds enough it expels a gout of water into the after part of the exhaust pipe. The sound is muffled in the process, and the water appears to exit in pulses. If the water is slow in accumulating in the muffler/water-trap, the sound of the exhaust will be louder, but water will still exit in pulses. White 'smoke' in the circumstances described, is usually steam, which increases in volume as the engine comes to full temperature.; slow running on the pontoon will not achieve this, but i fit is used to motor against a foul tide for a couple of hours, the overheat alarm will be sounding. The lack of water is caused by either a leak into the bilges or an attenuation of the raw water supply; 'less water in-less water out'.
The OP should check that the vapour is steam by holding something cold, like a frozen ice-pack, close to the exhaust outlet to see if condensation forms on it. If steam is confirmed he should check whether or not the skin fitting of the raw water supply is blocked, by a plastic bag or similar. In most raw water installations it's possible to 'rod' it directly, with a length of wire coat-hanger for instance, or use air pressure, from a dinghy pump, or his own lungs, to blow out the obstruction. A length of hose on the seacock, , enough to end above the waterline, will enable this operation to be done without allowing any seawater to enter.
I experienced similar baffling symptoms on my boat and eventually found that in clearing molluscs out of the water galleries of my saildrive with a length of steel rod, I had invertently rammed some mussel shell or bits of barnacle up into the seacock which is integrated into the saildrive.

Many thanks for your reply