Water in cylinders ?

[capjules]

Hello,

I have a Yanmar 3QM30F.

My heat exchanger is removed for service.

I was in the process of adjusting the valves, turning the
the engine by hand and water flowed out of the
hose that sends sea water from the heat exchanger
into the exhaust manifold.

Did I turn it backwards ? Did I get water into
the cylinders ?

Thanks ?

Jules

 

[Bill Roosa]

No you probably turned it in the right direction. The pump is a vane type and pumps no matter how slow you turn it.
you probably did get water into the cylinders. Not to worry though I doubt you got much and you know the source will not be dumping it in once you get the HE back on. Just have a helper deflect the water from the pump and rotate the engine through two complete revolutions of the crankshaft and it will expel enough of the water so you don't get a hydrostatic (water is incompressible) lock up. If the crank is hard to turn just go slow as that is the water fighting back with both valves closed and the piston coming up to TDC. The water will leak past the piston rings and into the crankcase.
You do need to run the engine to get all the water boiled off as soon as it possible though.

 

[capjules]

Bill,

I don't understand your respose, the hose connected to the sea water pump exit
is not connected to anything as the heat exchanger is off but the water did not flow from that hose. It flowed out of the exhaust manifold in the opposite direction it usually goes.

sea water exits the heat exchanger and goes into the exhaust manifold.

with the heat exchanger removed the hose that connects the exchanger to the manifold is dangling from the top of the manifold and water came out of that hose as I turned the engine.

I have a vented loop in good working order so I don't know how this is possible.

Thanks,

 

[RichH]

All depends on the configuration and location of the water injection nozzle on the exhaust/muffler system, and if the 'water lift' muffler was already filled with water when you disconnected the Hx.

The most common (OEM) water injection nozzle on the QM series is mounted directly to the discharge of the exhaust manifold and is at 'just below' the 'height' as the ex. manifold. If when you disconnected the Hx and the water did drain into and 'overfilled' the water lift, then there is always a possibility of water backfilling into the engine. However, if you have a 'heat riser' or modified water injection system (usually black iron piping that forms a 'loop' well above the engine) where the 'injection elbow' is 'much higher' than the Hx, then probably no you didn't get water into the combustion chambers.

All this is based on 'probability'; but, to be sure, simply consider to remove the injectors and LOOK for the traces of water in the cylinders, or even better/safer, 'just assume' that there is water and simply put in a *small* amount of a lightweight oil (Marvel Mystery Oil, WD40, etc.) into the combustion chambers and simply turn the engine over a few times by hand to distribute the oil on the surfaces and to lessen the possibility of any 'rusting' of the cylinder walls, and piston ring grooves - a 15-20 minute job.

BTW --- since the injectors would be removed at this time, it would be a good time to send them out and have them checked/rebuilt by an 'automotive injector service shop' --- every LARGE town has one.
BTW2 .... and as simple jobs like this always seem to 'grow' its also a good time to 'rod-out' / 'descale' all the water passages in the exhaust manifold and then pressure check it to assay if the ex. manifold has developed 'pin holes' between the gas-side and the water-side --- if pin holes, this is the 'highest probability' cause of water getting into the combustion chambers.
BTW3 ... on the QM3, the valve backlash is always set/adjusted with the engine AT near operating temperature, not 'cold'.

;-)

 

[RichH]

with the heat exchanger removed the hose that connects the exchanger to the manifold is dangling from the top of the manifold and water came out of that hose as I turned the engine.

Therefore LOW probability that you backfilled the combustion chambers with water. The raw from the Hx to manifold simply caused/allowed the drainage of the injection nozzle loop hosing. Turning the engine by hand simply supplied slight pressure in the exhaust system and it additionally 'exited'/shunted into the raw water loop because of the water level in the 'water lift' partly is blocking the muffler to hull exit.

 

[capjules]

Hi Rich,

The light bulb just came on, yes since the air being pushed into the exhaust by hand turning it could not go down the exhaust pipe which is blocked by water at the muffler it pushed back through the vented loop and pushed the water out of the manifold.

I think all is good but I will crank the engine with decompression on for a few turns before I let it fire.

Thanks !!

 

[Bill Roosa]

I guess I'm not getting where the water is coming from. If it is coming OUT of the exhaust manifold then it should be going in the normal direction. if it is going into the engine that would be backward IMHO.
In all cases you probably did not get that much and know it is not a leak so just get the motor clear of water in the combustion chamber with two full turns of the crank then run till she is good and hot to get any water out of the oil.

 

[Ray Bowles]

Once the engine oil is hot I would change the oil and filter rather than trusting the heat to remove the water.
Ray

 

[MrBill_FLL]

marvel mystery oil. -lots of it. and some pb blaster.