Dirty/brown/orange colour cooling water

[1moley]

Hello all,

We have two auxilliarys that before drydock and full overhaul were filled with distilled water and unitor cooling water treatment. Post overhaul both have the same problem.

Post major overhaul we are now using hard shore water.

Since the overhaul almost immediately water has turned dirty/brown/orange colour. Before DD water was always clean.

We have various things checked by the outfit who overhauled them for leaks but nothing has been found. The system runs a LT/HT mix with a plate cooler on the LT circuit. Other side of plate cooler is LT again which is completely clean.

Pressure tested water cooled exhaust manifold, air cooler, Checked pumps, thermostat valves, changed all heads again. Cylinders are always dry on head removal.

We have flushed the cooling system through various drains around the cooling circuit until water run cleans. Circuit capacity is >100ltrs and have flushed maybe 5m3 over the last few months. Once engine runsm within 5mins water is back to the same dirty water.

Has anyone had anything similar or ideas to try?
Thanks in advance

[Big Pete]

Possibly while the system was drained down for the overhaul work, the insides of all the cooling system corroded and this is now coming into the cooling water.
Unitor /Wilhelmsen etc make a commissioning cleaner for de-greasing and de rusting new pipework systems, maybe a power flush with that followed immediately by filling with treated water, so no time for corrosion to form while the system is drained down.

Good luck and let us know how you get on.

BP

[1moley]

Thanks Big Pete,

Just signed back on and only just read your post.

thanks for the tips and will get back with any results

Cheers
1moley

[1moley]

Update:

Engines are kept at roughly 60-70deg C and run between 74 and 78 degC

When starting the units throw out some water and when warming up there is bubbling in the header tank. Once warm and on load there is no bubbling.
The back to back crew did not flush the auxilliary and upon our return the water inside was like a runny mud texture (very dark and sludgy).

Exhaust manifold, turbo, air cooler, all heads have been pressure tested and a camera has been used to inspect inside the cylinder (all dry).



@BigPete: I hear what your saying and the Chief and myself discussed this possibility and believe it unlikely. We have flushed the system several times with hot water before and again since your post until the water runs clear out of several points around the system. Starting and flushing again. But each time after a few mins of running cooling water it is back to dirty brown/black colour. Do you still think it is from corrosion from just a few mins of running?
A shore engineer suggested the bubbling could be the system is overheating but we rejected this due to no bubbling once of full load.

Thanks
1moley

[Big Pete]

The temperatures are far too cold, you could have cracked the castings running them that cold and you may be getting gas blow from the cylinders into the water. I had cracked heads on one ship with MaK Medium speeds, we didn't lose any water, but when the power came up (and the cylinder pressures) exhaust gas blew into the cooling water.
I would be keeping the engine pre heated to about 80 Celsius (Jacket Water) and I expect that it should be running about 85 Celsius at the Jacket water outlet from the engine. I would urgently check your manuals for the correct values and adjust your pre heating and cooling correctly.

BP

[Atlantic]

Hi

I agree with big Pete it’s running to cold maybe a cracked liner or engine block.

[Merlyn]

Pump up the coolant system at varying temps and see if there is a psi drop.
And run it with the psi gauge attached

[Atlantic]

Maybe take a sample of the water you are using and mix it with coolant and let it sit to see if it gets discoloured. Look into the chemical you are using is it the right type for the material used in the engine cooling system.

[1moley]

According to manual the operating temperature should be between 75 and 90deg C.

Due to constant flushing of system. No coolant treatment is added. Also the system we are supplied with requires a colour identification change to adjust to correct amount of additive which due to sludgy water is impossible to determine.

Fitted should be 76 and 2x 81 thermostats which were changed only 300 running hours ago. No visible change to symptoms

Looked in operators manual, parts manual and owners manual there is no reference to having a pre-heater even fitted to be fitted to the engine.



Good idea with the pressure gauge Merlyn. Cannot hurt to try this. I shall fit a few around around the engine to compare.


As always thanks for the input lads
1moley

[Merlyn]

Might be an idea to test the stats. too.
We got a machine like a giant kettle, round holes in the top plate for the stat. to sit in, large electric element in the water container side of things to provide the heat and a built in temperature gauge to indicate water temps.
Turn the stat. over, read the temp. opening stamped/ etched in it and have a boil up.
Watch it slowly crank open ( or not )
If you haven't got a tester sacrifice a saucepan or similar just to see if it's fully opening when it's boiling and bubbling.
In conducting your pressure test ( there's some good kits, ours has loads of adaptors in it for most header tanks etc etc ) if you have a pressure drop present when standing ( with no external leaks present ) or an engine pumping up under load apon stripping don't forger to whip the valves out as I have searched and searched for a hair crack only to locate it in the head underneath usually an exhaust valve.
As a matter of interest what engine / model do you have?

[1moley]

Hi Merlyn,

We have already checked the stats are operating correctly and check the calibration of FW temp probe using the same water bath, all okay. I think this giant kettle thing you call i think is what I would call water bath. Sounds similar at least. When you say boil up. Do you mean check when the water is boiling that the stat stays open or just check it begins opening at correct temp and fully open at correct temperature?

Unfortunately we do not have a pressure test kit. When engine is running though, the standard fitted pressure cap lifts only once a few mins after startup and throws out about a cup of water or so. And the water level in the header tank rises by about 2-3ltrs running compared to when stopped.

Ours aux engines are 325kVA... small lorry engines.

Just to recap...
They are Volvo Penta TAMD1103A .. There are two engines and after full overhaul both have presented the same strange symptoms although one is worse than the other. The are two central cooling systems for the vessel; split PS and SB. Thus engines are completely separate from each other.

Only change after overhaul instead of using distillate water from AC unit drains, it is using hard potable water with high chloride level. It just seems very strange how both engines have presented the same strange symptoms, yet are completely separate from each other.
This company operates many of these engines in the fleet, using the same water supply with no problems at all.

Cheers
1moley

[Merlyn]

In what year would these engines be and what do you mean by " full overhaul " carried out?
Piston/ liners/ bottom end/ crank grind / heads / new oil pump etc?
Interesting one.

[1moley]

Vessel was built in '03. I haven't found reference to the auxiliaries manufacture date.

Yes, you are correct. Bottom end, top end, new turbo, LO cooler, air cooler plates and all new 6 heads (well 12 new heads as they have all been replaced). I may be missing a few bits as I wasn't on board when this was done.

Now you mention new LO pump, which it has had. We noticed that LO pressure is 5.6bar when cold and 5.3-5.4 when warm. In manual it states max working pressure is 5.3bar but again this is the same for both engines after overhaul. Before overhaul it was 5.2 cold, and 4.8bar once warm.

The new parts which connect to FW system have all been pressure tested ashore since overhaul, camera down the injector pockets. No water in cylinders.

As an update on progress.
We have asked the super if it is possible to send a water sample ashore to work out what is in the water. Combustion products, excess oxygen, iron oxide etc. This may help us narrow down the source of the problem.
And source a pressure testing kit

Cheers again Merlyn and all else who have contributed.


1moley.

[Merlyn]

Ref. your remark concerning combustion products if you have access to a decent 4 or 5 gas analyzer machine another quick easy check is to ensure it's set to the HC mode and waft the sensor across the top of the header tank with the cap off having just run it up for a while and it will "sniff" the water.
Any HC's present will immediately show up on the screen.
No HC's ( hydrocarbons = unburnt fuel ) should be present at all.
As a matter of detective work I wonder did the same person do both engines?
Seems it's got to be down to the refit somehow to me?

[1moley]

Great idea with gas detector. Have you done this yourself before?

I believe so yes, there was two guys present from the outfit but it was always the same two. The overhaul company are arguing they did everything right and we did something to cause the problem. Typical blame game. At least the politics of which is way above my pay grade.

Thanks