black specs in coolant fluid and head gaskit leak

[Bluey]

Hi all:

 

I have lately noticed some small black flecks in my coolant overflow bottle and the level of fluid in the bottle is very slowly reducing. The rate is about 10ml over about 5 hours of flying. I cannot see any obvious leaks in the system anywhere and no emulsified oil in the fluid. There is a small leak begining in the head gaskit. This shows itself as a fine line of fluid about 1.5cm long with tiny drops along the boundary only noticable after about 4 hours of flying. It doesn't seem to be getting worse and it was first noticed about 20 hours ago. The funny thing is we did a full top end overhaul about 80 hours ago. The engine is a blue top (oil injected) with 560 hours since its only rebuild. It has 1321 hours from new. Should I be too concerned at this stage?

 

Thanks, Bluey.

 

 

[alf jessup]

G'day bluey,

 

The only thing I can think of is maybe carbon getting back into the coolant system through possibly a leak somewhere starting to happen between the combustion chamber and the water jackets around the cylinders / heads.

 

I am only guessing as my old ute started losing water and that was through the water jacket corroding through the exhaust port as I thought the head was cracked and when I got it tested it was fine but after some searching it was found to be corroded out through the exhaust port and was very difficult to trace, maybe yours is starting to corrode somewhere else as it has a few hrs on it, it is definelty worth investigating.

 

cheers

 

Alf

 

 

[Kev]

Bluey Hi,

 

I would say that it is definitely worth investigating. The black flecks could be either rubber material from a seal, or possibly more likely carbon. If carbon, they should crush to a powder.

 

That aside, you appear to have a definite coolant leak in the top end, and this needs to be looked at. If you do this , have a really good look at where the cylinder seals contact the head. A small amount of corrosion/pitting here will promote leaking. Rotax allows you to skim the head up to 0.012". Obviously this should be recorded in the engine logbook.

 

Also worth considering is that even a full overhaul only replaces most of the consumable items and not all. The rest of the engine will continue to wear/deteriorate, and you seem to have a lot of hrs on this engine. It might be worth you considering replacing with a new one. Expensive, I know, but it really does give you peace of mind. Hope this helps.

 

Safe flying

 

Kev

 

 

[facthunter]

Losing coolant.

 

Check the water pump seal. The oil reservoir may show milkiness in the oil. Even though you have a weep of coolant at the head face, IF there is no trace of oil in the coolant fluid, I would not disturb the heads again yet. Nev..

 

 

[Bluey]

Hi all:

 

Thanks for all the replies so far.

 

I just spoke to bert floods about this and they say they have never heard of black specs like this in the coolant. They seem to suggest that it may be bits of a hose as they claim that there is nothing in the engine that will cause this ???? Anyway, the rate at which it is dissapearing was not of any concern to them either especially since no oil was mixed in the fluid. So it has me lost a bit. I will continue to keep a close eye on it but a new engine is on the cards. $6375 plus gst.

 

Regards Bluey

 

 

[facthunter]

Black specks.

 

A deteriorating hose can do this , but it would have to be very old or affected by oil. Bits of the interior will detach. IF this has occurred, the radiators should be reverse flushed after the hoses ars replaced. Nev.

 

 

[Tomo]

I haven't had anything to do with the engine in mention, so I'm not sure about this, but does the coolant header tank cap have a relief pressure overflow outlet or pipe on it?