'Oil' in Coolant Expansion Tank

Alastair · Borekit Bruiser Joined: 13 Dec 2005 Karma :

While I'm still waiting to get the engine re-build back I was giving the bike a bit of a check over and clean yesterday. The engine is obviously out and I drained the coolant to do that but never before looked at the expansion tank.

When I took the rubber stopper out of the top yesterday I noticed that it was full (within the level marks) of black oily fluid. It didn't really smell like oil however but was slimy. As a result the tank is not clear anymore so I thought is was empty as it looks like nothing is in it but it's actually coated in crap.

I should be getting the engine back within a week so am wondering what I should do with this? Take off the tank, drain and clean? What about the pipe that comes into it should I try and flush that too?

Bike is a Yam TDR by the way but is the same set up as a DT/R or TZR.

Any advice appreciated and also explanations as to why it would be black now instead of normal coolant.

I blame the previous owner Wink

finpos · World Chat Champion Joined: 13 Sep 2005 Karma :

In my experience, black oily fluid is usually.... oil.

Possibly a sign that the engine has had a head gasket failure (4 stroke?) when you may get oil in the coolant, coolant in the oil, or both, depending on the engine. But it seems like you're having a re-build, so don't worry.

If it's a two-stroke, then that's a bit odd, but could be down to a gasket failure somewhere else.

Just clean it out with de-greaser - hot soapy water if you are desperate. Put some gravel in it as well and shake it to buggery. Oh and make sure you have all the soap and gravel out before you re-fit it!

finpos.

Alastair · Borekit Bruiser Joined: 13 Dec 2005 Karma :

Thanks for the tips. I wouldn't leave any gravel or soap in don't worry!!!

It's a 2-Stroke so still dunno what's caused it. Think I better clean out as many tubes and pipes as I can too.

This bike is a damn lemon Sad

Davo · Davo To The Rescue! Joined: 04 Apr 2004 Karma :

If I remember rightly, I'd probably look at the seal around the water pump.

Obviously drain the reservior and flush it through with some clean water.

Alastair · Borekit Bruiser Joined: 13 Dec 2005 Karma :

Thanks for that, I'm hoping the mechanic knows enough about what he's doing that he'll be giving me back a 100% engine but I'll mention it to him anyway.

ZZR-Souls · Renault 5 Driver Joined: 20 Feb 2006 Karma :

And don't just fill it with water. Use a proper engine coolant that is either bright green or bright pink. That way you can see easier if it need topping up.
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Alastair · Borekit Bruiser Joined: 13 Dec 2005 Karma :

All coolant Question

Or 50/50

ZZR-Souls · Renault 5 Driver Joined: 20 Feb 2006 Karma :

Whatever it says on the container.
i.e. Read the instructions and do exactly what it says on the tin.
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Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Oil in the coolant will cause a horrible scum in the header tank. However hopefully any faults causing that will be fixed with the rebuild (although the water pump seal is a good call).

To clean it out try using some biological washing powder and leaving it to soak overnight.

All the best

Keith
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cokker · Spanner Monkey Joined: 22 Mar 2006 Karma :

I had a TDR with oil in the coolant, turns out the shop i sent it to do the head gasket put some crappy thin (looked like steel) head gasket in it, they showed me the one going in (copper or something) and never had a problem after that.
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