Oil in coolant?

[Jeff]

Just drained the coolant before flushing through, put into a bucket and noticed a light film of oil on the top, flushed the rad out and could see more oil in the coolant. Coolant was very brown (rusty colour) and had the OAT pink anti freeze after a full re build 750 miles ago,

Is this a sign of something serious?

Jeff.

[flying farmer]

I can't think of anywhere in a stag engine where oil could get through into the cooling system, except perhaps the oilway that feeds the cams. This is very unlikely however, as this feed is not under full pressure, is right next to a head stud and closer to the outside of the head than the waterway
Most likely if you have had a full engine rebuild, is that some oil applied when fitting the pistons has got into the waterways. When the engine is on a stand and the block is rotated, any excess oil tends to run across the head face and into the water jacket. You will probably find it doesn't happen again, but stag paranoia will!
Neil

[Jeff]

Thanks Neil,

That makes sense, first coolant change so that could be it, many thanks, phew! Jeff.

[martin]

I can't think of anywhere in a stag engine where oil could get through into the cooling system, except perhaps the oilway that feeds the cams. This is very unlikely however, as this feed is not under full pressure, is right next to a head stud and closer to the outside of the head than the waterway
Most likely if you have had a full engine rebuild, is that some oil applied when fitting the pistons has got into the waterways. When the engine is on a stand and the block is rotated, any excess oil tends to run across the head face and into the water jacket. You will probably find it doesn't happen again, but stag paranoia will!
Neil

Here's to Stag paranoia hic ! Nitram.