Radiator Foam?

[rednax86]

Went to do a few jobs on the Black Turd K11 today, popped the radiator cap off and noticed a little bit of foam. Started the car up, the level went down with revs, but every time I was back to idle, this foam was bubbling up and coming out.

Immediate thought of head-gasket, but, it's never got warmer than halfway, heaters work fine, no water in the oil, no white smoke from exhaust, the water doesn't look oily. Could it be something else?

I'll run a compression test in the morning regardless, but it's looking ominous.

 

[Enuo]

Could be contaminated with something else, knackered water pump could be causing cavitation...

 

[h701micra]

Or someone's chucked wash powder in it. I mean I've no idea where that came from

 

[rednax86]

Done a compression test, all cylinders within half a bar of each other around 13bar. The water pump suggestion looks more likely now.

 

[Enuo]

Done a compression test, all cylinders within half a bar of each other around 13bar. The water pump suggestion looks more likely now.

Drain all your coolant into a bucket, then fill system with water and run it and see if it still froths. If not it's just time for new coolant. Potentially saves you buying a new water pump

 

[SuperUno]

Had this on an Uno rally car of mine, never got too hot, but it was exhaust gases passing into the coolant via a tired head-gasket. Tried all sorts to cure it, but in the end it was a new head gasket.....

 

[check30]

I had this after changing the coolant on my 306 after I put rad weld in there

 

[Chris]

Hi Rednax86, did you find the problem/solution to your radiator foaming ? Your photo is identical to my problem. The radiator foams up shortly after reaching temperature. There is no oil/water contamination, and no overheating. But the foam eventually goes into the expansion tank where it floods over. Causing coolant loss. The coolant is a dirty brown colour,,even after a thorough flush through. but it has had a mix of anti freezes and Rad Weld type products over the last 3 years. I have had my head pressure tested and a light skim, new replaced the water pump and thermostat. Flushed out/chemically cleaned the cooling system. I have not found anything that looks suspicious in this c/h work. The engine will have to wait until next month before I can complete the job. The engineers who did the head testing said I should look at circulation problem.