My Worcester 24CDI combi boiler leaking brown sticky fluid badly!?

Hello all,

Hope someone can answer my question as I am quite concerned. I have a Worcester 24CDI combi boiler that had a pressure problem last week. The bar was down to zero, and I could not manually adjust myself as the tap to turn up the pressure was firmly wedged. I called out an engineer who adjusted this and turned the pressure up to 1.5-2. Unfortunately this has made no difference to the water pressure which switches between luke warm to cold when the hot tap is on every 10 seconds or so. The pressure is also lacking still.

I returned home from work this evening to find a huge puddle of brown sticky fluid underneath the boiler. It has splashed all up the skirting board, there is a lot of mess! The engineer said that he cleaned up some of this sticky goo as there was a small amount on the bottom grill of the boiler?? He said to keep an eye on it but didnt really explain what it was.

Does anyone know what this could be? I will call the engineer first thing in the morning but I am too scared to turn on the hot tap or heating just incase!

Your help would be appreciated. Many Thanks,

Sarah