I know this has been touched on before, but I could do with some clarification as I'm in Lima Peru, and my mechanic only speaks Spanish. My technical Spanish isn't very good and my Spanish speaking wife isn't technical.
He was supposed to of looped my heater core the other day and the job failed after running for no more than 75km.
Standing over him this morning as he was sorting things out, it appears to me that rather than loop the pipes, he has capped them both, one of which had failed.
Am I right in thinking that capping the pipes at the back of the engine is just going to cause a pressure build up, resulting in them failing again, or is this OK?
Thanks.

 

Capping puts pressure on both the caps, so both can fail.

You would be better off looping it by just sticking a piece of heater hose between the two capped hoses. Much less likely to fail.