Hi,

 

Has anyone else had issues with a blocked heater matrix resulting in no interior heat?

If so how big a job in terms of cost and time is it to rectify?

Rest of system is fine and water pump has been replaced.

Many thanks.

If it has happened after coolant system has been apart could it not be air-locked?

I would agree with Urrell, and suspect an air lock, especially as you've obviously had to drain the system to fit the water pump.

No the issue presented itself prior to a cam belt/tensioner/idler pulleys and water pump change. Whole system has been flushed but heater matrix is resistant to clearing.

My friend who’s undertaken the work suspects that K-seal or similar has been used at some point to seal a leak in the system. No signs whatsoever (so far) of head gasket failure or an issue with the block that may have caused sealant to have been used in the past and as a former VAG technician says such failures are rare on this engine.

Not quite the same vehicle, and not sure if it applies here, but some VW group vehicles have a bag of silicon (I think) within the coolant header tank to prevent corrosion. These have been known to fail with the silicon 'grit' escaping and blocking the heater matrix. My Grandson has an Audi A3 TDI (2013,) which suffered this problem. Others have replaced the heater matrix to overcome the problem, but in his case it was fixed by removing the hoses and reverse flushing the heater matrix directly from a mains water pressure hose (I understand it needed repeat flushing in both directions to completely clear it,) then replacing the header tank. On the Audi, replacing the matrix would have been an awkward time consuming job - the same probably applies to the Yeti. Hope you succeed with it.

15 hours ago, Gravitas said:

My friend who’s undertaken the work suspects that K-seal or similar has been used at some point to seal a leak in the system.

Then it sounds like heater matrix replacement needed.
Can you not detach heater hoses in engine compartment and reverse flush with hose?