Hello all

Needs opinions, thought, suggestions and ideas from others on this as I'm pulling my hair out with this.

2008 BKD running webasto aux heater, I can't get the engine block temp to increase to more than around 67-68 degrees. I have replaced the cambelt and water pump along with a genuine thermostat. The stat does work as I have tested it, but the block temp stays low therefore the stat not requiring to open. If I hold the revs up then the dash display will increase to 90 but the rad and obviously the lower hose remain cool. I have tested the temp of all the pipes within the system and they're all pretty much the same. To me its like I have another stat somewhere within the system that is at fault, but I can't seem to find another. I've never had any dealings with a car with webasto. Is there anything within this that I should know about ? THe aux heating works as It should be.

Any pointers, suggestions will be gratefully received atm

Thanks