I've looked through a few threads trying to solve this but just want to be sure before I arse it up As the title says just trying to work out how to plumb the mk2 scirocco heater matrix (upper hose red 1 lower hose red 2) into the 1.8T,I bought the engine already removed so unsure where the matrix was originally plumbed into. The hard pipe from the pump housing comes around the front of the block and up ( Yellow 1) beside the tip into a y-piece ( yellow 2) where the larger diameter hose (Yellow 3) branches off and connects onto the coolant flange at the side of the head, the smaller diameter hose ( Yellow 4) joins to a t-piece that goes to the small diameter hard pipe across to the coolant bottle ,other branches back onto the plastic flange for the upper rad hose. IMG_20220724_121106 by Paul Miller, on Flickr IMG_20220724_121804 by Paul Miller, on Flickr Would yellow 2 connect to (red 1) matrix in and connect Red 2 back into the y-piece where yellow 2 was originally connected?
Stop the bus. Found a similar engine on ebay for sale from a polo gti (BJX) mines is bbu and from the pics its looks as if Yellow 2 is disconnected from the Y-piece so the guy I got the engine from just plugged them together for whatever reason so that clears that confusion up. I now believe the heater inlet Red 1 will be fed from the y-piece and Yellow 2 will connect to the matrix outlet Red 2. I'm assuming the small hose Yellow 4 act as a bypass so only two reducers needed to plumb this in and no need for any additional t-pieces to worry about when the mk1 heater vale is set to cold as Yellow 4 takes care of this?
not sure which one it is so I'll post both: you dont need to worry about adding the mk1 style matrix bypass on the 20v engines as you can see they already have a hose in roughly the same place as the mk1 engines, presumably the yellow one you mention is the one on the diagram shown when gearbox oil cooler isnt fitted?
Some reducers and elbows ordered and hopefully get this plumbed in asap , as the diagram proves the matrix inlet is fed from the coolant flange and the outlet back towards the block so that's put my mind at rest Cheers
