DX metal coolant pipe ID help

Hello,

I have a GTI Cabriolet, registered in June 1990, though I think it may be a 1989MY (as it doesn't have a power hood). It has a DX engine.

I want to replace the metal coolant pipe as the one there is rusting.

I had a look at the pipes available from various places online (Heritage, Classic-VW.co.uk, Autodoc, B&B Components) and ordered a Febi one that was supposedly correct for the 1.8 DX GTI engine.

However, the pipe I received (and all the others online) look to be different from the one in my car. The new one has four outlets; the one in the car only has three. The bit circled in red on the VW diagram (and which is on all the pipes I've seen) is not on the pipe in the car.

The one in the car connects to a hose behind the oil filter, to another one beside the block, and another one that goes to the heater matrix. In the car, the lower matrix hose connects directly to the engine block rather than to the metal coolant pipe.

Can anyone help me identify the pipe that I need or explain what I need to do to make what's available work in my car?

Thank you!

Mmm, just had a look at mine. One goes to the heater matrix, the other end goes below the oil filter to connect to another hose on the water pump and a T goes to the plastic water reservoir. So no more  pipe connections on mine. I can't see the correct pipe on Heritage unless somebody else stocks it.. I would ask a plumber to make one up in copper. It looks to be 15mm but you need to check diameter

folks over here can go to
VW Coolant Pipe - Rein 037121065L | FCP Euro

to get one, there may be an additional hose that has to be capped off.

As some Dubs as in the 90's cabby has the pipe comes out of the Waterpump, then around the engine to the heater matrix.

Others as in 84-89 Cabbies has it run over to a "T" hose
up to the oil cooler on the oil filter flange, The other ende goes around the engine to the heater matrix hoses.
werk34.de  has a couple of them listed for the mk2