The A3 Cooling Installation
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Coolant is a bit harder on the cross flow head than on a 1.8 GTI engine. The 1.8 uses the same coolant hose connections as the Diesel does.
On this A3 conversion I was able to retain the stock diesel expansion and overflow tanks. The lower radiator hose fit in the stock place as well.
There was a problem with the thermostat housing nipple. The A3 nipple went right into the diesel motor mount. The Diesel one was too close to the A/C mount to allow a hose on. The power steering mount was already removed because it really got in the way.
I got around this problem by taking the aluminum diesel nipple and reducing its angle by about 15 degrees. I cut a vee out of it on the band saw that was about 1/4" on the open end. Then I put the two cut edges together and attempted to weld it. Suffice it to say that I'm not too good with a TIG welder. I ended up coating the inside with JB weld to seal it. I'm sorry not to have pictures of this. They are part of a roll that got killed.
The top radiator hose on the A3 comes out the front of the head where the diesel had its heater hose. The heater hose also comes out the same barb fitting but it points toward the left tire instead of forward
The heater hose I dealt with by using the barbed splice out of a hose repair kit and a piece of scrap heater hose with a 90 deg bend in it.
In order to maintain correct connections for the main top hose, I needed one of those ridiculous VW hoses that are 6 hoses molded into one. Instead, I made a custom manifold to tie all the hoses together.
This adapter is made out of 1-1/4" conduit main tube, 3/4" conduit, part of a steel heater tube from the Jetta, and a 5/16" barb off of a Subaru F/I pump. It's all MIG welded together and this one sealed the first time! the conduit has beads welded on the end to act as hose barb. (Thanks KEP for the trick!)
The pictures are not great but I'll try to explain what hoses went where. I went to my local Kragen Auto (Shucks Auto to some of you) and picked out hoses off the rack. Part numbers are all from there. Here they are from largest to smallest diameter.
The 1-1/4" hose from the front of the head to the left of the adapter needs to have more than a 90 and then return to 90. I found one end of a E71425 was ideal. I just cut it to fit.
The 1-1/4" upper radiator hose (just below the pony clamp in the picture above) is a piece of a E71309 though many could fit.
From the top of the thermostat housing to the 3/4 conduit on the adapter was a perfect fit for a C71221.
The hose from the bottom of the expansion tank to the end of the Jetta heater tube is a 3/4 heater hose from your FLAPS (try Napa).
The 5/8 heater hose from the remaining oil cooler line to the 5/8 fitting on the Jetta heater pipe is standard stuff. It's the one next to the old red dipstick in the picture.
The 5/16 line from the nipple on the adapter goes to the air bleed nipple sticking out of the back of the cross flow head. I hope it's enough to keep air bubbles out of the head.
I took care to make the head air bleed and the 3/4 hose to the expansion tank the highest points of the adapter to let air bubbles make their way to the expansion tank.
Close-up of the adapter
Filled it up, bled the system, haven't put any antifreeze in yet since I'm about to stretch it. No problems yet. Runs one to two needles past the indicator light.