whats the death pipe

Sort by date Sort by votes
Hello,

There's a black plastic pipe that carries coolant at the back of the engine. I'd guess it's about 18 inches long. Unfortunately, it's inclined to fail, resulting in a loss of coolant. If you're lucky, the failure is slow and you'll start spotting wet patches beneath your engine bay. If you're unlucky, it'll fail spectacularly and dump all the coolant on the motorway. I think there are now many FSI owners who take the attitude that it should be changed with the same regularity as the cam belt.
The coolant circuit of the 1.6 FSI is quite complex, meaning there are a number of little T-pieces to divide/combine the flow of coolant. These become similarly brittle over time, but their small diameter usually means their failure isn't catastrophic.

Cheers,

Tom
 
Last edited:
Upvote 0 Downvote
the cooling system on a 1.6 runs at 110C. That's pretty hot. It also has a negative effect on the life of the plastics involved in the cooling system. There are several weak points, one of them being the thermostat housing (and the thermostat is *not* a simple one) and another being a specific y pipe at the back of the engine. It's a pig to get to and therefore expensive to change, but failure will likely cause serious issues.


(timmus was writing at the same time as me)

- Bret
 
Upvote 0 Downvote
Having never studied the installation of the death pipe in any detail, can anyone tell me why it has a flattened surface rather than just being cylindrical? Also, do the two little round plastic studs that emerge from the flattened surface serve any purpose?

Cheers,

Tom
Andrew said:
PS. Note Tom's impressive use of semicolon.
Click to expand...

I'm something of a semicolon addict! Such a useful bit of punctuation. :)
 
Upvote 0 Downvote
I can only speculate, but first some figures. In rounded figures the diameter of the pipe is 37.5mm (almost sounds imperial 1 1/2" !!!) while perpendicular to the flat face it is 33.5mm, a saving of 4mm in thickness in that orientation - hardly seems worth it to me. I can only guess that it is to give extra clearance at some critical point, maybe from that steel support bracket the supports the upper inlet manifold from underneath, but I am not really buying it.

The protruding studs look to me like locating pins but as far as I know don't locate with anything????

I am not buying fluid flow either, my gut instinct is fluids would flow best in the natural symmetry of a round pipe.

All a a puzzle then.

My only other thought is that the BAD engine was used in other VW models Golf, Jetta and Bora in the period 1998 to 2004, according to a website I just browsed, and as this predates the A2 FSI then maybe the design of the death pipe originates there with elements of design redundant for the later A2.

Andy
 
Last edited:
Upvote 0 Downvote
Sorry, but I disagree about leaving it alone, change it if it hasn't been done yet. They are not designed to take the heat, very poor choice of material. Change now or risk possible head gasket failure when the engine dumps it's coolant. The flat side is toward the block. They begin to fail at the pump end which isn't obvious.
 
Upvote 0 Downvote
Thanks for the replies, chaps. Indeed, it seems that the flattening of the pipe and the little 'pegs' serve no purpose on the A2. Perhaps it is due to this part being shared with other cars that has resulted in these aspects of the pipe's design.

As can be seen in both the photos linked above, the flat side of the pipe faces away from the block.

Cheers,

Tom

PS: Andrew - I've received your PMs and will reply later this afternoon, once I'm back from today's activities.
 
Upvote 0 Downvote
I suppose flattening could serve to baffle swirl and encourage coolant from the edge of the pipe into the centre but that would only work if the coolant in the pipe was swirling - corkscrewing it’s way up the pipe.

Otherwise, Newtonian hydrodynamic theory would support any narrowing of the lumen increasing friction and thus reducing flow. (I think... it has been a while)

A wonderful mystery?


Sent from my iPhone using Tapatalk
 
Upvote 0 Downvote
that pipe or a very similar one used to be metal on earlier engines, it used to rot out. Something similar must have been used on early Polo's or Golf's or Audi's, I havent worked on VAG products since at least 1997 and the cars were at least 2 or 3 years old then but I recall changing something very similar, I think it has an O ring in the block to seal it.
 
Upvote 0 Downvote
the part number used 032121065D fits Golf's, Polo's, Seat Cordoba & others, in Stainless it would be £40 or £50 not the £10 you can buy them for.
 
Upvote 0 Downvote
I'm looking this morning, if I havent found some in stainless by tomorrow night I'll start and make some (10 ?) on Monday morning with a view to having them ready in a few weeks. The ends need machining then welding onto the tube, they will be round and possibly 38mm or 38.1mm = 1.5"
Chris
 
Last edited:
Upvote 0 Downvote
You must log in or register to reply here.
Back
Top