Alright, my 91 Tsi had a pretty noticeable exhaust leak that caused a rough idle. I found the problem lied in the pipe that came from the manifold down into the turbo...what I get is called the down pipe? I'm not too savvy on the names of parts, but I was wondering if someone could point me in the right direction on getting replacement parts to fix this leak and idle issue. To start with, what are the right sized bolts that hold the manifold on? When I took the manifold off the bolts were a mixture of standard and metric, which I know isn't right. I looked at the thread that lists all the bolts sizes, but I honestly don't know the name of the parts that they connect to, so that doesn't do much for me. I also need to know the nut sizes for the bottom row on the manifold, as these were also a mix of metric and standard. To top it off the bolts that hold the manifold on to the down pipe slide in and out and only one can be tightened down. I need the correct sizes for these as well. Ill include pictures of everything I have taken off, aside from the square gasket I pulled from the down pipe. I've located all of the gaskets I need to properly seal everything aside from this one square gasket that lies in between the manifold and down pipe, any ideas? Thanks for the help. I would like to get this lemon of mine running.

RidingJockey said:

Alright, my 91 TSI had a pretty noticeable exhaust leak that caused a rough idle. I found the problem lied in the pipe that came from the manifold down into the turbo...what I get is called the down pipe?

Click to expand...

No, it's turbo exhaust housing that bolts to the exhaust manifold. That ring is a seal ring that fits between the steps on the turbo exhaust housing and the collector of the exhaust manifold. People usually remove those steps in the manifold and housing when porting and the seal ring no longer fits or works leaving just the square turbo gasket to seal.

The 1G exhaust manifold is well known for cracking so if your is original you may want to check it and replace with a 2G, EVO 3, or Forced Performance cast manifold.

RidingJockey said:

To start with, what are the right sized bolts that hold the manifold on? When I took the manifold off the bolts were a mixture of standard and metric, which I know isn't right.

I also need to know the nut sizes for the bottom row on the manifold, as these were also a mix of metric and standard.

Click to expand...

On a 91 head there were 9 8mm studs, the nuts would have been matching copper 8mm nuts and there should be 8mm washers too.

Since it looks like some have been replaced with inch standard you may need to have helicoils or thread inserts installed to correct the threads for 8mm studs.

One upgrade made on later heads was to use 10mm studs on the two outside positions (one on each end). If you wind up using a 2G or later exhaust manifold tapping for 10mm studs on the outer may save you a couple of inserts.

http://www.dsmtuners.com/threads/exhaust-manifold-studs.425456/
http://www.dsmtuners.com/threads/broken-exhaust-manifold-stud.360358/
http://www.dsmtuners.com/threads/stripping-out-exhaust-studs.348455/
http://www.dsmtuners.com/threads/exhaust-manifold-stud-size-please.345164/
http://www.dsmtuners.com/threads/loose-exhaust-manifold-studs.418898/
http://www.dsmtuners.com/threads/exhaust-manifold-gaskets-and-bolts-studs.403734/

RidingJockey said:

To top it off the bolts that hold the manifold on to the down pipe slide in and out and only one can be tightened down. I need the correct sizes for these as well.

Click to expand...

There are 10mm bolts and a stud on the turbo housing. There are cupped washers used to keep tension on the fasteners due to heat expansion. It's common to use a fourth bolt to replace the stud so it's not in the way of future maint. Again here it looks like you'll need rework done on the threads of the turbo housing. More helicoils or inserts.

http://www.dsmtuners.com/threads/manifold-to-turbo-bolts.410803/
http://www.dsmtuners.com/threads/exhaust-manifold-bolt-size.351740/
http://www.dsmtuners.com/threads/stripped-turbo-bolt-holes.161865/
http://www.dsmtuners.com/threads/arp-stainless-steel-turbo-bolts.287711/
http://www.dsmtuners.com/threads/broken-turbo-stud-removal.368948/
http://www.dsmtuners.com/threads/fp-oem-manifold-to-turbo-bolts.382912/

Thank you man!