D2 Aftermarket Y-Pipe install

jsonova99

Well-known member
Apr 14, 2005
1,683
0
42
Snow Hill, MD
I'm in the middle of replacing the Y-Pipe on my D2 and ran into some issues with leaks. I bought an aftermarket one on ebay, comes in two pieces with the mate between the two halves done with a clamp. I went this route because I thought it might actually give me a slight bit of adjustment if needed to fit it.

Anyway, got everything installed and it leaks at all three joints, but no check engine lights at least. Best I can tell, the mating flanges between the manifold and the y-pipe are not parallel, so when you tighten the three manifold bolts (on both sides I believe, but definitely the passenger side), the inner most part is tight, but there is a gap at the outer most side, hopefully that makes sense. I stupidly broke a stud thinking that I could tighten the outer bolt some more to close the gap even though I should have known better. Anyway, since I had to remove the RH manifold to take care of that. my thought is to mate the LH side, then mate the loose RH manifold to the y-pipe to get a good seal at that joint and then mate the manifold to the head. Seems logical but I'm just curious what others have done to get the seals tight.

The rear seal at the muffler is also leaking, I'm not sure what to do there yet, but I think I do have some room to play there since I can move the muffler around some.
 

The Fourth Amigo

Well-known member
Apr 20, 2009
641
1
Bolt everything up "loose" so it floats a bit then tighten the RH and LH downpipe flanges (use a small amount of high temp RTV on these). Next, tighten the manifolds, followed by the ball type muffler connection. The last thing should be the clamp for the two sections of the y-pipe.

I just went through all of that.
 

jprover2

Well-known member
Apr 8, 2017
74
2
Birmingham,Al
Most aftermarket y-pipes are this way. I put one on last year and had my D2 on a rack and had to use heat and a lot of force to get the gaskets at the manifold to y-pipe sealed. The next time I have to remove my y-pipe I'll cut the old y-pipe and weld my newish cats in.
 

jsonova99

Well-known member
Apr 14, 2005
1,683
0
42
Snow Hill, MD
Fixed the broken stud, much easier than I was expecting. Going to try this again, when loosening or removing the manifolds, does anybody recommend replacing manifold gaskets? I've done it before with the manifold in place mounted to the y-pipe, not a hard job, but not fun either, just curious if anybody thought it was worth the effort or not. I do plan to put new gaskets on the RH manifold that I currently have off, they only cost $11, cheap insurance I figure but I was probably going to leave the LH side alone unless there's good reason to replace them.
 

jprover2

Well-known member
Apr 8, 2017
74
2
Birmingham,Al
You shouldn't ever have to loosen the manifold to make a y-pipe seal. You'll end up creating another leak that you will not seal. I'm not trying to bust your balls, but if you can't make the y-pipe seal to the manifold then how if they're bolted together will the manifold seal to the head? If anything you want the manifold sealed to the head properly.
You can use wire cutters or tin snips to trim the ears on the exh. manifold gasket so it will slide over the bolts. I'd trim 2 ears on each gasket to slide over 2 bolts each, then start the other manifold bolts.