How do you guys close/weld up the holes on OBD2 manifolds?

[Mike B.]

All I know is that I had fitment issues with the subframe with OBD-II headers and not with OBD-I headers. YYMV. I was also using an OBD-I midpipe.

Plus, in that picture above, the engine is on a stand and not mounted in the car.

[matt]

obd2 headers have (2) o2 ports that are not used. i found that an oil drain plug (cant remember which car) fit almost perfectly flush with the inside. i THINK the plug was an m18x1.5......but dont quote me. jason

You are exactly correct.

The manifolds fit the same OBDI vs II, but the midpipes are different. The OBDII midpipes have extra insulation that makes ignorant fools think they are 2x2.5" pipe.

[FredK]

The OBDII midpipes have extra insulation that makes ignorant fools think they are 2x2.5" pipe.

Haha, no kidding! They're like 2x2.25"!

[FredK]

SIKE!

[static]

Haha, no kidding! They're like 2x2.25"!

try less than 2"x2 (on double walled obd2 that is)

http://www.rogueengineering.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=CATS

multiple people with '95 e36m3s reported from first hand experience - "no direct swap" for obd2 manis.
albeit not much modification necessary (e36 perhaps offers more clearance), pipes had to be bent to accomodate obd2 manis.

[FredK]

Yeah, I was just kidding. They're close to 1.875" or so.

I cut my OBD-II midpipes and the internal pipes are pretty damn small. I didn't know that the midpipes are not directly interchangeable, though. Good info!

[matt]

You are exactly correct.

The manifolds fit the same OBDI vs II, but the midpipes are different. The OBDII midpipes have extra insulation that makes ignorant fools think they are 2x2.5" pipe.

BTW, the drain plugs are available at any BMW Motorcycle dealership. They fit K-bikes and certain transmission fill plugs.

07 11 9 919 143
07 11 9 963 300 is the crush washer.

I can ship some kits out for about $5 + shipping. If you guys need them, PM me.

[dougsic]

You are right to consider replacing the exhaust studs. They only cost about .32 each from the dealer. I replaced the copper nuts as well.

As in Freds experience, most of mine came out when I removed the nuts, so I only replaced those. Big Mistake!

Getting the nuts started on the partially rusted studs took a lot longer than getting them started on the new studs.

Be aware though. The studs are fine threaded and they screw into the block pretty far. If the engine is in the car, it gets tiring so I started them by hand, then ran them in with an air ratchet with the torque turned way down and finished tightening them by hand. Much faster and less tiring.

To install the new ones, I just double nutted them as seen below.

I only have experience with cast OBD1 manifolds but here are some interesting things I noted:

The combined weight of the stock OBD1 manifolds is 20.33 pounds.
The midpipe that connects to the front manifold measures 1.989" O.D.
The midpipe that connects to the rear manifold measures 1.765" O.D.

[FredK]

Be aware though. The studs are fine threaded and they screw into the block pretty far. If the engine is in the car, it gets tiring so I started them by hand, then ran them in with an air ratchet with the torque turned way down and finished tightening them by hand. Much faster and less tiring.

Yes, this is one of those tips and tricks that I learned from my first swap. Install the studs when the engine is on a stand. Installing them lying on your back underneath the car, or your hand snaked in some awkward position from up top is not fun.

[static]

i don't want to misinform anyone about the obd1/obd2 manifold fitment so here it goes:

multiple people on bf.c are swearing that the fitment is apparently exactly the same (i.e flange points and orientation) i.e a direct swap.
reference: http://forums.bimmerforums.com/forum...=761332&page=2

will check with my mechanic tomorrow

Alex

[equate975]

First I busted off the air pump by wiggling it back and fourth until it snapped off. That way you don't have to break the exhaust seal.



Then I took it to my machinist to cut the tabs off and weld them shut, then I bolted them back down.

[RyanZ06]

First I busted off the air pump by wiggling it back and fourth until it snapped off. That way you don't have to break the exhaust seal.



Then I took it to my machinist to cut the tabs off and weld them shut, then I bolted them back down.

That is what i did. Have you had any problems?