Exhaust leaking near manifold

[dan3317]

I have a major leak near my manifold that is creating alot of extra noise for my car. I spent time underneath and above while the motor is running, I saw puffs of smoke coming from the 2nd set of pipes(back), but I can't tell if it is coming from a leaking gasket or a hole or crack in the pipe. Which is it more likely to be? I am worried about taking this in, it seems like both parts and labor are going to be high. Would it be worth considering getting a set of higher performance headers if I need them replaced? This is for a '97 328IS with 180,000 miles.

[berlinetta]

check underneath when the engine's cold, you should be able to see signs of the leak. I vote headers leak or not:buttrock

[dan3317]

Tried looking from underneath, I can see signs, but not exactly where it's leaking, it's actually easier to see the leaking from the top, I can alsmost see where the smoke is coming out, but not quite. Is there a DIY anywhere for replacing headers? It looks like a scary job, but I don't want to pay high labor.

[dan3317]

Bump

DIY for replacing headers? Anywhere?

[Icecream ///Man]

BUMP.

I'm in your same boat. My 96 M3 got noisy and smelly under the hood at 155k miles. Gasket between header and cylinder head is leaking for sure. You have a cast manifold, a little different. I've done some research and the studs on the header (manifold) flange can break off so be prepared. I'm going to attack this project in spring. If you look around you can find e36 m3 headers (a bolt on power adder for you) for cheap. I hear that's a popular upgrade.

Here's my plan:

1) Buy air tools (With the clearance on that side of the engine and the corrosion on the nuts air tools seem like a MUST HAVE)

2) Buy all 4 gaskets

3) Soak the header bolts in PB Blaster then put a socket on the nuts and whack the shit out of them over and over every day for about a week.

4) Throw the air wrench on it and hope for the best. The Bentley's service manual had no instructions just a diagram. It showed....a bunch of bolts cranked on studs. This sandwiches the flat type gaskets. Straight forward until I break something.

Anybody with experience please chime in, thanks.

[dan3317]

I did get this taken care of at a shop, actually for my year, the headers are SS and the same as the M3's. I had a broken muffler mount that was causing my whole system to swing from side to side. It cracked and leaked near the flange connector to the cat converter pipe on the back side. The crack was not visible because it was so close to the flange and the leaking air shot upwards, I didn't catch that when I was feeling around while the car was running, I thought it was right at the engine block.

I had the header removed and welded back together, added a couple of new mufller mounts, costed me about $350, car is as good as new now.

Good luck with yours.

[Icecream ///Man]

Where did you get the work done? Would you recommend them?

[hellrot325]

BUMP.

I'm in your same boat. My 96 M3 got noisy and smelly under the hood at 155k miles. Gasket between header and cylinder head is leaking for sure. You have a cast manifold, a little different. I've done some research and the studs on the header (manifold) flange can break off so be prepared. I'm going to attack this project in spring. If you look around you can find e36 m3 headers (a bolt on power adder for you) for cheap. I hear that's a popular upgrade.

Here's my plan:

1) Buy air tools (With the clearance on that side of the engine and the corrosion on the nuts air tools seem like a MUST HAVE)

2) Buy all 4 gaskets

3) Soak the header bolts in PB Blaster then put a socket on the nuts and whack the shit out of them over and over every day for about a week.

4) Throw the air wrench on it and hope for the best. The Bentley's service manual had no instructions just a diagram. It showed....a bunch of bolts cranked on studs. This sandwiches the flat type gaskets. Straight forward until I break something.

Anybody with experience please chime in, thanks. I pulled the exhaust manifolds off during a HG repair, there are 24 nuts/studs. Air tools are only required because its a long slow process of 1/4 turns for many of them because of clearance...an air ratchet would have sped up the process. In my case, most of the nuts would easily break loose, but as I was trying to thread them up the stud they would bind, and the stud would come off with them. No big deal,just took the stud off too. Replaced both. The bigger risk is the manifold to exhaust connection...I busted one of the studs off...just drilled it out and put a bolt/nut through it to pull it tight.

[blue///m3]

I replaced the cast manifolds on my M3 with ones from a 98 328 (the tubular ones). I did the work myself with not many problems. Here is what I did:

Parts:
Tubular manifolds. If ODB1, get the air pump holes welded and get 2 plugs for the O2 sensor holes.
The exhaust manifold gaskets (should be 2) for the head
2 triangular manifold gaskets to the cat pipes.

Tools.
-Set of socket wrenches and extensions, Deep Socket should be available to to reach where the extensions are too long. I also got a few swivel extensions to help too
-Air tools. Impact gun may be necessary for the catpipe nuts but be careful not to break the stud. get the smallest air wrench possible, it will make it easier to reach the headbolts.
-Stud installer socket. Its a funny looking socket that has a set of camlobes in it to hold a stud while it gets installed. You may need it to reinstall some of the studs that may come out.
-loctite.
1. Soak the 24 nuts with a penetrating lube (I used wd-40). also soak the 6 nuts on he manifold/cat pipe joint)
2. Unbolt the 6 nuts connecting the cat pipe. You may want to drop the cat pipe a few inches to give you room.
3. Unbolt all 24 nuts. Don't worry if you pull some of the studs out, you can reinstall them using the stud socket, you'll just have to get the nut off by holding it in a vice and using the stud socket to unscrew it.
4. Slip the manifolds off the head. A small breakerbar or large screwdriver can be carefully used for leverage, just don't use it on any of the mating surfaces or you may scratch it and cause a future leak.
5. Take the old manifold gasket off and clean off the head and manifold surfaces of any leftover gasket and carbon with a scotchbrite pad, fine emory cloth and brake cleaner. It's also a good idea to take a scrub brush to the studs to clean off debris or rust that is still on there.
6. Install any new or missing studs. Use loctite too.
7. Slip the new gaskets over the studs.
8. Install the manifolds.
9. Install and tighten all the nuts. I recommend putting some loctite on the last few threads closest to the manifold and some paste lubricant on the first few threads. The lube will help the nut not bind while tightening it. The loctite will keep the nut from backing off once tight. also. DO NOT OVERTIGHTEN!! This will cause the stud to back out of the head and it is a PITA to reinstall them with the manifold in place (don't ask me how I know). I don't remember what the torque specs are but I went with a quarter turn after hand wrench tight and haven't had any issues. if your air wrench has torque settings, use a low one otherwise you'll pull every stud out.
10. hook up the cat pipe with the triangular gaskets. I used a bit of masking tape to help hold the gasket until the nuts were started. A bit of lubricant here helps keep the threads on the nuts aligned.

That's it! Expect to spend a good afternoon doing this.

[BMW&PorscheDude]

I had to replace them on my 97 328i. I seriously doubt your manifolds are bad. And performance mainfolds are very expensive and you're not going to gain much, if any, unless you get high flow exhaust the rest of the way down, ie., bigger down pipe, high flow cats, etc. = very expensive also. This is usually reserved for after you've done all of your other mods first, including intake manifold and cams. Remember, the 328 exhaust is the exact same exhaust that the factory put on the M3 (except the cat-back muffler) so it is not bad exhaust by any means.

My recommendation: Just buy the two manifold gaskets (about $40 at the stealer). Remove the exhaust manifold nuts, pull the headers away, remove the old gaskets, carefully cheat the new gaskets into place and tighten it all back up. Get one of your friends to help you on a Saturday and it should make for a good DIY.

Have fun and good luck!

[Icecream ///Man]

Thanks for the DIY info gentlemen :D

I've never pulled a car exhaust manifold before. Sounds like it's worth trying to do myself without the air tools as they would be overkill. I have good hand rachets (and a good mechanic down the street if I really screw it up).

[blue///m3]

Thanks for the DIY info gentlemen :D

I've never pulled a car exhaust manifold before. Sounds like it's worth trying to do myself without the air tools as they would be overkill. I have good hand rachets (and a good mechanic down the street if I really screw it up).

You can do it easily with hand tools. My air ratchet was too big for most of the manifold nuts. Have fun!!