Installing exhaust - a few quick questions

[markmalin]

Hi guys,

Thanks to everyone who contributed to my other exhaust thread. I've decided to remove the Paragon headers and M&K GT exhaust and go back to stock, installing everything from the OEM HE's out to the muffler tip. The previous owner used anti-seize so I should be OK removing the stud bolts. I have the entire original exhaust all dismantled, all the gaskets and nuts/bolts in hand and have a few questions. Here goes:

- Do I install all gaskets (including the 6 manifold gaskets) dry (i.e. no sealers of any sort)?

- What are the torque spec's on the barrel nuts and the hex nuts that mount the HE's to the manifold?

- Do I need any special tools?

- Any other advice?

Thanks guys!

Respectfully,
Mark.

PS - If anyone out there is in the Madison area, I'd happily supply some good, cold beer and pizza if you want to come help

[Quicksilver]

Tips for any exhaust work:
- Find copper or nickle based antiseize. The aluminum stuff sold everywhere is less then marginal.
- Use copper plated nuts instead of the stock nuts. It makes a huge difference when you take it apart later.

[markmalin]

Originally Posted by Quicksilver

Tips for any exhaust work:
- Find copper or nickle based antiseize. The aluminum stuff sold everywhere is less then marginal.
- Use copper plated nuts instead of the stock nuts. It makes a huge difference when you take it apart later.

I wound up buying some of this stuff when I ordered some of the parts, but I don't see where it says whether it's copper or nickle based or just aluminum:

Porsche RGR2012 LM 508 Anti-Seize Compound

Mark.

[tobluforu]

Originally Posted by markmalin

I wound up buying some of this stuff when I ordered some of the parts, but I don't see where it says whether it's copper or nickle based or just aluminum:

Porsche RGR2012 LM 508 Anti-Seize Compound

Mark.

I have that and it's copper.
Use a little bit of high temp sealant to "stick" the gaskets in place when installing HE's.

[Grady Clay]

Mark,

Good for you.
This is the continuing saga of: What are my options for dual inlet single out muffler?
If I were closer, I would come supervise – the pizza.

Spec torque for the M8 exhaust studs in the heads is 20 - 23 Nm
(14.6 - 16.8 ft-lbs).

I agree about using copper plated nuts.
There is a version of the copper plated nut that is still M8 threads but 12 mm wrench size.
This makes wrenching easier.
If you ‘round-off’ a nut, replace it now. It will be much easier than when they have been in place for a year or few.

There are a couple of Porsche ‘special tools’ for earlier heat exchangers.
If you find the need, take an inexpensive wrench (not SnapOn) and bend it (with an oxy-acetylene torch) to fit the nut location.
You will find most professional mechanics have a collection of these.

The M8 bolts in the rest of the exhaust are torque to 25 Nm (~18 ft-lbs).

Don’t over-tighten the two muffler straps. Spec is only 12 ft-lbs or so (in spite of the size bolt).
These need to be ‘just tight’ on the muffler.

Leave all the nuts/bolts installed loose until everything is assembled together, including the muffler straps (note that the muffler ‘hooks’ on the bracket).
Start tightening to low torque spec the cylinder 4-5-6 heat exchanger.
Next tighten the 1-2-3 heat exchanger.
Start at the 4-5-6 heat exchanger to crossover tube and work toward the muffler.
Fire the engine to warm the exhaust.
Tighten to the high torque spec.

Please post a ‘blow-by-blow’ (not to the 911 or you) pictures of the process with any improvements you see.
You won’t be the last to do this so your experience will help others for decades to come.

Smile that you didn’t try and install the entire system assembled.

Best,
Grady

[markmalin]

Thanks for the tips, Grady. Very helpful, especially the installation/tightening order you mentioned. I'll do my best to document the process and post pic's.

And yes, I think I will be forever greatful for your advice on dissassembling the exhaust! Holy cats but the parts are expensive to put this thing back together (~$200 including new straps just in case) ...but that said, given the weight of the thing I would have been an absolute fool to try to install it in one piece!

Mark.

FWIW - I'm sending back the Danks '74 2-in 1-out. I couldn't get it to fit with the existing header/"street adapter" combo from Paragon and the '85 era bracket. I'm going to ship it back tomorrow (at my expense) unless someone local wants to buy it from me at a discount.

[Trackrash]

I would add to check the "flatness" of the manifold surfaces that mate to the heads. (assuming you are using a thin flange manifold)

Mine had warped over the years and I could NOT get it to seal when I reinstalled it.

I had to remove one side and grind the flanges flat.

[markmalin]

Holy cats!!!! I just finished and took it for a drive - it is SO much quieter. I'm happy - still sounds like a 911, too... Will post pictures later...

[markmalin]

So I went ahead and removed the headers, street adapters and M&K dual inlet muffler from my 85 Carrera and re-installed the stock HE's and entire exhaust system. I thought I'd document the process in case someone needs it some day.

Removal:

Two days before I started this, I sprayed WD-40 over the exhaust stud bolts liberally. Then again the night before. Mercifully, the previous owner had used copper anti-seize on the nuts. I say mercifully because they came out like nothing! (This after reading all about breaking studs on the internet)

So to start the job, I first jacked up the car. I read a lot on Pelican about how and where to jack the rear end, then read the section on Jacking Up Your Car in Wayne Dempsey's "101 Projects for Your Porsche 911" book. (An EXCELLENT book, by the way! Especially for me, a new 911 owner). First I blocked the front wheel, which is important no matter how you jack up the car. In the end I took Wayne's advice and used a block of wood under the engine to jack it up.



The car went up very nicely and I was able to fit the jackstands underneath rear bushings as Wayne describes. Worked out really slick.



Next I shook the car pretty well to make sure everything was stable. Next step was to remove the M&K. This took about 5 minutes as it's only held on by 4 bolts.



After this I disconnected the O2 sensor and fished the cable through the hole on the bottom of the chassis, then used my handy O2 sensor socket to remove the thing from the street adapter pipe.

I decided to leave the street adapter pipes connected to the headers and remove them as a unit because it's all very light weight. Removing the exhaust manifold bolts was a piece of cake thanks to the previous owner's use of anti-seize. As for tools, a deep well 12mm socket and 3/8" breaker bar worked well on the nuts I could get at, the others I used a shorty 12mm box wrench. This shorty box wrench was Very helpful in this job!



After removing the headers, Dempsey suggests getting a good look at the exhaust ports. Mine looked pretty good from what I can tell.



So about 45 minutes into the job, the headers and exhaust was removed and I was ready to install the new system. Here's a picture of the entire setup on the garage floor, but I'd like to draw your attention to a few tools that were a big help. The set of extra long metric hex drivers are a must (well...and 8mm one is a must) for installation. Only $13.00 at Harbor Freight! Then, I couldn't pass up a jointed 3/8" drive socket wrench also at Harbor Freight for only $14.00 (shown next to the drivers). The other tools that are rather hard to see in the picture are the set of black shorty metric box wrenches (laying on top of the block of wood).



Installation:

It seemed best to start at one end and move to the other, so that meant installing the right heat exchanger first. I coated the manifold stud bolts with high temperature anti-seize and then laid out the exhaust on the garage floor in the order it would go on. Someone correct me if I'm wrong, but it seems the HE's are identical (left and right). Here's a picture of the pars laid out.



At first I decided it would be better to attach the crossover pipe on the right HE. It made sense ... until I tried to fit the exchanger to the manifold studs. The crossover pipe was in the way (hitting the bottom of the engine) and wouldn't allow me to line up the exchanger on the studs.

So I dismantled the crossover from the HE and started over. Some had suggested using some high-temp gasket sealer to stick the manifold gaskets to the exhaust manifold while installing the heat exchanger. This would have been a brilliant idea, but I didn't have any so I just set them on the HE and tried to line it all up. Once in place I loosely put the 3 hex bolts on to hold the exchanger in place.

After finger tightening the hex bolts, I used my 8mm hex bit to put the barrel nuts on. Here's a picture of the process - basically stick a barrel nut on the end of the hex driver and insert. It worked out pretty slick, actually. Originally I thought I could use my standard length hex driver with an extension, but some of the tubes were too tight, so I'm really glad I picked up these longer drivers.



The rest of the process was fairly easy.

- Install left HE (finger tight)
- coat all exhaust bolts with anti-seize
- Mount the crossover to the right HE and tighten fully
- Mount the Cat to the left HE (this required 2 people because it's rather heavy)

At that point I decided to torque the heat exchangers in place. I torqued the barrel nuts, but couldn't get a socket on the hex nut side, so I tightened them by hand trying my best to get the tension about the same as the torque spec on the barrel nuts. These guys are NOT on there very tight, so be sure to torque them so you don't over tighten them.

Here's a picture of the HE's installed, crossover pipe and Cat. All ready to install the muffler.



As it turned out, one of the muffler straps was too large - not sure why, but they sent me 2 different sizes. Still I got the system all installed using just one strap until I can exchange the other.



The job took about 3.5 hours all told and went very smoothly. I can't say enough about how thankful I am that the previous owner installed everything with anti-seize. Everything came apart nicely. I took the car for a test drive and oh my gosh...it was so nice and quiet. I realize that's not everyone's goal, but to be honest, driving the car with a track setup on the street is kind of cool, but commuting to work in it wound up giving me a headache by the time I got to work! Whit the OEM system my wife was happy to take this car to church, brunch and over to the garden center on a beautiful sunny Mother's day.

[andyt11]

Great write up. However, when rebuilding my engine I also could not understand why my straps were different lengths, until I went back to the photos we took during dis-assembly.

On the stock setup the two straps should be different lengths. One of them goes right around the pipe that runs behind the silencer. The other does not.

This pipe carries air for the passenger compartment, from the blower on top of the engine, down through the sheet metal and into the heat exchangers where it is warmed.

See attached pic. These straps have different part numbers too.

[markmalin]

Thanks so much for the explanation! I haven't installed the heater plumbing yet (my next project).

Mark

[andyt11]

It had me stumped for a short while too.

[PabloX]

I'm in the middle of this now. Great info.

One question though, what is the torque for the two bolts that hold the muffler support bracket to the engine? I can't find those in the Bentley manual.

Thanks.

[markmalin]

Sorry - I'm not sure what the torque spec is for those bolts.

Mark.

[PabloX]

Originally Posted by markmalin

Sorry - I'm not sure what the torque spec is for those bolts.

Mark.

Thanks Mark. I went with 15 ft lbs figuring better safe than sorry.

[PabloX]

FWIW, here's mine.



I had the whole exhaust system media blasted, painted it with high temp paint and I'm putting it together with stainless fasteners. This was all so I could get to the oil return tubes more easily.

At least I'll be able to get it apart if I need to.

[rokemester]

Can anyone please advise as to the proper exhaust stud length? Are they all measure the same exact length from the head? Seems obvious, but ran into the question when a previous mechanic used different length exhaust studs. THANKS!

[PabloX]

Originally Posted by rokemester

Can anyone please advise as to the proper exhaust stud length? Are they all measure the same exact length from the head? Seems obvious, but ran into the question when a previous mechanic used different length exhaust studs. THANKS!

I ordered from our host and in some cases, I had to use a couple of extra washers. So not a direct answer but if you order those, you should be able to make them work.

[Tidybuoy]

Originally Posted by rokemester

Can anyone please advise as to the proper exhaust stud length? Are they all measure the same exact length from the head? Seems obvious, but ran into the question when a previous mechanic used different length exhaust studs. THANKS!

I don't know the lengths but I do know that they are different lengths for thick flange heat exchanges vs thin flange. I found this out when I discovered my car has extra long studs and the PO used 1" spacers to compensate. Unfortunately, the spacers were aluminum so over time the crushed a little and caused exhaust leaks.

[rokemester]

I have an 87 911 with stock heat exchangers. If I'm not mistaken these have the thicker connection flanges. There seems to be a question between 30mm and 35mm length studs.