Changing exhaust manifold on the drive?

[yuffyhaggo]

I have a 2009 .2 and got some decat exhaust manifolds - my friend who used to work at Porsche says I'm mad to consider doing it on the drive and that some of the bolts will definitely snap.

 

Anyone got any input?

[Andrea]

37 minutes ago, yuffyhaggo said:

I have a 2009 .2 and got some decat exhaust manifolds - my friend who used to work at Porsche says I'm mad to consider doing it on the drive and that some of the bolts will definitely snap.

 

Anyone got any input?

 

Why don't you get him to help? (since he has worked at Porsche) 

 

It doesn't matter where you do the work. It's about the right tools...

 

On gen2 the bolts on the engine block are not a problem, but the ones on the flanges (so between manifolds and catback) are pressed in studs. That means there's no chance to undo them....you can undo the nuts but you'll have to drill out the studs or heat them up and tap on them to get them out. 

 

 

Edited May 25, 2022 by Andrea

[yuffyhaggo]

6 hours ago, Andrea said:

 

Why don't you get him to help? (since he has worked at Porsche) 

 

It doesn't matter where you do the work. It's about the right tools...

 

On gen2 the bolts on the engine block are not a problem, but the ones on the flanges (so between manifolds and catback) are pressed in studs. That means there's no chance to undo them....you can undo the nuts but you'll have to drill out the studs or heat them up and tap on them to get them out. 

 

 

 

I will certainly ask but our schedules are often at odds and it's just a few bolts... (famous last words)

 

Thanks for the words, I'm thinking the ones between the manifolds and the rest of the exhaust don't matter too much as I can just cut them out and drill them off the car. It's the ones in the block that will be a pain if they snap...

 

My plan is to

1. Use penetrating oil a few times the day before and over the morning on each of the bolts.

2. Heat the block up by driving the car first (and wear long sleaved clothes plus gloves to avoid the, otherwise inevitable, burns.

3. Use a breaker bar, and gently try to undo them, retightening as it undoes to work the threads loose

 

If they snap they snap. I am actually consoled to the idea that I can just have the car recovered to a local garage if worst comes to worst.

[Andrea]

 Well be positive, on gen2 the bolts on the engine block don't tend to snap like on the gen1! 

 

 

P.S. With catless manifolds your car is going to sound insane! Like a mini GT3!  

[Andy]

@yuffyhaggo could try using a tourque wrench to undo the bolts set to the tourque for doing them up, that way if they budge when you use that you can be confident that those ones will come undone. 

If they don't then you know to be careful, treat it to some direct heat and fluid then work it slowly rather than leaning on any and going straight to snapsville. 

Same process used when changing the glow plugs on my BMW E60 as those w@nkers like to snap! 

 

[yuffyhaggo]

2 hours ago, Andy said:

@yuffyhaggo could try using a tourque wrench to undo the bolts set to the tourque for doing them up, that way if they budge when you use that you can be confident that those ones will come undone. 

If they don't then you know to be careful, treat it to some direct heat and fluid then work it slowly rather than leaning on any and going straight to snapsville. 

Same process used when changing the glow plugs on my BMW E60 as those w@nkers like to snap! 

 

 

Oh that's a really good idea on the torque wrench front!

 

I'm going to start the penetrating oil process tomorrow... Thanks guys, I'll report back after!

[yuffyhaggo]

So as per Andrea's posts. The manifold bolts came straight off, no drama at all 👍

 

The join between the manifold and the exhaust were completely corroded. The nuts (or whatever was there before) were completely gone. Used a screwdriver to part the two pieces and the manifold just fell off the exhaust lol.

 

Had to drill the bolt holes a bit bigger to fit the bolts for the TopGear manifold but it's on now.. :))

 

If anyone's still reading this, is there a remap you can do yourself with a phone/laptop etc that will delete the engine management light? And what is a good solution for the O2 sensor plugs?

[Aaron]

On 29/05/2022 at 20:43, yuffyhaggo said:

So as per Andrea's posts. The manifold bolts came straight off, no drama at all 👍

 

The join between the manifold and the exhaust were completely corroded. The nuts (or whatever was there before) were completely gone. Used a screwdriver to part the two pieces and the manifold just fell off the exhaust lol.

 

Had to drill the bolt holes a bit bigger to fit the bolts for the TopGear manifold but it's on now.. :))

 

If anyone's still reading this, is there a remap you can do yourself with a phone/laptop etc that will delete the engine management light? And what is a good solution for the O2 sensor plugs?

 

Softronic is your best bet for a remote map.  Scott is renowned in the Porsche world and has a plethora of experience.

 

You buy the map from his site, he will post you a cable (with $50 or so value - keeps the taxes down).  Dump your map using the cable, send it, he will modify it and send it back.  You then flash the map on.  It's extremely easy to do.

 

The alternative is to move out the secondary oxygen sensor with a spacer.  It will cause a different reading between the primary and secondary sensors which will prevent a CEL.

 

I would highly recommend the map for manifolds as that's where the most gains come from.  Follow up with an IPD plenum and 82mm TB if you want to eliminate the mid range flat spot entirely.  The swap is pretty easy to do, as long as you don't mind leaning over and into the engine bay for extended periods!

[yuffyhaggo]

8 hours ago, Aaron said:

 

Softronic is your best bet for a remote map.  Scott is renowned in the Porsche world and has a plethora of experience.

 

You buy the map from his site, he will post you a cable (with $50 or so value - keeps the taxes down).  Dump your map using the cable, send it, he will modify it and send it back.  You then flash the map on.  It's extremely easy to do.

 

The alternative is to move out the secondary oxygen sensor with a spacer.  It will cause a different reading between the primary and secondary sensors which will prevent a CEL.

 

I would highly recommend the map for manifolds as that's where the most gains come from.  Follow up with an IPD plenum and 82mm TB if you want to eliminate the mid range flat spot entirely.  The swap is pretty easy to do, as long as you don't mind leaning over and into the engine bay for extended periods!

 

Thanks mate, I haven't actually refit either of the O2 sensors (still haven't started the car as I have to put the rest of it back together and it was getting late the other day...)

 

I suppose it's better to refit them so they don't get lost in my loft if nothing else??

 

I saw an exhaust install video where the spacer on the 2nd lambda didn't actually prevent an engine light hence I didn't bother...

[Aaron]

11 hours ago, yuffyhaggo said:

 

Thanks mate, I haven't actually refit either of the O2 sensors (still haven't started the car as I have to put the rest of it back together and it was getting late the other day...)

 

I suppose it's better to refit them so they don't get lost in my loft if nothing else??

 

I saw an exhaust install video where the spacer on the 2nd lambda didn't actually prevent an engine light hence I didn't bother...

 

You'll want to keep the primary sensors in or your closed loop running will be poor.

 

The spacers are hit and miss, but it is an option (albeit one that may not work).  I would go with the map, personally.

[yuffyhaggo]

Thanks for all the input guys.

 

All completed, I managed to strip a couple of threads doing the new bolts back up (in hindsight I think I'd get some SS threaded bar and make my own stud/nut kit in lieu of the Porsche e-Torx fixings.

 

The car sounds, INSANE. So exotic and you can actually hear the exhaust (I have stock exhaust not PSE). I will get a video clip at some point, the only negative is it sounds like there's a small piece of metal inside the backbox rattling/resonating around at certain RPMs now... Not replicatable all the time and does it stationary or moving which is why I'm sure it's not pinking... Bit irritating all the same, maybe an excuse to get a valved cat back next...

 

Just in case anyone is Google searching this 5 years later, the steps are as follows (the same for both sides so I'll only describe the perspective of one side)

 

This is for a 2009 (13 years old) 987.2 with 50k miles

 

• Spray penetrating oil on each of the existing bolts (9 on each manifold) several times before doing the work. I read of others doing it a week before, I did it the day before in the morning, evening and then again on the morning of the job. I used PlusGas (in aerosol form)
• Get the car in the air as high as you can (I jacked from the central gearbox mounting and put axle stands under each side of the subframe)
• Use a decent sized bar to undo each of the bolts, undo them very carefully. Ironically if you use a smaller rachet you run the risk of spiking the torque the bolt is exposed to and snapping the bolt (I managed to do this on one bolt). Method for undoing old rusty bolts
  • Apply some force, it should crack if you're gentle - don't apply too much though, you can also try tightening just to get the bolt to move (fraction of a mm is all that's required to get it started)
    • @Andy wisely suggested that I use a torque wrench with a torque setting applied to undo the bolts to measure what torque I'm reaching. For explicitness, the studs that go in the head are meant to be torqued to 17ft-lb (about 25nm) and I was getting torque clicks at 60ft-lb, but still got them off without snapping them (apart from that one...)
  • Gently undo each bolt, if it's very tight - retighten it half the amount you loosened it on each attempt
  • Eventually they will become loose and undo with a regular rachet, if they're tight all the way then be patient.
  • If you snap them, don't panic, drilling and thread repair isn't that expensive (a guy charged me £150 to drive to my house and repair 3 holes which are now better than new, the bolts do up all the way by hand)
• If you still have the original exhaust, the studs may well have rusted off - my manifolds just pulled away from the exhaust system with a little leveraging from a screwdriver- both sides were blowing as evidenced by the gaskets.
• The O2 sensors are the problem. You'll never get these off in situ I don't think.
• You will need to remove the top engine cover, and interior bulkhead cover to do this, 10mm socket + Tsomething screwdriver required.
• The upstream lambda has a blue cable and loops up from the cat, along the front of the engine, over the top of the head and back down to the plug that connects it to the loom (which then has a similar routing). I managed to unplug and thread the left hand plug back down and completely free. I couldn't figure out the fixing of the right hand side and ended up cutting the head off the plug to allow it to wiggle through the fixing below the air intake (this might be easier on a ramp)
  • There are a couple of cable ties, DEEP in the engine compartment, I was super lazy with getting access and don't have long nose snips, so I carefully used a dremel (I have very good hand motor skills, this might not be one for you if you have the shakes) to cut the cable tie that I couldn't reach with snips.
• The downstream is a lot easier, and should unplug and untangle quite easily.
• Once the cables to the O2 sensors are loose, you should be able to drop the manifolds out, they'll take a little wiggle but the hard part is over.
• Once off the car, I tried the same method using penetrating oil (at intervals over 24 hours) and a 22mm O2 sensor socket with a BIG bar and could not get any movement at all. I applied so much force that the socket stretched and skipped over the bolt, there was no moving this.
  • Solution: I bought a £60 plumbers blowtorch from B&Q and lit that baby up. I am also lucky enough to have a 1/2 drive air gun. The combination of which removed the suckers in a couple of impacts from the gun (for reference, the air gun did nothing without heat - and by heat I mean the outer metal of the manifold was going white, for clarity I applied the flame to the O2 sensor mounting socket, not the sensor itself. These will get RED hot during operation so don't worry about the flame applying too much heat, maybe if you did it for an hour, but a minute of torching will not do harm).
• Once the O2 sensors are off the manifolds, the manifolds can go in a box in case I ever want to revert to standard. I cleaned the threads on the sensors with a wire brush.

 

At this point you're ready to start assembly. This is a lot easier, but care must still be taken.

 

• The TopGear decat pipes I got come with exhaust to manifold fixings, but the bolts were thicker than the holes in the stock system so I had to drill these. I used a really old drill bit so this took absolutely ages, use WD40 to lubricate and cool the drill bit as you're drilling (one hand on the drill, one hand with the WD40 with intermittent sprays)
• I chose to install the manifolds first, then do the O2 sensors after, you might consider doing this differently as it's a bit awkward to tighten them sufficiently (I didn't have a torque setting, but used feel to do them up "tightly and then a little bit" as there's a brass washer supplied with my manifolds which requires a lot of compression to achieve a good biting force)
  • Point on the O2 sensors, with the Top Gear manifolds (and I imagine most decat pipes) you might have 2 bungs for the sensors. One will be on, or just after the collector (where the three primary pipes turn into one) and another will probably be on one of the primary pipes. I chose to install them the "wrong" way round, so that the primary O2 sniffer that detects air/fuel ratio (as @Aaron pointed out) will want a complete picture of what's going on in the exhaust, not just from one of your primary pipes...
  • The second one, which is just to detect whether you're an enemy of climate change or not will either want to be cable tied out of the way, or I actually installed it in the primary pipe mounting with one of these --- https://www.amazon.co.uk/gp/product/B07R4HBDM8/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
  • If the link is dead, it's a 90 degree O2 spacer with a "mini cat" built for £32 each. So far I haven't got an engine light although I've only done 30 miles or so on a few different journeys so the jury is out as to whether that's going to stick. Pro-tip, buy this from Amazon even if you hate Amazon, so that if it doesn't work - you just remove them from the car and send them back as faulty and let Bezos pick up the tab lol.
• Installing the gasket is meant to be awkward, it's not just you and use a few bolts to hold the manifold in place
• Install the bolts between the manifold and the exhaust to just hold it there, don't tighten them as you'll need some adjustment to align the remaining head bolts
• Install the bolts (with some grease to try and avoid future seizing in another 13 years) to hold the manifold in place.
• Tighten the head studs first, to 17ft-lb. The prescribed sequence is middle first, and then alternate the outer ones (I'm not sure this is hugely important, but there are 3 fixings for each exhaust port, 2 on one side of the port and 1 on the other- you tighten the 1 on its own first apparently)
• Once the head bolts are tight, shout WOO at the top of your lungs
• Now tighten the exhaust-manifold bolts, I just used a 3/8 air gun and would guess it was about 40nm or so. You just want them tight, if you're using the TopGear ones, you won't snap them and you can cut them off easily in future if worst comes to worst, I just didn't want them to blow again (you can probably cause a blow by overtightening mind you)
• Plug in the O2 sensors and gently loop and cable tie any excess cable out the way. Be careful not to crimp the cable, and I've read that you're not meant to twist the cable more than 4 times (installing before you route the cable makes this a lot easier)
• You're probably itching to start the car now, go ahead!
• Put the interior back together (if you're tackling this job and can't figure that one out I don't know what to tell you) and job's a good'un!!

[Aaron]

Don't use regular WD40 as a drilling lubricant... Use a real cutting oil (although WD40 make this too).  Your drill bits and time will thank you.

 

Great write up!  You can use OBD to check your O2 sensor voltages and see if they look normal, and if the cat trick is working.