Backyard Engineering of Intercooler Housing on 2013 Audi S7
!!!Disclaimer!!
Item List:
- Hakko FX888D-23BY Digital Soldering Iron
- Virtjoule Heat Set Insert Tips M2, M2.5, M3, M4, M5 - Soldering Iron Tips for 3D Printer Users, 3D Printing Accessories Compatible with Hakko FX-888D and Weller SP40NKUS Soldering Irons
- 340PCS M2 M2.5 M3 M4 M5 M6 Metric Knurled Nuts Assortment Set Threaded Insert Nuts Brass Heat Set Insert for Plastic Parts and 3D Printing (M5x10x7 QTY 6 was used)
- DA CLAW (Not technically necessary until you drop an insert or screw. Everyone who works on cars should own one.)
- M5x0.8 Metric Tap (For clearing threads of plastic)
- QTY 6 M5x25 Stainless Button Head Screws
- Assorted Drill Set (Used for clearance for inserts and clearing of plastic under insert)
- Razor Blade Scraper tool (For trimming flash. Alternately use exact-o knife. Don't cut yourself.)
- Extended Torx 3/8" Set (T30 used. Easier for navigating the rear stock screws out.)
Optional (But Recommended)
- EKLIND 92600 PSD Ball-Hex (allen) Precision Screwdriver - 6pc
- Propane Torch and Propane Bottle (used for clearing plastic behind insert)
Throttle Body Removal
There are better tutorials on the internet, probably with bolt torque specs and the like, but this one is mine and it's got lots of cool pictures so let's go. Pop off the engine cover, and remove the hose connected above the intercooler and move aside.
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On my car, I can pull this hose off and put on without messing with
the clamp. Your mileage may vary. |
Get your lucky 3/8" ratchet, slap a T30 extended Torx socket on it and remove the six bolts that hold the diverter bypass valves to the side of the throttle body.
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| Useful Extended Torx T30 3/8" Drive Socket |
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| Two bolts circled in blue are longer. Four red bolts are shorter. |
There are two gaskets on the underneath the black diverters where they connect to the throttle body. These can be damaged or fall out, so it's a good idea to remove them and place somewhere safe.
Using a pry tool and NOT a flat head screwdriver, pop off the clip holding the wiring on the throttle bodies.
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Be mindful of the routing of this wiring for later. |
Next, loosen the top clamps for each of the hoses between the turbo and throttle body connection. Get them loose enough to slide down the hoses to chill with the lower clamps.
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Next we'll be removing the 6 screws holding the throttle bodies to the intercooler housing. These screws were designed to thread directly into the plastic. Through multiple removals of my throttle bodies, the holes began to lose some of their "freshness". Increasing boost levels to 35psi probably also played a factor. Two of the six holes on my intercooler housing were nearly shot and the screws would come out, blowing out the throttle body gasket and causing idling issues and a massive boost leak. But not for long!
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Pro tip: If you have a strong neodymium magnet lying around, stick to
the end of the Torx to aid in screw removal. |
The front three screws removal is fairly straight forward. The back three is
another story. It is easy to drop said screws and for them to be swallowed up
by the abyss that is the engine valley. To successfully recover anything
dropped is an adventure to say the least involving bright lights, magnets, and
DA CLAW!
Sometimes, the item appears to slip into a worm hole present on all automotive
engine bays and will never be seen again.
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Out with the old |
The screw located in the rear left cover as facing the engine bay can be particularly tricky to get out if you have upgrade turbo inlets. If left for last, the throttle bodies can be moved slightly to get it out.
At this point, it's time to free the turbo hoses. Confirm you didn't forget to follow the above step loosening and moving the clamps, and reach under each hose and wiggle and pull with all your might to peel the hose off the turbo and above the outlet. This can be extra tricky if they've never been removed before as they seem to "glue" themselves to the turbos.
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Your hoses probably don't say "Forge Motorsport" on them. |
At this point, the throttle bodies can be lifted and placed to the side. Be careful as there are sensors and wiring still connected.
At this point, you can marvel at the innards of the intercooler housing, fins of the intercooler, and throttle bodies gasket which will need to be removed to continue. If you are stock, you will notice some diverter "blades" which are not in my picture. If you are modded and running obscene amounts of fire-breathing boost, these diverter blades will likely be partially or mostly melted. If so, you can choose to remove them as I did, or leave them alone. Be aware that anything that falls into this hole WILL be sucked into the intakes of your engine and most likely cause damage.
Carefully remove the throttle bodies gasket, taking care not to tear or puncture. Set aside somewhere safe.
Re-engineering German designed housing
This is the point of no return. If by this point, everything that could have gone wrong has, it may be best to cut your losses, order and replace any broken clips or torn gaskets, and abort what is about to be a non-reversible destructive, backyard engineered hack job.
No fear, huh? Okay, take a 1/4" drill bit and by hand, chase the top portion of the screw holes to create a lip for the heat set inserts to sit in. It is possible that removing additional material could help with extra plastic from working around, behind, and up into the threads of the insert, but I didn't want to press my luck with removing too much material and potentially lowering the bond between the insert and the housing so I did not.
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Test fitting the heat set inserts. |
Unlike the photo above, I would not leave all six inserts in place at the same time. The risk of one falling into the void is high.
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Hello darkness my old friend |
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| DA CLAW! |
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Take note that the heat set inserts have a diagonal knurling pattern and a lip to aid in install. Do not use inserts with straight cut knurling, as those types are meant for plastic injection molding and will likely pull out.
Set the soldering iron for a temperature hot enough to melt the intercooler housing. It is made of glass-filled PC-ABS blend if I recall and while 800°C is likely higher than necessary, I am inpatient and chose the temp with my heart.
When embedding the inserts, it is important that the soldering iron stay as close to co-linear as possible with the hole, both front to back, and side to side. If straight isn't your strong suit, you may want to seek out a friend or family member with a better calibrated eyeball(s) to assist.
When sinking the insert, aim for SLIGHTLY below flush of the surface. It is better to stop early, judge, and continue. Sinking the insert too far cannot be recovered easily, so be careful. Also, the design of the gasket is such that it will seal even if the inserts end up slightly proud.
I choose the M5x10x7 from the assortment pack listed above. This ensures the maximum about of brass to plastic engagement and threads for the stainless bolt. This may be overkill.
Once the plastic has cooled, trim the flashing that pushed up around the insert. Attempt to thread in the stainless steel button head bold (M5x0.8x25) into the insert. It is probably going to bind up from plastic that was forced up into the threads during the process. This can be cleared a number of ways.
I found on some of my holes, I was able to chase out small amounts of plastic with a small drill bit smaller than the inner diameter of the threads. On two of the six holes, the plastic was bad enough to interfere with the tap, so the base of a drill bit was heated with a propane torch and slid into the insert, displacing the plastic. The bit should be as close tolerance as possible to avoid more plastic in the insert's threads to clean out.
At this point, using the bolts as a judge, if any tweaks need done, the soldering iron can be re-inserted to the insert and small adjustments to the alignment and depth are possible. Do not allow the insert to remain at high temperatures for extended periods of time though, as the plastic will eventually begin to degrade, weakening the bond and damaging the housing. This would take several minutes depending on the temperature you chose.
The next step is to chase the threads with a tap (M8x0.8). This ensures a clean thread and that bolts thread in and out of the insert well. I highly suggest starting the tap by hand carefully to ensure you don't cross thread the insert. This would be all kinds of bad. While it MAY be possible an insert could be removed and another sunk in, the chance that the bond would be as good as the original is unlikely.
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No room for the tap handle. |
The bottom left insert was especially difficult to chase the threads with the tap. Looking back, it would have been much easier to deal with this hole by removing the longer turbo inlet. If you choose to go this route which I recommend, be aware that there are one-use Oetiker style clamps that are not designed to be re-usable. You will need to either purchase the replacement clamps prior or convert to using hose-clamps.
At this point, test fit all the stainless bolts. I eyeballed the thickness of the throttle bodies, but if you have a set of calipers lying around, it would be better to measure the thickness and verify all six bolts thread in enough to fully compress the gasket.
During the tapping process, it is important that no brass shavings fall into the holes into the intercooler housing. Taping up or packing the holes with rags would be a really good idea.
Before re-assembly, using a flashlight, double check that no plastic debris or
other foreign matter fell into the intercooler housing. Clean any brass
shavings with a vacuum. Use a Q-tip or small rag to clean out the gasket
groove.
Re-installation is mostly the reverse of disassembly. The turbo hoses can be fiddly to get back on the turbo outlets. Some people prefer to remove them from the throttle bodies completely, and install using the "taco" method, folding in half. They can be a pain either way, just try to avoid tearing the inner surface of the hose.
When getting the throttle bodies housing back into place, it's possible
to catch or pinch the gasket. Take your time.
It is difficult to get the back three stainless bolts into their respective holes. A trick to help with this is to utilize DA CLAW!
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It really is a versatile tool. |
After all 6 screws are in, tighten them down in stages to avoid rocking or binding the throttle bodies. A long handled hex screwdriver makes the process easier.
Tighten all the bolts to the same torque, between one and two ugga duggas. The gasket is pretty forgiving and not designed to be crushed into oblivion. It would also be a good idea to add some blue loc-tite, or a split washer to avoid these bolts backing out. I did neither, as I am going to monitor the long term success of this modification and will potentially remove the throttle bodies dozens of times this upcoming year.
Remember to route the wiring and clip back to the original location before re-installing the diverter valves.
Closing Thoughts
The screw hole at the back left corner turned out to be a giant pain. I don't believe the insert is 100% co-linear front to back and has a small forward inclination. That said, the diameter difference between the bolts and the throttle bodies is very forgiving and the inserts would have to be VERY crooked to introduce problems. If I were to attempt this again, I would remove the long turbo inlet to get more access.
I have no idea if given a long enough timeline, continued plastic deformation combined with above 2 bar of boost will cause these inserts to migrate causing the screws to loosen, but I highly doubt it and am confident this will be a more reliable long term solution.
If you currently have a soldering iron already, look for a set of heat-set tips for your iron. There isn't anything special about the hakko.
Another potential solution would have been to drill and tap the housing, then either thread larger fasteners into the housing, or thread in some type of thread repair (heli-coil). I did not go this route as I have experience with these brass heat-set inserts and had most of the items from other side hobbies.
I have concerns sharing my experience as the risk of damaging something, from
hoses, the housing, to the motor if a bolt is dropped into the wrong hole and
not found is medium to high. I would only suggest that someone familiar with
working on their own vehicle and all the headaches that entails attempt to
emulate this, and of course they do so AT THEIR OWN RISK.
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