Helo58

Does anyone know what material is used for the stock airbox? The 90 degree "snorkel" intake tube that is held on by two rivets on my airbox has a tab at one rivet that is cracked. This allows the snorkel to move around and come unsealed from the main airbox. It is "pre-filter" so there is no performance issue, but I would like it to stay in place and look right.

Depending on the material, I was going to shave some slivers from a thicker part of the box and mix it with a solvent to make a paste and apply it to the crack. This will only work if the material "melts" in strong solvents like acetone/MEK. Once it dries, it will be good as new. I have done this many times with ABS and PVC. There is a small gap to fill so simply gluing might not be as strong.

I8ABMR

its black plastic. In all seriousness just give it a try. I dont think you're going to get the polymer type or technical info here. Maybe check an engineering forum.

2URGSE

I would save the time and just get an HPS or Joe-Z intake.

What does the part cost at the dealer?

Some photos would be helpful.

Rickna

iTrader: (3)

Hot staples will do the job.

Helo58

I have been searching other forums to see what other car airboxes are made of and it seems that no one knows for certain on any forum I have searched so far. HDPE has come up a couple of times, but I am not sure that it could take engine bay heat.

I can't believe that finding this info is this hard. Finding the actual material is fairly important because not all adhesives work on all plastics. I do want it done right, so I will keep searching. If I can't find it, I will fall back on some less than ideal repair, but I won't be happy about it.

Thanks for all of the help so far.

Helo58

I will get some photos this afternoon. I do plan on getting the HPS tube from the stock airbox to the throttle body, but the crack is on the actual airbox. The stock part as best as I can tell, is part of the larger airbox assembly ($500+) so I am not going that route if $5 dollar glue will fix it.

It is one of those things that no one will notice, but YOU know it is there. Kinda like the mess of duct tape on the engine harness cover under the engine cover. What a mess, all because Lexus wouldn't spring for a 65 dollar cover that was brittle and broke during repair. Not a big deal who paid for it, but I wanted it over the duct tape solution they came up with.

My thought is just to repair it as simply as possible. If I knew the material, it is just a matter of buying the appropriate adhesive and applying it (10 mins). The search continues...

Piston1047

I was an interior development engineer at Toyota for a few years and most of the blow molded ducting for the HVAC was PP (polypropylene). The 90 degree bend is blow molded , so I'm pretty sure it is PP aswell, it is pretty common in the auto industry to use this under the hood, chemical and heat resistance is acceptable. Toyota usually marks all their plastic parts with the material type on the part since Japan is strict about recycling, If you take a closer look it might be on the inside or outside of the tube, it will say PP,ABS,HPDE ect. If the ducting is PP, which it probably is, then it is a thermoplastic, which means it can be melted down at the right temp and it should solidify when cooled without losing it's properties. It has pretty good chemical resistance so using a solvent to break it down might not work so well and may alter the chemical properties. Acetone or methyl benzene would break it down eventually though, so you could try. I suggest using heat, body shops to this to mend PP bumpers all the time.

Helo58

Hey thanks for the information! I will have to look for the recycling code to see if the material is identified. That would be great. If not, I have been looking a little further at some technical papers on the BASF and DuPont websites and it looks like the materials used most frequently underhood and for airboxes and manifolds are definitely one of three materials:

1) Polyamide
2) Polypropylene
3) TPE (Thermoplastic Elastomer)

Based on your comments, I will start with Polypropylene. There is a product called FiberFlex for plastic repairs that is common for most plastics (even the high surface energy ones). It also looks like you can plastic weld with PP rods. If it is polyamide, it is just a hot weld with Nylon rod. The repair is so small, I hope that I can use my soldering iron with the plastic welding tips.

Thanks again to all who offered help and suggestions. I hope this info helps some others in the future.

Jowett

The air box will likely be PP with a percentage of either TD or GF. TD is talc, and GF glass fiber. It will read something like PP + TD20. TD and GF are used to add stiffness and/or strength.

Helo58

Well, I finally got around to fixing the stock airbox. I used the Chicago Electric (Harbor Freight) 80W plastic welding kit. The black "rod" supplied with the kit is PP and matched the airbox almost perfectly in texture and color.

I plugged in the iron (plastic welder) and allowed it to heat up. While it was heating up, I rough sanded the surfaces I was going to join. I cut the appropriate sized piece of the included "welding rod" applied it to the surface over the crack I was filling/joining. I placed the hot iron on the filler and let the heat melt the filler into the crack. Once the crack was filled, I used the iron to shape the filler so that it appeared neat and tidy. I finished the job by using a heat gun to get rid of any scratches and gouges left in the material. Once cooled, I was pleased with the appearance and strength of the repair and would recommend this kit to anyone needing to replace or repair any of the black plastics of the airbox and possibly other things.

lobuxracer

iTrader: (2)

Got any pics? I have been curious about this kind of repair for some time. Way back in the 80's when bike manufacturers started putting fairings on regular street bikes, plastic "welding" was common when repairing an expensive OEM part. It was pretty primitive then, just a high wattage soldering iron (usually 250W) with a fat tip and a variable voltage supply to adjust the temperature of the tip. The key to success was getting the iron just hot enough to melt, but not so hot it would oxidize the polymer. Sounds like this kit is similar in its approach.

I had to do a repair to the nozzle on the diaphragm that opens the intake flap a while back. It snapped off while I was doing something stupid. I tried plastic welding first, but ended up drilling and installing a metal sleeve inside the hole, then a little bit of plastic welding around the break. It was way cheaper than buying a new airbox which is the only other option if something goes wrong with that diaphragm.

Helo58

Well, this was my first time attempting anything like this and my goals going in were 1) that it be structurally sound and, 2) that it not be butt ugly. I succeeded on the first and got a C+/D- on point #2. If I could have had anything different, I would have liked to have had some differently shaped tips to make the finish smoother. The included tip was triangular and flat in shape and the triangle's points found their way into the surrounding areas fairly easy. Something round or spoon shaped might have made finishing a little easier. However, the triangle tip easily melted the repair material into the crack after some preheat on the airbox edges I was bonding to.

I watched some videos on fairing and bumper repair, and they now use a variable speed/temperature hot air plastic welder welder. They can be very effective for people who know what they are doing and I was impressed when I saw the finished product. I don't think that type of welder would have been suitable for doing what I did though.





I understand about buying the airbox. I purchased my car used and it came with the K&N intake. Well, needless to say, in my new fast car euphoria I immediately got horsepower greedy. I read about how the open element filters heat soaked and the consensus was the stock airbox with a high flow filter eliminated heat soak and returned some of the low end torque. Then the dyno about true gains debate began, and so on and so on... I am still split on the actual real answer to the whole issue. Timeslips and dyno comparisons seem impossible due to the learning nature of the ECU. By the time it learns, you are at a different DA typically so I just haven't been in a hurry to do this repair. Here's a picture of my job. Not beautiful, but it works just fine.

v8sedan

Good job, is the (welding rod) you put a kind of metal mesh, because if you just put a plastic weld over the crack its not gonna last very long saddly, your job looks clean by the way