Fixed Air Box
Finally got the knackered air box on my GTV sorted. I bought it about 2 months ago, I have been slowly fixing up the niggly things that naffed me off.
Today I finished the air box. It was stuffed. The bolts holding the cover on where all rounded off and/or seized.
So, my mini guide on sorting it out!
1. The air box has to come out. Remove the bolt holding the support band round the air box.
2. Remove the air hoses from the MAF, kill the standard Alfa hose clips they are rubbish. I found that removing the resonator and the elbow helped too, but this isn't necessary.
3. Disconnect the air intake pipe from the bottom of the air box, again, it is hose clipped in place.
4. Pull it hard upwards. The whole air box will now come out including the MAF.
All the bolts and connectors on mine were proper stuffed, so I sprayed the lot with WD40 and left it overnight.
5. Spanner off, or drill our all three of the bolts holding the top cover on the air box. I found that drilling through each bolt/screw head with a 5mm drill span the head off and allowed me to tap the screw device out from below.
6. Take a socket or spanner to the nuts holding the MAF on the lid. On mine, two came away okay, the other snapped off.
7. Remove the MAF and its two steel locating plates + The rubber bung that locates the MAF in place.
8. To replace the broken stud, I used a power file to remove the plastic from inside the top cover. The stud is actually an M6 bolt held in place by the plastic it is in.
9. I then cleaned everything on a gentle cycle in the dishwasher, and finally degreased it all with brake cleaner.
10. Install an M6 x 45 bolt into the hole in the filter housing lid and use some quality metal epoxy putty to hold it in place. This stuff hardens fast. The bolt and the plastic need to be very clean for a good join. Leave it an hour before playing. That is a reasonable setting time.
12. The stuffed bolts in the main filter housing I replaced with M6x50 bolts. I metal puttied them to the underside of the main housing so the threads pointed up. I used big penny washers between the nut head and the bottom of the filter housing to help avoid pull through.
13. Put everything back in the car. I used 70-90mm diameter Jubilee clips to assembly everything but these are a bit too tight. Unfortunately the next size up the 90-120mm ones leave a long tail.
14. Clean up the metal MAF location plates. I power filed mine, then painted them with a spare touch up stick of clear laquer. That should stop the rust getting to them.
15. Use lots of copper grease on the threads of the MAF hold down nuts and the main air intake body nuts. I used A4 stainless steel nuts to hold everything in place they are softer than the BZP bolts I used so if a garage over tightens them etc. The easily replaced nut will strip not the solidly glued in bolt! Add plain and spring washers to help hold it all tight. Again, lots of copper grease to avoid rust.
16. When it is all back in place, cheack all the jubilee clips and plug the MAF back in.
All in, the cost of repairing the air box was abour £10 in nuts, bolts, washers and metal putty. The old air filter was really badly covered in filth. It clearly hadn't been changed in a while as the air filter was too hard to get to!
I also replaced the MAF with a BOSCH one I got off E-Bay as a spare for my 156. Together they have really helped the low down pull of the car, and at higher engine speeds it seems crisper and more urgent in acceleration.