83 944 airbox housing back retaining screw wont fasten in

[Hamad89]

Hope all is well guys

I was cleaning my air cleaner cartridge and while removing the box all 5 Philip head screws were torqued in , only when i tried putting back the housing back , the last screw behind the brake reservoir wouldn't fasten in and just turn loosely, the sequence i followed was left (breather hose) right near the coolant tank , then the 2 on the front ,
i tried putting my hand under the screw to see if there's a 12mm nut coming out like the rest ,

must you follow a different sequence to have them all 5 torqued in?




Best regards,
Hamad

[v2rocket_aka944]

There isn't a torque sequence but in general it helps to do them all a little at a time until snug before fully tightening.

There are thread inserts in the lower half of the airbox - it's probable that yours has stripped out.

I believe I had to buy screws for this one time and they were M5 - I would bet you could tap that one to M6.

[944 Ecology]

Four out of five ain't bad... relax and enjoy the ride.

[Hamad89]

Originally Posted by 944 Ecology

Four out of five ain't bad... relax and enjoy the ride.

Thanks George , was just worried it would result in a vacuum loss since its already having a rough idle .

Originally Posted by v2rocket_aka944

There isn't a torque sequence but in general it helps to do them all a little at a time until snug before fully tightening.

There are thread inserts in the lower half of the airbox - it's probable that yours has stripped out.

I believe I had to buy screws for this one time and they were M5 - I would bet you could tap that one to M6.

i had to use a 12mm open spanner for the front 2 screws along with the one near the timing belt breather hose to hold the bottom nut. probably the other ones are fastened in differently. will try using a new screw or tapping to M6,

Best regards,
Hamad

[944 Ecology]

Originally Posted by Hamad89

Thanks George , was just worried it would result in a vacuum loss since its already having a rough idle .

No vacuum loss... a vacuum loss would be between the Air Flow Meter and the Intake Ports. The air cleaner is on the other side of the Air Flow Meter.

[Hamad89]

Originally Posted by 944 Ecology

No vacuum loss... a vacuum loss would be between the Air Flow Meter and the Intake Ports. The air cleaner is on the other side of the Air Flow Meter.

Thanks alot for clarifying , excuse my lack of knowledge

Regards,
Hamad

[Monkey Wrench]

if you drill a hole that you plan on tapping you should first drill to the right size, or as close as you can.


if you want to drill a hole to tap to M5 , the pitch is probably .8 mm , drill to 4.2 mm or .165 inches, that's a #19 bit.

If you want to tap to M6 , pitch is usually 1mm, drill to 5mm or .197 inches, that's a # 9 drill bit.

6mm and 1/4" are not interchangable but they are close in diameter.

before you drill , look at what you are drilling, maybe ther eis a brass lug that's captive in the plastic, see if there is enough "meat" there to work with before you re- thread it.

If you want to restore the thread to original and it's stripped it is often possible to use a thrread insert , there are different companies, here's an example

https://www.clarendonsf.com/products/inserts/keensert-inserts


when people think of re- threading they often go to using a helicoil. a helicoil requires a special tap so you buy their proprietary kit. then you use their special tap and install a think that looks like a spring.

the thread inserts may need more "meat" but they dont requitre a special tap. I prefer them, if there is room, for somethign like a stripped spark plug the helicoil is probably a good option.

another place where the keyserts or stabloc or some other type of thread insert work well is in the case where you are often taking aparts somethign and putting t back together and you want metal other than alunimum or plastic , as it can take the action of being taken apart many times whereas holes in aluminum or plastic may wear out.

If there is a brass lug inset into he plastic, check if it's slipping, it might be loose.

Idont think they used a clip here, but if it were a speed clip you could replace the clip.

here's what a speed clip looks like
https://www.autofast.co.za/product-range/speed-clip-m6-5-50-per-pack/

If you do not have enough meat you can consider using a standard tap and screw.. If you dont mind this part not being metric then :

a # 12 - 24 that's NC ( national coarse) bit number 17 ( .173" )

or a 12 - 28 that's NF ( national fine thread) bit number 15 ( .180" )

those drill sizes you will have if you have a set of numbered drills. If you only have a small set of drill bits the size you need is close to the bottom depth of the threads or 75 % of thread depth. if your pre-drilled hole is too small that's when your tap will get stuck and perhaps break off in the hole. If the tap is getting stuck dont force it and break it , pull it out and increase the hole size.


if the hole is a teeny bit too big, it'll work the threads just wont be full depth.

a full set of numbered bits is a bit expensive, if you like you can just buy a replacement bit to to get the size you like.

in a pinch Ill just hold the tap up with the drill in front and estimate the size I need that won't get a hole that my tap gets stuck in, or If I drill and start to tap and the hole is too small I can increase the size to the next bit available..

If you have a typical drill bit set that only contains the basic most common standard sizes it isn't quite ideal but it may work. in other areas it may be more critical to do things correctly, In this case it's just a fan box nut and not super critical.

when you tap , put threading lube on your tap, go in about 3/4 turn , back out to break the chip off , turn in another 3/4 turn , repeat. If you get things clogged up with chips dont hesitate to back all the way out , clean off the chips and start in again.

anytime you put something together with a bunch of screws or bolts, try to get them all in loose first then tighten just to the point they bottom, then tighten them adequately..

on things like cylinder heads the torque pattern is important. That's a plastic box that can twist so the sequence isn't really important.

Its good habit not to tighten anything until you have all the screws started, that allows you looseness to shift the thing you are bolting to allow them to align.. also If you like to use things like electric drivers rather than using a hand tool to start the threads you may strip things because you dont have the same feel.. I tend to start everything by hand and then if I want to use a tool after, I can choose to . ..

in some spots you can do things like wrap a bit of black tape around the bolt head so it pushes into the socket tightly and holds. or if it's a Phillips screw, you can tape it to the tip of your screwdriver.. this saves crawling around looking for screws you dropped accidentally. I' ll often do this in awkward spaces,Then once I get the screw started then Ill pull my screwdriver off and discard the tape and then tighten. dropping a screw can cost time.. often another great thing is just to stop and spread some rags around your work area so if they fall you can spot them easily.

I have to work on rotating machinery in many cases a simple dropped washer or a nut can cause a huge amount of downtime, its not the washer, its where it can fall and get caught and cause damage. after a few embarrassing sessions of hours of looking for small dropped parts one starts to take care to hang on to their nuts ;-)

[16again2009]

Sometimes wrapping the screw with Teflon pipe thread tape works.

[Monkey Wrench]

or fill the hole with JB weld, then drill it close, then rethread to original size.

[curtisr]

Originally Posted by Monkey Wrench

or fill the hole with JB weld, then drill it close, then rethread to original size.

^^^^^^ What he said. ^^^^^