Things to do while replacing CIS air box question?
 

I have to replace my old cracked CIS air box.

Firstly does anyone know of a procedure for this?
I do like to read something before getting stuck in.
The haynes is typically vague.

Secondly, with the air box removed is there anything else worth doing that is not normally accessable?

I don't want to replace my engine compartment soundpad but any other ideas?
Are there any parts of the CIS that could do with a blast of carb cleaner while apart, or should I leave well alone?

Thanks, Jon

'76 2.7S

Replace the rubber boots which connect to the al. manifolds and any other seals that you come across. They all get dried out and stiff with age.

When replacing the box, I recommend spending a little more for the stainless steel air box.

Also, good idea to replace the FI o-rings.

When I look into my engine compartment and think about what to do, the first thing is to remove the motor and/or airbox to get access to everything.

As you have to do it anyway (sorry to hear), I really would take the opportunity to replace every sealing you can think of, esp. oil thermostat, oil cooler, manifold intakes (see above), pressure sender,...
Following previous posts, it also looks good to pull your injectors for ultrasonic cleaning, replace all vacuum hoses, check the fuel lines, check the CIS snsor plate for gunk etc.

OK, I know this never stops, but at least you have the one and only chance to have unlimited access-make your hazard to turn into a positive experience and enjoy driving the next 100.000 miles!

Good luck!
Jens
'76 CIS with '73 body conversion

Just did mine!!

You'll learn some colorful new words, and plan on at least 3-4 days of labor (because you'll invariably need a part that you forgot, which will not be in stock of course). The easiest way to get everything out (if there is an easy way) is to remove the Air Flow Sensor Boot, unbolt the intake runners from the manifold, and remove the whole "spider" assembly. Obviously, remove all of the heater components before going after the air box.

I also replaced and/or installed:

1. Intake runner sleeves
2. Air Flow Sensor Boot
3. Pop-off valve (which blew twice while setting up the new configuration)
4. Fuel Filter
5. Oil Pressure Sender
6. Oil Pressure Switch
7. Intake Gaskets
8. Oil Thermostat "O" Ring
9. Engine Sound Pad
10. Cold Start Valve
11. Vacuum lines

Parts that you might forget:

1. New intake runner gaskets
2. Intake runner sleeves
3. Fuel Distributor to Airbox Gasket
4. "O" rings for other stuff

Make sure you adjust the sensor plate height while everything is out of the car, because you simply cannot view it well enough with the whole assembly in place.

This is also a good time to do some tidying up of the engine compartment with some degreaser. Also, if you're so inclined (I wasn't), you can remove and refinish the air director shroud.

By the way, also check the rear air flow director going to the oil cooler, as mine was cracked.

Have fun!!

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Michael
'78 911SC Euro

the procedure is to remove the whole unit as a lump. less heater blower and the top ribbed rubber boot. account for every single nut and washer, so they don't slip into an intake port. removing the intake runners first really complicates things.

I would work very hard to find the reason you had a backfire while you have the whole thing apart so that you can prevent it from happening again.

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Eric Purdy - 1980
911SC

the backfire could have been from a piece of carbon trapped between the intake valve and the seat. a flame travelled up the intake runner and lit off the spray from the cold start valve. newer intakes had a metal distributor inside that helped to eliminate this problem. HELPED. put in a pop off valve too. they can blow up at any time, just for the hell of it. i've reached in the window to turn the key after a tuneup and had a couple of them blow. you just never know.