1982 911SC Airbox blown after engine out service

[wi54545]

Hello all…

I have a 1982 911SC US coupe that I had the engine out of to fix the triangle of death leaks as well as do a valve adjustment. It had no studs broken and they might be steel on the bottom. Felt magnetic with my mag pickup but not 100%. It was my first engine drop and it went along well until I put the new plug wires 180* out. I was working with the Bentley manual and did not put two and two together when I put the firing order clockwise instead of counterclockwise. I turned the key, no start, big backfire. My original airbox with no pop off valve went boom. It split along the seam.

Things I replaced during engine out:
- Plugs
- Plug wires
- Cap
- Rotor (this one was last replaced in 1990!)
- CIS intake boot (top one)
- Intake runner boots and gaskets
- New injectors (8 bucks each at NAPA for Bosch!) and sleeves with new O rings
- New idiot light sensor
- New oil coolers seals
- New breather gasket and hose
- New thermostat seal
- New s bend oil line
- Valve adjustment with kirk tool verified with backside method.
- Added safety collars to chain tensioners (non Carrera type)
- New sport mounts for engine and transmission

Did a cleaning of the engine and transmission and engine compartment. All to be disappointed by the airbox blowing. It was like somebody just ran over my dog (not that bad but close). Now I get to drop the engine again! I’m glad that I have the jack adaptor for my lump so I can get it low enough so I don’t have to take bumper off. What a great piece of engineering, well worth $180 dollars.

Now I’m at a delimma. There are a couple of part numbers for the proper airbox. The most common one is 911-110-904-00 at about 450. The other is 911-110-904-01 which is much cheaper at 250 from our host. Both are for the 38MM runners. Is the latter the newer part? It says it fits mine. Also, would you guys in your vast experience add a pop valve? It ran fine before, never a backfire on original airbox with no valve. I just don’t want to do this again for a 3rd time. Thanks for any input or suggestions for this 911 newbie.

Before:





After:





Blown Airbox:

[Steve F]

Bummer Is that a 3.0 engine? I might be doing this myself sooner than later.


Cheers,Steve

[theiceman]

I did this EXACT thing . My bently was wrong ( the earlier edition ) and I hooked up my wires with the wrong rotor direction . BOOM !! . Mine always ran great until that point .

I did a partial drop and did NOT remove the engine . I was able to remove the entire CIS in about 90 minutes.

I got an airbox at the time a dealer in Oregon I think and the new one I got was the updated one with the distribution tubing inside ( cant remember the name ) .
Anyway I did not feel comfortable cutting into my brand new airbox to put a pop off valve in . Especially since it was running so well . That was eight years ago or so and it still runs flawlessly with no pop off valve .

As you went through this you probably know .. there was no way a pop off valve would have saved you in this situation anyway , like yours , my airbox blew right in two at the seam and felt like a concussion grenade going off.

[Discseven]

Originally Posted by wi54545

Also, would you guys in your vast experience add a pop valve? It ran fine before, never a backfire on original airbox with no valve. I just don’t want to do this again for a 3rd time. Thanks for any input or suggestions for this 911 newbie.

After:

Is always wonderful to see a Porsche powerhouse spanked clean. Nice!

Pop valve offers peace of mind---is good install IMHO.

[jason2guy]

ive got an 81, so the same amount of plumbing for the FI. i just did what youre going to do. it was done engine in without even a partial drop. it took me forever, like 3 or 4 days. if you live in a house w/a garage, i would say drop the engine to do it- things will be easier to get to. you should check on ebay for an aluminum airbox- guy has a NOS one, never installed and a very fair deal.

[theiceman]

i wouldn't buy an aluminum one , I consider the plastic air box a fairly inexpensive link in he chain , 500 bucks ofr so and you are on your way ..
put an aluminum box in and where is that pressure gonna go ? probably will be fine but il stick with the plastic one.

[pmax]

Originally Posted by theiceman

put an aluminum box in and where is that pressure gonna go ? one.

The Webbs design stainless steel airbox and the other aluminum one I'm aware of both have a pressure relief valve in the same location as the "pop off" valve.

[Reiver]

I know some are adamant about not using a pop off valve but it has saved my box 3 times to date.
Two over lean conditions ( I put an afr gauge in place of the clock) and one failed thermo time switch to enrich the start sequence full cold.

If the alloy box has a pop off (all that I've seen do) there should be no over pressure issues beyond that.

If mine ever really blows I'd go that route if the alloy box was reasonably priced. The peace of mind is worth a bit too.

[Reiver]

Originally Posted by SCadaddle

Whats the name and number of the paint code on your 82SC? Also, if you have a spot where the paint is chipped off in the rear apron what color is the primer below? It looks identical to my car that my buddy the "Porsche Historian" claims is a wrong color re-spray. Thanks!

I suspect I know that very 'Porsche Historian'....lol, tell him to get a grip. Isn't he a Democrat?

[SCadaddle]

Whats the name and number of the paint code on your 82SC? Also, if you have a spot where the paint is chipped off in the rear apron what color is the primer below? It looks identical to my car that my buddy the "Porsche Historian" claims is a wrong color re-spray. Thanks!

[SCadaddle]

Originally Posted by Reiver

I suspect I know that very 'Porsche Historian'....lol, tell him to get a grip. Isn't he a Democrat?

Ha! Hey Pat, I deleted the message above and reposted it below so I could add a pic of my car, lovingly known by your Mississippi friends as "the gold tooth"; however, the "historian" I don't think you met. He's the 3rd porscheteer that is very fond of the 356's.

[Reiver]

Originally Posted by SCadaddle

Ha! Hey Pat, I deleted the message above and reposted it below so I could add a pic of my car, lovingly known by your Mississippi friends as "the gold tooth"; however, the "historian" I don't think you met. He's the 3rd porscheteer that is very fond of the 356's.

Oh, you mean down the street in that shaky barn.....Oh, yeah, met the family.
The motor you wanted is fantastic btw...thanks for not buying it

Sorry about the thread steal boys.

[wi54545]

It is platinum metallic. Code U1. I think the primer is grayish. Platinum metallic changes color with different lighting.














On the air box topic, where would an aluminum one be found?

[SCadaddle]

Thanks!

[wi54545]

Just want to clarify before I blow it again. Pun intended
I wired the distributor 162435 clockwise when I blew airbox. It should be counterclockwise, right?

[Reiver]

Yes...1 6 2 4 3 5...there should of been a decal in the bay indicating this with the direction arrow indicating CCW.

[mhackney]

I have a question for the PO and others here who blew their air box. After the blow out, what are the symptoms of the car? Will it start? Does it idle low? Run anemically? I ask because my 83 SC Cab went from great to horrible literally overnight last week. See 83 SC HOT muffler on the right side for my story. I now think the original spark plug replacement had nothing to do with the problem. I did discover a blown air box, but in my case there was no back fire. Perhaps the box was blown by a PO and fixed (perhaps not well) and the fix finally gave out.

[Reiver]

Originally Posted by mhackney

I have a question for the PO and others here who blew their air box. After the blow out, what are the symptoms of the car? Will it start? Does it idle low? Run anemically? I ask because my 83 SC Cab went from great to horrible literally overnight last week. See 83 SC HOT muffler on the right side for my story. I now think the original spark plug replacement had nothing to do with the problem. I did discover a blown air box, but in my case there was no back fire. Perhaps the box was blown by a PO and fixed (perhaps not well) and the fix finally gave out.

CIS is very pressure sensitive and leaks will screw up your afr and run ability in a royal manner.
I've read that attempting to seal a crack/leak is difficult as the plastic does not seem to bond well with adhesives.
No way it will run properly with a leaky box. Replace it.

[mhackney]

Thanks Reiver, the parts are ordered and on the way to replace it and the usual sleeves, gaskets, etc.

Cheers,
Michael

[wi54545]

Why didn't I see this when I needed it most? I could be 500 dollars richer and driving my car! Live and learn.