Removing CIS with engine in the car - the writeup

[gazzerr]

The hose clamps for the number 5 runner for me had to face backwards otherwise the clamp and the end of the screw holding it together will contact the engine shroud.

I was able to get the number 6 rear runner nut relatively easily with a 1/4 inch flexi wobble socket (the kind where the articulation is on the socket) and a 6 inch long 1/4 extension. Remove the AAR first then attack it from front of the nut between the number 5 and number 6 runner past where the AAR was. It's fiddly but doable. If the nut is tough add a 1/4 to 1/2 adapter to the extension and use your 1/2 inch ratchet. I did it up upon reassembly in the same manner.

Make sure you account for every nut and washer (I kept a spreadsheet and numbered baggies) before you try to remove the runners because if it goes down the intake you might be cooked.

[Charles Freeborn]

Follow up question - I need to do some trouble shooting on my '74. Car runs acceptably, but has an idle issue that points to vac leak (decal valve is already bypassed). Also is giving some illogical AFR readings at WOT.
I'd like to replace the runner sleeves and gaskets where they meet the heads (sleeves are original), as well as clean up airbox seats, clean injectors, re-check fuel pressures, etc. Can this be done without pulling the entire CIS system?
Secondly, would removing the fan housing give additional room needed, should the whole system end up needing to come out.
Thx.

[gazzerr]

Hey Charles,

The 1, 2, 3 side is not bad, 4 is maybe doable. 5 would be very tough but number 6 I can't see how it could be done without lifting the airbox out of the way. Did you mean the rubber sleeves? On the 4, 5 and 6 side they are under the airbox so I'm not sure you could reach the clamps on those. A 74 might be easier. It's not terrible to just disassemble it completely and replace all the seals and hoses. Just go slow and take your time. The phenolic sleeves are really hard to remove insitu. I think it's much safer to pull the runners and tap the sleeves out from behind. Then you haven't got junk falling into the intakes when you are wrestling with them.

If your airbox is old it will be leaking anyway. The adhesive that holds it all together typically fails on the underside seam along the top of the 4, 5 & 6 runner ports. That's how mine was. So I pulled the whole thing to remove and replace. The rubber mounts the whole CIS sits on where toast on mine too.

[Zaz]

I just pulled the CIS from my 74 for the second time in situ - much easier / faster the second time. I don't see how you could accomplish all those replacements effectively (and not twisting/straining every muscle above your ankles) without removing it. Leave the fan housing in place- with the 74 just remove the peanut/hat and it will clear.

[Steve F]

I did it as well, but a partial engine drop is your friend!Lifted the whole system off except the AAV and WUR . assembled and back on the same way. Great for leak checking everything on the bench and back on the car.

[Charles Freeborn]

Many Thanks all -
I'm easily equipped for a partial drop, so I guess that's how I'll go - then pull the whole CIS unit as a whole and refresh.
Someone in the past has installed a pop off - so I assume the box has been off - but I have no idea if it's sealed properly - or the pop off for that matter.
Sleeves at the injectors have already been recently changed (by me) as have o-rings on sleeves and injectors. I'll re-ring the injectors when I pull them for cleaning just because I can, but the injector sleeves I'll leave lie.
Great help on this thread. I've been putting off this project long enough...

[gazzerr]

You can plug the intake and runner ports and run some low (you don't need much) pressurized air through the vacuum port on the left side. Then dunk it in a plastic storage bin full of water. You'll find any leaks in about 2 seconds.

[jyt]

well done! I just removed mine and what a nightmare! would you be available to help if I need to...?

[brad951]

Great thread, I'm fighting some vacuum leak issues and have decided to do a full CIS refresh on my '83, new airbox, and this thread will come in very handy! I intend to do a partial drop.

[SalParadise]

Originally Posted by brad951

Great thread, I'm fighting some vacuum leak issues and have decided to do a full CIS refresh on my '83, new airbox, and this thread will come in very handy! I intend to do a partial drop.

Don't put yourself through the pain, agony, and suffering. Drop the entire engine. It will save lots of time and hurt hands. I've been there, and learned the only way to do this correctly is pull the engine.

[brad951]

Originally Posted by SalParadise

Don't put yourself through the pain, agony, and suffering. Drop the entire engine. It will save lots of time and hurt hands. I've been there, and learned the only way to do this correctly is pull the engine.

Thanks, I think this is good advice and I might end up doing that. I've had the engine out before to replace tranny and clutch so know what's involved (pretty easy actually, just time consuming).

[kavadarci]

For the people who continue to say drop the engine like it is any easier, I just did this and removed the CIS to address the triangle of death and do few other things.
I would do CIS removal anytime of the day over the dropping of the engine.
This is not as difficult as some people try to make it.

Don't get me wrong, if you have the space, capability and desire to remove the engine, go ahead but CIS removal is not that difficult of a job.

This step by step write up is awesome. Thank you.

[boyt911sc]

Originally Posted by kavadarci

For the people who continue to say drop the engine like it is any easier, I just did this and removed the CIS to address the triangle of death and do few other things.
I would do CIS removal anytime of the day over the dropping of the engine.
This is not as difficult as some people try to make it.

Don't get me wrong, if you have the space, capability and desire to remove the engine, go ahead but CIS removal is not that difficult of a job.

This step by step write up is awesome. Thank you.

Kava,

Not until you have done the removal/installation of the CIS assembly in situ and engine out would you realize and understand the advantage of one process to another. So far, you only done it in situ. You have not even dropped or removed a 911 motor in your life. So how would you know your preferred method is better than the other. Unless you have done both of these methods multiple times, you would not know the difference. It is not how hard you did the work but how smart you did the job. The late SC’s CIS have more fuel and vacuum connections than those for mid year CIS.

Tony

[SalParadise]

Yes, it's learning by experience. That's why I said not to do it above. After I dropped my engine (with trans) for the first time as a unit by myself, I scratched my head and said "Wow, I should have done this with the CIS the first time." And the CIS went on in an hour or so, no problem with the engine out. I could see everything line up, all the manifolds (and properly tighten them), check all connections and fuel lines. It's so much easier (and better, at least to me) with the engine out. Never going to ever do it again with the engine in. Ever.

[mike sampsel]

Originally Posted by stormcrow

I've removed mine with the intake runners attached makes it much easier and quicker. All you need to do is disconnect the fuel lines in the rear, electrical lines in the back, throttle linkage and cold start valve hoses. unbolt the intaker runnres and lift out.

I tried doing it the way mentioned above but it took much longer because of the runner connectors to the intake runners. I can remove mine in around an hour if all goes well.

So this method would appear to be preferred, to an engine drop, to correct the TOD (Triangle of death) leaks up top. Not so if rear seal is leaking.
Seems maybe the '78 SC is one of the easier ones to remove the CSI.
Thinking I could go this route then see what remains leak wise then decide if I want to go with an engine drop.

Thoughts?

[Brown747]

While on the project of CIS overhaul why not clean up the unused cast accessory bosses on the intake runners...

https://forums.pelicanparts.com/porsche-911-technical-forum/622947-wart-removal-cis-4-intake-runner.html

[mike sampsel]

Originally Posted by Brown747

While on the project of CIS overhaul why not clean up the unused cast accessory bosses on the intake runners...

https://forums.pelicanparts.com/porsche-911-technical-forum/622947-wart-removal-cis-4-intake-runner.html

A thing of beauty

On mine I see an obstruction on number 2 runner.
I see a “clean” one in your picture pic.

Guessing I need to remove it to reach the #2 intake runner?


And what is it? Difficult finding it in Bentley.
Looks like a K-jetronic part in Haynes. Humm

[faapgar]

I removed an 83 CIS today due to cracked airbox.1.5 hours and off.Ciao FRED

[mike sampsel]

Originally Posted by mike sampsel

So this method would appear to be preferred, to an engine drop, to correct the TOD (Triangle of death) leaks up top. Not so if rear seal is leaking.
Seems maybe the '78 SC is one of the easier ones to remove the CSI.
Thinking I could go this route then see what remains leak wise then decide if I want to go with an engine drop.

Thoughts?

Well I've started the slippery slope of removing my CIS at the runners.
So far I'm at about 2.5 hours not counting tool runs.

It's 102 deg here now and no A/C in garage.

The WUR was not too bad, then the runners for 1,2 were not bad. 4 and 5 are done (nuts and washers off).

I'll finish removal of the AAR and look at runner 6 tomorrow.
Hoping my 1/4" things will get me there.

Ready to do a partial engine drop too to assist in number 6 (if need to).
Quite possible the engine drop method was easier.
But I am going slowly with caution.

Number 5 inner was a little sticky and it needed the 1/4" u-joint and swivel.
The 3/8 one just was not letting the socket sit down on the nut.
Six point sockets are best here too.


Thoughts and prayers are appreciated!

[maddmason]

Is there any one in south eastern Wisconsin that has done this before? I have started and have the box out, but am not sure the best route to re-install the new box. Fuel distributer is still in car, throttle body is still in car, 4-5-6 runners are out. Its a 1979 911SC w/ A/C.

Any tips/help is appreciated

Thanks!