1980 CIS airbox replace/repair questions and writeup - help appreciated - Page 2

MichaelSJackson · 07-13-2019, 10:22 AM

Brian,

Drained my tank and was astonished how clean it already was. I'd use a gallon or so in my truck on each fill-up. Being that diluted, it never gave it any problems.

Definitely replace the fuel filter. FYI: The latest one I bought had the painted on flow arrow in the wrong direction. Very disconcerting.

Michael J.

patkeefe · 07-13-2019, 12:17 PM

Hi Brian,
Yes, you can replace the CIS with the engine in the car, but why would you want to? It really is so much easier to take everything out so you can work on it in relative comfort.

Put in a new airbox. I see them advertised from different suppliers for only a few hundred dollars nowadays. It is practically impossible to repair an existing airbox.

BTW, my investigation leads me to believe they all leak, some worse than others. Also, there is really no sealant that can be used practically, especially for positive pressure applications. Airboxes seem to be made from a material called PPS, which is the generic name. See CIS Airbox Plastic?

hughc · hughc's Garage

If you want an extra level of safety on your air box I'd like to suggest you remove all screws and replace with appropriate size sm bolts with washers and nuts

brian-80SC · 08:17 PM

Quote:

Originally Posted by pmax

Your airbox (small port 39mm OD) should be this one 911-110-904-00 ... odd it's not available from our host.

https://www.pelicanparts.com/catalog/SuperCat/0794/POR_0794_FULINT_pg2.htm#item6

Have fun w/the project.

Thank you. not sure what is happening with availability... I placed an order for that part number (EDIT actually I have ordered part number 91111090401) on Friday from a supplier that advertised it as in stock, but they cancelled on me due to backorder. I placed another order today but likely wont get confirmation until Monday. We'll see

brian-80SC · 07-13-2019, 05:05 PM

Quote:

Originally Posted by mhackney

I'm in north central east MA. It is a couple hour drive to Portland. I'll be driving up that way next Sunday with a Porsche friend.

I got everything out today and will post more details in a few minutes!

I don't think we'll be in town that weekend, but depending how things go it would be nice to meet up sometime and learn more about CIS from someone with experience. If you like lobster there's some good places nearby

. If you'll be back up this way and are interested send me a PM. Thanks!

brian-80SC · 07-13-2019, 05:44 PM

Quote:

Originally Posted by MichaelSJackson

Brian,

Drained my tank and was astonished how clean it already was. I'd use a gallon or so in my truck on each fill-up. Being that diluted, it never gave it any problems.

Definitely replace the fuel filter. FYI: The latest one I bought had the painted on flow arrow in the wrong direction. Very disconcerting.

Michael J.

That's good to hear

I got a new filter already based the "correct" catalog part for my 80SC (Bosch 0450905021) but the top fitting is wrong size (filter threads too narrow) for the male-to-male nut/connector. From looking around this is a common problem.

Hopefully if I order a replacement that cross-references the one that just came off my 80SC (Bosch 0450905083) it will work...? I assume that should be safe, but it looks like fitment has been more complicated for others in the threads I've read...

brian-80SC · 07-13-2019, 05:48 PM

Quote:

Originally Posted by patkeefe

Hi Brian,
Yes, you can replace the CIS with the engine in the car, but why would you want to? It really is so much easier to take everything out so you can work on it in relative comfort.

Put in a new airbox. I see them advertised from different suppliers for only a few hundred dollars nowadays. It is practically impossible to repair an existing airbox.

BTW, my investigation leads me to believe they all leak, some worse than others. Also, there is really no sealant that can be used practically, especially for positive pressure applications. Airboxes seem to be made from a material called PPS, which is the generic name. See CIS Airbox Plastic?

Hi. Well I've got everything out now and I can understand more clearly why a full drop would be easier. If I had space to do a full drop, I would! Problem is - no where to put the engine!

In car removal was certainly doable, as other have reported, but of course required careful maneuvering, specific tools (3/8 swivel sockets and extensions were essential for the runner nuts and quite helpful for other fittings) and planning to make sure I could access everything in a proper order.

Also, I'm heeding your (and others here) advice and have ordered a new airbox! Thanks for the link on material . I hadn't see that thread yet.

rwest · rwest's Garage

Good idea getting the new box- besides being difficult to get a glue to work, my unscientific thought is that the box has been sitting in a hot engine compartment for 30+ years and that has to affect the integrity of the plastic in the box making it more likely to blow from another backfire, where a new one would have some elasticity to absorb the shock. Just my thinking.

brian-80SC · 02:43 AM

Progress update:

I got a lot done today and have removed the whole system. I generally followed the original plan in first post. Here's the removed CIS and engine bay:

Some notes on the removal process:

* Tore out (and will be replacing) the old insulation as it was falling apart and mostly detached. this gave me a little more room to work, but it took a while to vacuum out all the degraded foam bits that were everywhere.

* Originally tried to remove the entire air box and runner assembly as a unit, but needed to take some of the runners out to access more fittings as described below.

* I stripped the screws for the cruise control bracket and will need to replace those. instead I removed the entire assembly attached to the cable.

* My throttle linkage bushings had disintegrated and there was a lot of play in the bracket! this probably explains a lot of the sloppy throttle I was experiencing!

* Had trouble loosening the fuel filter connections, but was able to get them after soaking with PB Blaster. Apparently this is a common problem! I don't know when the filter was last replaced -- not sure how old it is (EDIT: the date code is from 1994), but some of the gas that drained out the bottom (inlet) looked dirty in the cup. loilsnlike this definitely needed replacement!

* I will be replacing the fuel injectors (sleeves and all o-rings too) as preventative maintenance. The old ones were a little loose in the sleeves, so probably some air getting in there. Also they were really dirty -- the injectors (and the inside of the runners) look like they have a thin coating of oil. Is this normal?

* Removing the inside nut for runner #6 was tricky (of course). What worked for me was to use a 10" 3/8 extension with a swivel socket (*not* a normal socket with a universal joint adapter, which probably would not fit). The extension was at a significant angle, but it worked well enough. The pictures shows how i reached it after runner #4 was removed by going under the curve of #5.

* Removing the outside nut for runner #6 required the AAR to be removed. It took some time and viewing with a mirror to find the allen bolt hiding under the electrical connector.

* disconnecting the crank case breather required me to remove runners 1, 2 and 3 (all easy), lift the airbox slightly from the left and support it with a piece of wood. this gave me enough room to reach around and fit a short palm screwdriver into the hose clamp from the back side. A small extension mirror and flashlight helped me find and line up with the screw head. after the clamp was loosened I was able to work the hose off without much trouble.

* looking at the engine shroud there appears to be an oil leak from the crankcase oval gasket so glad to be able to address this now.

Next step is to start cleaning and assessing everything while I wait for new parts to arrive. And some cleaning of the engine bay too!

Brian