CIS - Before I make another mistake.....

[bobswei]

I recently removed the CIS from the top of the engine to replace the rubber tubes and o-rings on the injectors due to air leaks. When I put it back together and in the car. It was worse than when I started. I used all new rubber tubes and clamps. So, I just removed it again (not fun) and notice that the new rubber has a powder coating on it (release agent?). Very slight but could that cause air to pass by even though clamps were very tight? Could they have been too tight? Should I use a non-hardening sealer this time?
Thanks for any expert advice.....

[ArchHibb]

Bobswei -

Sorry to hear things did not improve after replacing those parts. I don't think the release agent alone would account for air leakage, but it could be a contributing factor. Those band clamps don't need to be death grip tight, but the intake runners should not be able to rotate. Check out this thread...
CIS reassembly

When I reassembled mine, I double-checked everything and followed a checklist that reversed the disassembly. Did you tug on each of the injectors to verify they are fully seated and the plastic insulators are properly pinned in place?

[porsche930dude]

this video has some good info. yes I know its from motorsheister. but things to check

[fanaudical]

Did you attempt to re-tune the CIS before removing again? As things age and leaks develop, most people end up tweaking mixture, pressure, etc to get it to run right. Now that those leaks are gone, you may need to re-tune.

Also, while you have the airbox off, it's worth doing a bubble test and ensuring the seams are tight.

[bobswei]

Thanks for the link and video. Tomorrow, after work will be my first chance to dig in again.
I made a jig out of plywood, to set this up (Thanks to a PP posting) and all the tubes were snug, no twisting. So everything was pretty close when re-installing and no loosening and fidgeting.
Didn't need to re-tune since I sprayed B12 underneath, at the tubes and the idle speeds up and smooths out. Had to be air leaks. Hopefully, Saturday will tell the story. Thanks again.... Bob

[T77911S]

you need to change the injector sleeves.

make sure the air box is not cracked

make sure the port surface and the intake runner surefaces are clean.

put it back in, snug the clamps back up and tune it up.

[kodioneill]

Did you remember to hook up the brake booster vacuum line? I also agree that you need to check your tune up specs if you repaired any leaks then you'll have a rich mixture.

[Robey5]

Hey:

I am sorry to hear about your CIS issues. I fought with CIS issues (air leak) for the better part of a year, which is embarrassing, but the facts remain....

Anyhow, I found that the air box could be tested very easily. Now that you have the intake out, you can easily test the air box in a water submersion test and a bike tire pump. From there, you may find that you will have leaks at the seam, or at the pop-off valve ... or wherever....

I had a couple of places that caused me trouble. One was the bolt that is near the back/bottom that doesn't connect anything (shown in your picture at the 5 o'clock position, and is rusty for some reason). I got annoyed (that I had to pull apart the intake a second and third time after installing the engine/trans) and put epoxy on these threads and tightened it down. I also had an issue with the intake runner/gasket interface; causing an air leak.

Good luck!

[bobswei]

Hey Porsche930dude, You got it right. That video help out so much. I didn't think I had a blown airbox since I had a pop-off on it. I watched video, checked for cracks and there it was. Right in the area that made a big difference when I sprayed B12 at it. So, it's getting sealed up right now and should be good to put together tomorrow.
Didn't need the submersible test since this was obvious (if you look in the right place and know what to look for).
So, I will follow Robey5's plan of action when putting back together. Thanks all, for the input. I'm confident I will have a leak free CIS by the end of the weekend.... Bob

[prebordao]

Hi bobswei
I'm putting together an efi/itb setup and i still have the linkages to work through.
Can you look at your jig and give me the distance between left and right cylinders ?
It would be a big help. Thanks !

[porsche930dude]

Cool. What are you sealing it with? Just curious since the video made it out to be wizardry

[boyt911sc]

Originally Posted by prebordao

Hi bobswei
I'm putting together an efi/itb setup and i still have the linkages to work through.
Can you look at your jig and give me the distance between left and right cylinders ?
It would be a big help. Thanks !

PJR,

I was in Lisbon Thursday and Friday and wanted to meet you in person. But the WFI signal at Fatima was weak and poor. I got two engines partially assembled and disassembled I could use. Email me or send a picture of what you need. Back home already.

Tony

[bobswei]

Hey Porsche930dude. When the video said top secret epoxy, (something like that), I automatically assumed it's JB Weld. Why would it be a secret unless it was something goofy that a factory race team would never use. So, I used it instead of buying a new airbox. If it doesn't work, I'll buy a new airbox. If it works, I save big $$$$.
prebordao: I'll get the dimensions for you tonight or tomorrow morning. It's not "exact" but very close since the rubber tubes have a little flex to them. This time, I put a little support under the airbox when assembling, just to hold it up a bit as if it were installed. It brought the runners in about a 1/2" which made the fit better than last time.
Thanks again for all that suggested "airbox cracked"..... Bob

[porsche930dude]

Alright well I hope it holds up for you. Youve got good practice taking it off now anyway lol. I would glue it then go around the seam with a soldering iron to weld it all together. With the pop off valve youll probrobly be ok either way.

[bobswei]

prebordao, here's all the details:





I thought of doing the plastic welding but once the sealer ozzes out of the seams, you can't really get in there anymore. Here's pix of the crack and the plastic was getting brittle so the thin part of the seam was falling apart in a couple areas:

[Nostril Cheese]

I wouldnt bother trying to re-seal it. Ive seen people trying to do this countless times and it never works.

[Josh D]

I can't tell from the pics on my phone if JB Weld was used, but it doesn't work well with plastics. A plastic specific epoxy would be better. I would also slather permatex black rtv along the seam to seal.

[Robey5]

Find a good plastic-friendly epoxy that sets in 24 hours and re-seal it.

I am aware that there has been mixed results on the re-seal, but judging by the number of people on this forum who have sealed the airbox back up: you are faced with 2 choices: re-seal or buy another (new) box.

I chose the former. I resealed mine and I have less than a year on it, runs fine. Also: you may want to remove and re-seal the pop-off valve just to be sure it is tight.

In all: if you have the box out of the car and are working on it, my suggestion is that it is tested in a submersion test before it goes back in the car. Worst case, you find out that you have a tight air-leak-free airbox, and can remove that from the equation.

Good luck!

[prebordao]

Originally Posted by bobswei

prebordao, here's all the details:

Thanks bobswei, just what I needed !

[prebordao]

Originally Posted by boyt911sc

PJR,

I was in Lisbon Thursday and Friday and wanted to meet you in person. But the WFI signal at Fatima was weak and poor. I got two engines partially assembled and disassembled I could use. Email me or send a picture of what you need. Back home already.

Tony

What a shame, Tony. It would be nice to meet up, if you ever comeback, be sure to warn me !
As for the measures, the pictures provided by bobswei are good to get me started. I'm playing around with a few options for the linkage, and as the engine is still in place and assembled, any measuring won't be very accurate.