Broken CIS air filter strap lower mount...FIXED!

[FunWithPaul]

Hi All,
I have learned so much from all of you, so I thought it was time to "help another Porsche owner"

I broke the lower left air filter cover strap mounting point a while ago
(note to EVERYONE: If the rubber straps are getting tight, GET NEW ONES!
or you may snap the lower "stub" that the strap attaches to...)

I have the airbox out (and the rest of the intake system) for a loose hose clamp on a fuel line (that is a different post), so I decided to fix the broken strap mounting point.

I would have liked to use stainless, but didn't have any that was "about that size", so I used some mild steel bar that I had. I put one bend in it to match the underside of the airbox, drilled and tapped a 4x.5 thread, and painted it black (except where it touched the air box).
Then using it as a template, I then drilled a pilot hole UP through the airbox floor, so I could drill a proper one in the correct location, to screw a 4mm screw down into the new steel mounting point.
I then added some black epoxy to the contact surfaces, and screwed the new mounting point under the airbox.

Does that make sense?

A picture says a thousand words.

View from above


View from below



For those of you CIS experts, Yes it is just slightly to the right of the original mounting point. I actually dremelled out the center rib, with the plan of putting it between the old mounting point ribs, but decided that 1/2" inch to the inboard, with a stronger piece of steel was a better idea.
So that is where it is.

I will post a pic when I get the CIS back in the car and the air filter on.

The "texture" in the paint job was unintentional. I couldn't wait to put it on, so there is rubber glove imprint in the paint...


If you broke one of your air cleaner rubber strap mounts, I hope this will help you.

Paul

[Funracer]

Thanks. Both of mine are broken

[pmax]

Well done !



But I'm confused... is the circled rivet(?) another repair ?

[FunWithPaul]

Originally Posted by pmax

Well done !



But I'm confused... is the circled rivet(?) another repair ?

Yes, It split after a backfire (a long time ago, before the pop-valve),
I don't remember taking it out of the car, so I must have repaired it in place, there is epoxy at the seam too.

[FunWithPaul]

Originally Posted by pmax

Well done !



But I'm confused... is the circled rivet(?) another repair ?

Just went and looked at it (it is still out of the car) I put small pop rivets all the way around (even under the throttle valve) so I did have it out.

I have had the engine out twice in 38 years, the pop rivet repair would have been the first time.
I remember having difficulty getting the car high enough for the CIS and fan to clear, so I disassembled the back bumper slowly (the first time... and before any forums like this) and finally got the engine out.

The second time (to rebuild the engine, 20 years ago) I took the rear bumper off at the beginning (the car was getting painted too, so EVERYTHING came off) and lowered the engine onto a thin sheet of plywood laying on small dowels. I rolled the engine out like an Egyptian moving a pyramid block. It worked great.

Trying to put the CIS back into the car yesterday
(it was not a good day, the CIS is back on the workbench)
I broke the drain tube mount and the WUR nylon feed line.

Here are some pics:



The test fit (that used to be a SS drinking straw. I thought "oh that is waiting to poke my eye out" so part of it is being used to fix my airbox)



And after applying some JB Weld (I hope whoever invented that stuff made millions and lived happily ever after...)



Yesterday I realized, yes you CAN take the CIS out of the car while the engine is still in.

But you can't put it back (you can't tighten the #5 and 6 intake runners with the box in the car)

So the engine is coming out anyway.

If I had done that in the first place I could EASILY replaced my leaking fuel line, without dis-assembling the entire CIS system.

I am going to do a seperate post on that experience (disaster?) when I have time,
right now, I need to learn how to repair broken plastic CIS lines...

Paul

[pmax]

Originally Posted by FunWithPaul

Yes, It split after a backfire (a long time ago, before the pop-valve),
I don't remember taking the air box out of the car, so I must have repaired it in place, there is epoxy at the seam too.

Remember to check for vacuum leaks before putting everything back in.

The second time (to rebuild the engine, 20 years ago) I took the rear bumper off at the beginning (the car was getting painted too, so EVERYTHING came off) and lowered the engine onto a thin sheet of plywood laying on small dowels. I rolled the engine out like an Egyptian moving a pyramid block. It worked great.

Yep, I did similar using a dolly. Removed the valance only, get the tail just high enough to squeak past. Could have removed the CIS "pope's hat" instead I suppose and the valance could stay put as well.

Trying to put the CIS back into the car yesterday
(it was not a good day, the CIS is back on the workbench)
I broke the drain tube mount and the WUR nylon feed line.

These lines compose of an outer wrap and inner polyamid core. Is it only the former which is torn ?

[FunWithPaul]

Originally Posted by pmax

Remember to check for vacuum leaks before putting everything back in.



Yep, I did similar using a dolly. Removed the valance only, get the tail just high enough to squeak past. Could have removed the CIS "pope's hat" instead I suppose and the valance could stay put as well.

These lines compose of an outer wrap and inner polyamid core. Is it only the former which is torn ?

Thanks pmax,
No, the polyamid tubing broke right at the WUR inlet.
There is enough length to re-set it, if I do it right. I will find out tomorrow.

The early years (1974) have a rubber supply line from the fuel filter to the Fuel Distributor and cold start valve. The other supply lines and injector lines are single wall plastic. The injector lines are 6mm O.D (I hope never to need to know the I.D.) and the WUR and Throttle Position Valve tubing is 5mm O.D. and 3mm I.D.
All of the return lines are rubber.

Porsche (Bosch?) made lots of changes as they figured out the "kinks" in the CIS system...

Paul

[FunWithPaul]

Originally Posted by Funracer

Thanks. Both of mine are broken

I just tried to put new URO straps on,
They are about 4" too short!

And they only stretch about 2"... that is how the airbox strap lower mounting points get broken.

I just measured a new URO strap, it is 222mm from inner mounting surface to the other. NOT LONG ENOUGH!

Does anyone else have a different strap (Genuine Porsche or Weltmeister ect?) what is the length of the strap between the two retangular holes? and how much do you think that strap stretches?

Thanks,
Paul

[FunWithPaul]

Originally Posted by Funracer

Thanks. Both of mine are broken

And "I think" you could do the repair without removing the airbox.
Just get the bend right, and (now here comes the hard part) figure out where to drill the hole in the airbox (mine was out, so I had it easy, I drilled UP through the hole in the metal). You will have to figure that part out on your own...

Good luck,
Paul

[pmax]

Originally Posted by FunWithPaul

I just tried to put new URO straps on,
They are about 4" too short!

And they only stretch about 2"... that is how the airbox strap lower mounting points get broken.

I just measured a new URO strap, it is 222mm from inner mounting surface to the other. NOT LONG ENOUGH!

Does anyone else have a different strap (Genuine Porsche or Weltmeister ect?) what is the length of the strap between the two retangular holes? and how much do you think that strap stretches?

Thanks,
Paul

Here's an OEM strap ... I think it is anyway.

[UROParts]

Originally Posted by FunWithPaul

I just tried to put new URO straps on, They are about 4" too short! And they only stretch about 2"...

Hi Paul, would you happen to have a photo of the packaging for the straps you received, particularly the label on the bag (which has a batch code). Thanks!

[UROParts]

Paul hasn't been on the forum since 4/27 so we haven't heard from him yet, but we checked our inventory and our Air Box Cover Strap 911 110 365 01 is about 281mm long (overall length) when relaxed and can stretch about 7" (which is more stretchy than our OEM Porsche sample). So it's plenty long enough for 1978-1983 SC cars that use late-version 270mm strap 930 110 365 00, and when stretched a bit should be long enough for 1973-1976 CIS cars that use early-version 298mm strap 911 110 365 01.

Several reviews of the OEM strap on Pelican mention the length of old vs new straps:

• "New Straps make you realize how much the old ones have stretched."
  
• "These hold the filter cover on much better than the original stretched out ones did. When you compare them to the old ones you removed they are shorter, because they're not all stretched out. Give them a couple pre installation stretches and they'll go on just fine."
  
• "So glad I changed these, way better fit than the old stretched perished ones."