Snark Shark

The T is that big pipe right in the center. It just looks like it's positioned more towards the passenger side than it should be. If there's no more sign of vacuum leaks, I wouldn't worry about it.

I do believe the straps are NLA. If they're stretched out and not holding tight you can make them shorter by bending the metal a little bit.

Mrmerlin

If your filter is new turn it over its upside down, ( hump points to the sky)
The blue check valve port is just infront of the brake booster check valve.
All of the plenum collar clamps should be tight ,
if your collars are soaked in oil it would be wise to replace the whole set of rubber collars including the center T collar.

928S MN

Chris, the air box straps are still available. The 4 straps you see in my Avatar are all brand new. Give Roger a call.

Question on that tow truck picture - where did they hook up the rear chains to your car? Hope they didn't bend something in the rear suspension.

928S MN

Also if you are looking to replace the air inlet pipes to that air box, Roger has the Mercedes plastic tubes and now the silicone angled connecting tube as well.

My son found that part which we then gave that part number to Roger so the 85/86 community can use.

This set up is also shown in my Avatar. Combo of 4 Mercedes tubes and 2 silicone connectors is very reasonably priced.

Christopher Zach

On the 86.5 there is a rear jack point with a hole in the bottom. They hooked to the hole. Maybe I should get 3 more tow eyes and just have them hook up to all four :-)

Christopher Zach

Interesting. I see the later model box clamps all the time, but the 85/86 used the ones with the embedded latches. Which Roger again?

As for the air hoses I have those (not really damaged) I treat them like glass. Getting them out is a *real* pain especially the driver's side where you have to remember to take off the PS cap and watch the throttle cables. I can see why they rip,how needed are they for general driving (I'd like to leave them off till I can get the engine pressure washed/cleaned and a couple of other things attended to).

C

928S MN

That would be Roger of 928sRus.

Info@928sRus.com

817-430-2688

Christopher Zach

Oh yes, that Roger. I believe I bought the ABS and brake sensor grommets from him, probably the greatest little investment in history and remover of a dozen zip ties in my life :-)

Meantime I just went out, installed the new AGM battery (H-8, how the heck can a H-10 fit in there?), flipped the filter over since it's brand new, and fired up the engine. Dead cold, started on the first crank with no problems at all, drove right up the driveway at power no problem. Guess that was it, will try driving a bit this evening and see what I get.

While I have the 85/86 928 people on the horn though, is the way to take off part of the plenum by sliding the sleeves inboard and just lifting up on the T part? That would give a fair amount of access to the center of the engine along with stuff like the TPS and other goodies.

Or is the procedure for removing the plenum similar to the later models?

bureau13

I wasn't able to get the center T all the way out with everything else in place. I did manage to pull it up a bit. Of course, then getting it back down properly was equally painful...

linderpat

Yes, you can get the center "T" out, a bit fidly, but it does come all the way out without having to disassemble and reinstall the rest of the pipe organ. The truly maddening part is getting it back in and properly seated onto the throttle body. You need to make sure your clamps and screw heads are all lined up properly so that these can be re-tightened with a long shank screw driver when you put it back together, or else you'll have another monster vacuum leak. Plus, it's just a real PIA to get it back in. Still worth it to yank it and service what's under there.

Christopher Zach

Ok, I'll put that on the list of things to do. In the meantime I took the car out for a fueling, and a long overdue car wash. Runs *well*. Better than before, the sag before acceleration is gone, and the throttle response feels a lot more snappy. So now it's back to pulling out the head unit and taking that footwell flap servo apart. And figure out what the heck is wrong with the cruise control again.

Thanks everyone, hope this helps someone in the future.

Christopher Zach

Just an update to close out the thread: Been 2 months and no problems. Engine starts fine, runs fine, accel fine. The problem was that loose plenum seal allowing air to leak in when it flexed under acceleration. Hope this helps someone else, thank you all for the assistance!