Dwayne

GREAT WORK MIKE! I was contemplating taking my '84 TB apart to see if this problem could be fixed. I had the same issue you did. I ended up ordering a used TB in case I destroyed my original during the "operation" but the used one actually sealed - so I put the disassembly of my orginal on the back burner and put the used one in the car. Now, thanks to your work, writeup and pics, I know it can be done - non-destructively. THANKS!

Mike Frye

Roger (928sRus) has a list already spec.ed out. I'd just ask him for the whole list, and add a few extra cam cover bolt O-rings for this and have at it.

Also, if I do this again (Adam?) I'll definitely plan on pressure checking the whole throttle body/airguide/ISV assembly with all hoses connected so that if there's a leak anywhere I'll have a better chance of being able to fix it without removing the intake runners.

I'm sure the whole community would appreciate if you'd do one of your patented write-ups with step-by-step pics of the whole procedure anyway, but thanks!

Tampa 928s

Ditto!

Adam Geist

Hey Mike, Great work! I haven't been on rennlist for a few days and just read through the post. I'm with Bill on Loctiting the throttle plate screws.

Before tightening the screws, hold the throttle body up to a light and adjust the throttle plate for equal clearance to the throttle body bore all the way around.

On the gold '86.5, I had to adjust the throttle plate slightly as it was rubbing against the bore on one side.

Adam

Mike Frye

Adam,

Thanks for the comments. I found that the plate only fits in one orientation without rubbing but when it's seated, there's no adjustment needed, so I think I'll be OK on that one. I should be getting the parts I need today so I'll be re-pressurizing the system on Saturday morning. Hopefully by Saturday afternoon I'll be up and running again with no more vacuum leaks.

Leslie 928 S2

Hey Mike, Kevin thought he should mention a little something here because he discovered when he went back in there that he doesn't have o-rings and bearings like you, he had bushings and lip seals. For those who follow behind.

It has o-rings for now, with the old bushings, until he gets some new parts.

Anybody know who's got 'em for an 85 Euro throttle body?

RichS 1986928

Ah, you guys are killing me. I finally thought I had all the parts to put my intake back
together..

So from this thread it sounds like it's not enough to just pressure test the Throttle Body.. I should
also visually inspect the Orings? True? How difficult is that procedure? I didn't have a vacum
problem before this, but if it's another good WAIT, I should probably do replace those o-rings.

Mike Frye

Rich,

My guess is: once you get the throttle body sitting on the bench and you take apart the assembly, you'll be glad you opened it up. Mine were completely solidified.

RichS 1986928

You were right Mike! Matt (leperboy) came over last night to help.
We got a look at these 'orings' I'm not sure if thats what
they really were. My guess is part of the original bearing assembly.

They were completely brittle and only held in there by the shaft itself.

I'm hoping to find some replacements at a regular autoparts store, it
did occur to me that they will need to be fuel compatible. Are you
sure the ones you are using are ok in fuel? I REALLY don't want
to wait to order these... seeing Matt's car in action made me jealous
and now I want mine back on the road more than ever!

Mike Frye

Rich,

I'm sure someone will come along and figure out the 'right' O-ring to put in there. The ones I used were the O-rings for the cam cover bolts (p/n 999 701 731 40) but I know they're probably too thick. The O/D was good, the I/D was probably too small, but once I lubed them up, they seemed OK and sealed really well.

Are you sure they need to be compatible with fuel though? There should only be air and some oil in that section of the intake AFAIK.

Great pic btw!

RichS 1986928

Mike, you're right, not fuel, oil. Usually when I've seen plastics and o-rings they are fuel/oil
compatible, that's all I was getting at. I just don't want to have to do this again! I'm going to
Autozone today and maybe I'll get lucky and find something adequate for this.

Rob Edwards

It's official: I suck at intake work. I finally found a bunch of plumbing bits that fit the top of an S4 MAF (96 mm OD), and cobbled together a pressure tester. The part that sits on the MAF itself is a flexible thin wall 4" to 3" downspout connector, American Valve product UPC # is 11918 01832, available at Lowe's. It needs a 4" hose clamp to hold it tight on the MAF. It sits on a 3" pipe with a threaded cap that I tapped for a 1/4" NPT-18 pipe, then a 1.5" pipe, a T-fitting, a 0-30 psi gauge I got at Ace Hardware, and an air fitting.

Anyway, I never got above 0 psi, as there's a massive leak somewhere under the intake, sounds like it's coming from the oil filler neck. Looks like it's all coming apart (again...)


WIAAT, I'll have a look at the throttle body and see if I can suss what the o-ring situation is on the S4 TB.

Peter F

Thanks Rob,

I would be interested to know about this as well.
My intake has been completely overhauled but I did notice a small leak in the thottle linkage when pressurised that would be nice if it can be fixed.
Maybe put on this winthers joblist

/Peter

Bill Ball

Oil filler neck? Breather hose between the base of the oil filler and the throttle right side may have popped off the oil filler end.

dr bob

I'm sure it's safe to remind folks that you won't be able to pressurise the intake if any cylinder happens to be close to TDC on the exhaust stroke, when both intake and exhaust valves are open. If you can't get pressure, and you can hear air flowing from the exhaust pipe, turn the engine slowly by hand until it stops.

We need to make a hot-wire smoke generator with a small fan to attach to the intake similar to the way you hooked up the air connection to the MAF there.