Jeff928S4

1989 S4

Here is a list of the seals/gaskets, etc I have...

999.701.627.40 - O-ring - Coolant Crossover - All
928.106.227.00 - Gasket - Coolant Crossover - 85-89 (2 of these......the red ones with the ribs)
928.106.129.17 - Thermostat 83 Degress C - Behr - All
999.701.632.40 - Thermostat O-ring - All
928.106.163.00 - Thermostat Housing - Inner Gasket

Now, where does each go in the pic below? I know the red, ribbed ones are for either end of the manifold and the "inner thermostat housing" one goes behind the thermostat. I'm stuck on the O-rings. One is bigger than the other. Apparently I didn't get the grooved seal that goes around the thermostat, or is the smaller round O-ring for this? Can't see it, as it isn't grooved.

AO

Hopefully you can read this...

AO

Sorry wrong pic...

Jeff928S4

Excellent (said like Monty Burns).

So, what I see is that part "22" (999.701.632.40 - Thermostat O-ring) is the right part number, but the old O-ring that came off has a groove in it - is this groove created in the "round" O-ring once it's pressed in?

heinrich

999.701.627.40 - O-ring - Coolant Crossover - lower big fat black
999.701.632.40 - Thermostat O-ring - between the therm and block

Jeff928S4

Is this supposed to be "grooved"?

I'm confused by the gasket that was on the old thermostat...the one that sits between the thermostat and the housing that holds it in from the back. You can see it is grooved and sits in the lip....but the pic above says "22" goes there and "22" is not grooved?

Jeff928S4

The pic below shows the O-ring in question.

It looks kinda "round" in the pic. It must form to the "groove" and eventually take its shape.

Jim bailey - 928 International

Correct new o-rings are round over time they may take the shape of the machined groove.

Jeff928S4

Would taking the shape eventually make it lose it's qualities that it needs to push the thermostat?

I mean, over time, would the compression/heat make the O-ring so thin that the thermostat doesn't sit where it should to the point where it would effect cooling?

davek9

Hello all, can this crossover be removed on a '91 w/o removing the intake?
I know it can be done on an '85.
Thanks..!

DaveK9

Richard S

I just did this with my 87, so your 91 should be similar. Dwayne did a great write-up https://rennlist.com/forums/928-forum/406385-oil-filler-gasket-and-thermostat-housing-r-and-r.html

Rich

davek9

I can not get a straight enough shot w/the rear driver side allen (it won't go in deep enought), I'll have to stop by Harbor Freight or Sears in the AM and pick up a set of the Allen's w/the ball end that work on an angle.

thanks guys.. and this is a great write up Dwayne.

DaveK9

worf928

Some can. Some cannot. It all depends upon the variations in manufacturing of the castings. I was able to remove the x-over on a '91 but not a '90.

You can remove the x-over without completely removing the intake; you just need to unbolt the intake and lift it up and back about an inch so as to get good access to the crossover bolts. MAS has to come out as do the fuel rails. The p-side breather hoses have to be disconnected from the cam covers.

I've done the job both ways and I prefer the lifting-the-intake method because it allows straight-down access to the crossover bolts for removal and the two-stage torquing process for re-install.


Note that as of '90 there are two paper gaskets for the head interface needed on the x-over in addition to the red o-rings. Part number - 928 106 167 01

davek9

Thanks Worf928, good to know, and i addesd to Dwayne's post I am going to try an allen with the round head next (after i buy a set) ... and I did not see any paper gaskets in the bag...

worf928

You will find them when you remove your crossover...