Oil Filler Gasket and Thermostat Housing R&R
 

So I noticed oil seeping from the oil filler neck on the 88 to the point where it was pooling in the block 'pits'. Being a newbie, I couldn't see how to get at the oil filler gasket except by taking off the intake or removing the thermostat housing. The thermostat housing looked like it would not come out without removing the filler pipe. After some research, I found a picture of the thermostat housing removed while the filler neck was still in. That was all I needed to get started...and I was looking forward to some quality under the hood time with the S4. :jumper:
So for the other newbies that would like to perform this job, I've included some pics of how I did it. Not too hard.

First, here's the gaskets I ended up replacing - thermostat housing to heads (2), thermostat housing to block o-ring, thermostat o-ring, thermostat sealing ring at back of housing, new thermostat, oil filler neck gasket - so it's best to get these ahead of time.
Attachment 250205

First, Jack up the car and support it with jackstands. Then, remove the cross brace. It takes an 8mm allen wrench.
Attachment 250206

Next, drain the radiator and the engine block (2 13mm bolts one on each side of the block). Radiator fluid looked OK, the previous owner changed it last in 2004.
Attachment 250207

Next, I removed the hoses from the thermostat housing. There are 4 - block to radiator, radiator to block, bleeder, and heater return hose. I replaced all 4 hoses since they were all original and 20 years old.
Attachment 250208

I then removed the fuel pressure damper. I took the plastic cover off the passenger fuel rail so I could access the hex mount to counter hold the connection - then disconnected the hose.
Attachment 250209

Next, came the remaining 2 connections - one at the driver's side fuel rail and the other at the bottom of the damper. Also remove the vacuum connection at the top.
Attachment 250210

Then I removed the thermostat housing allen head bolt (6mm) that also holds down the damper bracket.
Attachment 250211

The damper assembly comes out.
Attachment 250212

Next, I took the remaining thermostat housing allen head bolts out. The tricky one is the driver's side rear next to the intake. It's next to impossible to get a socket extension in there straight so I used a regular allen wrench with an adjustable wrench on top to turn it. This allowed me to get a straight and solid fit with the wrench and avoid stripping it out.
Attachment 250213

After the bolts are removed and the two temperature sensor wires disconnected from on top, the housing comes out but it's a tight fit. By rocking it back and forth and pulling up and toward you at the same time, it eventually comes out.
Attachment 250214

Once the housing is removed, it's a good idea to stuff the openings with something to prevent debris from falling into the openings while working on getting the filler neck out.
Attachment 250215

continued on next post....

Next, to remove the filler neck, I disconnected the two hoses attached to the base.
Attachment 250250

Then remove the two 10mm bolts that hold the filler neck to the block.
Attachment 250251

Remove the filler neck...
Attachment 250252

And plug the hole to prevent debris from entering the block.
Attachment 250253

With the thermostat housing out, I began disassembly. First I removed the thermostat cover plate.
Attachment 250255

I made note of the orientation of the thermostat. Notice the 'up arrow' on the thermostat oriented at the top as well as the o-ring on top of the thermostat.
Attachment 250256

I then removed the thermostat sealing ring at the rear of the housing. I used a screwdriver to bend the edge in toward the center enough to get a grip with some pliers then pulled it out with the pliers being careful not to damage the housing.
Attachment 250257

After removing the remaining gaskets and o-ring from the housing, I began putting in the new seals, gaskets. First the sealing ring at the rear of the housing. This just presses in.
Attachment 250260

The sealing ring sits flush...
Attachment 250261

Next, I installed the housing to heads gaskets.
Attachment 250258

Then the large o-ring for the connection from housing to engine block.
Attachment 250259

continued on next post...

Next came the thermostat and o-ring. I placed the thermostat in with the arrow oriented at top followed by the o-ring.
Attachment 250262

Then tighten the thermostat plate back on.
Attachment 250263

Here's a pic of the clearance between the thermostat and rear seal when the engine is cold - recirculating coolant through the engine until the thermostat closes against the seal and simultaneously allows water to flow to the radiator.
Attachment 250264

Next the parts are ready for installation. I installed the filler neck first (after cleaning it off and installing the new gasket, of course.
Attachment 250265

Then comes the thermostat housing. Installing it the same way it came out - rocking and pushing down and away from you. After some maneuvering, it will go back into place. Before putting the thermostat housing back in, you could fill the engine block with coolant to minimize the bleeding. However, I left it empty and needed to spend a little extra time allowing it to bleed off the air in the block before I would get normal temperatures.
Attachment 250266

At this point, finishing the job is a matter of installing the thermostat housing bolts back in (14 ftlbs - the manual recommends the 2 step approach - 7 ftlbs first then 14 ftlbs next). Remember to install the fuel pressure damper bracket back in place before tightening the driver's side front allen head bolt. Finally, re-attach the crossbrace and tighten down before lowering the car. Here's everything back to gether again...
Attachment 250267

Also did power steering hoses this weeked and can post pics as well....

Feel free to comment - especially on improvements to the process. THANKS for reading!

Dwayne-

Great writeup, as usual. That rag you stuffed in the oil filler hole is a little dirty, though.... :icon107:

Perhaps I've been under a rock, but where'd the white '88 come from? New shark egg hatched in the garage? Congrats on the addition to the stable!

excellent work, excellent pictorial thanks

More excellence from Dwayne's Garage! Yeah, whose white car is that?

Excellent description and fotos.
One question, I thought you risk a cracked screen if you jack the car after the cross brace is removed?

Marton

Thanks Dwayne for great account and photos. I'm just about to do same job on S4 but my intake is off right now so needn't be as ingenious as you! Still really helpful to see all the photos and confirmation of removal procedure though.

I was also puzzled by the order of jacking after cross brace removal but obviously you managed not to crack the screen. I know the brace has to be put back on with the suspension loaded.

Ah..a thread by Wayne...always good for lot's of pictures...and clean as a whistle as ever (dammit). Good job Wayne, thanks for the pic's. Added to the saved threads.

Only picture I'm missing is the oil filler gasket install. I winced at the jacking up without cross brace too, but then again you would have the same amount of stress on the body when removing it jacked up.

Great writeup:bowdown:

Thanks for sharing!

/Peter

THANKS for the comments!

I agree...I think the better procedure would be to jack up the car with the cross brace still in tact then remove it. Then I suppose you would have to be very careful lowering the car with the brace off for the same reasons as jacking it up - maybe this would work best - 1. jack up car 2. remove brace. 3. perform work. 4. replace brace. 5. lower car. 6 loosen the brace and re-tighten after weight on wheels.??

YES....my wife and I have been quietly planning an addition to the stable for the last few months and last weekend the stork brought us a baby shark...:jumper::jumper: We couldn't be prouder!! (I'll need to update my signature....)

What would happen if you hadn't drained the engine block (i.e. only the radiator)? Could you take out the thermostat with bridge still installed and suction out enough coolant that way to avoid spilling a bunch when the manifold came out?

WOW.

This guy is good. Dwayne, thanks for the post. I'm always amazed at how clean your engine and pics are.

Recently when Adam and I were removing his oil filler neck we used the old screen as a template and transferred the shape onto a piece of cardboard. We cut it out, and then we used some shorter bolts to just put the screen back on with the cardboard over it so we could work without dropping anything down into the crank case. It was like the covers DR makes for the intake refurb work, only made of cardboard instead of metal. It probably works as well as a rag, but we were cleaning some stuff and didn't want anything sneaking down there.

Great write-up, I agree with the change to the cross-brace procedure.

No, just don't do it.