90 C2 - 964 rebuild
 

I will not even attempt to detail all the steps in the rebuild which is about to get underway. Kirk has already done that with his 964, and better by far than I could ever do. But as I come to things I am unsure about perhaps I can post a photo or two, in hopes someone else has been there and can point out the errors in my approach. Haven’t done a 911 in about 30 years, and never a 964.

Looking today at the head studs and nuts, I haven’t really come to a decision yet. I took the studs all out of the case because the 1-2-3 side had been gooped up with red RTV at some time past ?? Don’t know how anyone could think that oil would be leaking out there. Anyway, I just took them all out for cleaning and to reseal the threads in the case.

I left them all in a tray of paint remover overnight to get all the epoxy paint off, so I could inspect more closely for signs of corrosion. In the photos below you can see that the intake studs all came out clean but the exhaust studs clearly show where the greatest heat has baked that epoxy so hard that the paint remover had no effect at all. In the last photo I have bead blasted the remaining paint from the exhaust studs and it also took off that gold colored surface treatment. It is a very thin coating, and I don’t expect they would have done any electroplating on these studs. Was it a hot bath treatment?

I have given them a new coating of epoxy paint now, but am thinking of replacing the 12 exhaust studs with new ones (they are all Dilavar studs) since they have already seen 16 years and 58000 miles of heat cycles. Then I wonder…….why don’t I just switch them around and let the previously intake side studs now get the heat ……and see whether they will all go another 58,000.


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Well today I finished the head studs. They have new epoxy paint now and also I bead blasted the nuts and plated them in yellow zinc.
http://forums.pelicanparts.com/uploa...1163461921.jpg

That second photo though got me thinking about how different the heat is on the exhaust side studs. And that line of thinking lead to the question of just how much advantage is there in Dilavar studs. They expand at about the same rate as the aluminum, true; but they are never at the same temperature as the aluminum.......and never at anything like a uniform temperature from the hot side to the cold side. It would seem to me that the tension on the studs will clearly increase as the cylinder/head temps rise, even with Dilavar studs. Also the increasing tension will be different depending on where the stud is located. My simplistic notion that the Divalar studs would maintain nearly constant tension across the operating range is really foolish, and a result of accepting the hype without ever really thinking. The Dilavars may have improved the thread-pulling situation on the magnesium cases, but they are certainly not without their own reputation for breaking. In short, it now seems really a moot point to me, steel vs. Dilavar......and thinking that way, why take a chance on a broken stud? Reluctantly and slowly, while working on and thinking about those studs, I have decided that I have joined the steel stud camp on this issue. I have read that the company also reached that conclusion late in the air-cooled model run.
So, I shall not be actually using the studs in the photos. Since it is to be steel studs the only question is which are the best among those presently available. That question at least is easy for me.....after posting this message I shall order a set of the Supertec head studs from our host.
James

Best choice you could make. I put steel in my rebuild as the budget just didn't allow for Supertec studs. Enjoy the rebuild! :cool:

Yeah I second that.... I would 100% at least buy all new 993 studs+nuts.
Its just not worth it to put that old Dilavar grabage back in there. You already wasted too much time cleaning those evil dilavar parts

993 stuff is pretty cheap also.

The pistons and cylinders will be this set. They are the later 964 design, with more seating surface at the head and provision for a sealing ring.
The heads, crank, rods, rockers and cams have been delivered to The People's Republic of California. They will soon be subjected to a close scrutiny under the watchful eye of Herr Henry Schmidt. Those parts which pass muster will then be reconditioned to the high, exacting standards of the Supertec team. I have done the best I knew how to do, for those parts.
Meanwhile, back at the desert, I am passing the time by attending to those needed repairs which can so easily be done in this partial state of disassembly.
The transmission has never had a thing done to it during the 16 years it has run like a thoroughbred. Well, other than fluid and oil changes, that is. While it is out I intend to replace all the seals where a rotating shaft leaves the case. Think it workes out at five seals and three or four o-rings. Plus a gasket, for that front section of the transmission must come off in order to change the intermediate shaft seals. Good thing I ordered early, for our host couldn't source those seals and Porsche is having to go back to the Fatherland for them. Not that many calls for tiptronic parts I suppose.
With the engine out this is surely the time to get at that engine bay with soap and water. My general attitude is that any part made from rubber needs renewal. If it has gone this long without failure, it should be retired with honors. The rear engine mounts have been replaced......but no honors there, as they were both fully collapsed. I have replaced all the oil hoses, both pressure, returns and vent hoses. BTW, those pressure hoses are expensive, because they contain large expensive fittings. In retrospect I could have just replaced rubber sections at a fraction of the costs. The hoses are 22mm ID and 30mm OD. Probably would be a pain to source the hose, but worth it and I have saved the fittings for next time. This is even more true for the oil cooler lines, with their long metal pipe runs.
I replaced the foam sound pad there on the firewall, and the rubber flaps that surround and seal the engine sheetmetal.
I replaced the rear shocks while they are so easy to get at, and will do the same for the front when the engine is back in.
There are three or four fuel hoses there at the firewall, which must be replaced while I can easily do so. Actually, they are just short rubber hose-ends of long metal lines running forward. Same story as the pressure oil lines. These particular hose sections appear to be unusual at 10 mm ID. I have some on order and will try not to forget them in the excitement of engine building. (Just went out and hung tags on them just to be sure).
Can you suggest anything I have missed here in the engine bay.http://forums.pelicanparts.com/uploa...1163521601.jpg
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The oil cooler was sent out for cleaning and pressure testing.
PACIFIC OIL COOLER
Laverne, Calif.
909-593-8400
Fast turnaround and First Rate Service.
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While it was apart for cleaning, I tested
the thermostat in a bath of hot oil. It opened
at 185 F. Seems about right to me.

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Oil tank was also sent to Pacific Oil Cooler, again for
cleaning and pressure testing.

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Correct thing here would have been to fit new
rubber hoses and reuse the fittings and brass pipes.

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While fitting complete new hose assemblies, as I did, would
probably be appropriate and normal practice at a dealership;
here with the DIY advantage of free and unlimited labor, I view
it as a boneheaded and wasteful action, deserving of the
Pelican Dunce-of-the-Month Award. Shame on me!
James

Wow-
You've got a nice, clean car there!
Looking good,

Doug

Wow, such a clean car throughout!!! I look forward to follow this thread!!

The case through-bolts were just cleaned up and the threads
chased out. There appears to have been no plating or coating
used and so I have left them natural; and there doesn’t seem to
be any need to consider replacing them. Are there any issues
here that I am not aware of?

The washers look to be a nice improvement, with that spigot to
extend down a drilling in the case, giving the o-ring just the right
compression, with the shoulder to prevent them going too far.
Old news I suppose – but new to me.

Well yes there is one issue I found that we need to be aware of.

While these washers seem to be an improvement, they are not
without a potential for mismatching them if replacements are
needed.
An early run of 964 engines were built up using a similar washer
but with a shorter spigot (5.8mm vs. 6.3mm). The short washers
are long since out of stock In the event you have one of those
early engines and need a replacement washer, then you should
order the longer version in this photo and dress it down to match
your others.
Porsche Tech. Bulletin 9107 has the details, or you can just
remember to compare any replacement washers you need with
the remaining originals. Or, if your memory is anything like mine,
get out volume one of workshop manual now, go to page 13-25,
and make a note in the margin next to item 23: Two spigot
lengths – check any replacement.


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The chain housings and covers were cleaned and also left
natural. One thing did surprise me when I attempted to back off
the cover nuts – those 19 shouldered studs around the housing
face all came out of the case instead. The manual refers to them
as collar pins and they are to be set into the housing with Loctite
270 and 5 ftlb. Yet the 6mm nyloc nuts all had a higher friction
grip…no exceptions. Does Loctite 270 not set up very well in
magnesium?? Any Loctite experts in the group?

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Porsche used all-metal locking nuts on the normally aspirated 964 so if you're finding Nylocks then someone else has been in there before? What did you use to clean the chain housings and their covers? They look really good!

Make sure you scrape the gasket surfaces with a razor blade or sand them. The magnesium corrodes over time and leaves a pitted surface behind. If you do not samd them true or scrape them chances are that they will be leaking after the re-assembly. Ideally - the scrapping should leave a shiny alluminum-colored surface behind. That allows the rubber gasket to do its job properly.

Cheers,
Ingo

Thanks fellows, great advice.
I send a closer look at one of the covers, for that last photo did
make them look darker than they really are. They actually look
more like aluminum now until they oxidize back to darker grey.
On closer inspection, yes the lock nuts were indeed all-metal,and
I have made a note to source some new ones.
The pitted surface you refer to is certainly present and can be
seen in this photo. I am thinking of taking the studs back out
and sanding the cases on a plate of glass to see whether they
can be brought to a more perfect surface.
Oh, the covers were soaked overnight with paint remover in the
gasket grooves, which did loosen all the stuck in rubber remains.
Then both the covers and the cases were blasted with small-grit
glass beads (oil inlet/outlet holes first covered w/duct tape.)
Finally everything washed with soapy water.
http://forums.pelicanparts.com/uploa...1163692401.jpg

Decided to proceed with sanding the chain case sealing surfaces.
Also did the covers, but they take almost no time at all.

Order of battle here is dry, Norton 220 grit paper on ¾ inch plate
glass surface. Surprising to me how out of level the case
surfaces were. In fact, by the time they were sanded flat, most
of the surface pitting was gone.

Tomorrow I will move on to 400 grit wet-or-dry briefly, then chase
out the threads again and put the studs back.

Thanks again for suggesting it.


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NICE job - it will make sure the chain housings won't leak. They are notorious to do that after rebuilds buts your look awesome now.

You also might want to really carefully smooth out the seating surface of the large O-ring to the cam housing. This is another spot where oil leaks are comon.

Cheers,
Ingo

A question:

Got back an order of parts from Porsche today including
the six bolts I ordered for the knock sensors. They are the
part number from the workshop manual........but the wrong
bolts. So the manual is wrong, or the numbers have changed.
Catch 22. Change every time - but bolts not available.

The manual specifies encapsulated bolts, to be renewed every
time. I presume the reason for encapsulated bolts rather than
the usual loctite 270 is because of the critical need that they
don't loosen, and given the location (one bolt in each head) the
loctite could break down in the heat (it's rated to 300 F, but
seems to give up sooner than that when I heat up studs for
removal).

The bolts that came were encapsulated but were 8x30 rather
than 6x30 as needed. Troy at EBS is checking around.
Do any of you 964 experts know the full story? Sure don't want
to end up with loose mounting bolts setting off false knock
signals and limiting power.

James

Knock Sensor Bolts-
In the end I used loctite on my old bolts. I asked around and everyone else said they had done the same thing.
I think someone else tried to source the bolts through pelican and were told they were no longer available.

Nice rebuild so far!

I cant believe how clean and new everything on your car looks.
Everything looks like new. Cars in the desert sure don't age.


Kirk

This is Las Vegas Kirk...........we use smoke and mirrors.

CAMSHAFT HOUSING SERVICE
In the Redkneck tradition

Clean the baked-on grime with M.E.K. or with lacquer thinner.

Remove the studs and have a go at the sealing surfaces using
the same sandpaper-on-glass-plate approach as with the chain
cases. Slower going on the aluminum compared to the
magnesium. Goal is a truly flat surface without removing more
than needed. Check progress often and not a stroke more than
required!


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Drill 4.8-5 mm hole into oil tube end plugs. Go in 8 mm or so
only – not completely through the plug. Use a bottom tap and
cut 6 mm threads. Fashion a jury-rig of your choosing to pull the
plugs from their bores. Now a soft rifle-bore style brush and
favorite cleaner (I used red-hot), with fresh water flush. Plug one
end with your finger and watch the oil line spray patterns from
the small drillings, as well as checking that the cam drillings are
free and have full flow. Scrub well and blow dry.


Press in new end plugs to just below surface, so no fouling with sealing gaskets later. Chase out all threads and replace studs w/loctite 271. Put in safe place until needed in rebuild.



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There is one open issue regarding the cam-towers-to-head
fasteners.

Porsche Tech. Bulletin 9403 advises the replacement of the
familiar cam-tower studs/nuts with Allen bolts, and doing the
same at the intake manifolds. Because this change to Allen bolts
strikes me as crude and a step backwards, unless otherwise
persuaded I do NOT intend to implement the change. Can
anyone enlighten us on the issue? What was the motivation
behind tech bulletin 9403?


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MICROENCAPSULATED BOLTS….REVISITED

OK Kirk, and anyone else with an interest, I believe we have
peeled away to the bottom on the knock-sensor bolts issue.

First, the encapsulated technology was/is new to me, but here I
think it is in a nutshell. Unlike loctite or other threadlockers
(which are anaerobic in their action), the microencapsulated bolts
are a two-part epoxy product, using tiny (.001 in.) capsules to
isolate one component and prevent catalytic action until the
fastener is tightened. Then the threads crush the capsules and
activate the epoxy, which then seals and locks the threads.

The confusion we have been faced with, regarding the knock-
sensor bolts, appears to be the result of a single typo in the
Porsche Workshop Manual. Go now to Volume One, page 15-19.
Under the “Installing” heading find (M 6 x 30) and correct it to
read (M 8 x 30).

The reference to “microencapsulated” and “always replace”
should correctly refer only to the single bolt which attaches the
sensor to the bridge. Those 6 x 30 bolts attaching the bridge to
the heads never were microencapsulated in the first instance.

James

The correct part number is #900-074-015-02 and it shows up in the November price list so they are still available.

Based on the date this changeover occurred (February 1993) and the decision to use caphead screws inplace of studs everywhere else on the 993 I'm guessing the reason was to reduce the number of steps in the manufacturing process and to have a reduction in the number of required parts? Instead of a stud and a nut all you need is one cap head bolt which involves one less operation during assembly saving time & money.

Thanks Jason,
And see the post just above your own. The confusion
was whether the three 6 x 30 bolts from knock sensor to heads
should be micro encapsulated. Answer is no - they never were.

I expect you are correct about the Allen bolts. That is what I
also suspected........and why I will stick with the studs/nuts, which
I consider to be a better fastening in this application.

Cleaning the engine case now and that work inevitably leads one
to the piston squirters. Here the sections of ¼ fuel hose are
blocking the through-bolt passage, and allowing pressure to be
directed on the squirters through the bearing oil feeds.

I have been at them long enough now that further cleaning isn’t
going to change the situation. They required a lot of air pressure
to open, especially at the start. Now they all send forth a nice full
spray with each tiny thimble-full of solvent, which can be filled
into the lines. I have done the exercise over and over……and
over again.

At this point I find that the squirters open and send a nice spray
at between 45 and 50 PSI, measured right there at the air blow-
gun nose. Below that pressure they just dribble. This is a
greater pressure than I expected, but this is my first time with
them. Anyone have a spec. for them? I haven’t found one. I
thought they were only going to protect idle oil pressure at, say
30 PSI or so, and am wondering whether I should change them
all???





http://forums.pelicanparts.com/uploa...1164221923.jpg

I believe the oil squirters are not supposed to open until they are around the level you noted. So don't worry :)

Good luck and enjoy the rebuild!

Thanks Chris,
That is certainly what I was hoping to hear. They must be
simple spring/ball valves.

Outstanding work, thanks for sharing. It looks like you have done this a time or two before.
I appreciate you taking the time and effort to allow me to learn from your experience.
Art

MICROENCAPSULATED BOLTS….REVISITED

Ahh thats what they meant.
I never removed mine from the knock sensor. So I guess I am safe on that one.

Kirk

CHECKING THE MAIN BEARING BORES

Assemble the case on the stand, including through bolts/nuts and
those 8 mm nuts surrounding the bearing bores at each end.
Nuts taken up but still slack.

Use the rubber mallet to persuade the case into as nearly perfect
alignment as possible. Take diagonal measurements and keep
adjusting with the mallet until differential is less than one
thousands of an inch.

Tighten the through bolts/nuts and 8 mm nuts to final torque
values. Check the case alignment didn’t change.

Break out the bore gauge, and discover it is too big for the job.
Switch to an internal micrometer supported by a good strong
magnet and check the bores. New spec. is 65.00 mm and wear
limit is only 0.019 mm (less than a thou. of an inch.). Converted
to inches, for my micrometer, the spec. is 2.559 inches and a
wear limit only out to 2.560.



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Use the internal micrometer as a go/no-go gauge. Set first at
2.559 and insure it will fit every bearing bore. Then go to 2.260
and insure that it will not.

Don’t know that the exercise is really necessary, where there
were no shiny spots on the saddles or other evidence of bearing
movement. Without checking there is always doubt though, so
worth it for peace of mind.


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ENGINE PARTS ARE BACK – RECONDITIONED

The crank remains standard, but has been mag-tested and
polished

The cam shafts were reground – Dougherty Racing Cams – to
standard 964 profile with lift set at 1.26 mm

Heads reconditioned and surfaced for the later style 964
cylinders – with sealing rings.

Rods reconditioned – new wrist bushings. Rockers were OK
except one – which was replaced – others reconditioned.

All machine work is beautifully executed and a joy to gaze at.
Thanks Henry!

SUPERTEC PERFORMANCE
FALLBROOK, CA
760 728 3062
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While using the dial bore gage it is advisible to leave the nose beraing in place for porper alignment, unless you are shaving the case it is much more cost effective to align bore the Thrust through no. 7 the nose brg. is terribly expensive and not that important to the task at hand.


regards

Thanks for that tip. It would have certainly made alignment easier, and I will make a note to that effect in my manual for next time.

This is the starboard (4-5-6) side cam housing, after the same
treatment the port side got, with one twist. That threaded hole
at the upper right had a broken-off nut/stud (?) complete with
embedded, hardened-steel removal tool, also broken off flush.

Question for you experienced 946 experts: Can anyone
remember what that fastener was used for?? I expect it was a
hex bolt, and probably fastened a hose or wire harness strap. It
was already busted when I came along, so can only guess. The
location is above number six and that bracket, in place for
reference, is the support for P/S pump.

Tower went over to California for electrical discharge treatment;
excellent service at very reasonable price, and with lightning fast
turn-around. Highest recommendation for:

JERRY’S BROKEN TAP
SANTA ANA, CA
714 836 6824



http://forums.pelicanparts.com/uploa...1165010996.jpg

On my non-powersteering RSA that nut holds the black plastic heat shield (PET calls it a duct) to the engine and nothing else. I have some closeup photos (if you need them) of that bolt on the other side (1-2-3) but nothing of the right side (4-5-6) bolt.

Thanks Jason,
That is probably the case on this engine also. I didn't notice
any hose or elect. wire clamp in the area that wasn't fastened.

BTW Jason, I notice that you call it a nut on the 4-5-6 side and
a bolt on the 1-2-3 side. Is that correct? Accepting that probably
it did nothing other than fasten that corner of the shroud, was
it a 6 mm hex bolt or was it a stud/nut combination?

HOPE SPRINGS ETERNAL……..

No effort is being made in this rebuild to increase power output
or to make the engine more able to sustain high rpm’s. The
simple goal is a sweet running engine WITHOUT oil leaks; clean
surfaces and no smell of burnt oil after a run.

The cam tower sealing surfaces have already been brought to as
flat, true and smooth condition as I am able to achieve. Now the
valve covers receive the same treatment. The two exhaust
covers are new, and are of an aluminum alloy as used on the
later 964 engines I am informed– though I cannot confirm from
the PET whether this is correct information. The hope is that they
will be less likely to distort/leak than the original magnesium
covers.

All outside surfaces, along with the air-guides have been powder
coated in an aluminum shade. Those plastic, wire clips were
moved over from the original covers. Do this change, and you will
find that the new aluminum covers already have the screw holes
in them, but they are not threaded. Those original screws are
stainless and can be reused, but I found it best to shorten them
by about 2 mm, as the new cover holes are not so deep. Also,
the threads on those screws are wider than anything in my
metric tap set; more like sheet metal threads. I found that a SAE
10-24 thread is nearly a perfect match. Set in with Loctite 243
(blue).

Don’t know anything else to try so now is time to hope, and hope
springs eternal!


http://forums.pelicanparts.com/uploa...1165091241.jpg

Sorry about that, it was me being sloppy at 2am. The fastener is an M6 x 16 bolt and I believe stainless steel.

Thanks for the information Jason

I just "finished" reconditioning my stock '90 covers and I envy your results. The paint/coating on the covers was very hard to remove, I did a lot of dental pick on the areas that my paint stripper/glass beading process did not clean. I chose to paint the outside in black ala the 993 covers, and left the insides raw magnesium. I spent _far_ too much time on this, and I am still not happy with the results!

Time to record the weights and decide which rod goes where. I
expected these rods to be right on, and they are. The bores are
as perfect as I can measure them and the weights vary only
about a gram.
http://forums.pelicanparts.com/uploa...1165271130.jpg
This is how I plan to put them in. They are so close it doesn’t
matter much, but it is interesting to note that this is not how they
went in from new.
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The crank measured near perfect too, as expected. The
measuring seems unnecessary really - worth the effort though,
for this part is fun, provided the time clock is not an issue. And it
provides calm assurance that all is well……….so far.

http://forums.pelicanparts.com/uploa...1165271328.jpg
I just used number one and eight bearings here to check for run-
out. Too little for me to measure on the dial gauge, though I
could just detect the needle wiggle. Would love to start building
it up now, but we are going to Berlin in the morning for a Holiday
visit with family there. So the project is on hold for a while.
http://forums.pelicanparts.com/uploa...1165271432.jpg

Enjoy your holiday.
I'm looking forward to seeing the project continue when you get back.

Kirk

Back in Nevada again and time to get on with the project. The
crank is a natural place to start. I cleaned it as well as I am able,
including flushing out all the oil passages with brake cleaner and
compressed air.
http://forums.pelicanparts.com/uploa...1166312304.jpg

Here the individual rod bolts are measured, to serve as a point of
reference when next the engine is apart. While I like to keep
things mostly stock and standard, I have deviated in this case,
and with a few other items. These are ARP, aftermarket rod bolts
in 9 mm, Part # 204-6005. The instructions do include a torque
value but the recommended installation is by controlled stretch of
the bolts to a value of 0.012 inch. A dial gauge is available for
stretch and I did use it, but that requires that the tightening be
done with a closed end wrench. The nuts are 12 point and nice,
BUT they are only 11 mm and we are up around 40 foot pounds
to reach the 12 thousands stretch. Therefore, I did find these
preliminary rod length measurements to be useful in the initial
setup. Several of the rod nuts were just much easier to tighten
with a socket, while checking often to bring them to the 0.012
stretch lengths.
http://forums.pelicanparts.com/uploa...1166312464.jpg

Lay out what will be needed, and get started. These twelve
fasteners are arguably the most important ones in the engine. I
moved slowly and deliberately to try and get the right rod on the
right journal, the right way around, and the rods all at exactly
twelve thousands stretch.
But what is wrong with this picture? Not to worry, the APR bolts
were put into the caps correctly - not as seen here.
http://forums.pelicanparts.com/uploa...1166312552.jpg

This was a fun day. I feel good about the completed crank/rods,
and I am still glad that I decided to use the ARP hardware.

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