Is the air shroud still connected to the alternator?

You can see it through the fan blades behind the alternator. it is a grey shaped cone with bent metal fanblades on it. it is bolted to the back of the alternator.

It directs air from the fan to the air shroud catch that sits atop the oilcooler that itself sits roughly between gearbox and engine on the right hand side.

What sometimes happens is that the cone is forgotten during installation of the alternator or that the cone is broken at the attaching points. Very annoying.
The cone attachment to the alternator was installed at the factory by a trained midget-monkey with hands made of translucent rubber.

Michel

There are two VERY important upgrades to your oil system that need to be done on a 78. They will cure the exact problem you are having.

You can screw around with the fan all you want. Until you update the oil system, you're going to have an issue. I did a search and here are some snippets..:

You are looking for the "bowler" style update, along with the pressure relief valve and spring setup. Typical upgrade on the early SC. The new screen type retains oil on hard turns and prevents the engine from being starved of oil which is cooling the engine among other things.

Here is an old thread from Mark Salvetti:

Regarding the oil screen and relief valve updates:

On my 1979 SC, the oil drain plug was originally at the rear (fan) and of the sump plate, in line with the case seam. When I installed the updated screen, there was no way to put the drain plug back
in that location, as the updated screen is different. I ended up with the
drain plug rotated 90 degrees towards the left side of the car. So I think
it's safe to say that if your drain plug is where mine originally was, you
can't have the updated screen. However, if your drain plug is already
rotated to the left side, that's no guarantee that you have the new screen.

The old screen looked like a bowler hat. The brim of the hat is the flange
that allows the screen to bolt to the case. The rest of the screen is all
wire mesh, with a hole to allow the oil pump pickup through. The updated
screen (PN 930.107.314.00) is similar, except the wire mesh part is only
around the perimeter of the flange. The top of the "hat" is now solid
metal, again with a hole
to allow the oil pump pickup through. The top is also concave, which is
why the drain plug won't fit in the same place. There is a large dimple in
the plate for the plug, but it's offset to the left. The new screens aren't
cheap, maybe $85. I managed to find a used one, but they seem to be rare.

According to UpFixin Volume VIII, "The 911 Lubrication System" by
A.L.Caldwell, you should be able to tell if you have updated pressure
relief valves by the screw cap you have. The original is round, 25mm in
diameter and has a slot across it for a large screwdriver. The first
update used a 23mm diameter screw head, with a groove machined around its
perimeter near where it contacts the case. My 1979 SC has this type. The
current version of the update uses a screw cap with a raised 17mm hex head
machined onto the 23mm circular base. The update was incorporated at the
factory beginning with SC engine numbers 6282539 (49 state) and 6581060
(Calif.).

BTW, this article also has a photo of the updated sump screen. This is a
reprint of the original article that appeared in the April 1989 Pano.

Hope this helps!

and:

SC's built prior to 1980 model should update;

1 oil screen 930.107.314.00
1 oil pressure relief spring 930.107.531.01
1 guide spring 930.107.533.00
1 screw plug 999.064.016.02


Update:
999.064.016.02 superceded by part # 999.064.026.02.


There are a few more thereads on this out there also.. But that is the nut of it..

My euro delivery SC had a brass row cooler.

Hi all

Update, just got the SC back from the shop, the fan belt was a little loose, but the oil thermostat needed replaced, when we got it out, we noticed the gates were not opening properly so the oil wasn't circulating properly, not only that the car was running probably two quarts low. Anywise, running incredible now, idle issue and temperature operating better than ever.

I just purchased my first 911 SC and it also had a known oil overheating issue when driven hard. The car was 95% restored so I bought it anyway and decided to tackle the project. Under normal conditions the oil temp would remain at about 210, but when driven hard the oil pressure gauge would begin to twitch and act erratically (due to cavitation) and the oil temp would rise to nearly 300!

Here's what I did to troubleshoot (in order) with the problem persisting until the final step:

1) I grabbed the front trombone cooler to check for heat. It was getting hot so the external oil thermostat was OK.

2) I removed the fan to check that the engine oil cooler ramp was free of blockages. It was partially clogged with sludge, so I blasted two cans of degreaser on it and on the cooler itself (from the the top down). During reassembly make sure you properly orient the shroud behind the alternator. Also clean your fan while it's out (sand blast, then powder coat and polish). Unfortunately all of this didn't prevent the overheating (still saw 280 on the oil), but it did improve the looks of my engine bay. Photos below.

3) Assuming it to be the engine oil thermostat, I removed it. On this car there is no need to drop the engine. I did it in 2 hours with an endoscope, a mirror, and a few extensions. First pull the AAR vacuum pipe, the intake air plenum and disconnect the breather hoses from the oil tank to help gain access from the lower right side of the CIS. Pulling the thermostat out of the hole was the hardest part, but since the thermostat is lipped you can use a $10 O-ring gasket removal hook to pop it out. I checked the thermostat using a stove (see photo below) and it was functioning perfectly. Also, replace your gasket with the green one pictured.

4) At this point, with everything properly sorted I was almost resigned to the fact that this was a design flaw and I would never be able to track the car... until I read the TSB mentioned in this thread. The 78 and early 79 models shipped with an improper oil pressure relief valve and a bad sump pickup which caused the sump to flood, improperly scavenge, and cavitate. I replaced the rubbish with these parts, solving the issue:

999-064-026-01-M260 Oil Pressure Relief Cap
930-107-533-01-M100 Oil Pressure Relief Sleeve
930-107-531-01-M260 Oil Pressure Relief Spring (Vertical)
930-107-314-00-M253 Engine Oil Sump Screen
PEL-RW-SP Vintage Aluminum Sump Plate

I can't believe it took me almost a week to figure that out. This is my very first Porsche, and although I have lots of experience building small block Fords this is definitely not the same. I'm glad I have experience, because this thing is an incredible mess of vacuum and oil lines! Elegant engineering though.

Oil cooler air ramp on right
http://forums.pelicanparts.com/uploa...1363641610.jpg

Alternator wiring in case you forgot what goes where
http://forums.pelicanparts.com/uploa...1363642511.jpg

Man, that is NASTY!
http://forums.pelicanparts.com/uploa...1363641665.jpg

Now we're cooking with gas!
http://forums.pelicanparts.com/uploa...1363641717.jpg

The engine oil thermostat is somewhat difficult to remove, but with skill it can be done with no drop, partial or otherwise.
http://forums.pelicanparts.com/uploa...1363641863.jpg

Here it is functioning to spec. Fully open at about 186.
http://forums.pelicanparts.com/uploa...1363641419.jpg

This is what makes all that hard work worthwhile. Very rewarding!
http://forums.pelicanparts.com/uploa...1363642853.jpg