SWB Oil cooling

[304065]

OK, this is too hot for me.



Now, the SWB cars have a fan shroud that does NOT include a channel to the oil cooler. Many people have reported a significant, like 20 degree, drop in oil temperature from updating to this later model shroud, which isn't concours, but neither is a seized engine. At the Parade swap meet, I picked up a green 911E shroud which I'll clean up and paint black (to resemble the stock shroud).

I am also concerned that the oil cooler might be externally obstructed, or internally sludged. Can this be removed and cleaned without an engine drop? Anyone BTDT?

Can I switch to the turbo fan merely by adding the outer pulley half? Or do I need to buy a new turbo fan?

Are the finned oil lines effective?

Ultimately, on the big restoration I'll install oil lines through the rockers like an early "S" and will put double 911R-style coolers up front. But for now, any advice as to bringing temps down would be appreciated.

[Grady Clay]

John,

Install the entire turbo fan set-up to get the 1.82:1 ratio. That will take the fan, pulley parts, crank pulley and belt. You will need to trim the engine mount so you can remove the mount without removing the crank pulley first. You won’t believe the improvement. You probably won’t need anything else although you can easily fit the later fan shroud with the duct to the cooler. (If you do, don’t forget the vanes on the back of the alternator.)

For track use there is no substitute for the “Rubbermaid Solution.” That makes power AND keeps the oil cool.

Best,
Grady

[304065]

Grady,

Thanks for the quick reply. Looks like I need:

930 106 012 00 Fan (shown NLA, but I bet I can find one)
930 106 564 00 Shims (six of them, current one is 901 105 561 00 and might be different size)
930 106 209 02 Outer pulley half
930 102 126 01 Crank Pulley

Stuff I probably don't need:

901 603 428 00 Tensioning cap (probably not with Bosch Alt)
901 603 905 00 Nut M16x1 - not used with Bosch Alt which is M14 x 1.5
999 093 005 02 Bolt M12 x 1.5 x 22 (same part # as '66)
900 028 014 01 Spring Washer (same part # as '66)

And to top it off, a 9.5x725 belt.

It's time to start looking for the fan, that will be the big item.

[bob tilton]

john,
ck out this older post:
Lowered temps with Updated Shroud ('67)

or this one:
http://d240157.u39.zeonhost.com/forum/showthread.php?t=6812

[304065]

Bob,

Thanks, I had seen both of those and was intending to compliment your work. . .very nice!

[304065]

Ok, the fan looks to be the same part number as any 11-blade 76-77 (78-79 used a smaller 226mm fan), 80-83 SC, 84-89 Carrera. That's a plus.

Also, some have recommended the use of a 730 or larger belt.

[304065]

Here's a good one:

Engine Temps and Summer DEs

[Grady Clay]

John,

Don’t use a longer fan belt. You want the pulley diameter at the
fan to be as small as possible (lots of shims), just shy of the belt
touching the shims. This maximizes the ratio. If you use a
longer belt then you must remove shims from between the pulley
halves and this effectively makes the pulley larger and lowers
the ratio. This defeats the whole purpose.
IMAGE FanRatio02.jpg
“
"
© Dr. Ing. h.c. F. Porsche A.G.



Talking about clearing the engine mount; I don’t remember if the
non-A/C pulley will fit the very early engine mount on your ‘66.
In the below image there are at least one intermediate mount
prior to the “Old Mount” and after yours. It may turn out that
you need to use this “Old Mount” or the one just prior. The one
just prior is the same but doesn’t have the cut-outs (red arrows)
to clear the large pulley. If you use the one just prior, you will
need to grind the clearance. I’m pretty sure that the “Old
Mount” or the one just prior will fit your engine just fine.

This image shows the change for the ’84 Carrera where they
moved the stud in the casting (purple arrow).

IMAGE EngineMount911a.jpg
“
"
© Dr. Ing. h.c. F. Porsche A.G.



The two issues are that you should be able to remove or install
the mount with the pulley in place and that you can get the fan
belt off or on the pulley with the mount in place.



Best,
Grady

[304065]

Hey, Grady, thanks! It's always good to have a sense of what I'm up against.

I have a few machinist friends who could help with turning the pulley down if need arises. This past weekend I saw a number of crank pulleys that cleared the fan shroud by mere milimeters. Here was a good example.



And this guy had an immaculate '67S with many factory mods, I KNOW you know him. . .

[Grady Clay]

OK John, I give up. All of us have aged so much…. Last summer I stood next to one of my former mechanics for quite some time without recognizing each other.

The 911 isn’t going to win many concourse d’elegance trophy points from me with that buggered up fan pulley outer half

Best,
Grady

[304065]

Grady,

That's Chuck Stoddard. I wanted to meet the fellow whose name was on the boxes being delivered to my house. . .

Would THIS win any points?



Alois and Estonia Ruf's 901, #37 off the line. Sorry about the sun.

[Grady Clay]

John,

Interesting the #37 doesn’t have the “911” on the dash or the
butterfly horn ring.

I thought that might be Chuck – the lips.
Here we are 30 years ago - yellow & brown.
Complete with pocket protectors.


And me last fall with Pelican Kurt V's 911


Best,
Grady

[Fred999]

I had posted previously about reducing my oil temps with the shroud upgrade and the pulley change as I had been experiencing 210F+. Since then I have had to return my pulley back to 110mm (original) vs the 120mm one. Reason is that I couldn't get my oil temps up enough - maybe 140-155F max (on hot 80F+ days). Now, with just the updated shroud with the duct (old T shroud), my temps maxed out at 175F the other day with spirited driving (ambient of only 65F). When it gets warmer down here I am sure I will get to 185F-195F max, but probably not much more. The shroud really made the difference. Thing is, you can always change things back if you ever need it to look totally original.

This is a shot of my car on a drive the other day.

[Grady Clay]

Fred,

I suspect there is another reason for your cool oil temperature (140-155F) on an 80F+ day with the 1.82:1 fan ratio. First I would want to carefully calibrate the temperature gauge. You can do that by removing the sender from the engine and putting it in a nearby pan of boiling water (212F at sea level). Remember to connect a ground to the sender also. You can leave the gauge in the dash just don’t start the engine!

Remember to reinstall the oil temperature sending unit.
Remember to reinstall the oil temperature sending unit.


Once you know the exact calibration of the gauge, you can do an experiment. Remove the tin cover from above the oil cooler and place a shop towel over most of the cooling fins of the oil cooler. Replace the cover and test drive. If the temperature rises significantly (to say 210F) I would suspect the engine oil thermostat is stuck in the open position forcing all the oil to pass through the cooler all the time.

Remember to remove the towel from the cooler.
Remember to remove the towel from the cooler.
Remember to remove the towel from the cooler.

My reasoning is that the thermostat should regulate the oil temperature close to 180F. This is the way it works when the ambient is -10F, a much more severe situation than using the 1.82:1 fan ratio on an 80F+ day.

Nice 911S, great 4 ½ X 15 Fuchs.

Best mate,
Grady

[Fred999]

Grady,
temp gauge calibrated - actually got a new sender and took it and the gauge to be calibrated by VDO servicers here.
Oil thermostat could be a culprit - when I was running hi temps we adjusted the thermostat to open very early. Although we adjusted the thermostat later, I am not sure how well its working since its 37 years old. Getting the thermostat to open at just the right temp is a little tricky too given that its fully adjustable. I might plonk down and get a new one one day but they are not too cheap.
But, truthfully, changing the shroud was an easy 30F change with my engine. The original shroud let virtually no air to the cooler. One way I could tell this was when I revved the engine up but not under any significant load it wouldn't have any impact in lowering the temp. Now, when I do the same, the response is within minutes (ie from 175 to 160F in a few minutes).
thanks for you suggestion in testing the thermostat.

Fred

[Jim Richards]

Will the Turbo or late SC fan fit onto an early alternator (shaft size, woodruff key size, and fore/aft position, etc? I'm interested in knowing if it just bolts up without drama.

Grady, I'm just about finished with the engine reassembly, but I'm still using the stock setup. I will upgrade the fan/pulley setup sometime this summer. Hopefully, before my car sees the track.

John, I hope my questions are relevant to your situation; otherwise, I apologize for hijacking your thread!

[304065]

Jim, no hijack at all.

To try and answer the question, I can do it backwards. When I installed a Carrera alternator into my early car, the fan fit with no problems whatsoever, which tells me that the shaft diameter and woodruff key slot are the same, at least between the Carrera and the motorola/marchal alternator. I suppose before I plunk down the cash for a new fan I could pull the fan from the 911E and see if it fits on the Bosch alternator shaft, but I suspect it does.

[Jim Richards]

Thanks John. I was a bit nervous about buying (more) parts that don't quite fit.

[Grady Clay]

Jim,

I hope you get the fan on asap, you want to keep those nice new P&Cs and heads cool. Just remember that the oil temperature is way downstream from the source of the heat. Did you get a front cooler?

The issue of the fan is simple – the Turbo fan (245 mm) fits everything except the small (226 mm) diameter SC fan housing. The problem is when you replace that fan housing in order to use the standard diameter fan. The depth where the alternator seats changed many times to accommodate the larger and larger ampere capacity alternators. I think the earliest like John’s ’66 are less than 50 Amps. The latest is possibly 115 Amps and required the fan with the cooling slots. All of that increase necessitated having a longer alternator since the position of the fan was set as was the diameter. This required the seat surface in the fan housing (alternator housing) to be progressively moved toward the flywheel.

John and Jim only need the fan, crank pulley and the associated shims, pulley half and belt. I’ll be interested to see the crank pulley fit on Jim’s earliest engine mount. Fred, did you change mounts? Your '67 should be the same as John's '66.

When changing the fan shroud to the version with the duct to the engine oil cooler, remember to also install the finned duct that mounts on the flywheel end of the alternator. When the additional air is ducted to the cooler it upsets the L-R balance of the air flow. The finned duct was Porsche’s solution. You remove the small fins inside the fan shroud.

Remember that when you duct more air to the engine cooler it lets the oil run at a lower temperature but leaves less cooling air for the cylinders and heads – the hottest and most critical parts.

Fred, see if you can just borrow a known good engine thermostat for a test. I agree it is difficult to set the adjustable thermostat from the early 911s like yours and John’s.

Best,
Grady

One of my projects this fall is to buy some good data acquisition instrumentation and quantify all this. Too much is from my memory and dyno experiments 35-15 years ago.
G

[Jim Richards]

Great info Grady. I have a fender mounted cooler; however my battery box impedes the airflow. I am considering an RS bumper and cooler up front. That's still iffy, though.

I was thinking a right side heater block off plate might improve the volume of air that's available to cool the cylinders. Don't know if that's effective. I guess this comment applies to John, too.