911 oil cooler

[davm]

I have a 77 911S which is overheating. It will not start or will shut down when the oil. temp reaches 210 +. It currently has a trombone "cooler"which I would like to replace with an oil cooler. I have a couple of coolers from an Aston Martin which resemble a Mocal unit, just slightly smaller. Any ideas on obtaining the proper fittings to make this work. What kind of fitting goes on the oil lines once I cut out the trombone? I have also ordered an 11 fin alternator fan to replace the 5 fin. I have also replaced the fuel accumulator. Anybody have any suggestions. Also, my home is in Colorado at 9000 feet. Thanks in advance!!

[Flieger]

Welcome, nice car.

Your altitude does make air-cooling harder. Fans/wings are less efficient and more prone to stall. Heat dissipation from an oil cooler is also harder.

I cannot comment on your AM oil coolers but any radiator style up front will be better. The 11 blade fan will also make a good increase in airflow.

Not starting or stalling at 210 F oil temps is unusual. That sounds like a fuel issue to me- vapor lock? 210 degrees F oil temperature is considered the target by many on this board. Hot enough to boil out water but not too hot to cook the oil. I have trouble getting the oil over 180 F.

Best of luck.

[RoninLB]

CIS is very altitude forgiving compared to carbs but there are other things that can be done for cooling and performance as long as you stay up there

if me i'd get a 930 fender cooler with a fan attached or an Elephant Racing cooler unit that's triggered by a switch in the cabin

the trombone unfastens and the 930 fits up on same couplings
save the trombone


also nice big watt headlights hooked up to relays with non-DOT lens either Bosch or Cibie work great in the Rockies

the pelican search function is your friend

[RoninLB]

Originally Posted by Flieger

Welcome, nice car.



Not starting or stalling at 210 F oil temps is unusual.

just my take
Oil temp is ofter a reflection of CHT on some original stock cars. Altitude is a headache enough starting a warmed up engine and in general cooler is better, to an extent, for starting in lean air

if my car i'd install a single CHT gauge to either #2 or #4 cylinder because even with a good cooler long climbs can rise CHT. If gauge starts to read high you can modify driving before oil heats up. Once oil heats up it's a pia to bring down.

I've spent weeks camping in Rocky forests in this car with original CIS and carbs, with the trombone and with a good fender cooler

[LakeCleElum]

Hard starting could be a bad check-valve in your fuel pump.....Let's fuel flow in after engine is shut off.......

[BoxsterGT]

Your factory lines use M30x1.5 fittings.

Adapters can be found for BSP threads. The only one I found after a quick look was BSP G 3/4" x M30x1.5 and this is likely too large for your Aston Martin cooler.

Why not sell them to a British car collector and use the factory 87-89 911 Carrera cooler w fan like has been suggested? It bolts up without hassle and works the best.

Good idea for a CHT gauge to watch your motor. The long grades really puts a strain on an aleady marginal engine (sorry but unless its a totally fresh 2.7 w an 11 blade fan its marginal). The operating temp of an air cooled motor varies greatly (180-230F) depending on load. If you still have "Thermal Reactors" you are cooking your motor even more.

The best fellow to talk to is Grady Clay. Perhaps he will chime in. Theres no-one who knows Porsches & the Rockies like he does.

Just my 02 cents.

Len

[davm]

Thanks for the quick response!! I may want to back up a little on the oil cooler. Over the winter I replaced the fuel pump(new Bosch) and last summer the fuel accum. When I first installed the fuel acc. I could hear the fuel returning to the fuel tank, but now I cant hear it at all. Could the acccumulator have gone bad or should I consider the possibility that the new fuel pump is defective? What about sediment in the fuel tank itself? This is my first Porsche, and I purchased it a little over a year ago. When the vapor lock problem first appeared I replaced The fuel acc. And that seemed to take care of the problem, but it seemed to return after the fuel pump replacement. Making any sense? I will still address the the oil cooler and get the 11 fin fan, but am wondering if the problem may be fuel related!! Thanks again, great info. Dave

[Walter_Middie]

Hard starting could be a bad check-valve in your fuel pump.

When you replaced the fuel pump, did you get one with the check-valve? Or do you have an external check-valve?

As mentioned above, 210 deg is not that bad - mine used to run up to 260 or more when driven hard. I've never had an issue with hard starting. Many Mid Years have run just fine with the trombone cooler - the 11 blade fan is a good upgrade.

[Grady Clay]

Dave,
Welcome to the Forum
You will find a lot of help here.

Very nice coupe. The (16”?) Fuchs are great.

Oil temperature of 210F is just fine. I suspect it is higher. It is worthwhile to calibrate your gauge. The gauge senses the temperature at the coldest oil temperature in the system. Using a Type-K thermocouple under the temperature sender is best but there many other ways.



I’m sure you have heard of all the details concerning the ’77 model year (and a few other) 2.7. I’ll review the basics for posterity.

In the name of USA (and California and other) emissions reduction, these were almost ‘cooked-to-death’. They had thermal reactors in the exhaust, 5-blade fans and not standard with any front cooler. A lot has been learned since these were new.

If not already modified, replace the exhaust with the ’74 and earlier version. Your nice SS ’77 muffler will bolt right on (with a slight mod to the EGR port).

You can fit the 11-blade engine fan from a Turbo or ’80-> 911SC. You already have the larger 134 mm crankshaft pulley and you want the 11-blade, 245 mm fan with the 80-83 mm pulley. This is critical as it pumps a lot more of our already thin air through the engine. This cools the important parts – heads and cylinders. Oil temperatures will follow.

The engine oil still needs additional cooling. The front oil cooler system you have is from the ’74 through ’89 models is a ‘bolt-on’ addition and may be the cooler system available in 1977 as a special order on your car.

The ‘big improvement’ available is the ‘full-fin’ cooler and electric fan from the ’87-’89 911 Carrera. Wire the fan so it is switch controlled from the cockpit. There are also great aftermarket full-fin coolers available (Elephant Racing is among the best with proper brackets and fittings.)

It is also worth searching Pelican for the “Rubbermaid Solution” and my name. While not an ‘all-the-time’ solution, it is of great benefit at track events and the long up-hill pulls in the mountains. (Psst … it also makes more power.)


Engine maintenance is high on the list of priorities. If the engine has not been run way too hot and is properly maintained, you can have many years of enjoyment. The issue is the cylinder studs pulling the threads in the crankcase. This allows the heads to loosen and leads to head gasket failure. The symptoms are usually an unusual noise when cold and under power. A 2.7 rebuilt correctly addressing the issues is a very nice and long-lived engine.

Your ’77 fuel pump should be on the front suspension cross member – that is good. It is possible to relocate the fuel accumulator there also. You should insulate the fuel pipes and hoses between the rear end of the tunnel and the CIS. That is a very hot area where the waste heater air is exhauster when the heaters are off.

There is also the technique of letting the fuel pump run a few seconds prior to cranking. This purges vapor bubbles in much (but not all of) the CIS system.

Hopefully some PO has installed a ‘pop-off’ valve in your CIS air box. This prevents an expensive repair when an intake backfire occurs – usually on starting.

There is a screen filter in the bottom of the fuel tank. It is part of normal maintenance (every few years) to clean the screen.

Again WELCOME.


Where in the Mountains are you?
There are Pelicans and RMR/AMR-PCA members all over. It is worthwhile joining or just participating in PCA events. Lots of fun and good people – many great Porsches too.

Best,
Grady

[davm]

Hey Grady, I am in Coal Creek Canyon, west of Boulder and would be really interested in some local clubs. Not sure if my new Bosch fuel pump has an internal check valve, trying to get that info. This was a Cali car , same family for over 30 years. Sat in a local garage for 5 years. Maybe flush the fuel tank? All ideas welcome. Thanks, Dave

[Walt Fricke]

Dave

Call me at 303 499 6540 (884-1369 cell if I am out and about) and drive down to see me in the south end of Boulder.

I'm futzing with my disassembled transmission, and doping out some issues with the brakes on my track car this weekend. I can show you two ways of dealing with vapor lock (if that is the cause of your hard starting when hot).

The local club is the Rocky Mountain Region of the PCA (see their website). It has a monthly social evening meeting coming up this Thursday, I believe. There is also a local Porsche Breakfast Club which does social things and tours (Google might turn something up), and from time to time some of those who frequent Pelican's site have get togethers.

My Euro '77 did fine with the trombone loop here until I got bitten by the race track bug, at which point more cooling was essential.

Walt

[Jim Richards]

Originally Posted by Grady Clay

snipped...

You can fit the 11-blade engine fan from a Turbo or ’80-> 911SC. You already have the larger 134 mm crankshaft pulley and you want the 11-blade, 245 mm fan with the 80-83 mm pulley. This is critical as it pumps a lot more of our already thin air through the engine. This cools the important parts – heads and cylinders. Oil temperatures will follow.

snipped...

Best,
Grady

I believe I have one of these fan blades/pulleys. I never got around to making this mod on my 73E and I'll cut these parts loose.

[davm]

Jim, I would definately be interested in your 11 blade fan. Give me a call at 303 883 0504 days. I met walt today in Boulder and got quite a bit of info, and some local contacts. Plan on troubeshooting the fuel issue first, and than the fan and the oil cooler. Will update on the results. Thanks again for all the info. Dave

[Jim Richards]

Hi Dave,

I left you a voicemail message.

[SpeedracerIndy]

Nice looking mid year Dave!

Dang, you guys are making me want to move to Colorado just for the level of Porsche support you offer to locals!!! I never get that kind of reception around these parts. If I had an American muscle car I think it would be a different story around my parts.