Porsche 911 External Thermostat

Porsche 911 Oil Cooling System Teardown

The next mechanical system to fall to my Rage Against the Greasy Machine was the external oil cooling system.

The goal was to remove the entire thing. This way I could clean everything underneath it, rebuild the external thermostat, clean the oil tank, and maybe upgrade my cooler. But most importantly I needed to make sure no existing garbage in the lines would run through my fresh engine’s oiling system.

I started at the rear near the oil tank. This oil tank hose looks easy to get to…

Porsche 911 Oil Tank Hose

…this external thermostat does not!

Porsche 911 External Thermostat

This prompted me to drop the hard lines assembled with the thermostat so I could disassemble everything outside of the car with lots of room.

This tank hose came off.

Porsche 911 Oil Tank Hose

All the hard line mounting brackets came off next. This one in the rear wheel well plus all the ones under the passenger rocker.

Porsche 911 Oil Cooler Lines

This left the rear oil lines hanging as shown.

Porsche 911 Oil Cooler Lines

The trombone oil cooler kind of hung up inside the front wheel well.

Porsche 911 Oil Cooler Lines

The external thermostat also got hung up in rear wheel well.

Its all kind of hung up because its a rigid assembly and you cant flex anything out of the way. There was no easy way to finagle it out.

Porsche 911 Oil Cooler Lines

In the end I disconnected my sad trombone and the lines all came out easily afterwards.

Porsche 911 Oil Cooler Lines

I disconnected all the mounting hardware and extra stuff on the engine compartment side of the oil tank and it came out.

Porsche 911 Oil Tank

Look how much oil was still in the lines and trombone after I removed them. I ruined the shoes I was wearing at the time with a nice big splash of old oil.

Porsche 911 Oil Cooler Lines

Lets see how successful we are at removing these lines on the floor. PB blaster left to soak in the threads over several days + heat + patience was the name of the game.

Porsche 911 External Thermostat

I only managed to get one off on the floor. Off to the vise we went. You cant tell in this photo but the remaining hard line was dangling off to the right and sitting on another table. It was a bit difficult to maneuver it in my limited space but it worked out.

Porsche 911 External Thermostat

More PB blaster + more heat + more patience.

Porsche 911 External Thermostat

::Liberty bell clanging::

Porsche 911 External Thermostat

I haven’t had much seat time in these cars to know, but apparently the trombone oil cooler does a poor job of keeping the engine oil cool in a perpetually warm climate such as Southern California.

Porsche 911 Trombone Oil Cooler

So I went ahead and bought this one. A European-market 28-tube brass cooler that I think was used for 1-2 years tops after the trombone cooler and before the Carrera cooler with the fan.

Porsche 911 Brass Tube Oil Cooler

This thing is an absolute unit. It is heavily built and looks like it should have no problem holding up in the harsh environment of the front right wheel well.

Porsche 911 Brass Tube Oil Cooler

I chose this unit because apparently they are great at slow speed and in traffic. Since I sit in a ton of traffic and the entire city of LA sits between me and the canyons, I decided I would give it a shot. I could always upgrade to the Carrera one down the line if this one was not up to the task.

Then I took apart my external thermostat.

Porsche 911 External Thermostat

I tried making several tools to engage the slot in the caps and loosen them. All of them failed. I then went to the tried-and-true pipe wrench on the cap OD and carefully tap-tap-tapped them both off with a rubber mallet. I left pipe wrench marks on the caps but thats ok because I will be replacing the caps with something much nicer.

Porsche 911 External Thermostat
Porsche 911 External Thermostat

This is where I reminded myself how lucky I am to live in the climate that I do. These threaded connections were all stuck due to old age but there was no corrosion due to road salt or harsh winter climates. No threads were damaged anywhere.

Then I stripped my oil tank to evaluate it.

Porsche 911 Oil Tank

I found this poor abandoned oil level sender inside.

Porsche 911 Oil Level Sender

Its living conditions were unbelievable.

Porsche 911 Oil Tank

I was planning on DIY cleaning this thing but after seeing the inside and learning that there are screens and other features in there that would make cleaning very difficult I decided to leave it to the pros. I dropped off both the cooler and tank at Pacific Oil Coolers, the same place that refurbished my engine oil cooler a while back.

I got to work scrubbing everything else clean with Purple Power degreaser and a garden hose.

Next time Ill cover putting this oil cooling system back together.

Please share with fellow enthusiasts.