356 Registry: The Maestro's Tax-time Quiz: The Blocked Oil Cooler Mystery! Chapter 1

The Maestro's Blocked Oil Cooler Mystery

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So you think you know Porsches, eh?
Then figure this out!

It was a Customer from the Southland- actually the East Southland, so far from LA that things were almost sane.

The Customer had a 1961 356B Coupe with a beefed-up 356C Engine that overheated when trying to pull the Steepest Grade in North America--from Sea Level to almost 7000 feet in only a handful of miles.
But the poor 356 would always overheat going up the hill, and the guy had to stop three times each time he tried the climb.

So, the Customer wisely brought the car up to the Maestro for a Million Mile Overhaul of both the Engine and the Transmission.

The Maestro fired it up. It started very quickly with 12 Volts on a 6 volt starter.

Then he eyeballed the oil pressure gauge--it was
idling at about 30 psi.

A tad low. He revved it up--the gauge went up nearly to 80 psi.

He let the engine idle again. Oil pressure went back down to 30 psi. That's interesting. With 80 psi at 3000 psi you'd expect 40-50 psi at idle. Not 30. Oh well.

The Maestro drove the 356 around the block to check it out. It was nothing terribly exciting. A little rough. Not a lot of Power. And a really sh*tty gas pedal "feel" that 90.356% of 356's have these days. The Cause?
Underneath the grime, rust and old candy and Trojan wrappers, inside the front Driver's wooden kickboards exists a "Bell crank" that takes your forward motion of the gas pedal, and transforms it over to the cable that operates the carburetors (eventually).

Anyhow, the owner dropped the ailing 365 off at the Maestro's Shop and left for Europe for a month on a business trip. Time for the Power Train Tiger Team to remove the Engine & Transmission for Transformation.

BAM! They were out.

The Maestro took the engine apart, and found not a bad overhaul actually--an increasingly rare event in this day and age.

The engine had an NPR Big bore Kit, with several thin (0.25mm) shims under the Cylinders to lower the compression, a wise move for Longevity.

It had a replacement wide lobe Ro 200.5 cam with several pits in the tops of the lobes. "AHA! That I can beat," thought the Maestro.

And when the Maestro removed the Fan Shroud and eyeballed the Oil Cooler, AHA! There it was--the outside of the cooler was almost completely blocked with dirt and crud--blocking a whole lot of he airflow
both through itself and to the #3 #4 cylinders. (As was shown by the deposits on the underside of the head of the Pistons- the hotter and longer the pistons run, the more crud forms from decomposing oil on the underside of the piston top.)

The 3/4 side had a good coat of brown deposits. The #1/#2 side had almost no deposits, brown or otherwise. Evidence of somewhat hotter conditions on the 3/4 side from the blocked cooler. Q.E.D.

Interesting Thing about oil coolers with a lot of Crud on the outside--they're really heavy, thanks to--Yep--all that crud on the outside, filling up and blocking the air flow passages between the blades.

All that extra weight makes for interesting Oil Cooler
vibration modes too.

But the next day when the Maestro went to clean the cooler in the Safety Kleen tank after letting it soak in the Glup overnight, he got a Big Surprise.

And he got Sprayed too.

No, that's sprayed, wise guy. Not Spayed.

The Safety Kleen tank has a pretty decent solvent pump and a tube to attach to the oil cooler inlet/outlet lines to flush the cooler of anything remaining inside.

When the Maestro stuck the tube to the oil cooler, the pump went to Max Pressure and sprayed solvent out all over. And all over the Maestro.

The Maestro tried again. And got sprayed again.

But nothing came out of the other oil cooler hole!

So he tried the other oil cooler hole. And got sprayed yet again!

He tried everything- but the solvent wouldn't go through the Oil Cooler!

And WHY was that???

Read on, to find out more about the Oil Cooler Mystery!