M96 Engine Intermix question

[RoninFL]

Hey there,

M96/21 - 02 3.2 Boxster S engine - posting here because I can't figure out how to post in the Boxster forum.

Should be the same answers for all M96 engines since mostly the same as 996...

So I bought an engine that had intermix & a Non-Porsche specific mechanic said blown head gasket. I figured cracked head & bought with that expectation.

Latte oil / no oil in coolant according to seller who did an engine swap on the car.

Engine turns fine - no issues

After stripping motor, I performed a leak down test with a basic Harbor Freight tester. 3 tests per cylinder & used a dowel in the spark plug hole to get TDC except on 1 / 4 there i used the Cam Lock tool. Obviously cold, but I can't exactly run the engine normal operating temps. Tested @ 98 PSI since the gauge said DON'T GO OVER 100 and wanted to leave a little wiggle room...

Average results:
- 1 - 7 PSI / 7.2%
- 2 - 2 PSI / 2.1%
- 3 - 3.5 PSI / 3.6%
- 4 - 5.5 PSI / 5.6%
- 5 - 2 PSI / 2.1%
- 6 - 7.7 PSI / 7.9%

Engine oil was drained for shipping, so I did put a squirt down each intake stack & 1/2 quart in filler day before I started hand cranking the motor & doing leakdown test.

So those #s look pretty good to me - all within spec according to some quick Googling.

The oil cooler was removed, so I can't pressure test it for a leak. The AOS / Plenum / Intake had Milky oil.

Am I crazy to think the Intermix was a failed Oil Cooler & the previous owner's mechanic completely misdiagnosed the head gasket when really heads are fine based on leakdown numbers??

Thanks for the help!
Ron

[JFP in PA]

Get access to a cooking system pressure tester, seal up the coolant openings in the engine, and pressurize it to 18-20 PSIG. If there is no crack anywhere, it will hold that pressure indefinitely; if the pressure drops, you have a problem.

[RoninFL]

PowerBuilt Cooling System Pressure Testing Kit 22 Piece??

"The Powerbuilt cooling system pressure test kit is one of the most comprehensive test kits on the market today. This kit contains numerous test adapters to fit more than 80% of all cars and trucks on road. This kit is designed to pressurize the system by including adapters to test the radiator, radiator caps and coolant reservoirs allowing the technician to easily identify if there are leaking in radiators systems."

I would plug the Water line holes / Oil cooler & then use an adapter to pressurize one of those holes - if it won't hold the 20 PSI then I try to listen for the hissing?

[JFP in PA]

No, if it doesn't hold pressure, you tear it apart to find out why................

[RoninFL]

Got it - appreciate the help!

So the Leakdown is more checking the condition of the valves / piston rings?

[JFP in PA]

Originally Posted by RoninFL

Got it - appreciate the help!

So the Leakdown is more checking the condition of the valves / piston rings?

A leak down test the seal of the valves and rings, but unless the combustion chamber in the head is cracked, or a cylinder liner near the top, it will tell you absolutely nothing about why oil and water are getting together. For that you pressure test the cooling jacket.