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Old 08-15-2016, 04:54 PM   #1
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Couple questions for compression/leak down tests

I'm about to do my first DIY compression and leak down tests - can't find a write-up specifically for our car so a few questions.

1. Is there an easy way to find TDC for each cylinder by yourself? And what's the recommended method for turning over our engines by hand?

2. Compression test should be done with warm engine. What about leak down - warm or cold?

3. How do you do a compression test solo to turn over the engine while watching the gauge? Is there a way to remote turn over our cars?


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Old 08-15-2016, 11:35 PM   #2
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I can't help you with the leak down test as its a bit more complex than a simple compression test, but this is what I do to check compression. You can do it on your own, but its easier if there is a second person holding the accelerator open & turning over the car on the starter motor.
The test unit should lock in at the maximum indicated pressure (at least mine does) so there is no need to eyeball the max number and hope you saw correctly.

1) The engine should be at operating temperature, or at least quite warm.
2) Remove the fuel pump fuse. Remove all 6 spark plugs - this enables the engine to spin more freely on the starter motor.
3) Screw in the tester to the first cylinder spark plug hole and have helper A) put foot flat down on the accelerator & B) crank the engine for 4-5 seconds - record the max reading.
4) Repeat for all other cylinders.

Hope this helps - let us know what you find....
2001 Boxster S (triple black). Sleeping easier with LN Engineering/Flat 6 IMS upgrade, low temp thermostat & underspeed pulley.
2001 MV Agusta F4.
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Old 08-16-2016, 03:51 AM   #3
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I will add to Steve's info that you keep cranking until the pressure no longer increases on the gauge. You should have the battery on a charger to make sure the cranking speed stays at 100% during the test.

Leak down is harder in that yo have to do each cylinder at their TDC and it should be help there while under pressure because it can (will) want to turn once air is applied.

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