A lakdown is good for determining the cause of a bad cyl but a comp test is better for general evaluation.

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2001 SLK 320 six speed manual
2014 Porsche Cayenne six speed manual

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X2

In my opinion a much better way of assessing engine health as with a leak down test the results aren't being influenced by starter and battery health and gunky cold engine oil etc - however, it is not as quick and easy to do as a compression test. A leak down test requires a certain level of intelligence whereas for a compression test virtually any Mungo can do that.

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

They both have their places, their advantages and disadvantages.

The compression test in effect analyzes the cylinder with the rings in all positions in the cylinder. The leakdown only analyzes the cylinder with the rings in one location in the cylinder.

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2001 SLK 320 six speed manual
2014 Porsche Cayenne six speed manual

Annoy a Liberal, Read the Constitution