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9
votes
2answers
10k views

Crank vs turn over vs start vs whatever

I see conversations like the following a lot: A: My car won't start. B: Does it crank? A: Yes but it won't turn over. B: Wait, I'm confused. So, it tries? A: Well it makes a sound. B: ...
10
votes
3answers
5k views

What exactly is a jackshaft?

The Wikipedia entry for the Ford Cologne 4.0L SOHC describes the use of a "jackshaft": It uses a jackshaft in place of a camshaft to drive a timing chain to each cylinder head. Three timing chains ...
20
votes
3answers
10k views

What is valve float and how does it impact engines?

The Wikipedia entry is hard to grok: Valve float is an adverse condition which can occur at high engine speeds when the poppet valves in an internal combustion engine valvetrain do not properly ...
18
votes
3answers
173k views

What exactly is a “burnt valve” and what causes it?

I've come across this term a couple of times in the context of diagnosing engine-related issues, but don't know what it refers to. Here is an example from an automotive forum I frequent: I gotta ...