What are early signs on lost compression in an engine in a 4 cylinder?

Answer 1

There are many signs an engine will give that could be attributed to low compressions in an engine, but although this list is not comprehensive you may find one or some of them to be helpful.

Poor or difficult starting is normally the first sign

Excessive crankcase pressure

High fuel consumption

Low (or lower than normal) power output

Cylinder misfiring

Blue smoke from the exhaust

Engine oil coming out of the Dipstick tube or the dipstick keeps coming off it's seat in the tube

However, don't be misled - there are several other reasons for some of these answers.

E.G

Poor starting and High fuel consumption can also be caused by :-

Worn Spark plugs or incorrect gap

Incorrect Ignition timing

Dirty Air filter

Contaminated fuel filter

Incorrect valve clearances

Incorrect Air/Fuel ratio

Air leaks on the Induction system

Partially blocked exhaust system or Catalytic converter

Etc, etc, and the same would follow for most of the other answers as well - the easiest and quickest way to find out if and engine has low compressions in the cylinder(s) is to carry out a 'compression' test and compare the results to the manufacturer's specifications.