Engine compression!?

[Jackson74]

I've been told my engine has no compression in my 3rd and 4th cylinders (ok with high revs, struggles when low or cold). Apart from giving my car/engine the last rites, does anyone know what might cause this and a possible solution, as don't want to scrap just yet!!?? Car is not burning off petrol properly!!

[essex bloke]

The piston rings in 3/4 cylinders are on the way out allowing the fuel/air mix to escape past during low revs . Two options come to mind 1. new engine or cylinder block or 2. rebore the cylinder and fit oversize pistons and rings . two is the cheapest option if the engine isnt too old

[gsr600]

well the other options are exhaust Valves burnt out or head gasket blown between these 2 cylinders,
only way it be sure is to take off the cylinder head & inspect it for the probable causes.
you also forgot to mention what car/year it is

[Toureman]

If your car has no compression on two cylinders it would not be OK at high revs, it would hardly run at all at any revs.

Did the person who did the compression test check them properly?

[Andyvon]

Sounds most likely the head gasket. You might take the head off Jackson as the gasket change is straightforward and any other problem such as a valve would be more apparent.

[Jackson74]

Thanks everyone! The car is a 94 vitara and I posted a question about a month ago about it using up petrol and not firing on all cylinders!! It appears that this may well be the problem. I had a new head gasket/skimmed block at Christmas. It looks like I will have to remove block and check the valve etc!

[Jackson74]

The chap who did the pressure check said it was about 13 in 1 and 2, and about 3, in 3 and 4!

[TWR]

Check the Spark flow in each HT Leads, are they the orig leads? has the Ing system leads or that area been disturbed causing the intermitted spark flow, I would go down theses lines before taking off the head, but as Tourman states was the person who checked the compression up to the job?