Engine misfiring - confused

bedrock#1

Long story short, on M50 losing power in the engine of my 01 Opel Astra 1.4l 16v, pulled off and engine is shuddering when trying to bite the clutch and got towed to a local garage. Was tole it could be a number of problems from needing replacement plugs, a new coil pack or worst case scenario head gasket or busted piston rings.

The problem is when he was explaining this to me in the garage he was showing me the lack of compression in the cylinder by hooking up a pressure gauge to the cylinder. He then tried to start the car but the engine never actually fired up. The gauge read zero pressure. My question is, with my limited knowledge of how engines work, is it possible to test the compression in a cylinder if the ignition coil pack has been removed and the engine is only being hit with the starter motor and not actually starting and ticking over???

Thanks

Nissan doctor

You can only check compression with the coil pack and spark plugs removed. the gauge reads the pressure created within the combustion chamber as the piston rises in the cylinder.

I can't imagine why, on an Astra, the timing belt is not the first thing that was checked, especially with a lack of compression on an engine that was presumably driving fine before hand.

bedrock#1

Thanks for the reply,

He did ask me about the timing belt but was very keen to tell me that there are apparently loads of problems with the head gasket burning out from overheating in Astras. The head gasket went on the car about 7 years ago and was replaced then. I'll be speaking to the mechanic on Monday so I'll ask him then.

Nissan doctor

The symptoms you are describing do not point to a head gasket at all.

TBH it sounds more like your mechanic is just naming problems that he's heard of rather then actually diagnosing the problem. A car will still run with a failed head gasket and will still have compression and also wouldn't have failed enough to cause major running issues without pretty obvious and major over heating prior to the car cutting out.

Mar4ix

recently had '99 rover, with 1.6 engine, i know, it is different car, but symptoms was nearly same, could hear , that engine, while trying start, spinning too fast, at the end i diagnosed slipped timing belt, exhaust camshaft was nearly 180 degrees turned around away from timing position, ... didnt check compression though , but after i put that camshaft back as it should be, started car, but few valves was bent. ... car goes to scrapyard, as it is not worth repair.

First you shall ask mechanic, check is timing spot on., then check is fuel delivered on proper pressure to fuel line, ask is sparks delivered to sparkplugs, after that, ask mechanic check compression again. i can't see compression be 0 , if all my previous advised checks are ok.

Did you hear any noises from engine bay, when engine died on M50 ?

bedrock#1

Just got off the phone to the mechanic, apparently there are 2 valves burned out on the 3 and 4 cylinder heads. He says as well as replacing these he will need to replace the head gasket. He also said the fan belt needs replacing.