Cylinder not firing

GerardKeating

So I have one of the Cylinders not firing.

Local Mechanic did a "compression" test on it, and no pressure in it, it also recently failed the NCT over "emissions".

it's a Mazda 5, 1.8 Petrol.

Am I looking at a replacement engine, or is this "fixable" ?

PukkaStukka

I'm not trolling here but did you not ask the mechanic for his (or her) opinion? If they are competent enough to do a compression test, they might be best placed to advise on this.

GerardKeating

PukkaStukka wrote: »

I'm not trolling here but did you not ask the mechanic for his (or her) opinion? If they are competent enough to do a compression test, they might be best placed to advise on this.

Sorry, should have mention this, but of course I have asked him, but my knowledge in the area is week, and I want to understand all the options.

biko

Not DIY effort.

"Cylinder not firing" - does mech mean the spark plug isn't firing? If so that's not a big deal.

No compression probably means piston rings, in which case you can have engine apart to fix or maybe source another.

Tbh, there's many questions and you should probably speak to the mech again and maybe also take car to a second mech for opinion (don't tell second mech what first mech said, let them arrive at their own conclusion).

gctest50

No compression ?

any or any combination of :

• Hole in piston
• Conrod broken
• Hole in valve
• Valve bent
• Head Gasket ( usually 2 cyls together though, or coolant all over the place )
• Rings broken

and more

GerardKeating

biko wrote: »

Not DIY effort.

"Cylinder not firing" - does mech mean the spark plug isn't firing? If so that's not a big deal.

No compression probably means piston rings, in which case you can have engine apart to fix or maybe source another.

Tbh, there's many questions and you should probably speak to the mech again and maybe also take car to a second mech for opinion (don't tell second mech what first mech said, let them arrive at their own conclusion).

I do plan to speak to him again, and hopefully will understand him more the second time.

He did replace the spark plug, but it made no difference, seems to be drinking the oil a bit as well.

9935452

GerardKeating wrote: »

I do plan to speak to him again, and hopefully will understand him more the second time.

He did replace the spark plug, but it made no difference, seems to be drinking the oil a bit as well.

If it is drinking oil my first thought is piston rings.
Basically it needs to be ripped to find out exactly whats wrong but if there is problems with one piston there might be problems with other ones ,

What did your mechanic say about it ? What does he think it is and is it worth trying to fix it?

Esel

9935452 wrote: »

If it is drinking oil my first thought is piston rings.
Basically it needs to be ripped to find out exactly whats wrong but if there is problems with one piston there might be problems with other ones ,

What did your mechanic say about it ? What does he think it is and is it worth trying to fix it?

Hope you meant 'stripped'.


As opposed to the OP being ripped (off).

Agree that cost is going to be a major factor though...

9935452

Esel wrote: »

Hope you meant 'stripped'.


As opposed to the OP being ripped (off).

Agree that cost is going to be a major factor though...

Ah no i meant rip the engine.

Cee-Jay-Cee

It might be cheaper to source and got a replacement engine. How old is the car and how many miles on the engine?

GerardKeating

Cee-Jay-Cee wrote: »

It might be cheaper to source and got a replacement engine. How old is the car and how many miles on the engine?

That is his recommendation, the car is 10 years old. I think it is 120,000km or so.

mullingar

The simplest job to see where its leaking is a leak-off check if the compression test proved a problem. These are really cheap tools and IMO should be in every mechanics tool box to quickly diagnose the possible fault area

You can easily diagnose where the air is leaking out of and its going to be either: inlet valves/exhaust valves/rings/head gasket.

Skatedude

no compression and drinking oil. the piston, piston rings and bore lining will most likely need to be replaced.
It's a lot of work and will be expensive.

a second hand engine would probably be easier and cheaper, but always get a second opinion from another mechanic first to confirm because of the costs involved.