Cylinder 3 compression fail

[Kimbo641]

Hello, I previously put a thread up about cylinder 3 misfiring. I’ve had the coil packs and spark plugs changed but still misfiring. I just took it for a compression test this morning which mechanic told me failed with it holding no pressure. What is my next step now. The car is on 170k miles. I’ve had this car myself for a few years as second owner and I’d say 80k miles were done on motorway. Is it worth me spending more money on finding out the exact problem inside the engine or what is the best step for me to take now?

 

[ALFAitalia]

Unless you can find a cheap engine its probably not worth it at 170k miles. Even with a later engine (which you won't really know the history of) you will still have a 170k car worth about three tenths of sod all!! Its had a good inning....time to say farewell. Stripping your current motor will probably be more expensive than fitting a used one unless you have the skills to DIY it.

 

[Will]

you will still have a 170k car worth about three tenths of sod all!!

I’d normally agree with most of what you posted but the CLA is a relatively modern car and probably worth a few £k even with those miles. Cheapest ones I can see on AT are £6/7k with 120-150k miles or HPI write offs. Probably worth £4/5k or so - depending on condition?

If the rest of the car was in very good condition it could be worth repairing - but I’d be tempted to sell it as is with the misfire disclosed and someone who has the skills/tools/knowledge maybe able to repair it viably.

Paying for someone else’s time is expensive and it will be a labour intensive repair whichever route you take.

Add the cost of repair to resale as is (maybe £2/3k?) and you could be better off with a lower mileage example, especially if you’re planning to continue putting quite a few miles on in future

 

[Bellow]

If it were mine....
I'd perform a leak down test listening for where the pressure is escaping to. If it's going downstairs then there's a problem with the piston/rings on cyl # 3 which will be expensive to fix as likely an engine out job.
If leaking past valves then lifting the head and replacing the valves could be a relatively cheap fix.
But, what needs to be ascertained is the cause of the failure - or it will likely reoccur.

I'd bet on burned exhaust valves and if so, crucial to find out why before any repair can be considered.
What grade (octane) of fuel is recommended and what was used?
Re-mapped?
Oil consumption (prior to misfire appearing)?

 

[ALFAitalia]

Or get a cheap borescope in there to look.....my cheap eBay one works with a free app on my phone.....paid for itself many times over.

 

[Kimbo641]

If it were mine....
I'd perform a leak down test listening for where the pressure is escaping to. If it's going downstairs then there's a problem with the piston/rings on cyl # 3 which will be expensive to fix as likely an engine out job.
If leaking past valves then lifting the head and replacing the valves could be a relatively cheap fix.
But, what needs to be ascertained is the cause of the failure - or it will likely reoccur.

I'd bet on burned exhaust valves and if so, crucial to find out why before any repair can be considered.
What grade (octane) of fuel is recommended and what was used?
Re-mapped?
Oil consumption (prior to misfire appearing)?

Hi thanks for ur reply. I’ve had the car stage 1 remapped before and I’ve been using normal petrol 95(e10). I also had an oil leak

 

[Kimbo641]

I’d normally agree with most of what you posted but the CLA is a relatively modern car and probably worth a few £k even with those miles. Cheapest ones I can see on AT are £6/7k with 120-150k miles or HPI write offs. Probably worth £4/5k or so - depending on condition?

If the rest of the car was in very good condition it could be worth repairing - but I’d be tempted to sell it as is with the misfire disclosed and someone who has the skills/tools/knowledge maybe able to repair it viably.

Paying for someone else’s time is expensive and it will be a labour intensive repair whichever route you take.

Add the cost of repair to resale as is (maybe £2/3k?) and you could be better off with a lower mileage example, especially if you’re planning to continue putting quite a few miles on in future

Sticky situation

 

[Bellow]

Hi thanks for ur reply. I’ve had the car stage 1 remapped before

A Rice Krispies (snap, crackle and pop) remap?

and I’ve been using normal petrol 95(e10).

Was that what the OEM recommended (in unmodified form) and was there a recommendation from the remapper to use higher octane after the remap?

I also had an oil leak

A visible leak - not burning it?

 

[grober]

A Drop in cylinder compression will be due to valve seat wear or valve gear malfunction-BROKEN VALVE SPRING ? [Repairable but involves lifting the head probably.] The alternative is bore wear or piston ring fracture or excessive wear in which case the engine is uneconomic to repair. A Borescope would confirm this either way as suggested