Low compression high emission 4GTL

[R4Algarve]

Hi folks, my beloved Portuguese 1988 R4 GTL has totally and repeated failed its MOT for emissions due to dud cylinder. Any idea of likely cost for a top end rebuild at a garage ( assuming they are all getting a bit slack ) or is it worth hunting for a new lump ? Based in Portugal but can ship bits to and from U.K easily...

Thank you for any words of wisdom, just don't tell me to scrap it ! Car otherwise sound..

 

[mojobaby]

Hello R4A, have you actually had a compression test done to determine which cylinder is dud?

There are many reasons for a low compression, rings, valves, cylinder head gasket to name a few.
Do you have any noticeable symptoms such as smoky exhaust, lack of power, overheating,

Perhaps its not a compression problem and you just need to reset your timing and ignition equipment (plugs points etc) and adjust the mixture on your carb. What were the results from your MOT test?

 

[R4Algarve]

Thank you M for your reply. Need to confirm compression test results with mechanic ( using my daughter to translate ! ), I have had an overheating episode with the thermostat this year so the gasket may be the culprit. They tried mixture timing etc.. I believe. They're pulling the head the next few days to see more.. always smells of fuel and some white smoke..erratic lumpy engine of late and doesn't pull well ( not sure if it's got worse in this first year of ownership ), so not surprised by a failing cylinder..

 

[Leonardo.IT]

I had a problem with low compression (but good performances) on my car and it was a leaking valve.
But I think it can be hard to investigate without taking off the cylinder head...