Anonymous
05-06-01, 12:15 PM
I had an argument last night with a mobile mechanic. We disagreed over what had caused my good friends GSi to self destruct. Here`s the storey:
1991 Nova GSi had new engine from Luton Vauxhall fitted less than a year ago. For the last two months or so it has been pinking when under hard acceleration, and about 3 weeks ago he comes to me with it in a bad way. I recognise the symptoms straight away as a blown head gasket, and sure enough when I took it apart there was a 1" gap in the gasket between 3&4. Fitted new gasket, put it all back together and started it. It drove fine, but wouldnt idle. It was really lumpy and would eventually die. Fitted yet another gasket thinking there might be a fault with the original, started it, and same problem. It was at this point that we noticed the huge amount of crankase pressure. Fumes pumped over a meter out of the car when the filler cap or dipstick was removed. Big problem. At this point my m8 turned to this mobile mechanic and asked him to help. He said that I had probably warped the head and removed it took it away and on inspection it was fine. The head was finely skimmed anyway and refitted, and when put back together although the mechanic got it to idle well, there was the same amount of crankase pressure and the car pinked more than ever. After a week of driving, the mechanic adjusted the timing and mixture and goyt the car running very well, but the crankase pressure was still there. Whilst driving behind my friend I noticed slight hints of blue in the exhaust gasses, but as it was running o.k. I said no more other than that the pressure was still not right. Whilst out in the car with him this Saturday he used superunleaded (about 1/3 of a tank) all was well until sundenly the car became lumpy again and developed a slight misfire under light load, but was fine under hard acceleration. My friend went back to the mechanic that afternoon and he blamed it on the leads (1 week old) and plugs. I disagreed, coz they wouldnt suddenly go like that and the misfire would be under heavier load. he said it would be o.k. at this point. The following morning (b4 we were going to leave for MK) he decided to go for a run and then disaster, he calls for my help and I find that the crankcase pressure is now unbelievable it would run properly at any speed or load and it was forcing oil from everwhere. Once stripped apart we discovered that the piston had collapsed and melted in pot 4 and left damage on the bore aswell. This is where the argument came in. The mechanic (who fitted the engine in the first place) immediately blamed it on my friend using superunleaded. He said it makes the car run to hot and the ecu wouldnt know that it had to retard the ignition. I disagree as the higher octane has nothing to do with power of explotion, just how well the fuel resists detonation, and if anything it means you can run more advanced because of this. In effect superunleaded should be safer to use and the problem would only occur if the other way around and you started using a lower octane when the car was set up for 98. I think that there was an underlying fault all along, which would explain the crankase pressure. Possibly a ring broke at or around the time when the head gasket went and the resulting abuse caused the piston to fail. Any ideas anyone, thats if anyone can be bothered to read this much.
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Whoopass! :D
1991 Nova GSi had new engine from Luton Vauxhall fitted less than a year ago. For the last two months or so it has been pinking when under hard acceleration, and about 3 weeks ago he comes to me with it in a bad way. I recognise the symptoms straight away as a blown head gasket, and sure enough when I took it apart there was a 1" gap in the gasket between 3&4. Fitted new gasket, put it all back together and started it. It drove fine, but wouldnt idle. It was really lumpy and would eventually die. Fitted yet another gasket thinking there might be a fault with the original, started it, and same problem. It was at this point that we noticed the huge amount of crankase pressure. Fumes pumped over a meter out of the car when the filler cap or dipstick was removed. Big problem. At this point my m8 turned to this mobile mechanic and asked him to help. He said that I had probably warped the head and removed it took it away and on inspection it was fine. The head was finely skimmed anyway and refitted, and when put back together although the mechanic got it to idle well, there was the same amount of crankase pressure and the car pinked more than ever. After a week of driving, the mechanic adjusted the timing and mixture and goyt the car running very well, but the crankase pressure was still there. Whilst driving behind my friend I noticed slight hints of blue in the exhaust gasses, but as it was running o.k. I said no more other than that the pressure was still not right. Whilst out in the car with him this Saturday he used superunleaded (about 1/3 of a tank) all was well until sundenly the car became lumpy again and developed a slight misfire under light load, but was fine under hard acceleration. My friend went back to the mechanic that afternoon and he blamed it on the leads (1 week old) and plugs. I disagreed, coz they wouldnt suddenly go like that and the misfire would be under heavier load. he said it would be o.k. at this point. The following morning (b4 we were going to leave for MK) he decided to go for a run and then disaster, he calls for my help and I find that the crankcase pressure is now unbelievable it would run properly at any speed or load and it was forcing oil from everwhere. Once stripped apart we discovered that the piston had collapsed and melted in pot 4 and left damage on the bore aswell. This is where the argument came in. The mechanic (who fitted the engine in the first place) immediately blamed it on my friend using superunleaded. He said it makes the car run to hot and the ecu wouldnt know that it had to retard the ignition. I disagree as the higher octane has nothing to do with power of explotion, just how well the fuel resists detonation, and if anything it means you can run more advanced because of this. In effect superunleaded should be safer to use and the problem would only occur if the other way around and you started using a lower octane when the car was set up for 98. I think that there was an underlying fault all along, which would explain the crankase pressure. Possibly a ring broke at or around the time when the head gasket went and the resulting abuse caused the piston to fail. Any ideas anyone, thats if anyone can be bothered to read this much.
=\_____
=/__|__\_
=|(_)___(_)\
Whoopass! :D