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ricardo Alfasud
Joined: 13 Mar 2003 Posts: 43 Location: wellington .... new zealand
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Posted: Sun Apr 18, 2004 11:48 am Post subject: 16v... burning exhaust valves |
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any suggestions guys as to why my sisters 16v has now shat it's second ex valve... looks like it got very hot with a oxy-acetaline like burn marks on the valve, molten hot... only one ex valve each time ...same cyl..no 1 _________________ alfa romeo trofeo series new zealand, video site .
http://alfa-racing.blip.tv/
alfatrofeo blog and interesting stuff .... unofficial ....
http://alfatrofeo.blogspot.com/ |
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paddy granger Alfa Sprint
Joined: 12 Aug 2003 Posts: 248
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Posted: Sun Apr 18, 2004 12:35 pm Post subject: odd... |
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Could be the following, perhaps...
Valve seats not cut properly
Valve faces cut too thin
And maybe detonation caused by poor fuel, but then it wouldn't be No.1 cylinder every time.
Perhaps you should perform a compression and a leak down test.
She isn't running the car on oxy-acetaline is she? |
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RFlower Alfa 33
Joined: 17 Feb 2004 Posts: 432 Location: S of France
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Posted: Sun Apr 18, 2004 2:38 pm Post subject: |
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Check concentricity of the seat inset with the valve guide, ie get the new valve (not the old one, it might be bent), put a smear of engineers blue or very fine oil painters paint or similar very thinly on the valve's seating surface, and gently turn it to make sure it touches all the way round. If you're not absolutely sure the valve touches all the way round, have the seat insert replaced.
I once had a [/u]new[/u] (not Alfa) engine which was hard to start, and finally found someone had either pressed in a valve seat crooked, or the valve guide bore had not been drilled straight.
Also double check the valve clearance _________________ Dick Flower, Nr. Carcassonne. '94 Trofeo 1.4 ie (F), '93 Imola 1.3/1.4 ie (now for breaking) (F), '91 1.7 ie (GB)(spare car), '86 Sprint 1.5 QV (F). '87 VW Syncro camper (F), '73 NSU Ro80 (F), '99 Fiat Seicento (F) |
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ricardo Alfasud
Joined: 13 Mar 2003 Posts: 43 Location: wellington .... new zealand
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Posted: Mon Apr 19, 2004 7:08 am Post subject: |
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Quote: |
She isn't running the car on oxy-acetaline is she? |
...may as well be on new zealands crap fuel.. but no , seats are fine , valves ok , there is quite a carbon build up on cyl 3.....................any one else had burnt valves on a 16v _________________ alfa romeo trofeo series new zealand, video site .
http://alfa-racing.blip.tv/
alfatrofeo blog and interesting stuff .... unofficial ....
http://alfatrofeo.blogspot.com/ |
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ZeNiTh-PbArM Alfa 33
Joined: 14 Mar 2003 Posts: 388 Location: Paris, France
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Posted: Tue Apr 20, 2004 7:15 am Post subject: burnt valves... |
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hi
i've seen burn valves due to a leak at the manifold : cold air gets to the hot valve and whaaaaaa!
otherwise, i already had a recurring burning valve problem on my 740 volvo due to an oil leak between the valve quide and the alloy of the head ; i had to bore the housing oversize and replace the guide.
regards,
zp |
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Guest
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Posted: Sat Apr 24, 2004 10:24 pm Post subject: |
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i would suggest a airleak in the intake manifold |
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