| View previous topic :: View next topic |
| Author |
Message |
ricardo
Alfasud
Joined: 13 Mar 2003
Posts: 43
Location: wellington .... new zealand
|
 Posted: Sun Apr 18, 2004 11:48 am Post subject: 16v... burning exhaust valves |
 |
|
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/ |
|
| Back to top |
|
 |
paddy granger
Alfa Sprint
Joined: 12 Aug 2003
Posts: 248
|
| Posted: Sun Apr 18, 2004 12:35 pm Post subject: odd... |
|
|
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?  |
|
| Back to top |
|
|
RFlower
Alfa 33
Joined: 17 Feb 2004
Posts: 432
Location: S of France
|
| Posted: Sun Apr 18, 2004 2:38 pm Post subject: |
|
|
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) |
|
| Back to top |
|
|
ricardo
Alfasud
Joined: 13 Mar 2003
Posts: 43
Location: wellington .... new zealand
|
| Posted: Mon Apr 19, 2004 7:08 am Post subject: |
|
|
| 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/ |
|
| Back to top |
|
|
ZeNiTh-PbArM
Alfa 33
Joined: 14 Mar 2003
Posts: 388
Location: Paris, France
|
| Posted: Tue Apr 20, 2004 7:15 am Post subject: burnt valves... |
|
|
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 |
|
| Back to top |
|
|
Guest
|
| Posted: Sat Apr 24, 2004 10:24 pm Post subject: |
|
|
| i would suggest a airleak in the intake manifold |
|
| Back to top |
|
|
|
