<VV> Verdict on: Bad Idle (66 140)
Sat, 14 Aug 2004 11:17:15 -0700
At 01:25 PM 8/14/2004 -0400, N. Joseph Potts wrote:
> The VALVE GUIDE on that intake valve, which had been resleeved with
>bronze, had broken, evidently near the end that's in the combustion chamber.
>I am missing that inch, more or less, from that end of the guide (which
>pulled out of the head by hand). This head had been professionally
>refurbished in May 2003, and installed in February 2004. Less than 5,000
>miles. Teflon valve-stem seals were installed then.
The question is: WHY? One idea is that the Teflon valve-stem seals might
have provided too good of a seal and starved the guide for lubrication. I
would recommend pulling the other intake valves and compare the look inside
the stems with a good microscope looking for evidence of excessive
heat. Do the valve stems have any evidence of excessive
temperatures? Also measure the diameter at the ends of the guides and see
if it has increased wear there. Another idea might be to pull the exhaust
valves and compare wear to those with the seals.