In this paper, the valve stem and
valve guide contact behavior is investigated for an engine with RFF valvetrain and overhead cam configuration.
The exhaust
valve guide clearance was 0.019 inch, which is well within the acceptable limits.
STI's strength is its engine component technology, particularly that of its
valve guide.
"A
valve guide had pushed out of the head, causing the valve not to open correctly thus blowing the oil out of the engine," explained Chris, "so it was time for another engine change.
The VGS-20
Valve Guide and Seat Machine lets shops set up and run heads up to 48" long.
Peterson Machine Tool has added the System 2000 XL
Valve Guide and Seat machine to its line of engine rebuilding and cleaning equipment.
We also asked about specific shortcomings, such as loss of compression,
valve guide wear and cracking and respondents were given the opportunity to comment generally on cylinder issues.
Three of the six cylinders experienced
valve guide failures at 384 hours time in service.
Valve stem seals are designed to allow a small amount of oil to pass through the seal lip to provide lubrication at the interface of the valve stem and the
valve guide. If too much oil is able to pass through the lip, emissions are higher and deposits can build up on the valve.
The valve stem was damaged and would not pass through the
valve guide.
The circumstances might be thus: You're at 1600 hours on a 2000-hour engine and a
valve guide tanks, taking the compression down to 50 pounds.