" . . . expensive sodium-filled valves are rarely seen anymore outside of heavy-duty, long-haul engines." Road&Track "Technical Correspondence" June 2003.
Filet-rolled crank journals, micro-polished cranks, six-bolt main caps, sturdy lower girdle, deep skirts, sodium-filled exhaust valves, variable valve timing, multi-resonance intake system . . . the '90-'93 VD45DE continues to appear over-engineered and over-built, even by most of today's standards. Bless 'em.
sodium-filled valves
-
Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Usually the exhaust valves and or seats are the first to go on an engine [ the cheaper the materials the faster they burn and crack], leading to leak downs and low effective compression.The idle misses [putt, putt, putt] and shakey vibration are the first indicators.
By 250,000 miles all of us might experience this to some degree but then again I have seen 300-400k Q with little, really a function of luck of the draw, gasoline, and coolant temperature control, EGR function in keeping cylinders cool on all the long trips, and heat conductance of the oil and lack of insulative varnishing.
By 250,000 miles all of us might experience this to some degree but then again I have seen 300-400k Q with little, really a function of luck of the draw, gasoline, and coolant temperature control, EGR function in keeping cylinders cool on all the long trips, and heat conductance of the oil and lack of insulative varnishing.
Exhaust gasses are running in excess of 1200 degrees F, and Q engines run hotter than most. Unless you transfer this heat out of them, and keep the valve temps down, they will burn. Non-sodium valves rely on heat transfer up the stem into the guides, and into the heads via conduction when the valves are closed. The sodium in the Q's exhaust valves melts when it gets hot, and the liquid sodium flows up and down inside the hollow valve chamber, providing increased heat transfer from the valve face up the stem and into the guides.