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From Wikipedia:
"Introduced in 1989 for the 740 GLE (and later used in the 940/960), The 16-Valve Redblock motors were offered in both a 2.0 litre Turbo and a 2.3 litre 154hp Naturally aspirated version. The head was designed for Volvo by Porsche.[citation needed] In addition to the 16 Valve head, these motors were equipped with twin counter rotating external balance shafts and the engine block itself differs from the 8V redblock. The block differed from the standard B230 in that the auxiliary shaft (used to drive the oil pump and distributor on models that had block mounted distributors) was replaced with an external oil pump. The 16-Valve head was itself a completely new design for Volvo: The head was of a multi-piece design featuring a separate cam carrier and lower section. The later "white block" motors can trace their head design back to the two-piece setup found in the B204 and B234. The 2.0 litre variant was available in turbocharged form in some markets (B204FT/GT). Unique to the B204 turbo was an exhaust gas pyrometer which was used to detect excessively high exhaust temperatures. When excessively high exhaust temperatures were detected, the fuel injection computer would richen the mixture. It has a forged crankshaft, cast pistons, and 13 mm (0.5 in) connecting rods.
Although a powerful engine for its' time, the 16 Valve engine can experience some problems that can be solved easily. One of the few problems is the oil pump gear. The oil pump gear itself can fail around the mounting flange, or, more often, the weak 8.8(grade 5) grade bolt holding the gear can break. It is strongly recommended to use a 10.9 (grade 8) grade bolt when replacing the oil pump gear. Another cause for timing belt failure is improperly adjusting the timing belt on engines with a manual tensioner (1989 to very early 1990 models only) or improperly adjusting the balance shaft belt. Because this is an interference engine, damage will occur if the timing belt fails. Another common occurrence is that the balance shaft's oil seals are prone to leak on older engines. New replacement sealings tend to start leaking again due to 'worn in irregularities' on the shaft itself. Many people have removed the balance shaft belt or the balance shaft assemblies altogether to prevent belt failure and/or leakage. The balance shafts are only there to lessen vibration for a smooth idle, and removing them will not harm the engine. Once all the common problems are solved, the 16 Valve engines are just as reliable as their SOHC counterparts.
The recommended timing belt interval for these engines is every 50,000 miles, or earlier if the engine is modified. It is also recommended to replace the crank and camshaft seals at every interval and to thoroughly inspect the tensioner and idler pulleys for wear."
Regarding Sodium filled valves- I have 2 760 1990 and 1989 turbos replaced the heads 7 and 5 years ago with regular heads ( from a non turbo engine, no sodium filled valves)
I live in FL (hot summers) and my right foot likes to push the gas pedal to the bottom every day on the interstate- the result is- well same as if they were sodium filled valves- I have seen merging speeds of 110mph and cruising at 90mph on a daily basis for 5-7 years with both Garret T3 and Mitsu TD04 turbos, with factory boost pressure 9 PSI ??
Bottom line is are you willing to work on the car more than to drive it, or in general is this a track car or a daily driver.
We are the volvo drivers, let's be friends and stick together!
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