Bookworm wrote: ↑Sat Oct 26, 2019 8:18 am
jolt wrote: ↑Fri Oct 25, 2019 10:29 am
What issue are you having that you believe the timing chain needs to be replaced?
Could simply be that you replace timing belts at about that interval for the first one, and the _old_ timing chains (pre 90's) had breaking issues, so required replacement as well. That's why they went to belts. The metallurgy is better now, as well as the tensioners.
Timing belts have been around since about 1974 in American made cars and timing chains way before that (mostly link chains). I have never seen a roller timing chain break unless it was cause by other issues like worn out chain guides or poor oil pressure to the chain tensioner because of blockage in the oil passages. Chains do stretch under use but roller chains do not cause as many problems as link chains do with messing to the gear teeth as the chain stretches. Timing belts are your cheapest to manufacture and produce, but also wear out and require far more service then roller chains do. Early engines with timing belts had a major problem that when the belt broke, the pistons would hit the valves and bend the valves. These are called interference engines. Some manufactures re-designed the pistons to prevent this from happening and those engines are called non-interference engine. Most timing belt engines are non-interference engine now. The main reason to use a roller timing chain now, despite the increase in cost to manufacture, is that the engine design is an interference engine. A interference engine provides better efficiency without compromises to the combustion chamber design that a non-interference engine would have for valve clearance when the timing belt breaks. Changes in materials and design have made big improvements for timing belts but the roller chain inside the engine, still will out last a regular timing belt under normal usage.
Still have seen no reply from the OP about why the timing chain. Is the problem this: