We recently had a customer come in with a 2008 Hyundai Sonata (generic picture above) with a 2.4L 4-cylinder and 93k miles. His concern was a ticking/knocking sound near the top of the engine at mid to high level RPMs.

We suspected the issue to be behind the timing cover, so we let the customer know that we would need to remove the timing cover, inspect the area, and advise him on the needed repair.

Our technician verified the concern by first draining the engine oil, some of which went into a styrofoam cup for inspection. In this cup, you can visually see metallic flakes floating around, which is not a good sign. The pictures above show these metallic flakes in the oil pan as well. He then removed the timing cover and found the problem:

Both the timing and oil pump chains had stretched out and were flopping around inside the timing cover. See that metal rod in between the chain guides in that last picture? That’s the oil jet that supplies the engine oil to the chain area. It was almost entirely rubbed through by the primary chain. These loose chains caused the teeth on both camshaft sprockets and both crankshaft sprockets to round down, losing grip on the chain. Both primary chain guides were worn out, and both the primary chain and the oil pump chain tensioners were all the way out, which you see. Notice the silver on the tensioner shafts? You shouldn’t be able to see that much of the shaft.

The metallic flakes in the oil are a scary situation because they may be internal engine damage that is unseen at this time. The customer had three options:

  1. Sell the car for a fraction of what it would be worth in working condition
  2. Repair the known bad parts and hope for the best
  3. Replace the engine with an 80k mile used engine (may end up having the same issues as this one soon) or a brand new rebuilt ($$$$$$$) engine

He opted to replace the known bad parts and hope for the best. After replacing these parts (at a cost around $2,600) and changing the oil & filter, the engine purred like a kitten. The customer is aware that unseen damage may have occurred and he could run into issues down the road, but he seemed happy with the results.

Want to know the kicker? Had he been the original owner, this repair would’ve been covered under Hyundai’s 10 year/100,000 mile powertrain warranty. Sadly though, he was the second owner and the warranty is not transferable.

A lot of people believe that a timing chain is a maintenance-free item, when the reality is, while it’s uncommon for these to fail under 200k miles, it can happen.

What steps can you take to prevent this? There is no surefire way, but what you CAN do, is change your oil at the suggested intervals. Engine oil breaks down over time, which is why it has to be changed. Sludge deposits can form, and the oil loses some of it’s heat dissipation capabilities as it breaks down. Heat causes things (like timing chains) to expand.