Engine noise diagnostic testing on an Infiniti QX80.

Engine noise on an Infiniti QX80

In Diagnostics by Steves Auto Repair and Tire

As your vehicle ages, you may begin to notice abnormal sounds or behaviors.

Maintaining your car through oil changes, mileage-based services, and the replacement of old parts can prevent a lot of problems. Some issues, however, can’t be avoided.

An Infiniti QX80 was making an engine noise recently. The driver brought it to our Woodbridge auto repair shop after hearing a whining sound that would go away when the vehicle warmed up. The car wasn’t too far along in its mileage – just a little over 120,000 miles.

Engine noise diagnostic testing begins

Our technician started his investigation, which involved the removal of many parts. This included the oil pan, the timing cover, and the 32 bolts that hold the cover on. Timing chain.

The cause of the engine noise, he found, was the timing chain rubbing against the timing cover. The tensioner was also out further than it should be.

Timing chains ensure that the camshaft and crankshaft, components that control the opening of an engine’s valves, are in correct timing. Overtime, they can stretch and begin to bounce around.

In addition to getting new timing chains, the Infiniti QX80 will receive a new timing chain tensioner and new timing chain guides.

New timing chains, timing chain guides, and a timing chain tensioner.

New timing chains, timing chain guides, and a timing chain tensioner.

The timing chain’s connection with other parts

For one of these engines, you may or may not get a PO340 code, which has to do with the camshaft position. It’s a sensor, so sometimes it can pick up if there’s some slack in the chain. 

Along with this particular vehicle, it would actually make a whining noise, not necessarily a rattling noise. If the chain was loose enough, you would have a rattling noise.

The other thing that’s important with these timing chains is the oil pump is right in front of the engine and is driven by the timing chain. On a couple of the camshafts, you have variable camshaft sprockets that are all oil controlled and driven off of the timing chain. There are many components that are connected with the timing chain.

Depending on what year it is, there could be an updated crankshaft timing gear. 

It’s also important to know that as the timing chain begins to stretch it can start to damage the oil sprayer. This requires a special tool to pull out and put back in to make sure the timing chain has the correct amount of oil, so it will last.

Maintenance and research

This timing chain problem is one that the company has had with its engines. Unfortunately, there isn’t really anything you can do to prevent this issue. It’s going to happen, even if you do take care of the vehicle.

But don’t let that discourage you from maintaining your car. A lot of other problems can be avoided with regular checkups. (Regular oil changes, for example, can prevent engine damage.) Also, if something were to happen to a part – knock on wood – you may be eligible for warranties, because you kept up with the recommended maintenance services.

Other than making sure your car’s basic needs are met, we recommend doing your research. Read your owner’s manual, and look up whether there are any common problems associated with your particular vehicle. That way, you have an idea of some potential issues to watch out for.

Steve’s Auto Repair & Tire is an authorized Goodyear tire dealer located in Woodbridge, Virginia. Automotive repair services are performed on all makes and models, including BMW and Mercedes. Services include oil changes, brakes, alignments, inspections, and computer engine diagnostics.