Question: Is there a product that quiets worn or older engines that actually “works”?
Answer: If you are looking for a mechanic in a can, the answer is no, as I know of nothing that will repair worn or damaged parts in an engine. However, there are several aftermarket additives that will help reduce some noise caused by wear or gummed up parts in an engine.
Knocking noises caused by collapsed or cracked pistons, worn main or rod bearings, badly worn valve guides or a worn timing chain cannot be fixed with chemicals. These require parts replacement. However, if the fault is slightly larger clearance, then using an additive that increases the oil viscosity will help reduce the noise. The thicker oil is now more difficult to force out between parts so there is less impact noise.
If the noise is a ticking sound, such as if a hydraulic lifter gets gummed up, some chemicals will help remove varnish and gum deposits from components in the engine. The lifter can then start working again. There are several brands on the market, so the best bet is to read the label to see if it is designed to remove gum deposits. If the lifter is worn however, the chemical won’t work. The lifter and possibly camshaft needs replacement.
Many of the aftermarket chemicals provide extra detergents, fiction modifiers and anti-scuff additives to help prevent wear or damage in an engine. I have always had excellent service simply by using quality engine oil, but in severe load conditions, an additive can help. They won’t repair your engine, however.
Question: I have a 2008 Impala with a 3.5-litre engine. It’s been in for service several times to check out a noise which seems to be coming from underneath the front of the car. It sounds to me like there’s a leak of some kind in the exhaust system. This only occurs when the engine reaches operating temperature and only during initial acceleration from a stop. Once normal running speed is reached, no further noise is evident. I’d say the noise started about six months ago, although prior to that, the windows would be generally closed during the cold months, so it may have been difficult to hear anything (especially if the heater/defroster fan is on during the winter). I thought this could be caused by the exhaust system heating up (expansion of the catalytic converter?), but why it wouldn’t persist when the engine is running at operating speed seems a mystery.
The dealer’s service department has been unable to duplicate the noise or pinpoint a problem, despite having the car taken in several times. Needless to say, I feel like the boy who cries wolf. Either that or I’m hearing things. If you could shed any light on this I’d very much appreciate it.
Answer: Finding a noise that occurs only under specific operating conditions can be difficult. The noise may sound like an exhaust leak yet really be something entirely different. Most exhaust noises are more noticeable when the engine is cold, but I have seen cracked exhaust manifolds that sealed when cold but leaked after they warmed up due to expansion. The leak couldn’t be heard at idle but only when accelerating, so a careful inspection of the manifolds would be one of my first tasks. Look carefully for cracks on the engine side of the manifold, as these can be difficult to see. Also look for leaks between the cylinder head and manifold. Sometimes these leaks will have some exhaust residue around them but not always, so don’t overlook any marks.
The noise could also be coming from an accessory mount that is loose or cranked. Torque all the bolts for the air conditioning system bracket, power steering and generator brackets. Also look for lines or hoses from the air conditioning or power steering that may be touching the body and rubbing. This can create a noise similar to an exhaust leak.
Finally, the noise could be coming from the fuel pressure regulator or a fuel line contacting body. Disconnect the vacuum line from the regulator and accelerate the car. If the noise is gone, the regulator could be vibrating and causing the noise. A fuel line contacting the body will amplify it.