My 97 Honda Accord LX recently occasionally has one knock sound while acceleration. I read it could be the carbon buildup in the engine. Is it safe and effective to use the Seafoam clean the carbon buildup or you have other better ideas to resolve the knock sound problem while acceleration? Thank you for your answer.

 

first thing I would do is a tuneup of cap, rotor, plugs, and even wires if they're old enough

 

Sea Foam is the bees knees for removing internal engine varnish and carbon buildup. If your engine has over 100Kmiles, follow the instructions and use it. Another area to look at is the EGR ports/manifold. On 94-97(CD Chassis) Accords the EGR system is very easy to maintain and clean. In the 'Accord FAQ' at the top of the page there is a very detailed writeup on how to clean the EGR passages for the 94-97 cars.

Like holmesnmanny mentioned, check the plugs, wires, cap+rotor. If these are worn or oil fouled it can cause a misfire which can cause knocking or detonation from an incomplete burn or uncontrolled burn.

 

I got the Sea Foam but do not know where I should add to the vehicle, the oil tank, gas tank, plug holes or where else. The instructions indicate added to crankcase; added to gas or diesel fuel tanks; used in fuel line, vacuum or induction systems and used in small (2-cycle or 4-cycle) engines. Does it mean I should pour the Sea Foam into both of the gas tank and oil tank or somewhere else? Can you explain how to add the Sea Foam? Thank you.

 

make sure the car is cold...start it up and undo the brake booster hose and pour a little bit into the hose that goes towards the intake manifold a little at a time...if the car stalls at any point in time make sure you do not pour any more inside until the car is started again...pour about a 1/3 into the booster hose, 1/3 into the gas tank and 1/3 into the crank case. However only put some into the crank case if you plan on doing an immediate oil change. That stuff is only designed to be idled for a few minutes before draining it with the oil. It's not oil.