I bought a 2016 Honda Accord 2.4 Sport from a private seller for $16k about a month ago. Car had 102k miles on it when I bought it, and have only put about 600 miles on it since. When I met the guy to see the car, the car was already warmed up, therefore I didnt know there is a tapping noise when engine is cold. I’ve taken the car to have a valve adjustment done and it did not fix the issue. Mechanic that did the adjustment said it could be a piston slap or “pin” and doesn’t sound like a rod bearing. Again, the sound goes away after car is warmed up. Sound is coming from the 3rd & 4th cylinder area, below the valve cover gasket. What is the best thing to do at this point that is cost effective.. Search for a new/used engine? Drive it till it gets louder, or have something else done to it before it gets worse? based on the previous service records, it seems that the car was serviced and well maintained.
Another mechanic said I could try replacing all the lifters ($2k) but can’t guarantee that it will fix the issue. Help
make a video of the cold start and share the link here.
Will do as soon as I can and will post it today
Do you have any codes? Does the engine idle smoothly, other than the noise? Piston slap is caused by the cylinder bore and piston not quite fitting together perfectly, the piston head is slightly loose in the block, and it shifts back and forth as the engine runs, until it gets hot enough that the expanding metal seals the gap again. Generally, that's caused by insufficient lubrication, and it can appear in engines that have been driven really hard for an extended time. You might try running a compression test on the engine when it's cold and look for a deviation in compression. The cylinder with noticeably lower compression is indicative of piston ring/ cylinder wall or valve sealing problems.
You should find a better mechanic. He should know you can use a mechanic's stethoscope to listen to the valvetrain and see if the noise is coming from the top of the engine, or in the middle of the block, especially if he's charging $2,000 to replace something and not guaranteeing it will fix the problem. A spun bearing and rod knock is a pretty distinctive sound. It comes from low in the engine and has a heavy banging sound, you would know it if this were the issue.
Thanks Justin.
No codes. Engine idles a little rough until warmed and Feels like slight misfires when sitting in the car. I didn’t notice the idling when I first bought it a month ago, but did notice the pausing/idle feeling more recently.
Sounds like the next step is to have a compression test done to determine if there is a deviation within the cylinders like you suggested. Once that is determined, would I then need to take it to a machine shop to basically do an engine rebuild? The mechanic I took it too said that would cost about $5k.
Is there anything else it could be besides piston slap? Also, how long can it be driven in its current condition/what will eventually happen over time?
If you're a gentle driver, it should last a while. The sound is probably annoying. Don't rebuild an engine, nobody knows how to do it these days. With something like that, all they can do is bore out the cylinder and slightly oversize it to return to round. They would then have to use slightly bigger piston rings to make it seal again. That's very expensive, and only really knowledgeable guys know how to do it. You would be better off for the money looking for a new or used engine. See if your dealership can get an engine ordered. I DD an old Ford Ranger, and Ford still offers remanufactured engines and transmissions for them. I would take it to a really good mechanic to look at it.
Thank You for the knowledgeable feedback. Much appreciated
Forgot to ask. Will this issue eventually throw a code and not allow me to pass smog? Smog is not due till next year but just want to be prepared.
It may eventually. Essentially what's happening is the piston is wiggling in the bore, if that is the issue and it'snot lifters. The wiggle until it heats up will eventually wear the bore to the point where the computer won't be able to compensate and it will throw a Check Engine light. It'll probably come up as a misfire. Driving like a maniac when it's making noise will hasten the process. How long does it take for the sound to go away?
I’d say the sound goes away about 10 minutes or so after startup. However the tapping noise does not occur immediately after cold start, takes a few minutes to start tapping, then goes away 10+ minutes after tapping starts.
Would a good mechanic be able to tell if it’s a lifter versus a true piston slap? I would hate to replace the lifters then find that it didn’t fix the issue. I can make a video of the whole process of startup, tapping start, and when tapping goes away and post the link on here as well.
Here is a video I was able to do today. The tapping/knocking wasn’t so bad today and only lasted a few minutes. Other days it lasts about 5 minutes once it starts (previously I had stated it lasted about 10 min). I will take another video tomorrow to see if I can capture the knock/tap a little better, as some days it sounds more distinctive than others.
Scotty, your moderator has been a great help so far and has provided very helpful feedback. I’m a huge fan of yours and would love to hear any additional feedback and advice you may have as well . Thank You!
A good mechanic will be able to tell the difference. Post your next video under the "Your Answer" section and you should get a few more opinions on the source
Thx again. I just posted it as you suggested (hopefully I posted it correctly)