Xzn31

My 2007 Acura TL Type-S just recently had its 105k service and the valves are now LOUDER!

Around 2000rpm it makes the clak clak clak clak sound that a diesel makes. It's not super loud but if you listen you can hear it as long as the fan & stereo is off. It doesn't do this when it's cold, however.

Brought it back to Acura of Sunnyvale and they said they "went over it again". Hooked it up to some vehicle map sensor and said all the valves are within spec and good.

Service manager said the noise is normal and should go away after about 3000 miles as the valves tighten themselves on this engine type.

Are they blowing smoke in my car? What can I do? They just dismissed it.

nismopowerdqg

take it to another reputable shop and get a second opinion, valves shouldn't be louder when a valve job is done.

Xzn31

So I took it to a shop and a mechanic said I have carbon buildup.. possibly noisy lifters. Worse case but he HIGHLY doubt it, it's a rod.

It sounds slightly like a diesel engine around 1300-2500 RPM. But it ONLY does it when the engine is hot. Which is why he dismissed the valves.

Makes sense I guess? Seafoamed it twice. Still the same.

Should I switch to thicker oil? like 5w-30?

I hate cars

It's odd that it would start after the dealer touched it. Make sure it's not stuck in vtec. Any decent mechanic should be able to tell the difference in valvetrain noise and a rod knock. A rod knock is a solid knock that sounds like the engine is going to come apart at any second. It gets worse as the oil warms up. It gets worse under load. Valvetrain noise changes with rpm but load makes no difference.

Seafoam should never be put into the oil or through the intake. It's very bad for the engine when put into the oil especially if you drive the car with it in there. Through the intake can cause several issues. as well.

Have you checked the oil level?

Wacker

Possible pre-ignition (spark knock) maybe? Mine does this on very hot days with cheap gas in it. Its not a steady sound though. Just happens for a second when I blip the throttle quickly. What grade fuel are you running? Try filling up with premium from a different gas station than you use normally.

Xzn31

Well. I need to add detail to my first post.

All service for the vehicle has been done at the dealership, but the owner did the 105k service here and sold me the car after. I called him shortly after buying the car and he said the noise was from after the 105k. Not sure but he seems like an honest guy. There is room for discrepancy though. Since the dealership has an entire folder full on maintenance from the day it was purchased, they've been somewhat willing to help me figure it out, but currently they are pretty much "sorry, it's not valves, it's normal"

I always use Chevron 91 octane. Noise only comes after 10 mins or so of driving, regardless of temperature.

I put seafoam through that hose in the DIY section. Funny. I can almost swear the ticking / knock is louder now.

I searched around youtube, and it sounds slightly like this video @ 0:49. Except in the video it's a slightly deeper & louder knock and mine is a little lighter & quieter sounding. I attempted to make a video recording but I can't get it onto my cheap camera.

I hate cars

The guy in the video doesn't realize that the knock gets worse when he puts a load on it, as the rpms are climbing, not so much when they're steady state.

Hold the rpms at a steady rpm, maybe 500rpm increments, note noise. Put it in gear and power brake with the car stationary, which is worse?

A rod knock is a dull, deep sound. It will make you want to jump clear of the engine. Many people mistake other things for rod knock but once you hear it, you'll never mistake it for anything else.

Usually a hurt piston will be worse when cold but not always. A rod knock will always get worse the hotter the engine gets.

If you really want to separate valvetrain noise from piston/rod noise, pull one coil wire at a time and see if the noise goes away on a certain cylinder. If the noise goes away on a certain cylinder, you have a piston/rod issue. If the noise never changes, you have a valvetrain/pulley/other issue.

Xzn31

I can re-create the noise in Park/Neutral and as if I was in gear. Can't hear it until 1,400 RPM. It goes with the RPM, but after 3000 you can't hear it as the engine's deep standard "roar" overtakes it.

Also after I seafoamed it, when I started the car I got rod knock for a second, then it went away. Sounded identical to this video: . But it has been a day since and didn't get any of that sound.

I hate cars

Have you checked the oil level?

If the noise changes with rpm but not load, it's probably not a rod knock but it's probably time to start pulling coil wires to verify, it could still be a piston. When you spin a rod bearing, it follows a very predictable pattern. It gets worse with time, worse with temperature and much worse under load. It always knocks once warm and under load, it's not intermittent.

Is there a squeak when it knocks?

Xzn31

Oil is up to the full mark - Mobil 1 5w-20.

For giggles I took it to a shop by my work and he thinks it's valves. But if it's valves, shouldn't I hear it from idle - 1,400 RPM?

And my theory behind the whole only makes the sound when it's warm is maybe the oil thins? Or should I hear the valves ALL the time regardless of temperature?

Xzn31

...could it be the timing belt tensioner?

flytldr

The 2007- and early 2008 TL S models have an issue with spark knock. This is a 'known' issue with these models, but Honda has no repair for them. I had my car to the dealer so many times, they brought in Honda's field engineer to diagnose it. He told me its a problem with too much heat in the cylinders, combined with the ambient temp, combined with relative himidity(as this affects the amount of oxygen in the air), combined with fuel that has slightly too low of octane rating(89 or lower), and combined with the aggresive air/fuel mapping in these particular models(only the 3.5L's). His answer to repair it, as ALL attempts by himself and the dealer had failed) was to run the highest octane gas I could, and only from a reputable gas station.
Oh, and he also mentioned, that has stations start to change out their fuel formulations around this time of year to prepare for winter season. This changes the fuels chemistry, but not the octane rating, and this can also be a factor.
Even with all of his suggestions, as I run nothing but 94 octane from Sunoco, I still get the odd day I get that nasty spark knock noise. It drives me nuts!
But I will say this, since I've switched to 94, I get the noise VERY rarely now.
My spark knock can start anywhere from 1400 all the way up to about 2500. But it only happens at just the right temp, throttle angle, and engine load. So I try to stay out of that range as well.
The car does run a ton better with that fuel. More power too! But it's costing me an arm and a leg to fuel this girl!!

Hope this helps!
If you find a fix, PLEASE let me know!!

Cheers!

I hate cars

You will never get knock under steady state rpm without a load on it (in park or neutral).

One or a few rockers can be on the vtec rocker which makes noise at lower rpm.

Xzn31

After 2 weeks of moaning and bitching, Sunnyvale Authorized Acura finally took it in and did another valve adjustment. They said the intake valves on cylinder 1&5 were off, and it looks like the tech never adjusted the intake valves.

Sounds like butter again..