Engine Noise on Cold Start of 2016 RDX
 

Hi everyone! Brand new to this forum. I have a 2016 RDX that I purchased new. It’s been a great vehicle and is the 6th Acura I have bought or leased. Now that I am older (and wiser - LOL!) I am keeping my vehicles longer and am approaching 96K on this one.

I recently had an oil change at my dealer. Soon afterwards I noticed an occasional ticking/tapping noise from the engine on a cold start. Not all the time - just some of the time. When it occurs, within a minute or so it is gone or at least drastically reduced. And pretty soon I can’t seem to detect ANY more noise until a day or days later on a cold start. Starting the car later in the day does not seem to trigger the noise.

The sound seems to increase with the engine speed. In poking around online it seems that one possibility is that such a noise can be due to engine oil not properly coating the upper engine parts due to a variety of reasons, such as the engine oil being dirty or not the right grade, oil level low, oil pressure low, or an issue with the oil filter. And with continued operation the oil eventually coats the components making the noise disappear.

I have checked the oil and the level does appear OK. And there has been no check engine light or low oil indicator (if there even is one). The issue does seem to have a higher probability of happening on a day that is colder (but not always). I wonder if the variability is related to the positioning of certain engine components when the car is shut off i.e. perhaps in some cases enough oil remains trapped higher up in the engine so the noise on the next cold start is missing? I am not a mechanic so this is a total guess.

I talked with my service advisor and he suggested the noise may be related to the timing belt, which I know needs to be replaced. I plan to change this out if I keep the vehicle much longer, but I am skeptical that the timing belt is causing this noise. If it is unrelated, I would prefer to get to the root cause of the startup noise BEFORE moving forward with the rather expensive timing belt / water pump surgery.

Can anyone provide guidance on what might be going on with my RDX? Thanks in advance!

I cannot understand how timing belt can be a source. I think it is related to hydraulic lifters. They can make ticking noise at cold start and the noise typically goes away once the engine is wormed up. In Florida, where you are (based on your profile), the engine can stay fairly warm and not produce the noise up until late in the day/evening, thus no noise on second start later on.

Sounds like the lifters. Only way to verify is by opening up the top of motor and examining it closely.

As far as I know, Honda has never used lifters in any of its engines until 2023.

There are no lifters. I had the same issue. Replaced the timing belt myself and the noise went away.

Oops my bad. I'm on other forums like Dodge and remembered the 5.7 Hemi motors can have the same issue lmao.

Correct. I was wrong. First Honda V6 with lifters was inroduced in 2023.

I appreciate the feedback everyone. I have attached audio from both a normal and abnormal startup:

RDX Normal Sound on Cold Start - https://recorder.google.com/629f5fa4...4-69a4209caa49

RDX Abnormal Sound on Cold Start - https://recorder.google.com/7ff7f3e1...4-aaf8fab0e260

To begin with, I would take a stethoscope and localize the exact location of this cracking noise.

Yes, this is the rattle my car had before the timing belt service. And the car had very similar mileage, somewhere between 90k and 100k. This service is scheduled at 105k. I was skeptical at first that timing service would solve it due to the nature of the rattle. But since this scheduled service was nearing, there was not much to lose.

Very interesting! Do you recall if your noise also only briefly after a cold start and even then only on some of the cold starts?

It occurred only in the mornings after the first start. Initially it wasn't frequent. And it was subtle. But it got worse over time. As for the length, it usually went away by the time I got out of the parking spot. At the end it became so severe, I thought I broke something in the engine. This was 1.5 year ago. The car is smooth ever since.

Thanks for the detailed feedback! Did you have an Acura dealer do the timing belt / water pump change out? I wonder if it is worth shopping around for this service as it seems rather pricy.

I did it myself. I don't trust the dealers here. Once they quoted me a brake job when my brakes were totally fine. They put down in writing that the brake pads are 1mm thick. In reality they were at around 6-8mm. Another time I asked for transmission flush. All they did was just draining the transmission fluid and refilling it. That's 3 quarts. Transmission holds 9 quarts of fluid. If I had to, I would look for a good mechanic instead.

Same here. My wife's 13 RDX Tech did exactly the same thing. IIRC, almost from the time we bought it with ~60k miles on it in 2018. At the time I was researching the issue, the (few) prevailing opinions I was able to find, indicated it was the timing belt tensioner. It made an awful racket till the car was warm. Since the engine was not in danger of going "kaboom," I left it be. When I had the TB replaced at ~115k miles...the noise on startup went away.

I appreciate the feedback. Do you recall, at least in the early stages, on a cold start, if sometimes the noise was present while at other times the noise was not present? This is currently what seems to be happening to me.

Two things:
-It's my wife's RDX and I rarely get behind the wheel, though I could certainly hear the noise if I was around when she'll started up and pulled away.
-It's been 3yrs & ~75K miles since the TB service.

Having said that, it's my (feeble) recollection the RDX didn't make the noise every time...just almost every time, till the TB service was performed.

Hope that helps.

Cruising forums regarding (another) noise and came across this. There were two correct replies, I'm just weighing in to state that the noise you posted is most definitely a weak timing belt hydraulic tensioner assembly. It causes the timing belt to rapidly slap against the timing covers from excess slack. They famously wear out just before the 105K TB interval and cause this. It usually goes away after the engine warms up a bit.

Thanks for the heads up!

What about the age? Mine started ticking exactly 7 years after installation (the minder says 105,000 miles or 7 years). It's been ticking for six months now when cold, but I haven't gotten around to replacing just the tensioner yet.