2016 Accord - Rattle On Startup, Intermittent Oil Warning Light

All good points. I will definitely send oil off to Blackstone in a few thousand miles. It is something I was planning for the recently built engine in my E30 anyway to keep track of break in, so Ill just pack up a second vial. Fingers are crossed that no significant damage has occurred. In 20+ years of driving, this is the only car I have ever had where an engine oil light flashed for any reason other than a total failure of an oil pump.

It sounds like 7k may be high for a service interval on the K24W engine. For sure it is considerably more complex than its predecessors, particularly the one in the 2003 Civic my wife had prior to this. That car was amazing...nearly zero issues in 250k miles with just basic maintenance.


Quality synthetic oils will easily do 5k on street engines that are not abused, but the factory spec 0W20 is pretty thin and from what I understand it is more subject to breakdown than 30W oil. I run 5W20 since it almost never gets down to freezing where I am. Anyway, assuming the oil analysis does not indicate shot mains or cam journals, I might as well switch to a 5k interval.

The car must have known I was asking around about it lol. Here's a little update after driving the car this evening. I went to grab dinner, and it was just me in the car. Radio and HVAC off, just listening for noises.

When cold it didn't make many or any odd noises. However, while idling in the drive-thru line (fully warmed up at this point) I was definitely getting an audible rattle pretty consistently. It is never super easy to tell where these things come from, but it strongly seemed like it was from the left-front of the car. If I put the car into neutral, the noise would go away. If I turned the steering wheel more than ~150deg from center (holding it or not) the noise would go away. When I let off the brake (in drive) to start rolling, it would go away. It would seem that maybe I have been confounding two separate issues. Now that I came across a video of the valvetrain noise (linked below), the main difference is that the valvetrain noise is higher in frequency than the rattle I heard tonight (and really, it is probably what I have been hearing on the rare occasions when both the radio is off and nobody is talking with me in the car while sitting at idle).

This seems like it could be an engine mount or suspension thing. All of those items are original still (5.5 years / 75K miles). I would guess that it could be engine mount related since the engine loading seems to have a direct effect, but the steering angle thing indicates suspension. There are zero audible rattles from the front while driving, and no clunks or anything when switching between reverse, drive and neutral. Naturally, when I got home the car would not make the noise in the driveway, so I was not able to pop the hood to try to narrow it down.

I found this post (link below) with a video clearly showcasing the sound of a low oil engine with the valvetrain rattling away. The sound I heard tonight was distinctly NOT the same as in the video. However the sound I heard when the oil was getting old and low was definitely very similar to the video, albeit I was only hearing it in <1sec bursts, I don't think it was nearly as loud, and only when cold for at most a week or two.

OK, updates. I replaced the CCT, its filter, the VTC strainer, and the PCV valve. The result is no more rattle at start up, and as far as I can tell the engine runs a little quieter overall.

The original CCT shows some signs of light wear on the moving parts, but nothing egregious. It did not seem to be extended excessively; it looked like ~2 teeth were exposed above the top of the CCT body. That presumably bodes well for the timing chain NOT being stretched (and as far as I am concerned, "stretch" is not really the right term since chains do not stretch in the sense that links get pulled into yielding, but rather it's wear on the link pins and the bores they run through, causing more slop at the joints and allowing the chain to effectively lengthen). After taking it apart, I think that I have at least some idea of a possible cause, which aligns with what TSB 19-019 says regarding internal check valve wear. The original CCT filter was clean and did not have any crap in it.

The VTC strainer was not damaged, but there were little chunks of crud in it. Said chunks seemed to be bits of Hondabond as far as I could tell.

I have no idea what condition the PCV valve was in, but at least I can rule out excessive oil leakage from it with a new one in there.

Regarding the other rattle / shudder that I have observed at idle, it still persists, but I am 99% sure that it is an engine mount. When idling and producing the rattle, with my father in the driver's seat pressing the brake (the rattle does not occur if in Drive with the parking brake, only in Drive with the main brakes applied), I went under the hood and was able to hear it a little. The engine was also moving visibly more when the rattle (more audible in the car) was occurring. If I grabbed the engine by the back of the valve cover and pulled forward with maybe 40lbs of force, the rattle would go away. So, being that the rattle is very dependent on RPM and engine loading, and pulling on it stops it, it seems like a classic case of a dying mount. WHICH mount is the culprit is going to be more work to parse out, and they are expensive enough that I do not intend to replace them all, so I will need to dig in next weekend and pull the battery, air intake box, etc. to get a better look. Hopefully it is the front one since that is the easiest to access.

Anyway, enough talk. Here are a bunch of photos that I took today, which will hopefully be useful as a reference to others.

Here are the parts that I replaced today.






The new CCT came with the locking tool...I sort of wish that office supply stores sold push pins of this length lol. That would be useful for all sorts of other stuff!




The CCT filter, which is considerably more expensive than the CCT itself, is a nice little piece of laser cut stainless steel. My engine had one in it (others have said that their engine was missing it from the factory), so I could have cleaned and reused it, but since I already had the part I chose to use it.

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This is the new VTC strainer. It is, thankfully, SUPER easy to replace this.




To get at the CCT, you just need to pull the right front wheel and pop out several of the plastic expansion clips that hold the splash guard in place. I removed the metal underbelly cover and some of the lower front clips, and this allowed the guard to be moved entirely out of the way. I folded it onto itself and tied it out of the way.






The CCT cover is very easy to access. Remove the 3 bolts and gently pry with a screwdriver as shown to pop the cover loose from the Hondabond. Prior to removing it, I used a toothbrush to knock out as much dirt and dust from around the cover as possible.








Now, if you happen to be messing around with the new CCT and accidentally expand it all the way, it is pretty easy to reset if you have a vise (doing it by hand would be possible, but a bit of a hassle). Gently apply a little closing force on it until the locking pawl is retracted as shown in the first picture. Then use a finger to hold it in that position as you compress the piston. You need to prevent the pawl from dropping in at all, otherwise it will catch and you CANNOT force it closed without damaging the thing (probably destroying it). Once it is fully compressed, you can release it a little until the top notch is engaging the pawl, compress it down again (just slightly) and insert the locking tool.






When you are looking at the one in the car, here's how it looks when it is "fully engaged." This is when you stick the locking tool in. After you insert the tool, rotate the crank counterclockwise 45-90 degrees until you can tell that the guide is minimally engaged with the CCT. You definitely do not want to loosen the bolts securing the CCT when it is in this state since the cams are under a lot of load from the valvetrain and things could jump.




Here it is "disengaged" with the tensioner rail WITHOUT the locking tool installed. Do not loosen the bolts securing the tensioner when it is in this state or you are going to be set up for headaches. You will be removing the CCT when the engine is effectively in this state, but you will have the locking tool holding the CCT piston down. If the tensioner is allowed to expand while it is still in there, you will have a hell of a time trying to get the pawl into the fully disengaged position, pressing the piston down, letting the pawl reengage, and inserting the tool. If your CCT is extended more than 2 or 3 teeth past the top of the body, I'd suspect that there is severe chain and/or guide wear in your engine, and you should consider rebuilding the timing chain assembly. Getting a CCT out if it is 4+ teeth extended is probably a major pain in the ass.




Once the CCT is locked in the "fully engaged" position with the crank rotated so that the chain is "fully disengaged", you can unbolt the CCT and carefully wiggle it out. Basically, let it drop down a little so that the notched top of the piston gets out of the slot in the guide rail. Then wiggle it out. Try not to scrape metal on metal, and don't knock dirt or other crap in there. Oh, one thing that I learned the hard way...a bunch of oil will spill out from behind the CCT, and it is all too happy to go right out of the engine. Stuff a rag down below the opening to avoid a mess on the crossmember and your floor.




Don't drop any fasteners in to the engine, or the CCT filter. From here, you just need to pop the new CCT into place and do some cleanup of the old Hondabond. Try not let chunks of it fall in, but as long as the a CCT is in place none will get anywhere critical. The main oil filter can handle any little bits that fall in to the crank case, although it's better to avoid that. To be honest, I found that a rag with 99% isopropyl alcohol was more effective than a scraper for Hondabond cleanup, at least for the thin films. A window scraper worked well on the cover and thicker chunks.

Carefully put the new CCT in without dislodging the locking tool...the locking tool only inserts a couple of millimeters and is not held very securely. You will notice that there is a lot of play between the CCT body's holes and the mounting bolts. I used a screwdriver to slightly lift the CCT up so that the bolts were approximately centered in the CCT mount holes...letting it sit all the way down didn't seem like the right move to me. Anyway, the TSB says nothing about this, so it's your call. Also, when removing the locking tool, I did not let the piston fully release on its own...the timing chain is a bit loose during all of this, and having the piston snap hard against the guide seemed like it could potentially make the chain whip around / jump a tooth. To release it slowly, I put a flat blade screwdriver between the ledge on the piston top and the outer edge of the guide rail slot and turned the screwdriver to compress the piston a little so that the locking tool would be released (do not let it fall into the engine). From there I rotated the screwdriver to allow the piston to slowly rise and meet the guide rail. Thereafter, I rotated the engine through a few full revolutions (counterclockwise, slowly, in 45 degree increments) to make sure that everything was properly engaged and functioning as expected. Once confirmed, I slapped some new Hondabond on the cover, carefully toed it into place (toe it in behind the crank pulley and then seat it to avoid smearing it all over).

It goes without saying that you should not rotate the crank at all when the CCT is removed. Do not do it. It's a recipe for a skipped tooth and a destroyed engine.

Follow the TSB and ONLY remove the CCT when you have rotated the crank such that the chain guide is in the "disengaged" position with the CCT in the "fully engaged" position. The disengaged position is reached when the cam lobes are approximately in between maximum lift positions, and the cam is not experiencing reaction torque from the valvetrain. Removing the CCT when the chain is in the "engaged" position would be a tremendous mistake since the cam is up against a substantial load from the valve springs, and pulling the CCT at that point could easily cause the cam to rotate very quickly and allow the chain to jump a tooth.

As far as the VTC strainer, it's super easy to deal with. Two 10mm bolts, a little gentle prying, and that's all there is to it. Again, stuff a rag below it because a bit of oil will spill out.




My strainer had some crap in it...probably Hondabond. You could very easily clean and reuse it, but I don't like reusing compressed o-ring seals so I replaced the whole thing.

As far as the old CCT and my inspection of it, there was light wear as I noted at the beginning. There are two check valves inside, a lower and an upper (upper is in the piston). As far as I could tell, the upper one had crapped out and was not holding any pressure. My guess is that it is designed to create some amount of back pressure to ensure that sufficient oil pressure exists in the CCT piston to keep the chain adequately tensioned. If the spring inside breaks or loses stiffness, it will not allow proper oil pressure to develop. This post is getting pretty long, so I will just dump the rest of the pics below lol. Feel free to ask questions.

Blackheart said:

Fantastic post! You could work on my car any time!

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Ha, thanks for the kind words. I learned the hard way, many many years ago, to take my time and triple check things. The alternative is usually an unfortunate result!

LarryP said:

Thanks for the detailed write up!! I suspect I'm getting to a CCT replacement myself, just trying to determine difficulty level to doing it myself. On the other hand, not sure I trust a dealer to do the required fulsome/proper job either.

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Difficulty was low, in my opinion. You just need to take the time to get a good look at what is there, and do not rush when removing the CCT bolts so that none fall into the crankcase. I can definitely see how it might happen if someone was just blasting away on the bolts with a socket extension...keep a finger on the bolt head as it becomes loose so that it comes out with the socket lol. The hardest part, I felt, was getting the cover back on with wet Hondabond. It's a cramped workspace, and toeing it in behind the crank pulley before seating it seemed to make the least mess.

andrewtl96 said:

Yup, cam/timing chain tensioners are a bit more complicated than they look. Regarding the noise when idling & you holding the engine it going away, I'd be suspicous of the exhaust & flexpipe, especially if you live where rust is an issue. A bad or worn engine mount can exaggerate this.

My G35's had a very similar designed CCT design. I replaced it one of them that had a cold start rattle. Problem was solved. The G35 service manual also had two notes for when replacing the CCT:
- After installing new or reinstalling CCT, were supposed to run the engine at 3k RPM for a brief period (can't remember exactly, I want to say 1 to 2 minutes) to charge the high-pressure chamber
-It also noted that over-torqueing the fasteners that secure the timing chain tensioner can damage the internals.

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Now that you mention it, there is a slight rattle at/around the flex pipe. Since I did not see anything obviously loose or torn when looking, I started tapping on stuff with my fist to see of odd noises resulted. The flex pipe definitely had a little metallic rattle to it. However, it seemed far too high pitched to be what I was hearing at idle. Still, maybe it is related.

Based on the unhappy noises that the engine made for ~2 seconds after the first start with the new CCT, I'd say that it takes about...2 seconds to fully charge the CCT in this engine when idling. Some of that might have also been from air being pushed through the VTC actuation system as well, since I changed the strainer. Whatever the case, it runs nicer now!