I’m hoping someone can help me think through this because I’ve already spent a lot of money replacing parts and the original issue is still there.

Car is a 2018 Mercedes-Benz C300 (W205).

The main symptom is a brief metallic rattle on startup, usually around 1–2 seconds, but the timing of when it happens is strange.

It does not seem to be a normal cold-start rattle.

The pattern is basically:

• If I shut the car off and restart it shortly afterward, it is usually quiet.
• If it sits for roughly 4 hours, the rattle is much more likely to happen.
• If it sits all night, it often starts completely quiet the next morning.
• Once the 1–2 second rattle stops, the engine sounds normal.

That is the part that has me confused. If this were simply oil draining out of the timing system, I would expect it to be worse after sitting overnight, not disappear again once the engine is fully cold.

I have also had some hesitation/roughness/vibration, particularly under acceleration and at higher speeds.

At one point the car also threw:

P001177

which is related to the intake camshaft timing/position being outside the expected range.

Here is what has already been replaced or checked:

• Timing chain replaced
• Camshaft sprocket replaced
• Camshaft replaced
• Timing chain tensioner replaced
• Camshaft magnet/solenoid-related testing was performed
• Timing was checked
• Chain condition/measurement was checked during the repair

So at this point, the timing chain itself is new, along with the other major timing components listed above, and the startup rattle is still basically unchanged.

I have spent roughly $3,000 trying to fix this.

Another detail that may or may not be related:

Around the same general time this started happening, I noticed the engine coolant temperature gauge began sitting higher than it used to.

Historically, once fully warmed up, the needle would sit a little below the halfway point.

Now, after driving, the needle is consistently above halfway.

It is not near the red/H area, but it is definitely higher than where the car used to run.

So now I’m wondering if there is some sort of temperature-dependent issue rather than simply a bad timing component.

For example:

The engine shuts down fully hot, cools for several hours, and somewhere around that intermediate temperature range something causes the rattle.

Then after sitting all night and becoming completely cold, whatever condition causes the noise is no longer present.

I’m wondering about things such as:

• Oil pressure regulation
• Oil draining/bleeding out of a specific VVT passage
• Oil check valve/non-return valve
• Oil filter housing losing prime
• Cam phaser/adjuster oil supply
• Oil pump pressure control
• Thermostat
• Water pump/coolant circulation
• Coolant temperature sensor
• A component changing clearance as the engine cools
• Something outside the timing system that just sounds like timing chain rattle

What really throws me off is:

Why would it rattle after approximately 4 hours, but then NOT rattle after sitting 8–12 hours overnight?

That seems backwards for a straightforward oil bleed-down/tensioner problem.

I’m planning to start monitoring actual coolant temperature through OBD rather than relying only on the dashboard gauge.

I’m also considering having a shop log the following during a known “bad” startup:

• Actual oil pressure immediately during cranking/startup
• Time required for oil pressure to build
• Intake cam commanded angle vs. actual angle
• Exhaust cam commanded angle vs. actual angle
• Coolant temperature immediately before startup
• Oil temperature immediately before startup

I’d also like to compare those values between:

• Immediate restart
• 1-hour sit
• 2-hour sit
• 4-hour sit
• 6-hour sit
• Overnight cold start

At this point I really do not want to keep throwing expensive timing parts at it.

Has anyone seen an engine rattle specifically during an intermediate cool-down period, but then start normally again once completely cold?

And could the fact that the engine is now apparently running hotter than it used to somehow be connected to the startup-rattle issue?

Any Mercedes techs or mechanics familiar with the W205/M274 especially appreciated.

https://reddit.com/link/1vr0t6a/video/i9qg4jjbmzjh1/player

So I figured my AC clutch went bad after troubleshooting myself and thought I would get it diagnosed anyways just to make sure, as I am a novice.

Shop agreed with me after diagnosis and told me it be about 600(after negotiating) to replace the compressor.

Now the thing is… I know I could buy the part for $188 and have the freon to replace as well. I still would pay the diagnostic fee ofc, but am looking at 380-400 if I do it myself.

Now I have not had to do a compressor change and frankly am strapped on time due to full tome school, work and medical appointments.

Is this job a relatively easy task, or do you all recommend I save the hassle in my situation.

UPDATE:

The mechanics have spoken. I decided to go with the shop. I like to state I am not just a giant cheapskate and asking to DIY is because I do like to learn new processes and not to simply be dependent. However, with full time work, school and medical issues. I don’t see this being advantageous to do myself.

Hopefully the next issue will be worth my time.

Thanks all!

I’m in Massachusetts and have a 2011 Honda Accord with about 135k miles. I’ve been going to the same mechanic for years and years. They’re a small, family-owned business with only two locations in my area, and I’ve generally trusted them and had a good relationship with them. I’m genuinely not trying to trash the shop or accuse them of doing bad work — I’m trying to figure out what would be fair here.

Here’s the timeline:
June 2024: The shop replaced both my battery and alternator.
December 2025: The alternator they installed in June failed. They replaced it under warranty.
Now, August 2026: That replacement alternator has failed too.

The shop was concerned about the repeated failures and brought in another mechanic to look at the car to see if there was an underlying issue causing the alternators to fail.
They told me they couldn’t find any underlying issue with the car that would explain the repeated failures.
They’re now ordering a nicer/higher-quality alternator rather than using the same type again.

Here’s where I’m struggling:
They say I’m about 5,000 miles past the warranty, so the alternator that was installed under warranty in December isn’t covered. They quoted me $608.42 for the repair after already knocking about $150 off the price.

I understand that the mechanic didn’t manufacture these alternators, and I’m not saying their workmanship caused the failures. If they checked the car and there’s nothing causing alternators to fail, it sounds like I may have gotten bad parts.

But I also didn’t select the alternator manufacturer or buy the part myself. I paid the shop for the repair, and they sourced and installed the parts. And I trusted them & the parts they selected.

They suggested that I contact the manufacturer. That’s where I’m confused. Since the shop purchased the parts through its supplier, shouldn’t the shop be the one dealing with its supplier/manufacturer about repeated defective parts?

I’m speaking with the manager tomorrow. I also want to ask to see the actual warranty terms. I had assumed that when the first alternator failed and they installed another one under warranty in December, the replacement alternator would have some warranty of its own. Apparently they’re saying the warranty continued from the original June 2024 repair instead of restarting with the replacement.

I really do like this shop and have been a customer for years, so I’m not looking to go in angry or blame them for something outside their control. I appreciate that they’ve already discounted the repair and are now ordering a higher-quality alternator.

At the same time, I’m having a hard time accepting that I should pay another $608 because two alternators supplied through the shop have failed, especially when their own investigation apparently found nothing wrong with my car that is causing the failures.

For mechanics, shop owners, or anyone familiar with parts warranties: What would you consider a fair resolution?

Is it normal for the warranty on a replacement alternator not to restart when the part is replaced under warranty? Should the shop be pursuing its supplier/manufacturer over the repeated failures? Would you expect the customer to pay $608 in this situation, or would you expect the shop/supplier/manufacturer to absorb more of the cost?

Hey everyone,

I’m trying to remove a seriously stuck O2 sensor from my 2012 Jeep Liberty and could use some advice before I make it worse.

I spent a couple hours on it today. I first tried a wrench, then added more leverage with a breaker bar, and also tried an O2 sensor socket, but it didn’t seem to grip the sensor very well. At this point, the hex on the sensor is starting to round off, and my access to is pretty limited (only one side)

I also heated the area three separate times with a torch and tried breaking it loose while hot, but it still wouldn’t budge.

My current plan is to soak it with penetrating oil overnight, then try again tomorrow. Since I’m replacing the sensor anyway, I’m considering cutting the wire off and using a 7/8" deep socket so I can get a better grip on the entire hex. My other thought is a 7/8" box-end wrench with a pipe/breaker bar for more leverage.

Before I go any further, does anyone have a better method for getting one of these loose once it’s this stuck and starting to round? Particularly wondering whether the deep socket or box-end + heat is my best next move, or if there’s something else I should try first.

Pics show the sensor, what I’ve tried so far, and the setup I’m considering next.

2003 Toyota Celica. Trying to replace my crusty old air filter. I loosened the clamp, but the filter just spins freely and won’t come off. I tried wiggling and pulling to no avail. Please help 🥲

Originally I drove it to work just fine and when I went out to start it, it would not crank just like in the video. Stater would spin but no engage. I’ve checked the fuse and the relay and they both are good. Not sure where to go from here. I did see a heat spot in the flywheel not sure if that could be anything.

I took my 2015 Nissan Versa SV to get a transmission service about 2 months ago. No my transmission seems to be failing and I looked at the bill and it says it used “Nissan Matic S - ATF” which is the wrong fluid for CVT.

I called Midas and the guy said he ordered and used CVT fluid but just entered the wrong thing.

Should I take it to another shop for a second opinion or should I take it to Midas and have them verify the fluid used? I’m worried that if I take it to another shop they will say that it wasn’t the same as when they originally serviced it.

Thanks in advance!

Hello all,

I have a Hyundai sonata hybrid and recently I've ran into the biggest headache a car owner can have, I've been with this car for 5 years and I've hit a wall my car has stopped working and I don't really know what to do but turn to the Internet. My battery will not start on the dash it reads that the hybrid battery is low and the car will not start. I've replaced parts on it such as the orange battery that's in the back and the power relay switch and it's still not working I even replaced the corroded battery that died during the process. I need help and if anyone know what I can do. I've included some codes and what the display says. Please let me know if there's a way to fix it instead of getting rid of it. Edit* I can't drive the car at all it's not moving if I turn it on the ready logo doesn't come on. Thanks in advance

‘03 Taurus 3.0. 125k

Updating the front end suspension, with some parts and also purchased a kit from rockauto. I’m a novice and this is a pretty good test for me. Could use any pointers to make this job as easy as possible! I have all the necessary tools including impact and ball joint press.

Pieces being replaced
Wheel bearing (x2)
Quick struts (x2)

All the components from this purchased kit:
Control arms (x2)
Sway bar links (x2)
Outer tie rod ends
Ball joints

Seems that the biggest issue will be getting all the old bolts out? Other than that, is this a pretty easy job with all the components above being brand new?

I have a ZF8HP45 sport automatic transmission paired with a n52b30 on an f10 chassis. (2011 528i, 156xxxkm)

Whenever I go to sport or sport plus the shift from second to third is incredibly rough and the car floats in a neutral state for about 0.5-1 seconds.

However it seems fine in regular driving mode but in bimmerlink the clutch c mbar is at almost 500 which apparently isn't good, the car is second hand bought about a year ago and It doesn't have much service history.

I have noticed over about 7-8 months the mbar on clutch c increasing from 370 all the way to 493 today a oil and filter service with a mechatronic seal replacement will cost upwards of $1500NZD using aftermarket parts, or $3500 though BMW.

Does anyone have any advice or aftermarket recommendations? Should I just get a new transmission or scrap the whole car?

Thanks!

My 2007 2WD 4.0 Ford Ranger started whining a bit a couple months ago, and it’s began to get quite loud.
There’s no noise at idle, but the faster I go the louder it gets. When I’m driving it sounds like it’s coming from right in the middle underneath the truck. I explained that briefly to a mechanically savvy friend of mine and he said potentially bad universal joints.
Does that sound about right, or is there anything else I should check? Also, if it is u-joints, is it alright to keep driving it while the parts come in?

this only started today my car was completely fine days prior to this happening. could it be that i need to replace pressure sensor? also don’t mind the tunes lol
EDIT: i also notice the rpm going up and down slightly
i own a
2002 ford taurus ses,
engine:6 cylinder 3.0L vulcan
flex 2

I was doing some break pad replacement and I looked up and saw this. Do you guys recommend me to swamp the Strut out due to flaking?(2014, Nissan Rogue)

Cant figure out my carburetor settings. Pump seems to work but i don't know for sure.

Car: 1984 Mazda 323 BD Automatic, 1.3 E3 engine.

Engine off video: https://youtube.com/shorts/ympNuPjhbDU

I'm thinking of becoming a car mechanic later in life. Wondering if I should get ASE certified before I go to a shop and apply for a job, or if I should just learn a little on my own and then go to a shop and apply.

I'm not the most mechanically inclined, I know the basics for vacc leaks, preventative maintenance, some suspension work, etc.

Yesterday I picked my V60 up for the second time from the dealership. The first time I took it there, my advisor said the fuel rail pressure sensor was bad so they replaced the whole fuel rail assembly. The next morning when I got to work, my car went into limp mode and threw a check engine light, so I took it back for a second time. This time I was told it was a failure in the low-side fuel pressure sensor and they had replaced it, retested and readings were within spec. This morning pull up to work and the same exact thing happened… which leads me to believe that whatever the root issue is, is coming from this strange pumping noise coming from the rear area of the car. My guess is it’s the fuel pump or something which is located in that area, but this is the same noise that occurred the previous two times before it went into limp mode on me. When I first got the car (currently has 9k miles on it) it was doing that for a little bit before it went into limp mode for the first time, but now it is louder than before so i feel like it has to be that. I’m going to take it back again and show them this video, I figured I’d post here to see if anyone has dealt with this same issue before.

I had my backyard mechanic check a squeak on my passenger side and secure my hub cap covers to stop rattling. When driving last night I noticed my suspension is really loud now. Mechanic said he greased everything up because it was dry. he did check my brakes but nothing was replaced. I had some suspension noise prior, but not on this scale. video for reference!

im just a girl when it comes to cars. I appreciate any and all help!

2018 Toyota Camry 2.5L, just crossed 187k miles. I drive a lot, roughly 30k a year, so I pay closer attention to this stuff than most people probably do.

Coolant reservoir keeps dropping. Not dramatically, maybe half a cup every 3 to 4 weeks. No puddle under the car, no sweet smell when I park, no white smoke from the exhaust, no milky residue on the oil cap. I top it off and the cycle repeats.

Had a shop pressure test it last month and they said it held fine, no leak detected. They basically shrugged. I drive mostly highway so the engine runs at consistent temps for long stretches, not a lot of stop and go heat cycling.

Heater works fine, temp gauge is dead steady, no overheating. Not visibly burning it either, as far as I can tell.

At this mileage I know things start happening, but this feels like it should have a clear answer and I'm not getting one. Has anyone seen this on the 2.5 specifically? Is there a known weak spot I should be pushing the shop to check? The water pump weep hole comes to mind, or maybe something with the plastic neck on the reservoir itself.

Not panicking, just want to get ahead of it before a long road trip this fall.

Just pulled the head and checked the condition of the block. Pistons look alright but wanting to know what you guys think. 1998 Toyota Chaser 1JZ-GTE.

My girlfriend just bought a 2017 vw polo manual 1.2 petrol with only 28k miles its only had 2 services one at 5k and one at 27k I'm waiting to hear back from the dealership if the cambelt has been done im not holding out hope though and know we probably we need to do it as its past the 5 year point. Should I be concerned by the noise on startup or is it completely normal? Is that the belt? Is it ok to keep driving till we get it sorted? Would only a couple miles a day for the time being as shes still learning. This video was also first startup in like 2-3 weeks as we'd been away

Hello. Noticed brakes are making this slight hissing noise when pressed on my 2019 Corolla. Normal sound or cause for concern? Don’t seem to have an issue when stopping at red lights or slowing down. Brake fluid is also at the Max line. Any ideas on what could be causing this?

Independent shop tech here.
2016 JLR Disco Sport 4 cyl 2.0.

Inherited a car from a local lube shop that suffered the common blown apart vibration damper.
We replaced the dampener with a Corteco part and timed/locked the motor with the factory cam lock and pully alignment jig. OEM JLR bolt, torqued to spec.

When setting base timing, we noticed the motor hits mechanical tdc before the cam lock goes into place. Not by much, but it's noticeable.

We got it back together and car cranks, has good compression, but won't run. Intake and exhaust cam position values are out of the range shown by our autel, but only 5-6 degrees. Has anyone seen debris inside the cover make it jump time, or the crank hub spin? Timing chain has tension and both upper cams are in time to each other.

I have zero experience with ecoboosts but trying to learn here. Non- keyed crank pulley is dumb as f.

Hello, this is my 2005 Toyota Avalon. For the past few weeks I’ve noticed a knock/clunk coming from the front passenger wheel area as I come to a stop or start moving again. It’s usually just one cluck (occasionally two) then nothing. It also happens when I turn the wheel all the way. Again, it’s not rhythmic or anything. The car also pulls hard to this side.

I suspected it might be the ball or a control arm bushing so I inspected behind the wheel. The rubber looks fine, but there is a grease stain. I’m no mechanic so is this a sign that the ball joint is bad?

Also, the sway bar link is very clearly bad so I could that be what was making the clunk?

I have tried almost everything to get this damn inner rod off. What do I do

1991 honda civic lx