Corolla Engine Humming - Corolland: the Toyota Corolla Forums

Hi, I have a Corolla S 2001 with 113k right now.

I've had it since it was 97k. Everything has been perfect with the car (I know the original owner and know how the car has been taken care of) as you can expect with a Corolla.

At around 107k I started hearing a noise (like a vibration that made a plastic bang against another) when I downshifted, it only lasted for a couple of seconds when the car was at around 2200 rpm.

I took the car to a place this friend recomended me (Toscalito, in Terra Linda) to see if they would tell me what the noise was and they found a couple of things (as they usually do default_tongue ) and recommended rotors changed (they were warped) enginge clean, and they found out that the Engine mounts were loose and that could lead up to the vibration.

Stupidly, I decided that I wanted to get the engine mounts replaced (400 bucks T_T, let's get over that, i don't even want to remember it).

I did, and that's when my "problems" started.

The car runs perfectly, but the noise has increased, a lot, at least a lot for me.

If I throttle the car while parked, I hear the engine humming, as it normally would on higher RPM but this time, at a lower. I'd say that noise scale has been changed and it starts 25% before than before.

(when I can I'll upload a video to try and illustrate the issue)

I complained to Toscalito, they rechecked the mounts and claim that they are fine, and that the reason why i feel this is because now the mounts are not loose anymore and therefore the vibration that the engine was making, now it's being transmitted directly to the car.

Also, as you can imagine, the vibrations can also be felt in the front of the car where my headlight will "bump" with the fender resulting in a really annoying vibration noise.

I can definitely feel the difference in idle and also on the highway. When I'm doing 80mph the revs are around 2800 and it sounds like if they were on 3500 or something like that.

I'm a freak of nature when it comes to sound and driving like this drives me crazy to the point I don't enjoy it anymore and to me that's sad default_sad

I don't think brakes/tires matter but front/rear brakes are brand new and so are the tires(less than 2k)

I also changed the sparkplugs 1k ago. Nothing changed.

My mpgs vary between 33/35 depending on the usage (which is anyway mostly highway)

Any help on what the causes could be and what I could do to fix this would be greatly appreciated.

Newer mounts would transmit more noise that older mounts for sure - but that effect should be temporary, as soon as the mounts see a couple of drive cycles, that amount of transmitted noise will be diminished slightly.

One thing to check are the exhaust donuts on the front pipe - one is between the exhaust manifold and front pipe (spring bolts hold that one on) and the other is after the cat and before the resonator (conventional clamp on that one). Those have a tendency to wear out completely on this generation of Corolla and can make a considerable amount of racket at lower RPMs. Some cases can sound like the motor has ingested nuts and bolts into the engine.

In this case, sounds like you had some resonant issue (loose exhaust pipe, bad exhaust gasket, etc.) that was strongly present at one particular RPM range that was shifted due to the new mounts. Likely that the original mounts were shot, but were also likely not the root cause of your noise.

Newer mounts would transmit more noise that older mounts for sure - but that effect should be temporary, as soon as the mounts see a couple of drive cycles, that amount of transmitted noise will be diminished slightly.
One thing to check are the exhaust donuts on the front pipe - one is between the exhaust manifold and front pipe (spring bolts hold that one on) and the other is after the cat and before the resonator (conventional clamp on that one). Those have a tendency to wear out completely on this generation of Corolla and can make a considerable amount of racket at lower RPMs. Some cases can sound like the motor has ingested nuts and bolts into the engine.
In this case, sounds like you had some resonant issue (loose exhaust pipe, bad exhaust gasket, etc.) that was strongly present at one particular RPM range that was shifted due to the new mounts. Likely that the original mounts were shot, but were also likely not the root cause of your noise.

Thanks for the response!

I'd like to clarify a couple of things in my post.

The vibration I feel, is all in the front. I can see the front bumper and left and right fenders "shaking" more than they used to (more in the right side than in the left).

I'll check the things you see this week and post my findings.

However, my gut tells me that the engine is making "more effort" to produce the needed rpms and that's why is humming so much.

What can I do/check to see if I'm right? Will a throttle cleaning achieve something? Do i need to clean the engine?

Thanks in advance

Here are some videos

Engine running:

Engine sounds good... With a length of hose held to your ear, point or touch the other end on the alternator, and other components to confirm the noise source.

I actually did that and I couldnt hear anything wrong.

Im totally frustrated at the moment.

Everywhere I read about my problem, the solution seems the same, replace passenger mount, but the weird thing is that my car STARTED to have this issues, AFTER the engine mounts were replaced.

I did an oil system cleaning and replaced with Catsrol GTX HM Oil to see if anything changed but nope, nothing.

I used to love my car now I hate it default_sad

I'm gonna go back to that place and see if I can get some sort of solution to this because it's driving me insane.

Definitely looks like some resonance issue - hence the vibrating door (which is way more than I expected).

Oil system cleaning?? What did that involve. I've never heard of that before, hopefully, it didn't cost you too much money.

Possible that the shop used the wrong mounts. On the OEM mounts - some of them are fluid filled, not solid rubber. Almost every aftermarket mount I've seen for the 8th gen are solid mounts. That means it will vibrate like a paint can shaker.

Also, have to replace ALL the mounts - that includes the one on the transaxle. Should be a total of four - one by the serpentine belt, front mount right behind the radiator, under the engine (hidden by a cross brace) and one of the transaxle. If you don't replace them all - 1) nothing happens, which makes you feel like it is a waste of money, or 2) shakes like crazy because of the excessive compliance brought on by the remaining soft mount. They also have to be pretty careful when they change the rear most mount - tough to get to and there is an exhaust bracket that can be messed up easily. When I installed inserts on my car - I accidentally damaged that front pipe bracket - engine sounded like it was filled with pebbles.

A quick test you can do - try jacking up the front corner of the car up, see if it changes the noise any, as this will load the outside mounts. Then carefully lift up the bottom of the engine - use a low floor jack and a piece of wood over the lift plate. Put it under the oil pan and lift up on it slightly, don't want to pick the wheels off the ground, just want to load those mounts. See if there are any changes in the noise/vibration. If there is a marked difference when you load the mounts - they either used the wrong mounts, installed them incorrectly, or worse - screwed something up in the process of changing those mounts.

Definitely have them recheck their work - if push comes to shove, have a dealership do it right and have that shop pick up the tab. Don't take "that's normal" line - as I've never seen a door shake like that, aside from some dB drag or SPL audio competitions.

Good luck

Thanks so much dude for the response!

the oil system cleaning i did was at OilStop, it was only 12 bucks, and it was an additive he added to the original oil and we let it run for 10 minutes. then the oil was changed.

I did it because it was only 12bucks and I thought "maybe it'll help with my noise" but I knew it wouldnt change a thing default_tongue

Regarding the mounts:

I went to them today cause I wanted to get a copy of the records cause I couldnt find them at home.

To my surprise, i see only 2 mounts replaced. RT Upper Mount ($149.95) and LFT Trans Mount ($123.95) for parts and $240 of labor.

They used the the following mounts MTC 12305-0D010 and MTC 12372-0D030

From what I see on the internet it looks like OEM but i'm not sure.

(I'm 99% sure that in the original piece of paper they gave me, the invoice, it just said that they replaced the mounts not which ones)

I think this explains everything.

Now what I would need just in case they don't want to cooperate is some kind of record or official info saying that the mounts should all be replaced together.

I'll go to them next week and the battle will start as I can't really understand why they did this, cause it's only logical that if you replace 2 mounts with new ones, and you leave the other 2 used there, its definitely going to do some kind of vibration, specially if the old mounts have 110k miles of usage.

That aside, i'm really happy, because now I know 1) i was right 2) my corolla CAN be fixed so I can be happy driving it again

Sounds like a plan. As for an official or manufacturing requirement that all mounts should be changed - that will be pretty much impossible to find. Like you mentioned, makes sense that when you replace something like a mount, you want to make sure that they all are changed to not adversely affect the operation of the vehicle.

Another problem you'll run into is that chassis/engine mounts and suspension work are a major revenue generators for shops, other is emissions - as parts are relatively expensive and usually very labor intensive. You could run on some badly worn out mounts and suspension, and still be "OK" - but shops like put a "safety" spin on these types of repairs - makes it more likely to get owners to agree to replace them.

Sounds like a plan. As for an official or manufacturing requirement that all mounts should be changed - that will be pretty much impossible to find. Like you mentioned, makes sense that when you replace something like a mount, you want to make sure that they all are changed to not adversely affect the operation of the vehicle.
Another problem you'll run into is that chassis/engine mounts and suspension work are a major revenue generators for shops, other is emissions - as parts are relatively expensive and usually very labor intensive. You could run on some badly worn out mounts and suspension, and still be "OK" - but shops like put a "safety" spin on these types of repairs - makes it more likely to get owners to agree to replace them.

I'll let you guys know how this turns up.

I honestly wish they kept my original mounts somewhere and i think I would be happier if I just get those back installed and that's it default_tongue

I'll see what they offer (if they offer anything) and go from there. As far as I know, this place has a good reputation so they'll probably try to help me, but you never know default_sad

btw, what exactly did you mean by

Definitely have them recheck their work - if push comes to shove, have a dealership do it right and have that shop pick up the tab. Don't take "that's normal" line - as I've never seen a door shake like that, aside from some dB drag or SPL audio competitions.

I mean, i get the idea but how can i force them to take care of it if they do not want to? You meant file a complaint with the FTC or what?

UPDATE:

well, went to the store today.

Store manager was friendly and took the car in and had ANOTHER tech look at it.

Called me back couple of hours later to tell me that the technician looking at my car was leaving, and that he'd be back tuesday and ask me to take it back on tuesday. He said "I'm on a mission now to get this problem fixed, I was able to see the vibration. We'll get this snip fixed"

So far, so good, at least that's the feeling I have, he seemed to agree with me in how big of a problem this was for me, but maybe it was just his "friendly manager face". who knows.

We haven't discussed money or anything yet, I feel like they are going to take care of it but for now, I'll just wait.

Sounds like so far so good! Keep us posted!

Sounds like so far so good! Keep us posted!

UPDATE:

Well, they are gonna change the 2 mounts they already changed for Toyota OEM ones.

I wonder if I should pay for the other 2 mounts and get the 4 replaced with BRAND NEW OEM ones instead of keeping 2 old OEM and two new OEM.

You think is worth it?

Or should I first try with just replacing those 2?

I'd start with those two mounts - see what they do to the vibrations. If they don't help - then you can see if they will do the remaining two mounts, make sure they use OEM. That bottom most mount (the one they did not change yet) has a HUGE impact on vibration - if they screw it up, it will make the vibration you have now seem like nothing. Ideally, you should not have pay for the others - as the shop screwed it up first by trying to replace them. If they just left them alone - you probably wouldn't have to deal with this issue - worn mounts would cause vibrations to tend to propagate/fail fairly slowly

Whatever happens - see if they will give you the old parts back. I always do that with any shop repair - as it keeps the shop "honest". If they say they can't for insurance/environmental issues, etc. - I ask them to just show me the old part off the car. If they refuse, that is a sure sign that they did not do the work at all.

I'd start with those two mounts - see what they do to the vibrations. If they don't help - then you can see if they will do the remaining two mounts, make sure they use OEM. That bottom most mount (the one they did not change yet) has a HUGE impact on vibration - if they screw it up, it will make the vibration you have now seem like nothing. Ideally, you should not have pay for the others - as the shop screwed it up first by trying to replace them. If they just left them alone - you probably wouldn't have to deal with this issue - worn mounts would cause vibrations to tend to propagate/fail fairly slowly
Whatever happens - see if they will give you the old parts back. I always do that with any shop repair - as it keeps the shop "honest". If they say they can't for insurance/environmental issues, etc. - I ask them to just show me the old part off the car. If they refuse, that is a sure sign that they did not do the work at all.

Ok, I went with replacing the 2 "new" ones for OEM ones.

I'm gonna see what happens from there.

They guy seems to be really trying to help me, but of course he's not suggesting to replace all 4 right now.

However, I do get the feeling that if the 2 new OEM mounts don't resolve the issue, they are gonna try changing the other 2 mounts for new OEM ones as well.

We'll see what happens next tuesday.

Thanks for the help fishexpo!

Ok, got the car back.

O M F G

The difference is unbelievable!!!

I can't believe I drove for 4 months like that.

It's running so smooth, I was speeding yesterday without realizing! (I got used to accelerating based on the engine noise so I knew when I was speeding now I'll have to start using the speed meter again default_tongue )

Thank so much for the responses, specially fishexpo101, you've been more than helpful!

For all of of those who will come to the thread in the future and don't want to read everything:

ALWAYS REPLACE MOUNTS FOR OEM ONES!

Sweet! Glad to hear the car is back to that way it should be.