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Discussion Starter #1
I have a '98 Corolla CE Automatic with 250k and am trying to figure out what is causing excessive engine vibration. The vibration happens mostly at 900 rpm and below, and is the worst while idling at stop lights (in drive with foot on brake). It is also noticeable while in neutral and park. If I am sitting at a long light I will often switch to neutral and push the gas pedal to get the rpms above 1000 (and thus stop the shaking). Its gotten steadily worse over the last year and at this point its so bad that I don't enjoy driving the car.

I took it to a mechanic and they said it was due to worn motor mounts. I had them replace the mounts (all 4) for a ridiculous price, but alas that did not fix the issue. In fact, the vibration feels worse with the new mounts! I took it back and the mechanic inspected it further, but said they couldn't find anything wrong and sent me on my way. After a bit of online research I have done the following:

• Replaced spark plugs with new OEM plugs
• Put in new air filter (OEM)
• Replaced PCV Valve and Grommet (OEM)
• Checked for loose hoses
• Replaced transmission fluid and filter (I realize this is probably unrelated, but it was due anyways)
• Inspected MAF Sensor (it looked clean to me)
• Inspected throttle body; it was slightly dirty but didn't seem that bad.

I also purchased some fuel injector cleaner, but haven't put it in yet (waiting until my tank is about empty as per instructions).

At this point I am not sure where to go from here. I've had 3 different mechanics inspect it and they all agree that the vibration is excessive, but none can find anything wrong! Suggestions? Also, please note that I am not very mechanically inclined and have a limited tool set. I can do basic stuff like switch out parts, etc.. but don't feel comfortable doing anything super technical.
 

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Another common thing to cause this is dirty injectors.

Run seafoam through your gas tank and it's a possibility it will help or eliminate the issue.

Might take a second treatment to see results.
 

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2002 corolla ce
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Check the bill from the engine mount job. Genuine toyota mounts are fluid filled and expensive just for the parts. If the mechanic used cheap aftermarket parts then thats what is likely wrong. Also did they replace the transmission mount? Its a beast to remove as you have to drop the subframe but see if they did 3 or 4 mounts and report back.
 

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A broken exhaust hanger could certainly cause severe vibration. Ask your mechanic to inspect the whole exhaust system.
 

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Discussion Starter #5
Another common thing to cause this is dirty injectors.

Run seafoam through your gas tank and it's a possibility it will help or eliminate the issue.

Might take a second treatment to see results.
I was wondering about dirty injectors. That is why I got the fuel injector cleaner (as I mentioned in the original post). I didn't realize Seafoam could go in the gas tank, so I will look into it.

BTW; I gave the mechanic a bunch of grief for giving up on my issue and they decided to give it another shot with their best technician. Its in the shop now, so we will see what comes of that. :)
 

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Discussion Starter #6
Check the bill from the engine mount job. Genuine toyota mounts are fluid filled and expensive just for the parts. If the mechanic used cheap aftermarket parts then thats what is likely wrong. Also did they replace the transmission mount? Its a beast to remove as you have to drop the subframe but see if they did 3 or 4 mounts and report back.
I did check the bill and they installed aftermarket parts (and marked them up a ridiculous amount). I confronted them about this and they claim that the parts they installed are just as good as the OEM mounts. They also said the OEM mounts for a 98 Corolla are not fluid filled (which the dealership confirmed), so theoretically the parts should be somewhat similar. And yes, they replaced all 4 mounts (including the transmission mount). When I brought it back to them they checked the mounts and said they looked to be working fine.
 

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Discussion Starter #8
A broken exhaust hanger could certainly cause severe vibration. Ask your mechanic to inspect the whole exhaust system.
I'll take a look. I am guessing this is something that I could check myself by crawling under the car with a flashlight? As I mentioned above, the car is back in the shop being inspected further, so perhaps the issue will be remedied when I get it back.. but if not I will definitely check out the exhaust system.
 

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Discussion Starter #9
Update

BTW; I gave the mechanic a bunch of grief for giving up on my issue and they decided to give it another shot with their best technician. Its in the shop now, so we will see what comes of that. :)
UPDATE: I got the car back from the shop, and alas the vibration is still there. In fact, it feels just a tiny bit worse now. They spent over 4 hours diagnosing the issue, and they did the following:
• Engine compression test
• Checked for vacuum leaks
• Inspection of entire drive train
• Various tests of fuel system
• Inspected throttle body, MAP sensor, etc
• Raised engine and re-adjusted the new motor mounts to make sure everything was seated well
• Inspected exhaust system
• Test drove it 3 times
• Etc etc etc..

Basically they said that they did everything possible to diagnose the issue, and came up with nothing wrong. Their final diagnosis was that it is an "aging engine" and that the increased vibration is simply a byproduct of the engine being old. They didn't charge me for all the diagnostic work, and they even refunded me $200 from the installation of the engine mounts since they had originally told me that the mounts would remedy the vibration. They are the highest rated shop in the area, so I would assume they know what they are up to.

So what do you all think? Is it simply an issue I need to learn to live with, or is the mechanic somehow missing something?
 

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One last test before you throw out the towel. Have someone push on the front edge of the hood while you listen to the engine. If the rattle stops then you found the cause of your vibration(the hood).You need to adjust the 2 hood stay located on top of the radiator cross member. Turning them conterclockwise will tighten the hood and stop vibration.
 

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I still suspect the aftermarket mounts are too hard and not as good as genuine toyota mounts and thats the issue however considering all the free work they did diagnosing your car and the refund i really dont think you could ask for more from the shop. Sounds like an honest place to me. You could try contacting @ToyotaOfCoolSprings here on toyotanation in a private message. They give discounts and fair shipping to memebers on genuine parts could be the issue. Here are the part numbers you might want
12305-0d010 engine insulator rh
12371-0d020 engine insulator rear
12372-0d030 engine insulator lh
12361-0d021 engine insulator front
Please ensure you double check these part numbers before you order. Toyota of cool springs will ensure you get the right parts.
 

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OP if you pursue this, there is one thing not mentioned that is meant to dampen engine vibrations.
The harmonic balancer that is part of the crankshaft pulley.
With 250k the rubber could well be deteriorated.

Regarding worn engine theory, if compression tests shown uneven cylinder contribution, vibration is probably there to stay.
 

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Discussion Starter #13
One last test before you throw out the towel. Have someone push on the front edge of the hood while you listen to the engine. If the rattle stops then you found the cause of your vibration(the hood).You need to adjust the 2 hood stay located on top of the radiator cross member. Turning them conterclockwise will tighten the hood and stop vibration.
Actually, yes; the hood does rattle. In fact, it makes a very loud rattling/squeaking sound when the car is shaking at low RPMs. Yesterday I added some cushioning to it that stopped the sound, but the engine still vibrates just as much. I didn't realize those "hood stay" could be adjusted, so I will go ahead and do that as well (thanks for that tip!).

So yes, adjusting the hood definitely helps with the annoying sounds, but doesn't address the engine vibration. If the car is running and the hood is open, I can visually look at the engine and see it vibrating excessively. In fact, if I watch while it warms up and the RPMs drop.. the engine goes from a minor vibration to a substantial shake.

Something I forgot to mention in the last post; the mechanic said that when they disconnected the transmission from the engine that the shake completely stopped, and something about when there isn't any load on the engine it is just fine.

-shawn
 

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Discussion Starter #14
I still suspect the aftermarket mounts are too hard and not as good as genuine toyota mounts and thats the issue however considering all the free work they did diagnosing your car and the refund i really dont think you could ask for more from the shop.
You could be right, but the vibration was there before the new mounts and I'm fairly sure at this point that it wasn't completely due to the old mounts being bad. The mounts were bad for sure (well, 2 of them were at least), but I think they were actually cushioning the vibration a little instead of causing it. The mechanic actually said the same thing, and said it might take some time for the new mounts to soften up, which may decrease the vibration a little.

Getting new mounts just isn't an option at this point, and I am guessing it won't address the issue either. If the mounts were a little softer then the vibration might be a little less intense, but I suspect it would still be there. I also can't afford to switch out the mounts again. I don't have the skills (or tools) to do it myself, and even with discounted OEM parts, I doubt I could get it done for less than $600. I had originally called 5 different mechanics to get quotes and they all ranged between $950-$1300.

I can live with the vibration if need be, but my main concern has been that its a symptom of something else that needs to be fixed/replaced.
 

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Discussion Starter #15
OP if you pursue this, there is one thing not mentioned that is meant to dampen engine vibrations.
The harmonic balancer that is part of the crankshaft pulley.
With 250k the rubber could well be deteriorated.

Regarding worn engine theory, if compression tests shown uneven cylinder contribution, vibration is probably there to stay.
How does one diagnose an issue with the harmonic balancer? Can I simply inspect the rubber for deterioration? And where exactly is this harmonic balancer at? :)

Unfortunately they didn't give me specific information/data on all the tests they performed. Since they were doing all the diagnosis for free, they didn't want to take the time to notate it all for me. However, I think I recall them saying that the compression tests indicated that everything was fine considering that its a 20yr old engine with 250k on it, but that if the same results were found on a newer engine that it might be a concern.
 

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Actually, yes; the hood does rattle. In fact, it makes a very loud rattling/squeaking sound when the car is shaking at low RPMs. Yesterday I added some cushioning to it that stopped the sound, but the engine still vibrates just as much. I didn't realize those "hood stay" could be adjusted, so I will go ahead and do that as well (thanks for that tip!).

So yes, adjusting the hood definitely helps with the annoying sounds, but doesn't address the engine vibration. If the car is running and the hood is open, I can visually look at the engine and see it vibrating excessively. In fact, if I watch while it warms up and the RPMs drop.. the engine goes from a minor vibration to a substantial shake.

Something I forgot to mention in the last post; the mechanic said that when they disconnected the transmission from the engine that the shake completely stopped, and something about when there isn't any load on the engine it is just fine.

-shawn
The hood stay is a one piece rubber construction and can be adusted slightly by turning them clockwise(down) to make the hood tighter.I adjusted my hood recently due to rattles I felt at very low idle. I know for a fact that 98 model year came with a 3 speed tranny instead of a 4 speed.Maybe they are just a little more shaky..my 2 cents.

Regards
Phil
 

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Discussion Starter #17
The hood stay is a one piece rubber construction and can be adusted slightly by turning them clockwise(down) to make the hood tighter.I adjusted my hood recently due to rattles I felt at very low idle. I know for a fact that 98 model year came with a 3 speed tranny instead of a 4 speed.Maybe they are just a little more shaky..my 2 cents.
I ended up adjusting it up (counterclockwise) to get the hood to stop rattling. Now it is rattle free, which is great.. but the vibration is still there. :) If I get a chance, I will attempt to take a video of the vibration so that people can actually see what I am talking about.

-shawn
 

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Great! Now that you adjusted the hood its time to do a simple test. You mentioned in your first post that you checked the vaccum hoses in case one was disconnected.As you know, a leak could be anywhere along the lines and not just at the connection. I would pinch them at several places and see if the engine stop vibrating. The first one that comes to mind and the easiest one to test is the brake booster hose.Test that one first and do the other lines afterward.Please report your findings.
 

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Discussion Starter #19
You mentioned in your first post that you checked the vaccum hoses in case one was disconnected.As you know, a leak could be anywhere along the lines and not just at the connection. I would pinch them at several places and see if the engine stop vibrating. The first one that comes to mind and the easiest one to test is the brake booster hose.Test that one first and do the other lines afterward.Please report your findings.
As I said before, the mechanic said they checked for vacuum leaks and everything checked out. However, I will go ahead and try pinching the lines just for the heck of it. Where exactly is the brake booster hose? Still figuring out what everything under the hood is exactly.

Also, here is a link to a video I just took that shows the vibration. I put a glass of water in there to help show how strong it is. I am curious to know if people agree that the vibration is excessive after seeing the video! BTW; the camera is mounted on a tripod and is perfectly still, so any movement you see is from the engine.


Thanks,
Shawn
 

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I agree that your engine vibrates after looking at your video . Is your vehicule equipped with A/C? My engine shakes more than usual when the A/C compressor turns on. Discard my last post because I somehow missed that your mechanic already tested for vaccum leaks.
 
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