Car is shaking
February 25, 2013 3:59 PM   Subscribe

My car (or car engine) shakes.

Once in a while (perhaps five times total, but twice in the last few weeks) my car has begun shaking after turning it on. Not shaking left and right, not up and down, but back and forth. If that makes sense.

Once I put my food on the gas and get a reasonable speed (15 mph?) or gear (it's automatic), the shaking goes away. It doesn't appear again when stopped at stop signs or lights.

My impression is perhaps that this happens only after the car has been sitting in the heat, but not sure.

2001 Nissan Altima with lots of miles. Obviously, I should take this car to the shop, but two questions.

a) How urgent is this? Can it wait until Saturday?

b) Any advice on how I describe this to the mechanic? The car will not be doing this shaking after I drive it on to their lot, so I'm not sure what I should tell him to look out for.

posted by lewedswiver to Travel & Transportation (22 answers total) 1 user marked this as a favorite
Super weird and might be just me, but last night my car "shook" when I turned it on, the engine mount was loose and then eventually broke (and lead to horrible grinding noises and general terror) as I was driving down the street. I allowed my car to "shake" for probably three months before the engine actually fell out.
posted by banannafish at 4:04 PM on February 25, 2013 [1 favorite]

Coming in to mention engine mount. Saturday, probably but be careful.
posted by deezil at 4:11 PM on February 25, 2013

For a car shaking as described, my first suspects would be a broken motor mount or transmission mount. I'd rule those out before you dig any deeper.

As for how bad this is...well, your motor has two mounts, and if one is broken, the motor will move more. This could cause your motor to move into your radiator and damage it, and/or the movement could break your exhaust pipe(s), transmission linkage, etc. It isn't something you want to allow to persist, because the motor mounts and transmission mounts prevent excessive engine movement, and thus prevent damage associated with movement from happening.

I'd get this fixed ASAP, but that's me. You can live with it for a while, but you have to drive "old lady careful" - no pot holes or sudden stops, please.
posted by mosk at 4:15 PM on February 25, 2013

Came into say exactly what banannafish said. It might make it until Saturday, but me putting something like this off for too long resulted in me having to say the sentence, "how much does a new engine cost?"
posted by something something at 4:19 PM on February 25, 2013

While based on your brief description it does sound like it could be an engine mount, there are other possibilities. Is the check engine light on? Even if it is not on (yet) it could be sending pending codes. I would borrow a reader or go to a parts store and have them read it for you to see if there are any codes. If you cannot do that by Saturday, certainly ask your shop if it is throwing any codes and what those codes are. (If you get the code numbers, you can google their meaning easily.)

I just replaced an engine that was doing what yours is except that mine would also do it at idle even after it had been running for a while. It started out as yours did. Rarely doing it. The short of it was that oil was not circulating correctly due to issues with the cams and the cam phasers and well the engine eventually seized.

Have you been changing your oil and oil filters regularly?

I think you are ok to use it lightly until Saturday, but I would take this seriously.

I have heard the shaking sound referred to as "dieseling" sort of rumbling like a diesel engine would. My shake was reproducable by the shop.
posted by JohnnyGunn at 4:32 PM on February 25, 2013

Is there loss of power when it's shaking?
posted by jeffamaphone at 4:36 PM on February 25, 2013

Consider parking it at the shop Friday night and getting a ride home so that when they start it in the morning they will actually see it in action. Tell the shop that is what you are going to do. They will appreciate it.

What makes me think it might be more than an engine mount being broken is that it goes away and stays away after starting and running for a few minutes.
posted by JohnnyGunn at 4:37 PM on February 25, 2013

Is there loss of power when it's shaking?

That was my question. If it was an engine mount it would likely be more consistent. I'm tending towards it being some kind of misfire (one of the cylinders not firing or not firing completely) which caused a misbalance in the engine.

Does the car feel more sluggish when the vibration is apparent?
posted by Brockles at 4:47 PM on February 25, 2013 [1 favorite]

some more info we need:

does it do it when in park or when you put in drive or just all the time until you get to 15mph?

when was the last time you checked the automatic transmission fluid or have it serviced? and if you have checked it recently was it red (cherry red actually) or brown/orange with a burned smell?

do you get any whining at higher speeds? say over 40? is the car harder to turn in one direction than the other? any noises when turning?

Are all your tires the same size? and when was the last time you check inflation pressure?

could be: bad transmission, bad differential, bad torque converter, bad transmission mount, bad engine mount. The order is in decreasing likelihood. The answers to the questions could narrow it down, but nothing beats the opinion of a mechanic able to look at the car.
posted by bartonlong at 5:00 PM on February 25, 2013

oh, and the last thing it could be, vacuum leak. This would be great news if it is as it is very easy to fix.
posted by bartonlong at 5:01 PM on February 25, 2013

have driven two cars that exhibited a "shaking" sort of feeling. in one, the transmission was slipping. in the other (actually, a Nissan Altima with a lot of miles, though significantly older), it was low compression on all cylinders and possibly faulty injectors. (the injectors were the last straw but I don't know if they were an issue throughout that time - the car was driven for a year+ in its condition. replacing engines is expensive.) in the car I broke the motor mount on, it was a constant weird sound but no real loss of power and no real "jerkiness". the Altima came pretty damned close to stalling out a time or two and sometimes wouldn't start as time progressed.
posted by mrg at 5:03 PM on February 25, 2013

No loss of power when it's shaking. It does it in park and in drive. Fluids were last checked ~2000 miles ago at last oil change, don't know about transmission fluid color. No whirring at higher speeds. Nothing strange about turning. I think all the tires are the same size, but I should check inflation pressure more often.
posted by lewedswiver at 5:47 PM on February 25, 2013

ok, does it change at all when you have your foot on the brake (when in park)? I am now leaning toward vacuum leak or bad injectors (or maybe sensor-but that would make the check engine light come on). Since it shakes in park and in drive it is most likely the engine and not the transmission or differential (or any tire issues). I would think it would always shake if it was bad compression, but maybe not. Engine trouble is actually pretty good news as far as it goes. AT this point I would hook it up to a code scanner to check for any codes (unlikely without a CEL) than check the engines vacuum. There isn't as much vacuum lines on modern cars as their used to be (back in the 80's/early 90's) but there are still a few. It could be a bad O2, crank position sensor, maybe something to do with the valve timing (if this year/engine altima has variable valve timing). Could even be carbon buildup in the throttle body causing it. None of these things are big emergencies and can wait till the weekend. All the things you answered with are great things to be able to tell the mechanic. Be as specefic as possible as to when/how the problem occurs, time of day, car cold/warm, weather cold/warm, how you are driving (accelerating fast/slow-freeway, slow speeds, etc), is the gas tank full or empty? stuff like that.
posted by bartonlong at 6:17 PM on February 25, 2013

My 2001 Pathfinder which I think has the same 3.5L engine as your Altima had the same shaking problem. Turned out one of the ignition coils needed to be replaced. In my case, the check engine light went on eventually.
posted by reformedjerk at 6:37 PM on February 25, 2013

Huh. 2000 Maxima 3.0L V6 here with the same rare issue. For me it tends to happen during cold mornings once I get up to 30mph, and as soon as I pop it out of gear (it's a manual), the shaking goes away. It happens so infrequently that I've never even asked about it when I've had the car in for service.
posted by Nonsteroidal Anti-Inflammatory Drug at 7:27 PM on February 25, 2013

I know I wouldn't wait until Saturday if it were my car, especially because I commute on the freeway. If you can get away with putting only a few miles per day on the car, you can probably wait.
posted by twblalock at 12:04 AM on February 26, 2013

Sounds like it isn't transmission at all if it happens in park. I'm still thinking some kind of mild misfire - most likely electrical if it goes away after start up (once load or rpm is added it seems).

It may stay the same all week and you'd be fine waiting until Saturday. I don't think - if there are no other signs of an issue - it is likely to be catastrophic but there's jut no way of knowing for sure if this will leave you by the side of the road. If it is a severe shaking that has happened suddenly, then it is best to err on the side of caution. If it is a relatively minor shaking (you're just more observant than most maybe) then I'd be more inclined to risk it.

Agreeing that taking it to the garage on the friday night (discussing why with the mechanic) is the best way for them to diagnose it.

The safest thing for you to do is not to drive the car. You need to weigh up the risks of the car failing more fully against how bad you need to use it. I have kind of a gut feeling that it won't damage it more if you drive it, but I can't say that with any confidence with the assessment ability we have over the internet.
posted by Brockles at 4:56 AM on February 26, 2013

Could it be something as simple as you not having changed the oil for 10,000,000,000 miles so that now before your engine is warmed up you're basically lubricating it with acid tar sands? That might drop the idle speed enough to make it cough some.
posted by flabdablet at 5:42 AM on February 26, 2013

Being as that is is extremely unlikely to happen, no. If the oil quality affected the idle speed more than almost imperceptibly the engine would have seized. Also, the last thing that would make poor oil quality better would be load and rpm.

Especially as the last oil change was only 2000 miles ago.
posted by Brockles at 5:50 AM on February 26, 2013

Ah, missed that. My bad.
posted by flabdablet at 6:34 AM on February 26, 2013

Like other commenters, I suspect this could be a faulty motor mount. I used to have a car for which the oil system would leak over one of the motor mounts, causing it to corrode quickly.

Provided that you have a stout jack and two people, it's possible to replace it yourself by jacking up the engine. But it's complex and potentially dangerous work.
posted by John Farrier at 10:12 AM on February 26, 2013

For anyone who comes across this thread--

I took it to the shop, but they couldn't diagnose because it wasn't doing the shaking at that exact time.

A week or two later, it started doing the shaking particularly strong, and the check engine light also popped on -- which made me immediately take it right into the nearest shop that was open on a Sunday. The guy took it look, checked the code, said it "just needed a tuneup," did $300 worth of tuning up the engine... and then a week later it was shaking again with the check engine light popping back on.

So I took it to a mechanic that I trusted more, he said it was a broken injector #2, he replaced it, and it seems to be running fine after that. I'm marking the "best answer" based on that... let's hope it lasts. and this mechanic is right after all.
posted by lewedswiver at 8:38 PM on March 29, 2013

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