My mechanic told me the other day that he thinks the best way to fix the rough idling and shaking coming from my 2005 Mustang since it doesn't seem to be coming from an engine problem is to to change out the after market motor mounts the previous owner of my car put in and swap them out with OEM motor mounts. He's telling me there are 3 engine mounts,a transmission mount and an engine mount bracket needed and he wants $800 for the parts. Does this sound like the best way to fix a shaking problem and does this sound like a fair price?

 

For what it's worth, this is a video regarding replacing of the motor mounts. Caution, lil' language, but hey, shade tree mechanic happening:

Ok. So... hang on. IS the engine itself running rough? IS it jumping around in the cradle? IS it shaking around?

I mean... if it's acting like a jumping bean the problem is *waaaay* not motor mounts, engine brackets or transmission mount. Well mostly, anyway, as broken motor mounts will cause the engine to move... but under load. Definitely not at idle. Engines should be smooth running, for not having a smooth running car means the mounts get destroyed. You'd just be replacing and replacing them, not actually fixing the issue, but fixing the result. You want to fix the issue. Throwing mounts at it sounds wrong to me.

If you have a race motor, that's different. But the stock one in a 2005, whether V6 or V8, should be a computer controlled smoothness that you can actually balance a nickel on a cover somewhere while the motor's running. At idle, in park/neutral it shouldn't be bouncing around at all, *even with* bad motor mounts, as there's no load on it except itself.

If it is bouncing around, there's a problem with the engine. That has to be fixed first and foremost.

Aftermarket mounts can cause more noise, vibration and harshness, true, as they're usually more stout and stiff than OEM ones, for that very reason: OEM is trying to reduce NVH so as to prevent complaints, but the problem is they're soft and give and break eventually as they age. A replacement 'race' mount won't (or not nearly as quickly as OEM), but it also has no relative give to it, so you feel and hear more things from the engine than you would with OEM.

But that wouldn't result in a jumping bean. If anything, the stiffer, tougher motor mounts would cause the engine to be rock solid in the cradle, but maybe the whole car is a jumping bean due to the engine being messed up in those mounts...

The transmission mount really doesn't enter into this picture much. It has some purpose, true, but it's well removed from the engine. Leave it out of this mess.

And THAT is assuming that previous owner didn't screw those mounts up in the first place. That's entirely possible. But I still don't see how that affects the thing at idle, it should just sit there and hum along not movin' or shakin'....

Perhaps a video, well lit, shot and audiolized(sp? word?) might help to further a better overall diagnosis.

For what this armchair quarterback's figurin' on a 'long distance not really all that much detail' description of events is worth. Hope it helps, good luck

And welcome to the forums!

 

Yeah, what he said ^^ there are only two engine mounts if your car is the GT, btw

 

I think houtex covered it very well, but here's a slightly different angle on it:

I just swapped out my original OEM motor mounts for aftermarket poly mounts. The new motor mounts are fairly solid, much firmer than the original oil-filled rubber mushrooms. So yes I did expect some increase in NVH (noise, vibration, harshness).

I have a very minor increase in vibration under some conditions, but nothing major. If I wasn't looking for it, I might not even notice. If anything, the engine and car in general feel smoother than before -- maybe because some of the drive train lash has been removed, since the engine isn't moving around as much as it was before.

So, if you have major shaking and vibration going on, I don't think the motor mounts are the cause.

Regarding cost -- my local shop charged me 1.5 hours, $140 for labor. I don't know the price for the OEM mounts, but you can look it up on line. I was going to do it myself, I'm told it is a fairly easy job, you can do it from the top without a lift, just jack up the engine a little bit to remove the load on the mounts . . . but I ran into a time crunch so paid the shop to do it instead.

 

In that video, what is he jacking up the engine from? Looks like maybe the harmonic balancer?

 

Looks like its the front of the oil pan to me. Definitely wouldn't want to jack from the balancer. I did a block of wood between the jack and the pan so you dont' dent the oil pan. He's got a pretty wide cup on his jack and lots of rags to spread out the weight which I think works too. Was actually just talking to my shop about one of their other customers this weekend and they were dealing with oil starvation issues because somebody dented the oil pan and it really restricted the space between the bottom of the pan and the oil pump pickup tube.

 

I see the front of the engine oil pan in my pic here, it wont dent the oil pan lip?

 

Okay like this? The front?