Noob with excess Vibes

[zagger]

Sorry if this topic has been discussed to death but I'm new here and my searches haven't found the answer I need. Any engine mount geniuses out there?

I bought my 95 SW2 new and I now have about 166K miles. Lately I'm getting lots of engine vibration. I had a shop replace the top mount on the engine and the vibrations got worse, not better. I checked the "dogbone" mount on the drivers side transaxle but it looks happy and intact. In any case, the vibration seems to come from the passenger side in the engine compartment. I got a Saturn chassis manual and it appears that there is a similar dogbone mount just under the crankshaft pully. To get at this, I'd think that a hoist would be necessary. What is the common wisdom on this mount? Do these routinely crap out or what? Any suggestions?
zag

[Puck head]

All u need is a jack, jack stands, and a block of wood(besides sockets and wrenches) to protect yr oil pan. Take off the front passenger side tire and the splash shield and wha la. Thar she blows! After u support the motor w the block on the jack take off the top motor mount then take off the bottom dog bone one then just jack it up enough to get the new one in and there u go. FYI make sure u lower the jack enough to get the top one on properly but not too low so that the dog isn't supporting the motor. I did this and still had the problem took me two different motor mounts to figure out it wasn't the mounts it was the idler pulley. I got my dog bone from oreillys the autozone one was cheap. And the pulley from napa. Both cheap and easy parts to install. No excuse for further delay or neglect. Good luck.

[PlasticCarsRock]

Often, replacing the top motor mount will shift the engine slightly, adding excessive tension to the lower mount (with the car off, or idling in neutral, there should be no tension on that mount). The correct procedure for replacing the top motor mount includes releasing any tension on the lower mount (but many shops won't bother to do this, even though it takes less than 30 seconds, on a lift). If you leave tension on that mount, it can cause significant vibrations. Before you waste money replacing it with something that may not be as good (OE mounts are very expensive; aftermarket mounts are garbage), loosen the two 15mm nuts below it (the bracket that holds it has studs that stick straight down, into the subframe--they can be reached though holes in the bottom of the subframe). Once they're both loose, wiggle it a bit to make sure it's loose, then re-tighten them.

For best results, this should be done with the car as close to level as possible (jack it up, remove the tire, than lower it to it's normal height, with the jack).

The motor mount may need to be replaced, but if that were the only problem, it wouldn't have become worse after replacing the top mount. Tension on the lower mount, on the other hand, certainly could have become worse by replacing the top mount.

See this video for instructions: http://www.youtube.com/watch?v=zaugUfILmGE

[off-track]

I'd mostly agree with what PCR said but.. Making sure the mount pre-load is removed is the first thing to try. There have also been many posts of aftermarket TAM's actually being worse than a failed OEM. Try a search for "frownie" and you will see what you need to look for.

[Signmaster]

What the last two posts said.

Not loosening and torquing the dogbone can make things continue to shake or get worse, and the wrong upper mount will often still shake just as bad.

If you have the good mount and follow the dogbone procedure and still have an issue, check the tranny mount on the opposite side of the car. It doesn't seem to cause as many issues but it can sometimes completely fail.

[zagger]

Thanks for the advice! I'll try to relieve the stress on the lower mount today.
zag

[OldNuc]

As has been posted above the presence of any stress on the torque axis struts will cause problems so start with those. The torque for those bracket nuts are 32ft-lb. If you have an uneven idle that is an engine issue and no mount will get rid of all of it.

Go buy a gallon of liquid bed liner and coat the inside of the floor pan. That will do wonders. As I said before, OEM top mount, trans mount, late 97 or newer torque axis struts and the polly inserts. Engine must have an even smooth idle. That means good even compression. Clean flow balanced injectors. The 3 rubber exhaust mounts should not be stretched when the car is at rest, just supporting the exhaust. These 3 suspension pieces will be what couples the exhaust vibration into the floor pan so the stretchiness and thickness of these is how you tune them to not appear solid at some inconvenient RPM. The Walker 35119 isolator is thicker than the original OEM. They are cheap so modifying them is not a big deal. They thin nicely on a belt sander but if too thin they break and you will be buying a new exhaust.

If you have an uneven idle you will never reduce the vibration to zero. Setting the torque axis struts to zero tension/compression at rest is critical.

These are some other steps you can take to reduce the vibration in the cabin.
The torque axis struts are of 3 different designs and the 3rd design, late 97 production, have replaceable inserts. These are the stamped and welded design. There are 2 pictures in my gallery. What you are attempting to accomplish is restrain the engine free motion as much as possible without going solid. The main axis of rotation is on a line between the top mount and transaxle mount. The torque axis struts are positioned to restrain the normal torque reaction and drive axle wind up. The poly inserts allow enough motion to not act as a solid link but do not transmit vibration well either. The idea is to keep large excursions of the engine/transmission and exhaust to a minimum. Small displacement of the power train transmits to large displacement in the exhaust. The rubber hangers will deftly transmit this exhaust motion into the floor pan which simulates the head on a large kettle drum, with you inside of it. You can get a buzz in the floor that does not transmit into the upper frame or seats but the large low frequency pan displacement is pushed up to a higher frequency. the characteristics of the rubber mounts determines where this buzz occurs. The trick is to get it somewhere you do not care. By minimizing the powertrain displacement you minimize the magnitude of the exhaust displacement you have to deal with. You can slightly change the static exhaust position to take all the stress off of the flex connector and have the mass of the exhaust evenly spread over the 3 mount points. The muffler hanger basically controls axial twist on the exhaust. I used the Walker 35119 isolators and just stuck them on. Ended up with the buzz from about 50 to 57mph and this is a speed range that is only passed through so I did not pursue any further elimination. the bed liner should kill this 50-57 mph buzz all by itself. The OEM isolators are a softer rubber and thinner and would possibly isolate the floor better but as they were 10+ years old and I am adverse to dragging the exhaust down the road I decided to replace them. The harder-thicker isolator appears as a solid at given frequencies.

[zagger]

Just got done loosening the lower dogbone mounting bolts and retightening them. Does not appear to have helped significantly. The engine seems to be running on all cylinders but I haven't done any engine testing. I will look into the "frownie" thing since replacing the top mount made the vibrations increase bit time. The vibration is strongest at idle and RPM's somewhat above idle and does not seem to be related to the torque load on the engine. At highway speeds it actually settles down a bit.

To me the strangest thing is that the vibration gradually goes away as the engine warms up. If I drive a few miles and park the car for a little while, the vibration is nearly gone. It is winter here so I assume that the engine compartment is getting warmer when the car is parked than when it is moving through the cold air. I suppose that the warmth might make the rubber mounts a bit softer but who knows.

The transaxle dogbone appears happy and healthy - no cracks in the rubber or anything like that. Bolts were tight. The lower engine dogbone also appears to be ok but due to the general crud in the area is is hard to be sure. Didn't see any cracks though.

I assume that the crankshaft pulley has a keyway so that it cannot change position on the shaft? I cannot imagine that it wouldn't.

Don't know about exhaust system rubber mounts. Last week I had the flexible section and the muffler replaced but the vibration was not reduced or increased by the exhaust work. Vibration was strong before and after the work.

Gonna research frownies.
zag

[OldNuc]

It would help immeasurably if you would list the year and model of your car your profile.


From a cold start. First open the hood and then start the engine and go out and look at it, is it thrashing around in there or is it steady and smooth? Put your hand on the timing cover left end and see if you can feel motion. If it is moving then using the correct mounts will help but the fix is to get the engine smoothed out. This may be as simple as actually getting the injectors cleaned to a major engine overhaul. I would suspect shot mounts is a big part of the problem. Contrary to the conventional wisdom of some people the transmission mount is not an insignificant part of this system that may be ignored. It is a mount system and piecemeal part replacement is only marginally effective in addressing this issue.

[zagger]

Ok, found a picture of a frownie type mount and the new one installed in my SW2 by the shop is definitely that type (although the "eyes" on my frownie face are spaced a bit further apart than the picture someone posted). I cannot see any manufacturer label. The metal part bolted to the top of the engine is about 1.25" thick and the studs have threads extending well above the top of the metal.

So what's the wisdom here? Review of my sad tale: I was experiencing some excess vibrations before dropping the car off at my usual shop (who I somewhat trust) for an oil change. They noted the vibration and suggested replacing the upper mount - said that they had done hundreds of upper mounts on Saturns. I told them to go ahead and got the car back with vibrations about 4x worse. I complained, they "investigated" and had no useful suggestions. I was not happy with them. If I had put on a new mount that made the problem worse I would have taken it off and tried to figure out what was going on - not just put the car in the lot and say it was ready to be picked up.

If the frownie mount design sucks, then I imagine that the old mount taken off by the shop was gradually going bad but then the shop replaced it with a new and worse one. So now I have to find a "good" one and replace it again?
Sound about right?
zag

[zagger]

GMpartsgiant has P/N 21012185 for $63 plus shipping. Can I assume that this is the OEM mount that works correctly?
zag

[OldNuc]

Yes but check and see if you need longer studs while you are spending $$$.

Top Engine Mount 21012185
long studs 11518885 use these if replacing a frowny mount and there are NO threads showing above the nuts.
Top mount nuts (5) 21006320
Transaxle Mount 21012951

The metal part that is bolted to the timing cover is different thickness depending on the mount and is easy to measure.
Frowny Mount 1.275" ~1 9/32"
Solid Mount 1.475" ~1 15/32"
The good mount is ~3/16 thicker than the frowny mount.

Saturn OEM Parts Source
GM Parts Giant- http://www.gmpartsgiant.com/
GM Parts Direct- http://www.gmpartsdirect.com/
Get Saturn Parts- http://www.trademotion.com/splash/in...?siteid=214643
GMparts4U.com- http://gmparts4u.com/
Your local dealers - http://www.partsvoice.com/
http://www.vpartsinc.com/

Transmission mount replacement
http://www.saturnfans.com/forums/sho...=1#post1825741

[Signmaster]

Originally Posted by zagger

Ok, found a picture of a frownie type mount and the new one installed in my SW2 by the shop is definitely that type (although the "eyes" on my frownie face are spaced a bit further apart than the picture someone posted). I cannot see any manufacturer label. The metal part bolted to the top of the engine is about 1.25" thick and the studs have threads extending well above the top of the metal.

So what's the wisdom here? Review of my sad tale: I was experiencing some excess vibrations before dropping the car off at my usual shop (who I somewhat trust) for an oil change. They noted the vibration and suggested replacing the upper mount - said that they had done hundreds of upper mounts on Saturns. I told them to go ahead and got the car back with vibrations about 4x worse. I complained, they "investigated" and had no useful suggestions. I was not happy with them. If I had put on a new mount that made the problem worse I would have taken it off and tried to figure out what was going on - not just put the car in the lot and say it was ready to be picked up.

If the frownie mount design sucks, then I imagine that the old mount taken off by the shop was gradually going bad but then the shop replaced it with a new and worse one. So now I have to find a "good" one and replace it again?
Sound about right?
zag

It might be worth seeing if the shop will refund your money and take back the frowny mount. They shouldn't install a crap product that makes the situation worse. If they don't want to do it just remind the service manager that you might tell the entire internet and all your friends to avoid that shop.

[zagger]

Good point signmaster but something tells me this local shop won't care about internet chat. They aren't bad guys, just regular sort of mechanics who cannot be experts in all things. I ordered a new GM top mount. Guess I will find out if the frownie rap is true. Why would anyone go to the trouble of tooling up to make a mount that doesn't work? Geesh.
zag

[PlasticCarsRock]

Originally Posted by zagger

Why would anyone go to the trouble of tooling up to make a mount that doesn't work? Geesh.
zag

Saturn redesigned the mount, at some point, to reduce vibration; thus creating the "frowny" mount. From what I've heard, they do typically work (less vibration than the solid mount), but unfortunately, they had a very short lifespan (a couple years at best) before vibration increased and in some cases, the mount broke apart, so Saturn soon reverted back to the old solid mount. Unfortunately, the aftermarket manufacturers were not so quick to abandon the "frowny" design (why spend money to switch to a longer lived product when they can sell a lot more of the short-lived ones). Also, aftermarket mounts don't necessarily conform to OE specs, so in some cases the aftermarket "frowny" mounts may increase vibration (despite the fact that the design was to reduce vibration).

[Puck head]

Originally Posted by Signmaster

It might be worth seeing if the shop will refund your money and take back the frowny mount. They shouldn't install a crap product that makes the situation worse. If they don't want to do it just remind the service manager that you might tell the entire internet and all your friends to avoid that shop.

I had to do that with this local shop in my neighborhood. I took it to them to diagnose my window problem they charged me $80 I think and they said it needed a whole new assembly motor and all. After I has already installed the motor. I went home pulled them relay put back in and wha la. It worked! I took it back up there and told them to figure it out while I waited. And then they asked what is the problem I said "no that's why I paid u is to find the problem so find it I did". They didn't like that so they just gave me my money back cause they were wrong. Well I don't like getting ripped off by lazy mechanics that just throw parts at cars. We're paying for their expertise and advice not to just slap a part on and hope it works. Oh btw they wanted $300 to fix the window. So what if I paid that and then they change the whole assembly and it still wouldn'tve worked. Douche bags!

[zagger]

Big thanks to everyone who helped with my vibration problem! I ordered a genuine GM top engine mount and installed it - what an unbelievable difference! My SW2 has ZERO vibration and seems like a new car.

A Review:
I brought my 95 SW2 in for an oil change and the mechanic suggested that a new top mount should be installed to get rid of the vibration. The aftermarket mount installed by my mechanic caused a somewhat annoying vibration to become 4 times worse. I complained and the mechanic came up with a variety of lame ideas for the vibration - ignoring the obvious fact that the new mount made the problem worse, not better. That's when I turned to the real experts - you guys!
The attached pictures show the crappy aftermarket mount that I took out - definitely the "frowny face" design.
zag

[OldNuc]

Those things make excellent paperweights or to be thrown at the next riot.

[zagger]

I'm returning the mount to the repair shop with the suggestion that they can refund my "repair" charges. I've been going to this shop for many years and have been generally happy with their work so I'm not going to throw the mount through their front window. However, I was pretty unimpressed by their dithering around when the aftermarket mount made the vibration so much worse. As an engineer myself, I have to confess that I'm completely shocked by how much better the GM mount works. Perhaps the aftermarket mount is ok for some models but for my 95 SW2 dual cam engine, it was a complete disaster.

Now I just need to find a fix for the oil consumption that doesn't require engine removal! Oh well, oil isn't that expensive.
zag