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Bad Motor Mounts?

51K views 34 replies 18 participants last post by  pinellas 
#1 ·
So the latest problem with my TB is a horrible shaking that at times is so bad that I think the engine wants to jump out from under the hood. The entire front end of the truck is vibrating so much the screws must be loosening up. This only happens in Drive with the brakes on, not in neutral. I'm thinking that because of the load and torque on the engine that this is the problem.. or maybe it could be the transmission mounts.

Anyone had experience with this? Is it doable yourself or best left to a shop with a lift and the proper tools? Any idea on the cost if this is the problem?

Thanks, guys.
 
#2 ·
also check your fan clutch-
if the water pump shaft is failing the fan clutch will wobble--- at its worst it WILL make the engine vibrate. (been there--- I6 though).

with engine off-- grab fan and see if it moves sided to side on the water pump shaft.
 
#4 ·
Awesome info, guys.

Just had the fan clutch replaced in October and that's good. Yes, the engine runs well in neutral. Drive at 0 mph is the problem. Take off and drive and no issues - smooth. The engine is torqued to one side, I guess, so it doesn't allow for the shaking.

Is this a DIY job or is a visit to the shop required?
 
#5 ·
Update:

I took the truck to a local shop and they confirmed that there was some play in the two motor mounts. They replaced them and, wow, what a difference! It's amazing what you get used to over time. It's so smooth now that I can't even feel the engine starting anymore, just like when my truck was new. The vibrations while sitting at lights are totally gone. Apart from a hardly noticeable rough idle (which I can live with), it's like driving a totally different car. Even while driving, which I thought was smooth before, is even smoother.
 
#7 · (Edited)
They got me for $400. The mounts were a little over $100 each from the dealer. They were unable to find aftermarket mounts locally and even the dealer I called had only one in stock. They called another dealer that had only three. I guess it's not a high-demand item. Anyway, I figured that since the OEM mounts lasted 97K miles, it didn't hurt to put the same mounts back on. It's possible that I may have overpaid a little, but I'm happy with the end result so that makes it worth it for me.
 
#11 ·
I had a little vibration at the red lights. Neutral would solve the problem. I thought it was the idol. Dealer said its :duh::duh:the motor mounts. They said 3 need to be replaced for $900.00+!?!!?!?! Are they crazy!!!!
That's a gouge.

There are two engine mounts and one transmission mount. I replaced both engine mounts for $400 - my transmission mount was still in great shape. Even if the third mount needed to be replaced, I'm sure it wouldn't have been to the tune of another $500.

Take your car to a good mechanic for this fix. It's not something that you need the stealership for.
 
#14 ·
I did not know about the aftermarket MM's not having the gel insides like the OEM's do until after I replaced them---I read on this site to never go w/aftermarket MM's----ALWAYS GO W/OEM!!!!

I ordered a set of OEM MM's w/tranny mount from http://www.gmpartsdirect.com/ $160 w/shipping and when I turned on the TB it was like silk! Almost like a new truck!!

There is a great write up on this site on how to go about replacing the mounts

A lot of unnecessary $$$ was spent, but I look @ it this way she paid for and I learned a lot about my TB....hope this helps!

Thanks to everyone who gave their :m2:
 
#17 ·
You must have skipped over the MANY posts that say - do not use aftermarket motor mounts. They don't have the same dynamics, and they may hold the motor up just fine, but they don't solve the rotational vibration issue that causes the 10 Hz oscillation. We're stuck with GM OEM parts, from the dealer network or any of a number of discount online vendors.
 
#20 · (Edited)
Im sure there is somewhere... You have a 2wd which makes your life 1,000,000 times easier! However until then:

- Put front of truck on ramps/jack stands and safely secure.
- Disconnect Battery.
- Remove skid plate underneath engine. There are four bolts that hold it on, I cant remember the exact size at the moment but I want to say its 13,14,15mm. One of those 3.
- Get back under truck, using an 18mm socket and probably at least 1 swivel (on 4wd models, 2 swivel adapters are absolutely necessary) and at least 18" of extensions. Loosen the lower engine mount nuts on each side.
- Go up top and loosen both top 18mm nuts on each motor mount.
- Remove fan shroud nuts. I believe they are 10mm. You dont have to remove the shroud, just remove the bolts so the shroud can lift up with the fan when you jack the engine up.
- Now is the time to take your hydraulic jack with a 8" piece of 2'x4' on the plate. Place the jack toward the left side of the oil pan. Jack up very gently. It helps to have 2 people so I person can jack up the engine, and 1 person can be up top making sure the fan/shroud and all peripherals are not binding/breaking.
- Once you jack the engine up on the left side as far as it will go, remove the motor mount from the bracket. It might fight with you and not want to come out - keep on jacking up the engine in small increments.
- Lower the jack once you get the left motor mount out, the do the same for the right side. Be very gentle with the oil pan - its imperative to have a piece of wood on the jack, otherwise you will crack that pan and be up the creek without a paddle!!
- Install the new mounts. Go with OEM ONLY! Do NOT NOT NOT use aftermarket or any other brand of engine mount besides Delco. Trust me on this one. Sometimes the new mounts need the studs to be ground down a little bit (1/4" or so) to ease the re-installation process. Be careful not to fubar the threads.

Once the new mounts are in, lower the jack allowing the engine to rest on the new mounts, reinstall the lower & upper nuts on the mounts, re-install the fan shroud bolts, re-install the skid plate, re-connect the battery.

Now this is from what I can remember when I did mine - I have a 2002 TB with 4wd. Yours may be easier with the 2wd - you may not even have to remove the skid plate. YMMV.
 
#22 ·
Ahhhh yes. I forgot about that one :duh:

I had to use a ratcheting wrench to get the drivers side upper - you'll have to contort your arms down there somehow to get some torque. Be very careful not to hit the brake/fuel lines with the wrench AND do not disturb the wire harnesses going to the PCM. Its tricky, but once you get the nut loose (and IIRC mine werent super tight), then you're on your way...
 
#23 ·
Just finished.
Thanks to everyone in this forum and some other tread for all of the suggestions and tips.

Here is my story:

Got a quote from independant guy who came recommended for about $250 per mount.

I picked up the mounts for $135 for the pair at a Chevy dealer.

I was able to get passenger side out without having to undo fan shroud but when I did driver's side one of the pins on bottom of shroud snapped so I recommend taking the two bolts out of the shroud.

Really had to contort to get top driver's side nut off.
Ended up using U-joint, 18mm deepwell, and 18" of extentions. Also some Liquid Wrench.

To get the Driver's side installed I put upper bolt in and then put the nut on it. When I tightened the nut this brought the mount up and I was then able to drop lower bolt in place. I couldn't get the lower one clear of bracket by hand. Try this before you grind the bolts as some have suggested.

Other than that, I follwed the directions given by in this thread.

I test drove and thought I was in a Prius because it was so smooth and quiet.

Thanks again for the help.
 
#24 · (Edited)
Just called my local dealer to get a quote on how much each mount cost, thinking they were around 75 dollars a piece, was shocked when I was quoted 97.98 a piece... I guess Gmpartsdirect it is, coming in at $144 shipped for both...



Edit

Just called my next closest dealer and they want 120.08 a piece... SERIOUSLY!!!! HTH do they stay in business? :D
 
#25 ·
SERIOUSLY!!!! HTH do they stay in business? :D
Easily, with people paying those prices! :laugh:

Im going to give you the best advice in the world: Befriend a parts department guy. Or if you know somebody, they can get parts at cost. Has saved me a ton of $$.
 
#27 ·
ok so we just got our truck back from our buddy at the dealership who installed our fuel pump (under the table) and they and my uncle said we need to replace our motor mounts i found gm motor mounts for 74 bucks each plus install! my questions is how many do our trucks have i have seen answer sayin 2-4 mounts can anyone tell me how many i need to get to replace all of them? thanks
 
#29 · (Edited)
TrailBlazer vibrations = bad motor mounts

FWIW:

Both left & right OEM motor mounts are $116.16 @ gmpartsdirect plus shipping. A reputable repair shop quoted me $175.00 today to install both mounts ! So we are looking at $291.00 to have a decent garage do the work properly for us, lest we decide to do it outselves.
I am not familar with removing the hardware to do it myself, so I opt to have it done by this shop.
No ! I am not paying Chevy 675.00 to do the work. That is thivery !

My TB LTZ is a 2002 with 148,000 miles on it & running strong !

jevans
 
#33 ·
I got the passenger side replaced, am having a hard time getting the drivers side out. While jacking up pan, the other side is not quite getting enough clearence to remove. I guess i need another 1/4". Any advice would be appreciated.
I just replaced them on my wife's truck 2 weeks ago. Driver side was a real pain. A few things that helped was to remove the top bolts for the fan shroud.(Make sure to align the bottom "set" pins on the shroud when bolting the shroud back in place. I didn't realize there were pins on the bottom and my fan was rubbing when I took it for a test drive.) I also had to make a few different attempts at it with having the passenger side bolt slightly tightened and then again mostly tightened. I don't remember which way worked best.(Loose or sort of snug).

I'm not sure if you already got past the point of unbolting the mount but I drilled a 1/2" hole in the bracket that is directly on top of the mount so I could run a 3/8" socket extension through it to get to the bolt. My swivel extension just wasn't doing to trick.

My vibration went away but now I'm dealing with a slightly rough idle.

Good luck with yours.
 
#34 ·
Thanks,

I've had the rough idle for a little bit, but like you said the shakes went away. I also replaced my fan and shroud. They were damaged because of the clutch fan replacement years ago. Apparently they didn't know how to align the radiator( wasn't in the notches). Now my upper radiator hose is collasping and cap was broke. yeah!
 
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