hiljak Posted July 19, 2004 Report Share Posted July 19, 2004 Has anyone changed the front motor mount on a 99 STS? I am looking for general instructions and any special tools/procedures needed. Any help is appreciated. Thanks, James. James 1999 STS 65k 1995 STS 127k Link to comment Share on other sites More sharing options...
Logan Posted July 19, 2004 Report Share Posted July 19, 2004 Engine Mount Replacement Front Removal Procedure Tools Required J 42504 Engine Lift Bracket J 28467-A Engine Support Fixture Remove the front two radiator cooling fans. Refer to Cooling Fan Motor Replacement - Electric in Engine Cooling Install the J 42504 Engine Lift Bracket to the engine. Install the Engine Support Fixture Adapters and J 28467-A Engine Support Fixture. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information. Remove two nuts securing the mount bracket to the engine block. Remove one bolt securing the brace to the transaxle. Remove the nut securing the to the frame. Lower the vehicle. Remove the two upper bolts securing the motor bracket to the engine. Raise the engine. Remove the mount and bracket. Installation Procedure Install the mount and bracket. Loosely install the two upper bolts securing the mount bracket to the engine. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information. Install the engine support brace. Notice Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems. Install two nuts securing the support brace and the bolt to the support brace. Tighten Tighten the nuts and bolts in the following sequence. Tighten the mount bracket left nut to 50 N·m (37 lb ft). Tighten the right mount bracket nut to 50 N·m (37 lb ft). Tighten the motor brace bolt to 50 N·m (37 lb ft). Tighten the two upper mount brace bolts to 50 N·m (37 lb ft). Remove the J 28467-A Engine Support Fixture. Remove the J 42504 Engine Lift Bracket. Remove the Engine Support Fixture Adapter. Install the two radiator cooling fans. Refer to Cooling Fan Motor Replacement - Electric in Engine Cooling Logan Diagnostic LLC www.airbagcrash.com www.logandieselusa.com www.ledfix.com www.ledfix.com/yukontaillightrepair.html www.ledfix.com/ledreplacements.html www.ledfix.com/j42385toolrental.html Link to comment Share on other sites More sharing options...
hiljak Posted July 19, 2004 Author Report Share Posted July 19, 2004 Thanks Logan, thats exactly what I was looking for. Thanks alot. Are the numbers given for the special tools the gm part numbers? James 1999 STS 65k 1995 STS 127k Link to comment Share on other sites More sharing options...
hiljak Posted July 19, 2004 Author Report Share Posted July 19, 2004 Logan, could this job be done without the engine lift bracket and support fixture (i.e. are these just for safety)? James 1999 STS 65k 1995 STS 127k Link to comment Share on other sites More sharing options...
Logan Posted July 19, 2004 Report Share Posted July 19, 2004 Yes, it can be done without the specfic tools listed. Logan Diagnostic LLC www.airbagcrash.com www.logandieselusa.com www.ledfix.com www.ledfix.com/yukontaillightrepair.html www.ledfix.com/ledreplacements.html www.ledfix.com/j42385toolrental.html Link to comment Share on other sites More sharing options...
bigfoo Posted July 19, 2004 Report Share Posted July 19, 2004 Jacks, jackstands, 2x4's, vice grips, wrenches, hammers, socket set, screwdrivers, some random pieces of metal and wood.. can do just about anything you want on the car Wether or not it's easier , or safer, is another problem. if you can borow the tools they will save you time but if not just use some pieces of wood in place of the brackets and things Link to comment Share on other sites More sharing options...
hiljak Posted July 19, 2004 Author Report Share Posted July 19, 2004 Cool, I ordered the mount from GMparsdirect for $63.28 shipped. Not bad. Based on the procedure listed by Logan, I'm guessing the swap can be completed within 3 hours or so. I know where I'll be this weekend James 1999 STS 65k 1995 STS 127k Link to comment Share on other sites More sharing options...
Logan Posted July 19, 2004 Report Share Posted July 19, 2004 On my 2001 Deville. I had to lower the front engine cradle....and remove the engine mount with the Y bracket. Logan Diagnostic LLC www.airbagcrash.com www.logandieselusa.com www.ledfix.com www.ledfix.com/yukontaillightrepair.html www.ledfix.com/ledreplacements.html www.ledfix.com/j42385toolrental.html Link to comment Share on other sites More sharing options...
JohnnyG Posted July 20, 2004 Report Share Posted July 20, 2004 hiljak, I assume from this post that you found your engine mount to be bad, after following Logan's check procedure. What sort of vibrations were apparent? Where were they being felt? Never underestimate the amount of a persons greed. Link to comment Share on other sites More sharing options...
Logan Posted July 20, 2004 Report Share Posted July 20, 2004 This is a better image on how to replace the mount. Its from the 1999 STS procedure......the complete Y bracket and mount must come out. On the Deville....I did not have to remove the fans. I spent at least 1 hour trying to follow the GM directions.....BS.....no way to access the upper mount bolt. The old Ford Taurous had the same problem. Lower engine mounts of the same basic design. Failure after failure. There was a TSB....they would replace the first set...then you were on your own. Same issue.....vibe...vibe...vibration. It was the complete powetrain shaking is what you felt. Logan Diagnostic LLC www.airbagcrash.com www.logandieselusa.com www.ledfix.com www.ledfix.com/yukontaillightrepair.html www.ledfix.com/ledreplacements.html www.ledfix.com/j42385toolrental.html Link to comment Share on other sites More sharing options...
hiljak Posted July 24, 2004 Author Report Share Posted July 24, 2004 do these suckers commonly go out in the 99? I noticed they did away with the "dog bones" that were used in 95 so this mount probably takes a lot of torque if you flogg it like I do. If thats the case, I may get pretty good at changing it James 1999 STS 65k 1995 STS 127k Link to comment Share on other sites More sharing options...
bigfoo Posted July 24, 2004 Report Share Posted July 24, 2004 I hope not I 'flogg' it everywhere. I think I had this mount changed under warranty once but I don't remember.. would have to check records.. Link to comment Share on other sites More sharing options...
shiden_kai Posted July 24, 2004 Report Share Posted July 24, 2004 This is a better image on how to replace the mount. Its from the 1999 STS procedure......the complete Y bracket and mount must come out. On the Deville....I did not have to remove the fans. I spent at least 1 hour trying to follow the GM directions.....BS.....no way to access the upper mount bolt. You can do these mounts without taking the metal bracket all the way out. I usually just remove the studs and bolts holding the bracket to the head and block, rotate the entire assembly "in there" so that I can get a wrench on the upper mount nut. It's fairly simple once you have done a few of them. I prefer the models that don't have the upper dogbones as you do not have to support the engine and trans while you drop the sub. It's much easier when the engine and trans is supported by the mounts that are attached to the body. Link to comment Share on other sites More sharing options...
hiljak Posted July 28, 2004 Author Report Share Posted July 28, 2004 I got it changed. Shiden Kai, I tried your method of not removing the fans and removing the mount from the bracket while its still in between the motor and radiator fans. It worked, but it took me about 3 hours. I couldn't get it to rotate all the way so I could see the upper nut. It was hitting on the exhaust manifold. I did manage to get it partialy wedged to the side enough to get to the nut, just barely, with an 18 mm wrench. Hoever, it took almost an hour to get the nut off as I could only turn it about 1/8 of a turn at a time due to limited throw distance. I got her done, but I hated it. The old mount was seperated on the top and the rubber was completely hard and cracked After changing it, I took the car on a test drive and the driving was much better with no clunking. However, this morning while driving it to work, I tried letting off the gas while going about 45 mph, then hitting the gas again and "clunk". What the hell. I will check the remaining mounts tonight to see if they need replaced but I just hope the new mount didn't break already. Anything else that could cause the clunk noise? James 1999 STS 65k 1995 STS 127k Link to comment Share on other sites More sharing options...
MARK 99STS Posted July 28, 2004 Report Share Posted July 28, 2004 That clunk could be normal "chuggle" from the transmission when you get on and off the throttle at higher speed. When my mounts went the idle speed was erratic and the car seemed to shake a bit when stopped at idle. MARK 99STS TURBOCHARGED Link to comment Share on other sites More sharing options...
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