Discuss your Bonneville GXP and/or any other Northstar powered Olds or Cadillac... Including the Intrigue / Aurora 3.5L Twin Cam V6 (Short Star ) , 4.0L and 4.6L Northstar V8's. Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.
The project GXP needed a new front engine mount, and I got Seth's custom solid mount:
I started digging into this expecting it would take a few hours because of all the horror stories I've heard about it. When I finished up after only 30 minutes I was scratching my head about a few of these steps. It doesn't have to be this hard!
repinS wrote:0) Remove the torx screw holding the airbox to the front fender. This may have already come loose on most cars when the busted trans mount flops the powertrain around. Why? I never touched this.
1) Raise and safely support car - not via the subframe - stands at the jack points at the rockers are ideal. You want to go pretty high. Don't forget to chock your rear wheels and set your parking brake beforehand. I used a hoist, but is easily done with a jack and stands as well.
2) Remove the clips holding the front airdam. Don't force them out, pry up the center section of the clip and they will just slide out. Yes
3) Optional: Remove the front wheels. Recommended if you don't have an impact extension and air tools. Not necessary
4) Support the engine/transmission with a jack. I use a bracket covering the exhaust between the oil pan and transmission pan. It'll be pretty hard to miss. Yes I did this.
5) Unbolt rear half of the front trans mount, there are three or four locations: Bottom nut under the subframe, two nuts near the exhaust manifold that hold the bracket, and two studs that are bolted into the transmission. There is also a secondary bracket/bar that will need to be moved out of the way. Instead of the rear half of the mount, I would call it the upper bracket. I removed the 2 - 15mm bolts at the top by the exhaust manifold with a socket, swivel and 12" extension. I removed the 2 - 15mm nuts at the bottom of the block with a gear wrench. I also removed both studs for clearance.
6) Undo the bolts for the two side engine mounts - they are near each wheel. If you pulled your wheels, you'll have lots of room. If not, you may be able to cheat and access them by steering the wheels to one side. Why? This seems completely unnecessary. The engine doesn't have to be moved at all.
7) Undo the front two bolts for your subframe. You may want to use a jack (I use a spare tire jack) to ease the subframe down. Air tools may come in handy here to break loose the thread lock compound. With the engine/trans being supported by the jack stand, the subframe isn't holding anything up except itself. The 4 bolts on the back of the subframe hold it up just fine.
8) At this point the front mount should be loose and flopping around - here comes the challenging part.
9) Slinky the mount AND bracket assembly out from the engine bay. You may have to pry downward on your subframe to create enough space, OR jack up the engine/transmission to create enough clearance between the body and subframe. Play around here. I find a good place to pry would be off the AC compressor. Be careful about the metal lines (oil? fuel? ABS? I forget) that pass through this area. You will have to move them around, but make sure not to pinch or break them. I have found the best way to take it out is by turning the whole assembly upside down so that the bracket comes out first. Prying off the AC compressor with a large pry bar worked great. Turning the mount and bracket upside down also worked great to get it out.
10) Cuss, swear, and take a break. Have a beer or six.
11) Hopefully you'll get the mount out. Installation is pretty much the reverse of removal. You may want to put some new thread locker on the subframe bolts.
Andrew - owner/operator of Bonnevilles Unlimited 2004 Bonneville GXP | 60k | White Gold Tricoat | custom built supercharged 3800 hot rod | garage queen 1997 Corvette | 57k | Silver Metallic | Z06 wheels | Date-night Hauler/Parts runner 2014 Town & Country Limited | Cashmere Pearl | 115k | Family Hauler 2002 Ram 1500 Quad Cab Sport | Black| 280k | Official Bonneville Hauler
I wrote that off the top of my head a while after doing the mount, and I probably did do some extra steps. That's simply what worked for me
I imagine with a hoist the job would be easier. Engine went up so that subframe didn't have to go down as far and/or I didn't have to pry as hard while lying under the car.
On a hoist, with the right tools, and having done it once or twice (or more), so your learning curve is helping, it's different than doing it on your back, crawling under a car, and perhaps not with correct tools and even limited mechanical ability, all makes a difference.
Retired Bonneville Owner and former GM Tech: 2004 Pontiac Bonneville GXP: Black/Ebony *SOLD*
Daily Drivers: 2019 Chrysler Pacifica Limited: Mommy's new RGC 2015 Chrysler Town & Country Limited Platinum: Kids new RGC 2011 Camaro SS 2009 Pontiac G8 GT: L76, Sport Red Metallic 2004 GMC Sierra 2500HD: Victory Red - 8.1L Big Block and Allison 2003 Chevrolet Suburban 2500: Doeskin Tan - 8.1L Big Block... RIP 1999 Chevrolet Suburban: Sunset Gold Metallic - RIP
Yeah, I'm sure the crap in the stock mount is sticky...
Good start to a good how to thread!
Will
91 Riviera | S2 L67 Swap/4T60E | 127K mi | Antelope Met. w/ Tan Int. | Saved From Death By Crusher
92 Bonneville SSE | L67/4T60E | 77K mi | Med Slate Grey w/ Two-Tone Grey Int. | Low Miles Time Capsule
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99 Tahoe LT | L31/4L65E | 276k mi | Spiral Grey Metallic w/Grey Int. | Truck for Truck Things and Portable Concert Hall
02 Bonneville SSEi | 171k mi | Black w/Neutral Int. | Backup and road trip car
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05 Acura RL | 165K mi | Carbon Grey Pearl w/Ebony Int. | The Super-Hooptie Daily
Thinking about this again, I seem to recall that the bottom stud on the aftermarket mounts may have been longer. That could have been why I needed engine to go up in conjunction with subframe going down.
repinS wrote:Thinking about this again, I seem to recall that the bottom stud on the aftermarket mounts may have been longer. That could have been why I needed engine to go up in conjunction with subframe going down.
Yes, Jerry the anchor mount I got had a stud that was too long. I actually had to grind it down to make it even able to fit on my Cadillac.
Good start to a good how to thread!