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2005 Cadillac STS 4 V8
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Discussion Starter · #1 ·
First post, found lots of good info on here but no info on motor mount replacement for the STS AWD with the V8. The following is my experience from completing this job tonight. The V8 AWD is by far the hardest combination to perform this job. To my knowledge there are no youtube videos or posts from someone attempting this but I’m sure it has been done before. If you are looking for info on V6 or RWD models you do not need to do what I did here as it will be unnecessary extra work.

I managed to complete this on jack stands with no special tools. But more importantly did it WITHOUT removing exhaust manifolds, heat shields, cats, or steering components. It took me a long time since I had no guides to go by, so hopefully this can help you. It can be done in a weekend, maybe one day if you’re organized. I’m in the rust belt and the car has 150k on it, so not as easy there and was the reason I wasn’t taking my manifolds or cats off. My most important advice is to have some patience, I nearly gave up on the driver side one. I also am replacing brakelines and did both serpentine belts so I took a few more parts off than I needed to.

Steps:
1. Spray penetrating oil on all bolts in advance
2. Remove bumper and wheel well liners and all engine plastic covers, air intake
3. Unbolt radiator shroud
4. Remove electric radiator fans
5. Evacuate refrigerant
6. Disconnect A/C lines from condenser coil
7. Unscrew power steering cooler
8. Unbolt oil cooler
9. Remove plastic rivets on flexible shrouds on both sides of the coil set
10. Unbolt condenser coil and remove
11. Unscrew trans cooler lines
12. Leave oil cooler hanging, all other coils should now be able to be removed
13. Remove mechanical fan and clutch using the three bolts holding the bracket on
14. Unbolt the 3 bolts holding the alternator in, remove belts as needed.
15. Remove passenger side motor mount. You can access the top nut from the front by shuffling the alternator around. You will need to jack up the motor from oil pan and make sure to use a piece of wood to not damage the pan. Both my mounts were corroded to the top mount bracket. Use a pry bar and hammer to free them. I also had to tie a rope around the top stud of the motor mount and yank it out (with a sledge hammer in the rope loop) to free it. My new motormount was not depressed like the bad one so it was taller. I cut the bottom stud a little so that I could angle it in and also needed a hammer to line up the studs. You could remove the mount bracket and not have to cut it I suspect. Compare old to new to make sure dowel pins line up the same.
16. Install the top nut to passenger side mount but leave the bottom free
17. Start on the driver’s side mount by removing the cv axle. You can unbolt the upper control arm ball joint and tie rod ball joint to give just enough clearance to get the axle out of the spindle. See attached picture for working area with cv removed.
18. There are hard power steering lines in the way of prying the axle out of it’s cup with a fork, so I was able to use a crowbar to work it out.
19. There are 4 bolts holding in the motor mount bracket to the engine. They need to be removed now. Every one of them is hard to get to, especially the top two. I was able to loosen with a rachetting wrench. ( They are all 15mm btw or equiv english size. Motor mount nuts are 13/16 and you need a deep well socket.). But the trick here is remove the wrench before it gets stuck between the exhaust manifold. Use long reach needle nose pliers on the threads of the bolts to free them. If you have small hands you may be able to turn them. See attached picture. Also, the pivotting rachet wrench may be good here, I didn’t have one. You will only get enough room for one or two clicks on the rachet so take your time and be patient.
20. With the engine jacked all the way up you can get a socket on the top motor mount nut and remove.
21. At this point I discovered my mount bracket was fused by corrosion to the top of the motor mount. I removed what was left of the mounts heat shield here. Prying didn’t cut it, so I finagled an air chisel in there and busted it free. I had to lower the engine first and bolt the bottom of the mount down to put tension on the assembly. Isn’t rust fun. Try not to bust up the aluminum mount bracket surface.
22. With the bracket now free both bracket and mount can come out via cv axle path. This is very tight but they will both come out separately.
23. Compare new motor mount dowel pin alignment to old one, and test fit it in the bracket. My dowel pin didn’t fit so I had to ream put the dowel pin hole with a drill bit.
24. Install new mount, sending in the bracket first and wedging up high with the motor fully lifted. They should fit together with just enough room to where you don’t need to cut the stud short.
25. Install top nut on the mount, wedging the bracket with something. Motor still raised all the way
26. Lower engine so bracket holes line up to engine block.
27. Install lower right bolt loosely, then install top two bolts. I used a magnet pen to line up the top bolt and threaded in using needle nose pliers. This is probably the trickiest part.
28. Once that is done lower engine and torque both bottom mount nuts. Install all the other parts in reverse order.

Disclaimer: I am not recommending anyone follow this but this was the order that worked for me. Follow all laws like refrigerant evacuation work and be safe with jackstands etc. Also you won’t be able to get a torque wrench on hardly anything since it is so cramped.
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Thanks and I hope this helps someone!
 
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