Before you get too far, are you lowering the engine cradle with the engine and transmission on it, or are you trying to pull the engine up through the top?
GM engines are removed by lowering the cradle with everything on it, but there is one major thing you have to watch out for. Those four cradle bolts have to be marked in some way so you reinstall the cradle the way it came out, meaning it is not slid to one side or the other. Remove the three top nuts for each front strut upper mount, then the struts will come down with the cradle.
When you raise the cradle back into position, you'll need to look at the way you marked the bolt locations so the cradle is positioned the way it was. You'll notice the lower control arms are attached to the cradle too, so if that cradle is off-center a little, both control arms, and therefore, both lower ball joints will be moved to that side too. That is going to change two alignment angles that I will be happy to explain if necessary. The first one is "camber", which is the tilt in or out on top of the wheel, as viewed from in front of the car. That is the first one adjusted, of the three basic angles, during an alignment. While the mechanic will be able to get the wheels standing upright and in specs again, the often-overlooked secondary angle is "steering axis inclination", (SAI). Basically that is the tilt inward on top of the struts, as viewed from in front of the car. There is no spec given for SAI. All that is required is it is exactly the same on both sides. That can be adjusted during the alignment by prying the engine cradle sideways as necessary to make both sides equal, but we rarely look for that unless we're told there is a reason to do so. That adjustment never changes on its own, so we only need to look at it when the car was repaired after a crash, or for GM front-wheel-drive cars, when the cradle was removed.
Even when camber is corrected during an alignment, if SAI is overlooked and is not equal, I can guarantee you'll have a car you will not want to drive. "Predictability", meaning you expect the car to respond a certain way when you hit a bump or turn the steering wheel, will be completely non-existent. Every tiny bump in the road will send the car off in a random direction. Even if you mark the cradle and try to reinstall it the same way, don't panic if the car handles miserably afterward. Take it in for an alignment, but be sure to specify they need to look at SAI and tweak it if needed.
For another warning of great value, most people disconnect the brake lines at the master cylinder, then let them drop with the cradle. If you place a stick between the seat and the brake pedal to hold the pedal down about an inch, the pistons and rubber lip seals in the master cylinder will move just far enough to block brake fluid from running out of the reservoir. If the reservoir were to run empty, I have another trick to avoid having to bleed at the wheels later.
Most importantly, when you reconnect the lines at the master cylinder, there is going to be a little air in them. Absolutely do not push the brake pedal more than half way to the floor. That holds true for any car with a master cylinder that's more than about a year old. Crud and corrosion build up in the bores where those pistons don't normally travel. Running the pedal to the floor, as many do-it-yourselfers and inexperienced mechanics do, runs the lip seals over that crud and can rip them resulting in a slowly-sinking brake pedal that often doesn't show up until two or three days later.
There's an even bigger concern with GM front-wheel-drive cars. There's a valve in the master cylinder that trips when there is unequal pressure in the two hydraulic circuits. Once tripped, no brake fluid will flow to one front wheel and the opposite rear wheel. There's a way to manually reset that valve with compressed air, but it's a tedious step that can be avoided by not pushing the brake pedal over half-way to the floor. If there's a little air in the steel lines yet when you reconnect them to the master cylinder, it is going to work its way out when you apply the brakes lightly a few times. When you press the brake pedal slowly, fluid will run down the lines but the air bubbles will float back up. When you release the pedal quickly, the fluid rushing back to the reservoir will wash those air bubbles up with it.
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Tuesday, May 14th, 2019 AT 4:39 PM
