: Need help removing 99 STS northstar motor

12-19-07, 11:34 AM
Hoping I could get some help from many of you that have pulled the northstar motor or done the Head Gasket job. (done search but it doesnít answer some of my questions below) I am new to working on the Cadillacs (Ö I said I would help a friend timesert and replace his head gaskets) but not new to mechanical work. I typically work on Audis and Acura NSXs.

The car is a 1999, 99 Seville STS

I am at the point of unbolting the 6 bolts that hold the frame to the body but I already forsee some problems as Iím not sure on the questions below Ö

1. Remove the brake pressure switch and bracket.
What is this and where is it located??

2. Disconnect the electrical harness from the underhood relay center.
Iím a little lost on this one, are these the 3 block harnesses under the relay box held in by a 7mm screw? If so how do you get them out after you loosen the 7mm screws? I even tried pulling all the fuses and relays in case they were holding them in. Am I undoing the wrong harness?

3. Disconnect the right and left road sensing suspension electrical connectors.
are these the servo type boxes with a little servo link attaching to lower control arms on either side?

4. ABS Brake unit
finally I have a question in regards to the ABS unit behind the radiator on the drivers side. Is this suppose to be removed from the frame before I drop the motor? I have already disconnected the lines at the proportioning valves, but noticed the lines to the front brake calipers is still bolted to the frame, do I unbolt the line from the frame or do I unhook the ABS unit completely? (may be related to question #1)


12-19-07, 12:33 PM
I've done a 97 (my brother's) but it should be very similar.

We did not disco any brake lines. We hung the calipers from the inner fenders and the ABS unit stayed with the body. We did have to disconnect the AC lines near the radiator.

The wiring harness wasn't bad (easier than the 94) but I do not remember the details. The fuses don't have to come out...possibly there is a bolt you are missing. Check underneath, you may see threads showing.

Carefully look over the cradle and make sure everything is disconnected. Even though I have the FSM I didn't necessarily follow every step in order.

There have been a couple of recent threads on dropping the cradle. Are you lifting the body with an engine hoist?

12-19-07, 12:39 PM
car is on a lift, will be dropping car onto jackstands, unbolting and raising car back up

Mark C
12-19-07, 04:01 PM
Mine was a 97, did it in my driveway with a floorjack and some jackstands, 99 should be similar.

Fuses stay in the car. Pop the large fuse panel cover off and you will see the fuse block is made up of 2 or 3 separate blocks that are up on plastic stands. You press the legs of those stands together and pull the top of the fuse block and plastic stands up off the base, and you will see a large red cable bolted to the bottom of the fuse block base thats the bolt you want to remove, pull it out (and watch out for washers that will fall out) slide the bolt off the cable terminal and then put the bolt back into the fuse block base so you don't loose it. You also have to disconnect the wiring harness that passes thru the passenger side firewall. There are a couple of electrical connectors and a vacuum line connector up under the passenger side of the dash that needs to be disconnected. Other than the positive and negative battery cables, A/C lines at the condenser, oil cooler lines and tranny cooler lines at the radiator, ABS reluctor connectors to the front wheels, the connection between the A-Arm and the RSS box that control the active shocks, the active shock connectors and a couple of grounds on the body, and on the ABS module plus the stuff referrenced above you don't have to remove any additional wiring from the engine/transmission to get it out of the body. The less you disturb the easier it is to reinstall.

I also just pulled the ABS module out of its bracket and tied it to the radiator support (so it wouldn't fall out as I lowered the cradle), and disconnected the clips for the front passenger side brake line that runs along the front edge of the cradle. I tied the calipers to the top of the wheel wells and disconnected the brake line clips from the front strut so that basically the whole front brake system remained with the body so i wouldn't have to bleed the brakes.

If you can disconnect the front strut links (I couldn't get mine apart) between the sway bay and the front struts I'd recommend just pulling the bottom of the strut out of the steering spindle and leaving the strut hanging from the body by its upper bolts.

Pull the radiator and fans before trying to drop the cradle out.

12-19-07, 04:20 PM
mark thanks for the extra help. What about the rear brake lines? I disconnected mine at the proportioning valves leading to the back brakes per manual, wouldnt this imply that i'd have to bleed the system?

Mark C
12-19-07, 05:45 PM
If you leave the ABS and master cylinder up in the car you don't have to touch any brake lines, except for the ones going to the front calipers, and then you only have to unbolt the clips that hold the lines to the front suspension, so you don't pull the lines out of the ABS unit. Bleeding a car with an ABS system is a pain in the but if you can't activate the ABS unit something the dealer can do with their equipment, but I can't in my driveway.

Don't forget the pinch bolt on the steering column coupler as well. You need to pull the bolt all the way out to get the rack separated from the column before you lower the cradle down to far, or you may damge the universal joints in the column. You will have to reach up under the back edge of the frame or in from the drivers wheelwell to get at it.

12-20-07, 10:25 AM
Alright, I got the motor out last night. Heres a couple tips that may be specific to the 99s only.

1. The lines going to the ABS unit HAVE to be unhooked in order to pull the motor. I looked it over and over again and there is no way the motor and cradle drops out leaving the lines in the car. (unless you want to remove the passenger side suspension and control arm assembly because that is where the lines run through)

I unhooked the rear lines at the proportioning valve and the 2 lines from the master to the ABS unit.

2. in regards to my relay box question. There are 3 harnesses under the relay box each held by a 7mm bolt and a 2 red wire harness for the jump start pont on the relay center.

unplug the 2 wire harness, and loosen all the 7mm bolts holding in each harness block. at this point the harness is loose but wont come out of the relay box. As you wiggle each block around, you will see a small blue clip on the side. I used a small flathead to unclip the blue part and the blocks come out.

12-25-07, 11:20 PM
if you just disconnect the two brake lines coming out of the master cylinder and the rear lines just behind the rear of the cradle, you can drop the whole cradle with the abs unit still attached to the cradle. It's generally to just disconnect everything that goes from the body to the power train assembly, then remove the entire unit. I'm not too sure exactly how you did it but if you separate the strut from the knuckle everything just drops down.
Also if you have a vacuum pump the brakes are very easy to bleed.