|
Fixing up my "new" 1990 740 non-turbo wagon has been a lot more work than I originally estimated. This car had faithful oil changes, but has been repaired, from what I can tell, by the lowest bidder only when something broke. It is sporting a replacement alternator and the R12 A/C works, but all 5 bushings for the A/C compressor and all 3 bushings for the alternator were hard or oil soaked and completely worn out causing pretty severe belt misalignment. The alternator on this B230F engine mounts top left (US driver's) side and the A/C compressor mounts beneath it on an aluminum casting which holds both accessories. This bracket on my car was 100% covered with 1/4" of greasy road grime, so I decided the easy way to replace all the bushings is to remove the bracket, (clean it up), install new bushings on the bench and then replace it and re-install the alternator and A/C compressor.
The trick is to get the A/C compressor off without losing its valuable R12 charge of refrigerant. This means that one has to remove it without disconnecting any A/C lines, and there is a clearance issue with the lower rear bushing/bolt and one of the A/C metal pipes. I used the following procedure to remove the casting for replacement of all 8 accessory bushings:
1. Disconnect the negative battery terminal -- on this one you really need to do this or risk shorting out the alternator.
2. Remove the alternator -- keep track of where the mounting hardware goes. In my case the intake manifold was already off, so I just hung it out of the way in the general vacinity of the intake manifold.
3. Remove the top holding hardware for the A/C compressor, and the belt.
This will allow the compressor to pivot on its lower mounts and give better access to the bolts holding the lower pivot.
4. Remove the bolt & nut holding the ground wire to the commpressor, remove the wire and loosely replace the bolt and nut until reassembly.
5. Remove the 13 mm nut on the lower front bolt. Use a 12 mm socket ratchet on the bolt head. Make sure the pivot bolt is loose, but don't remove it yet.
6. Loosen the four (14mm) bolts holding the aluminum mounting casting. Remove the two front bolts, and the upper rear bolt. Do not remove the lower rear yet.
7. Fan shroud on my car was already off, you may need to remove it for this next maneuver. You may need to remove the belly pan. During this project I came to realize that the one on my car is missing, whicn explains why the engine is so filthy with oily, sandy road grime, the presence of which, has slowed down every fix I have done to this car.
8. To get decent access to remove the last (rear) A/C compressor pivot bolt, rotate the aluminum cast bracket clockwise on its remaining mounting bolt. It will move the compressor forward several inches, and will give decent access to the rear pivot bolt. Use a 13 mm and a 12 mm box wrenches (no ratchet clearance) to remove the nut from the bolt. The bolt will not come out of the bushing due to lack of clearance with the A/C tube.
9. Be ready to tie up the compressor with a rope or wire. I used a rope between the left strut tower bolt and the a/c metal line which forms a perfect tie-up loop.
10. The front A/C compressor pivot point lies between the two front bushings. Remove the front pivot bolt and pull up on the front of the compressor until its mounting plate clears its bushings. Then rotate the casting further clockwise. The rear pivot bolt will come out of the rear bushing and stay with the compressor. Tie the compressor up to avoid straining its hoses and the clutch wire.
11. Remove the last rear lower mounting bolt for the casting and pull the casting out from the top. You can then clean it up and install new bushings.
Hint: Bushing holes in the casting have only one side chamfered. The bushings press into the casting from the chamfered side. Even if you didn't make notes on which way they came out, it's easy to figure out which way they go in.
Some have recommended the use of ATF fluid to lube the bushings prior to installation. I wouldn't use any petroleum lube, as it eats rubber. I am going to try them dry with appropriate washers to drive them in without pushing too hard on the molded in steel spacer. The units I have still have some mold release compound on them which make them a bit slippery.
I have considered using a bit of water with dishwashing liquid (like the tire store swabs onto the bead of the tire before installation. Another possibility is silicon grease (spark plug silicon) which does not attack rubber.
Since the worn bushings were loose, the rubber rotated freely in the mounting hole. With tight rubber, it is important to tighten the accessory mounting and pivot bolts with the accessories in the correct position to avoid putting a permanent torque on the rubber. (Just like when you tighten suspension bushings with the car on the ground).
This part of the project is still on the bench.
12. Installation is reverse of disassembly.
|
