91 740 Regina Tune up

neworleans · Post by **neworleans** » 26 Nov 2012, 11:36

Hello friends,

I am going to do some tune up on my 740, planning to replace belts (except timing belt), spark plugs, wires and distributor cap. I think I can handle all this without any reference but if there is any DIY write ups regarding any of these, can you please post it here? I tried to look under repair database but didn't see anything.

Thanks in advance...

Post by **billofdurham** » 28 Nov 2012, 12:33

On the 740 the drive belts are changed by loosening the fixing nuts and the 10mm adjuster bolt, pivoting the accessory toward the crankshaft, and changing the belt. The attached shows how the tensioning system for the alternator works (part#7) It is similar for the other units.

740 Alternator mounting parts.pdf: (122.01 KiB) Downloaded 226 times

For safety reasons when replacing the belts disconnect the battery earth (ground) cable first after making sure you know the radio code. Drop a small amount of releasing oil, do not spray it, onto the bolts to ease their removal. They are usually corroded so it is best to use use six-point sockets to prevent rounding them off. When you reinstall them use an anti- seize compound.

To access the power steering and air conditioning belts you will need to raise the car, using jack stands at the jacking points, to remove the engine under-tray.

Changing the outer, air conditioning compressor belt requires the loosening of a total of four bolts, two at the top of the compressor and two at the bottom of the compressor. The bolts at the bottom of the compressor must be accessed from underneath, after the engine under-tray has been removed. The top two bolts are on each of the two curved mounting arms at the top of the compressor (one in front and one in back). The front bolt is part of the tensioner assembly. The tensioner bolt has a 10mm hex head, and is perpendicular (90 degrees) to the compressor case. The nut on the rear bolt can be hard to reach. The wrench will be close to the point, where a wire goes into the compressor case. This nut is behind and in line with the front nut. Loosen both of these nuts. Then loosen the tensioner, by turning it anti-clockwise.
Once you have loosened the top two mounting bolt nuts and the tensioner, go underneath to loosen the compressor's two pivot bolts. These are closest to the base of the bracket, on which the compressor is mounted. Loosening these bolts allows the compressor to be swung upwards and towards the engine. The belt, which should be in place on the crank pulley, will then slip over the compressor pulley. If necessary use a round shank screwdriver to ease the belt over the compressor pulley. With the belt in place tighten the tensioner until the belt can be pressed downwards with your thumb about 1/4" in the middle of the longest belt run. Tighten the nuts on the lower pivot bolts.
The middle alternator belt requires two nuts to be loosened (not removed) other than the adjusting tensioner bolt. One is at the back of the long top fixing bolt; the other is at the bottom in front. The tensioner bolt is beneath on the side. Turn the tensioner screw anti-clockwise to move the unit toward the engine and loosen the belt. You should check the three rubber alternator bushings when you replace this belt. They can be pressed out and replaced by hand.
The inner power steering pump belt requires that you loosen the 13mm lock nut at the front of the power steering pump bracket (just above the pulley) and loosen the tensioner bolt (anti-clockwise to loosen). You may also need to loosen the nut and bolt through the bottom of the pump which is best reached from below. To get enough slack to remove the belt you may need to remove the bolt that tightens the pump against the adjustment bracket. With this bolt present, the pump will not move freely through the entire adjustment range. You will need to replace the bolt after you put the new belt on.

The distributor cap on the 740 can be hard to replace because you have limited space between the cap and the bulkhead (firewall). This topic covers removal of the cap. Make sure you mark the leads in some way so you get them in the correct order for the new cap.

Bill.

The plugs and wires are straightforward.

neworleans · Post by **neworleans** » 29 Nov 2012, 11:41

I appreciate your time and effort for responding to my message.
The parts will be coming next Tuesday, I wasn't planning to put the car on jacks to replace the belts but will do now.
I don't think the distributor cap comes with o rings, now wondering where to get them...
I hope everything will go smooth but if it doesn't it is good to know that you all are here to help.

Post by **billofdurham** » 29 Nov 2012, 11:58

The O rings go on the drive shaft of the distributor. You only need them if you are replacing the complete distributor, not just replacing the cap.

Bill.

neworleans · Post by **neworleans** » 26 Dec 2012, 12:37

billofdurham

Thank you very much again for your instructions, they really helped a lot when changing the belts. All good now.
The only thing I couldn't remove was the distributor cap, it is pretty tight, what kind of tool would work there to unscrew those three screws??

russellengineering · Post by **russellengineering** » 26 Dec 2012, 17:28

Hi New Orleons,

It is a 8 mm bolt, or so. I use my box end wrench, if you own a ratcheting wrench it is even easier.

The bolt are captive, so when you loosen them they will not fall.

Keep up the good work on the tune-up.

Dave

lummert · Post by **lummert** » 26 Dec 2012, 17:38

I've used an 8mm or 5/16" box end wrench to loosen the distributor cap bolts without any problem. Just need to have patience.