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1968 Sonett Alternator and radiator fan upgrade.
Please note: The following mechanical advice is offered to enhance the overall knowledge of the automobile owner only. Any and all work described in the following article should be performed by a licensed mechanic only. The author shall be held harmless in the event of injury or accident by the automobile's owner and occupants, should the work be performed by an unlicensed mechanic.
By Buce Turk
Keep in mind this article describes alternator installation on a 1968 Sonett. If your car is a different year, you may have slightly different lower mounting and belt adjustment brackets.
The alternator on my 1968 Sonett was rebuilt just two years ago at a cost of nearly $200. This spring it failed to charge once again. Part of my diagnostics was to test the diodes which can be done as follows: Disconnected the alternator from the battery and voltage regulator, connect an ohm meters black lead to the alternator's positive terminal and the red lead to ground. If you get a reading, the diodes are bad. I did get a reading, so I needed to rebuild the alternator again or go in a different direction.
I decided to install a 70 amp 1981-83 Saab 900 alternator, readily available from a multitude of sources on EBay, Amazon and others for under $100. The advantage of a 900 alternator is more amperage and bolt on installation. The fan on a 900 alternator runs clockwise when viewed from the front, the fan on a V4 alternator runs counterclockwise. The 900 alternator that I received did not come with a fan or pulley, so I removed them from the V4 alternator and installed them on the 900 alternator. This solved the fan rotation issue.
The 900 alternator has a built-in voltage regulator, so there is no need to use the one on the car. Simply attach the heavy red wire to the positive terminal on the back of the alternator and the thin red wire to the spade connector as shown in the photo. The 900 alternator mounting and belt adjustment holes differ from those on the V4 alternator. The good news is the 900 alternator will sit further away from the #1 spark plug, making plug removal easier. The bad news is you will need a different fan belt. Bring the old belt to an auto parts store and ask for one that is a half inch longer, make sure it is 3/8” wide. Good luck on purchasing the correct length on the first try!
Before I replaced my alternator, the car had quite a bit of rotational noise at the front of the engine. I attributed much of it to the cars steel balance shaft gear but also thought the alternator bearings were at least partly to blame. After installing the new alternator, I had a bit less noise, but I still heard quite a bit of hissing. I removed the fan belt, started the car back up and sure enough the sound went away. The new alternator spun freely and quietly as did the water pump when spun by hand. The radiator fan on the other hand felt notchy and made a grinding sound when spun.
Unfortunately, the fan bearing is located inside the timing gear cover and removing the cover is not fun with the engine in the car, so I decided on plan B, install an electric fan. My first preference was to install a Saab 900 radiator fan on the back of the radiator, but it would not fit. The funny thing is it does fit on the back of my 1974 Sonett III. After taking a few measurements,
I decide on two Everest-way 12V, 80W 10” fans from Amazon for a whopping $35.00 for the pair. The fan manufacturer recommends an inline 12 AWG waterproof 30-amp fuse, which was also purchased from Amazon.
The old fan was no longer needed, so I removed the four bolts that hold the fan and pulley to the timing gear cover. I then realized there was not enough room to lift them out; the radiator was in the way! Out came the radiator.
Should an electric fan be mounted on the front or back of the radiator? If mounted on the front, you can argue it will reduce the CFM’s (Cubic feet per minute) flowing through the radiator when the fan is not running. You can also argue the CFM’s will be reduced if mounted to the rear of the radiator, creating back pressure that reduces CFM’s when the fan is not running. The way I see it, the fan has a job to do, and it only performs its job when it is running. So, the real question is (to me), does the car run cool when the fan is running? If it does, I don’t care where the fan is mounted! Feel free to debate this in the comments
The electric fans came with long plastic anchors that press through the radiator fins and are held in place by plastic compression nuts. Installation was not fun and required small hands and plenty of knuckle cuts when reaching down below the water pump to secure one of the anchors.
The next step was to install a SAAB Engine Cooling Fan Switch (82 Deg) 8547572 - Wahler 601082D 6010.82D in the upper radiator hose. I used the same fitting and switch as found on a Saab 900. I also had to install a shorter fan belt, 3/8” x 34 ¾”, because I eliminated the fan pulley.
The fans were connected in series, the hot wire through the 30-amp fuse which was attached to the back of the alternator. The fans ground wire was routed through the cooling fan switch. When wired this way, the fan will continue to run until the engine cools off, even with the key removed. Another option is towire the fan to a fuse that is only hot when the key is on.
This article was written a couple of months ago, the car has since been driven in 98° F (37° C) at 80 MPH for an extended period of time, I can report the car ran cool, well within the normal range. The 70-amp alternator resulted in brighter headlights and the directionals blink more quickly. Aside from that, no noticeable difference. I will be replacing the 82° C cooling fan switch with a hotter one. The 82° C turns the fan on earlier than is necessary.
Keep in mind this article describes alternator installation on a 1968 Sonett. If your car is a different year, you may have slightly different lower mounting and belt adjustment brackets.
The alternator on my 1968 Sonett was rebuilt just two years ago at a cost of nearly $200. This spring it failed to charge once again. Part of my diagnostics was to test the diodes which can be done as follows: Disconnected the alternator from the battery and voltage regulator, connect an ohm meters black lead to the alternator's positive terminal and the red lead to ground. If you get a reading, the diodes are bad. I did get a reading, so I needed to rebuild the alternator again or go in a different direction.
I decided to install a 70 amp 1981-83 Saab 900 alternator, readily available from a multitude of sources on EBay, Amazon and others for under $100. The advantage of a 900 alternator is more amperage and bolt on installation. The fan on a 900 alternator runs clockwise when viewed from the front, the fan on a V4 alternator runs counterclockwise. The 900 alternator that I received did not come with a fan or pulley, so I removed them from the V4 alternator and installed them on the 900 alternator. This solved the fan rotation issue.
The 900 alternator has a built-in voltage regulator, so there is no need to use the one on the car. Simply attach the heavy red wire to the positive terminal on the back of the alternator and the thin red wire to the spade connector as shown in the photo. The 900 alternator mounting and belt adjustment holes differ from those on the V4 alternator. The good news is the 900 alternator will sit further away from the #1 spark plug, making plug removal easier. The bad news is you will need a different fan belt. Bring the old belt to an auto parts store and ask for one that is a half inch longer, make sure it is 3/8” wide. Good luck on purchasing the correct length on the first try!
Before I replaced my alternator, the car had quite a bit of rotational noise at the front of the engine. I attributed much of it to the cars steel balance shaft gear but also thought the alternator bearings were at least partly to blame. After installing the new alternator, I had a bit less noise, but I still heard quite a bit of hissing. I removed the fan belt, started the car back up and sure enough the sound went away. The new alternator spun freely and quietly as did the water pump when spun by hand. The radiator fan on the other hand felt notchy and made a grinding sound when spun.
Unfortunately, the fan bearing is located inside the timing gear cover and removing the cover is not fun with the engine in the car, so I decided on plan B, install an electric fan. My first preference was to install a Saab 900 radiator fan on the back of the radiator, but it would not fit. The funny thing is it does fit on the back of my 1974 Sonett III. After taking a few measurements,
I decide on two Everest-way 12V, 80W 10” fans from Amazon for a whopping $35.00 for the pair. The fan manufacturer recommends an inline 12 AWG waterproof 30-amp fuse, which was also purchased from Amazon.
The old fan was no longer needed, so I removed the four bolts that hold the fan and pulley to the timing gear cover. I then realized there was not enough room to lift them out; the radiator was in the way! Out came the radiator.
Should an electric fan be mounted on the front or back of the radiator? If mounted on the front, you can argue it will reduce the CFM’s (Cubic feet per minute) flowing through the radiator when the fan is not running. You can also argue the CFM’s will be reduced if mounted to the rear of the radiator, creating back pressure that reduces CFM’s when the fan is not running. The way I see it, the fan has a job to do, and it only performs its job when it is running. So, the real question is (to me), does the car run cool when the fan is running? If it does, I don’t care where the fan is mounted! Feel free to debate this in the comments
The electric fans came with long plastic anchors that press through the radiator fins and are held in place by plastic compression nuts. Installation was not fun and required small hands and plenty of knuckle cuts when reaching down below the water pump to secure one of the anchors.
The next step was to install a SAAB Engine Cooling Fan Switch (82 Deg) 8547572 - Wahler 601082D 6010.82D in the upper radiator hose. I used the same fitting and switch as found on a Saab 900. I also had to install a shorter fan belt, 3/8” x 34 ¾”, because I eliminated the fan pulley.
The fans were connected in series, the hot wire through the 30-amp fuse which was attached to the back of the alternator. The fans ground wire was routed through the cooling fan switch. When wired this way, the fan will continue to run until the engine cools off, even with the key removed. Another option is towire the fan to a fuse that is only hot when the key is on.
This article was written a couple of months ago, the car has since been driven in 98° F (37° C) at 80 MPH for an extended period of time, I can report the car ran cool, well within the normal range. The 70-amp alternator resulted in brighter headlights and the directionals blink more quickly. Aside from that, no noticeable difference. I will be replacing the 82° C cooling fan switch with a hotter one. The 82° C turns the fan on earlier than is necessary.
