Cassman500 »
I’m about to replace my alternator which has recently died in my 240, I was wondering if anyone had any tips for this. I noticed I’m going to have to remove a radiator hose. Is there any easy way to drain the radiator before I remove it? Also is there a serpentine belt tension pulley I can loosen to remove the old one?
billofdurham »
You shouldn’t need to remove a radiator hose to replace the alternator but if you feel it is necessary the coolant can be drained by removing the bottom hose from the radiator and draining the coolant into a container. You don’t need to drain it all, just enough to drop the level below the top hose. Before draining any coolant set the heater controls to max heat to prevent an airlock in the heater and leave them at max heat until you refill the system which should be done slowly.
There is no tensioner per se on the 240. The tensioning is done by moving the alternator. At the top of the alternator there is a tensioning arm with an elongated hole in it. There is a square necked screw which goes through the arm and fastens to the alternator. At the end of the arm there is an adjusting screw. As you are removing the alternator forget about the adjusting screw. Slacken the nut on the square necked screw and push the alternator to the side, releasing the tension. If the alternator won’t move, loosen the flange screw underneath the alternator until it will. With the belt off remove the wires from the back of the alternator, making sure you know which goes where. Remove the two bolts you have loosened and remove the alternator.
Installation is, as usual, a reverse of the above. At this time don’t fully tighten the two bolts. Leave them slack enough to allow the alternator to be moved with a little pressure. Put the belt around the pulleys and pull the alternator to take up the slack. Holding the alternator so the belt is reasonably tight adjust the tension using the adjusting screw on the end of the tensioning arm. The belt is tensioned correctly if you can depress it 5/16″ with normal pressure from your thumb midway between the fan and the alternator.
240 DL 1989 Alternator replacement
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Last Updated on August 4, 2026
1 Comment
There is a problem on the older 240 series, 1984 B23F I know from personal experience, with the ground not being intact between the alternator and the metal grounding point. Please check the wiring loom before you re-install your new alternator for a good grounding wire, or you’ll be wondering why your Swede won’t crank when you’ve just replaced the alternator. If worst comes to worst, you can create a temporary ground for the alternator with a piece of copper wire. Connect one end to a good unpainted ground near the alternator(strut towers will do), and the other to the attachment bolt on the alternator mounting bracket itself. This will suffice until you can get it properly fixed.