[Jacob]

It looks like I have to have a motor lifter to enable me to change out the belt on my 2001 diablo 180, 4 cylinder. The motor mount is in the way. Can anyone help me figure out an easier way? I was hoping to get it out on the river today.

[mikeyt]

If you check out page 308 of Mercruiser Service Manual 13, the one that covers this engine, you will see that the sea water is pumped to the cooling system by the impeller pick up pump in the lower unit that delivers water to the centrifugal pump on the front of the engine block. The centrifugal pump then pumps the water through the block, manifolds and head. After circulating through the head, it goes into the exhaust elbow, mixed with exhaust gases, and is pumped overboard.
As for how to change the belt, you need to block up the motor, remove the power steering belt, remove the two motor mount bolts (port side) and the spacer. Loosen the alternator. Feed the belt through where the spacer was, put belt on centrifugal water pump pulley (lower) and top pulley, and alternator pulley. Replace spacer and engine mount bolts. Adjust tension on belt and tighten down alternator. Some people suggest feeding a spare belt through while you have the engine bolts out and zip tying it to the spacer, so that the next time the belt breaks, you don't have to go through the hassle of removing the mount bolts. This was definitely one of Mercruiser's dumber designs.....


Sounds like it is a good time for you to obtain a Mercruiser 3.0L service manual. You can access those manuals for free here on our site if you become a contributing member.

[Jacob]

Thanks Mikey. I already replaced it this morning and was back on the water by 1pm!!! I got the same instructions online, but thank you for all your help. You seem to be quite knowledgeable and I'm sure you will be a great resource for help and it is much appreciated!

[Wakeboarder5272]

Originally Posted by mikeyt

If you check out page 308 of Mercruiser Service Manual 13, the one that covers this engine, you will see that the sea water is pumped to the cooling system by the impeller pick up pump in the lower unit that delivers water to the centrifugal pump on the front of the engine block. The centrifugal pump then pumps the water through the block, manifolds and head. After circulating through the head, it goes into the exhaust elbow, mixed with exhaust gases, and is pumped overboard.
As for how to change the belt, you need to block up the motor, remove the power steering belt, remove the two motor mount bolts (port side) and the spacer. Loosen the alternator. Feed the belt through where the spacer was, put belt on centrifugal water pump pulley (lower) and top pulley, and alternator pulley. Replace spacer and engine mount bolts. Adjust tension on belt and tighten down alternator. Some people suggest feeding a spare belt through while you have the engine bolts out and zip tying it to the spacer, so that the next time the belt breaks, you don't have to go through the hassle of removing the mount bolts. This was definitely one of Mercruiser's dumber designs.....


Sounds like it is a good time for you to obtain a Mercruiser 3.0L service manual. You can access those manuals for free here on our site if you become a contributing member.

Thanks for info Mikey. I was about to ask the same question about replacing the belt. I have no idea why the manufacturer would have built the engine this way. What a PIDA. Do you just place a few 4X4's under the block to support it or is there another/better way?

Thanks!