Drive Pulley

I have a 92 Isuzu pickup with a bad water pump. I could fix it if I could get drive belt pulley bolt loose. Is this thing reverse threaded (righty/loosey)?

Which engine? My manual (which has been wrong before) says you don’t have to remove the pulleys for the 4-cylinders and the pulley should just slide right off after you remove the fan on the V6.

Its a 4 cyl engine. To uncover some of the water pump bolts, the timing belt cover has to come off, to get this off, the drive pulley has to come off and I can’t get the bolt that holds the pulley to come loose. Any ideas?


You are right. There is a pulley which is threaded in reverse. I would guess it would be the idler arm pulley, as this is the most expendable.

I apologize, I missed that you are asking about the drive pulley.
First of all, I seriously doubt that you need to remove this pulley to remove the timing belt cover. I also have doubts that the water pump is somehow fastened underneath the timing belt cover, but anything is possible.
I would recommend buying the Chilton’s manual for your year and model, although I have often been frustrated by phrases in these manuals such as “Remove the water pump” without offering any insight as to which tools might best be used to best do the job.

First of all, the timing gear is driven by the crank shaft via a belt or chain but sits well above the crank shaft. It drives the cam-shaft, which times your car’s ignition. The drive pulley is attached directly to the crankshaft and is hightly torqued. I have replaced a dozen or so water pumps and timing chains or belts and have never had to remove this pulley. Forget this plan. Unless you have an air compressor and an air ratchet, and can fit this apparatus onto the drive pulley nut, you will never make it happen. The engine will always turn before you achieve enough torque to break this nut.
So instead you need to focus on the removal of the water pump.
If you are trying to do this job with a socket wrench, try buying a set of hand wrenches, decent quality, each size open and closed. The water pump and the timing chain cover are both almost certainly removable by means you haven’t discovered yet. The timing chain cover bolts require almost no torque to remove. They are also very small and might very likely be removed (barely) without removing the pulley.
I have found that doing many jobs in these new tight engines requires many types of standard tools and experimentation, as well as a great deal of patience and coffee breaks. Not to mention a good deal of muscle memory. Oten an open ended wrench can win only an eighth turn, and then you have to reverse the wrench. I have thick fingers so I have had to use a strong thin magnet to retain control of small bolts as they come free.

I hate to add this but if you have never replaced the timing belt, you should do it while replacing the water pump. It’s right there but you must know the rules. Buy the book.