Hi all,
In May of this year I replaced the timing belt, tensioner, and water pump on my '96 Trooper (3.2 SOHC). This required removal of the crank pulley, and I wasn't too keen on the various methods of removing the crank pulley bolt that had been previously discussed here. I also wanted a way to verify that the crank pulley bolt was tightened to the correct torque during installation.
My solution was to make a tool that engaged the pulley but allowed access to the pulley bolt. I wanted a tool that a) could engage the pulley at any angle of rotation, b) could be used with standard hand tools, c) could be used to turn the crankshaft, and d) was simple and inexpensive.
The crank pulley tool I devised is made to fit the interior 'cup' of the pulley. It engages the two nubs that house the bolt holes used to assist pulling the pulley off of the crankshaft. A hole in the middle of the tool allows a 1/2" drive extension to pass through it, enabling access to the crank pulley bolt with a socket drive. Five 1/2" square holes spaced at odd intervals accept the drive end of a breaker bar or socket wrench and allow the pulley to be engaged no matter what position the crankshaft is in.
You can see some pictures of it here:
Crank Pulley Tool I made some measurements of the pulley with a set of calipers (kinda hard to do while you're dealing with the fan blades and shroud!), made a CAD drawing of the part, and sent it off to be laser-cut...
The result? Not bad. The only measurement I totally missed was the radius where the nubs meet the interior walls of the pulley. A little bit of judicious work with a file on the notch tips corrected that problem. I also increased the depth of the notches that engage the nubs a little.
After fine tuning the tool I was able to proceed with the actual maintenance. Using the tool to break the pulley bolt free required two breaker bars, a 4" long extension, and a 24mm(?) socket. The socket and extension had to be inserted through the tool and attached to a breaker bar before I could use the tool.
To tighten the pulley bolt back up I used a socket/extension/torque wrench assembly along with the tool.
When I wanted to rotate the crankshaft I used the pulley and the tool/breaker bar.
Hindsight:
I spec'ed the part out of 1/4" plate steel. I didn't go with thicker plate because surface finish and final dimension were concerns. However, the tool could have used some added thickness around the notches or a flange around the edge to give it more mating surface.
Since the part is only 1/4" thick, care had to be taken when filing the notch tips. The edges needed to be kept square. (Lay a penny flat on the table and look at the vertical edge - that's the edge I'm talking about. Rounding the edges here decreases mating surface.)
Some of you may think that the design is bass-ackwards. Well, you're right. Ideally the part should have only two 1/2" holes for the breaker bar and a series of notch pairs around the circumference. This would allow the tool to be repositioned by disengaging it from the pulley and rotating, rather than having to disengage the entire assembly and move the breaker bar from one hole to another. All I can say is when I was designing the part I was concerned with the amount of force that would be applied to the notches. I probably could have gotten by with 1/2" of separation (metal) between pairs of notches.
When I sent the drawings to the shop I ordered 4 blanks. I've tuned one so far, and intend to keep another as a backup. I intend to give the other two to the 4x4Wire Isuzu community, as CPetrak had intended to do. In other words, the tool blanks are free, but you pay the postage. I figure we could use this thread to keep track of who has the tools.
Comments?
Ed
