What did you do with your Bus today

[Tailfins57]

Started to rebuild my PTO pump and convert to wet spline yesterday. Got hung up on the main gear shims, .040 too thick. Getting them ground down tomorrow and notching case to accept anti-spin tooth on shim. Hope to assemble PTO tomorrow. Today its time to get really dirty and prepare underside of bus chassis for all the newly refurbished hydraulic system parts.

[Ilulissat]

A few weekends back I had one of the idler pulley belts break on my 1979 FC 31 with a Cat 3208 NA engine. This resulted in less tension on my air compressor and alternator belts and the compressor would produce only 25 PSI as it was turning at about 10 rpm, obviously a no-go situation.

I do not have a swing out radiator, so I decided that I would replace all the belts at one time. After the removal of the bumper, front grill cover, radiator and all remaining belts I noticed a considerable amount of play in the idler pulley. I consulted the WOG forum and found a handful of posting from a decade ago related to catastrophic failure or the idler pulley while in transit and the pros and cons of replacing and rebuilding the idler pulley.

I called my local Cat dealer in Chattanooga and inquired on the price of a replacement pulley, they quoted me just over $550. I was immediately convinced that rebuilding the idler pulley would be the best way to go.

Armed with invaluable information from previous postings on the WOG forum thanks to John Finn, Randy Dupree, Bill Pape and Gardner Yew, the Caterpillar Idler pulley details diagram pictured below, and a little Google research I felt confident enough to undertake the task at hand.

Because the WOG forum has been so valuable to me as a relatively new Wanderlodge owner (2+ years) and I have constantly relied on it and members of the WOG during this time. I wanted to attempt to give back in some way and create a step by step account of my actions over the past week and share it with the forum. I have posted pictures as well. Due to the fact that I can only post 10 photos I will post the additional pictures on a follow up post immediately after the first post.

Based upon the previous posts I read I suspected I would need at a minimum a handful of parts.

From Stowers Machinery, the Cat dealer in Chattanooga, I purchased the following.

1 ea P/N 9N-3342 Shaft $25.86
1 ea P/N 2D-1523 Ring $4.90
1 ea P/N 458-9587 Cat Yellow Paint $10.37

From my local Motion Industries, I purchased.

2 ea P/N 305 PP BRG Timken Bearings $20.52 ea.

From my local O’reilly Auto Parts, I purchased.

1 ea 1-3/4 inch freeze plug $1.90

My total cost of parts not including Tennessee sales tax. $84.07

My step by step process is detailed below. I have also placed a number of corresponding photos for your viewing pleasure.

1) Clean idler pulley assembly with solvent based cleaner or in a parts cleaner tank. Remove to the best you can all grease, grim and dirt.

2) Remove retainer ring from the back side of the pulley. The ring rests within a channel on the back side of the pulley. This is the side that the bearing will be pressed out, so the ring is necessary to retain the shaft and bearings. The ring is made of spring steel, but it is not a typical retainer CLIP. It is in fact a ring, imagine a tight slinky toy with only two complete turns and you will have an idea of the design. The starting point of the retainer ring has to be pried out with a tool and then continue to rotate the pulley almost 720 degrees and the ring will be removed from the pulley. It is very likely that the spring will be in good condition and it may not need to be replace. I purchased my replacement for $4.90 prior to disassembly so I replaced mine. If I had waited I most likely would have not purchased one. The ring itself will not come off the arm of the assembly until you complete step 4. See picture below of ring still on assembly without the pulley.

3) Next using a hydraulic press like the one pictured you can press the on the front side (face side) of the pulley the freeze pull, shaft, bearings and engine mounting arm out of the pulley. I used a 1-1/2 inch socket as a spacer because the ram on the press was larger than the 1-3/4 inch hole covered by the freeze plug. You can see it in the picture below.

4) From the back side of the engine mounting arm/bracket use the press to push the shaft out of the arm towards the bearings (front side of the assembly).

5) Place the shaft head side down and support the bearings including the inner race with blocks and press the small side of the shaft out of the bearings.

6) With the disassembly now complete, clean all components as good as possible for inspection. See pictures below.

7) Discard the old bearing, you would not be having a problem if there were not an issue with the bearings. You can also discard the old freeze plug.

8) Visually inspect the pulley shaft, look for mars, nicks, gashes or complete destruction of the shaft like mine. See picture below. If there is minimal to no visual damage, I suggest you use a set of calipers and compare the shaft diameter of your old shaft to the new shaft you have purchased. If they are identical you may consider reusing your old one. You may have identified the bearing failure early enough where it has not damaged the shaft. However, the likelihood of that is minimal because most of us do not service this part on a regular basis.
Bill Pape stated in his post from 2010 that he is going to service and rebuild his pulley every 3 years. In Bill’s case he most likely will be able to reuse his pulley shaft. Hopefully, Bill will respond to this post and let us know how this have been going with his idler pulley over the past decade.
If you review the photo below of my pulley shaft you will see that mine was severely grooved and worn by the inner bearing races. I measured the damaged area and the diameter was 1.7 mm less than the new bearing shaft.

9) Place the new pulley shaft and freeze plug into a freezer for 15 or more minutes.

10) While shaft is in the freezer, visually inspect the bearing cup area of the pulley for any debris or damage. Rub your finger inside the area and feel for any nicks or gashes. You may use a small and fine machine file to smooth out minor rough areas. Be very careful not change the concentricity of the pulley bearing cup or make any markings on the surface with the file. If the bearing area of the pulley has significant damage, I recommend taking it to a machine shop, having it bored, and resize bearings if necessary. I do not know the tolerance of the pulley bearing cup, so I am unable to provide any advice in this area. Or purchase a new or used pulley.

11) Inspect the engine mounting bracket arm shaft insert area for damage. It is not likely, but possible. Repair as required.

12) Remove shaft from freezer, using a deep socket the size of the inner race of the new bearings, stack and align the bearings on top of the socket opening, press the shaft into the bearings until the head of the shaft is set to the inner bearing race as pictured below. Place the bearing and shaft assembly into the freezer.

13) Stuff a shop towel into the pulley bearing cup area and tape off on both sides. Media blast the pulley to remove any remaining, dirt, grease, grim and paint. See picture below. Air blast pulley and clean with solvent based cleaner and rag to ensure all media particulate is removed. Remove tape and shop towel from pulley and place in an oven set to bake and 125 degrees Fahrenheit for 15 or more mins. Turn the oven on to preheat before you begin to media blast the pulley.

14) Repeat process 13 with engine mounting bracket/ pulley arm. Shop towel not required. Protective taping of shaft insert area is highly recommended.

15) Remove shaft and bearing assembly from freezer and pulley from oven. WEAR AN OVEN MITT. Place the pulley face down on a flat surface. Take the cold bearing and shaft assembly and carefully place, align, and level the bearings into the hot pulley bearing cup area. Head of the shaft facing down into the pulley. With a large socket or bearing setting tool set on the outer race of the top bearing and gently tap with a rubber mallet until bearing contacts the stop inside the pulley bearing cup. Due to the temperature differential and coefficient of linear expansion the freezer was used to shrink the bearings and shaft assembly and the heat of the oven was used to expand the pulley. See picture of completed assembly.

16) Insert the retainer ring into the slot/groove above outer bearing race. You will have to rotate the retainer ring around the groove almost 2 full circles. Ensure the retainer ring is well set and in place.

17) Place a socket or stop block into the face of the pulley position the head of the pulley shaft on the socket or stop block and place face down in press. Remove the arm from oven (wearing an oven mitt) place, align and level the engine mounting bracket/ arm onto the bearing shaft and press the arm down onto the shaft. Leave the oven on. The socket inside the face of the pulley on the bottom of the picture prevents the shaft from pushing out of the bearings. The socket on the top was a spacer because the ram of the press would not stroke low enough to press the arm fully on the pulley shaft. Shaft should not protrude out of the back of the arm. If it does the socket in the top of the picture on the back side of the arm was facing with the open end down.

18) Place pulley assembly arm side down with the pulley face upward on a flat surface. Remove freeze plug from the freezer. Using a bearing press tool or 1-1/2 inch socket hammer the freeze plug into the face of the pulley as shown in the picture below.

19) With reassembly complete as pictured below, clean the entire assembly with a rag and solvent of choice to remove any oil or dirt that may have contaminated the surface during the reassembly. Tape the mounting surface areas on the back of the pulley arm. Place the clean assembly into the oven for 5 mins to warm the surface.

20) Carefully remove the heated assembly from the oven and place it on wire hanging rack. Hang the assembly in a well-ventilated area.

21) Using a high temperature primer Prime the entire assembly and allow to air dry for a few minutes. When no longer wet carefully place the primed assembly on a wire hanger back into the oven and allow it to bake for 10-15 mins.

22) Carefully remove the primed assembly from the oven. Increase oven temperature to 220 degrees Fahrenheit. Return warmed primed assembly to the well-ventilated area. Using Caterpillar P/N 458-9587 yellow spray paint apply a light coat of paint on the entire assembly as pictured below. Allow to air dry for 5 mins and apply a second coat of paint. Allow to air dry for 5 minutes and carefully transfer to and hang in oven. Allow assembly to back in the oven for 15 minutes.

23) Carefully remove from oven and hang in doors in a well-ventilated place for 12 hours for the part to cool and the paint to cure.

I spent about 6 hours doing this work. A lot of time was spent looking for the right size sockets and walking to from different pieces of equipment in the shop.

I hope this information will be useful to anyone who will be faced with rebuilding their idler pulley in the future. I understand that many people do not have access to the equipment and facility that I do and will have to improvise. Or it will simply not be practical for them to perform the work themselves.

Therefore, I make the following offer to any WOG member. If you have any idler pulley that you want to rebuild and you’re in the area you are welcome to use my place to rebuild your pulley. I will be happy to assist you as well. I want to support fellow members as I have been supported.

I also realize that might not be feasible, if you want me to rebuild your idler pulley as I have rebuilt mine. Ship me your idler pulley and I will rebuild it for $250 to include; new bearings, new shaft and retainer ring. It will also be primed and painted with Cat yellow primer and paint.
If the pulley casting or mounting arm are damaged and cannot be reused the price would vary depending upon cost of replacement parts.

Finally, if anyone has a used idler pulley for sale, I would like to talk with you about purchasing it. I plan on having 1 or 2 rebuilt assemblies available at any time to speed up the turnaround time.

[Ilulissat]

Here are the additional pics of the rebuild

[Stretch44875]

Nice work, that shaft was done.

[Bill Pape]

Originally Posted by Ilulissat

Here are the additional pics of the rebuild

Thanks Kevin great post, Our travels are less than 10 years ago. But still feel that pulley needs checked, we do carry a spare. This is the only front end pulley /bearing that has had troubles. Same alternator, power steering pump. Horton fan clutch, did replace the leaky water pump. When working up front I replace all belts.

[Randy Dupree]

Nice job,and thanks for the pics and the blow by blow instuctions..

[Zog]

Replaced the step solenoid including all new fittings, air hose, mufflers, and stainless steel hardware to mount the assembly. Minor tweaks on the mufflers and we now have a smoothly operating step. The old assembly was a corroded mess fused into one rusty mass. Did not replace the pressure switch that pops the step out when the pressure drops. If I decide to replace that later, I'll tie into the pressure supply line with a Tee fitting. Now if I could get the light for the dash indicating when the step is out...

Worked on the Corlon flooring install some more. Just the bathroom remaining.

Found more stuff that I need to fix. One item fixed and the list grows by 2! But she sure is starting to look good!

Oh, and we had a new panel fabricated for the back window cover. The old one was rusted and falling apart along the bottom. The new one is completely epoxy primed and they did a fantastic job of matching the bus paint. Trying to get it wrapped with the picture below. Also decided to call the bus "Flyin' Low". Hope that name isn't taken

[ChrisRasman]

I think you rewrote the book for generations to come. Nice job.

[Alever]

The front electric heater has never worked on our bus. I finally figured out how to access it today. Blue Bird craftsmen still amaze me on ways they built cabinets and access to things. The whole drawer section was held in with four screws (2 on each side) and then it just slides out to access the heater and stereo amp back there. I also discovered that the heater 120 vac power was controled by the front AC switch on the dash and the 120 vac contactor back in the bedroom under the closet and also another 120 vac contactor behind the heater. The contactor behind the heater is operated by the combination kool-a-matic fan/heat thermostat on the wall by the kitchen counter. I moved the wire in the rear to bypass the front AC contactor since I probably would forget to turn the AC switch on when it's cold. It works great now!

[isp2952]

Originally Posted by Alever

The front electric heater has never worked on our bus. I finally figured out how to access it today. Blue Bird craftsmen still amaze me on ways they built cabinets and access to things. The whole drawer section was held in with four screws (2 on each side) and then it just slides out to access the heater and stereo amp back there. I also discovered that the heater 120 vac power was controled by the front AC switch on the dash and the 120 vac contactor back in the bedroom under the closet and also another 120 vac contactor behind the heater. The contactor behind the heater is operated by the combination kool-a-matic fan/heat thermostat on the wall by the kitchen counter. I moved the wire in the rear to bypass the front AC contactor since I probably would forget to turn the AC switch on when it's cold. It works great now!

I wished I had known you had that problem, I would have let you know about the "quirky" set up to get it to work. I used mine all the time, especially since the Primus never worked.