Thursday, August 13, 2015

A Common School Bus No Start Problem

Thomas School Bus Vandalock

This a common no start problem with all school buses and will continue to be since Vandalocks are standard equipment. The Vandalock as the name states locks out the start circuit and locks the access entries to the inside of the bus. The Thomas pusher in the video does not have any lock out for the entrance doors just the side door and rear emergency exit window.

However there's a cheap and easy solution which is to purchase a metal bike lock (u shaped) and install a couple pieces of angle iron to the entrance door leafs. We only do this with our sports run buses which do a lot of out of town trips. Just recently one of our sports run pusher buses were in Vancouver and the batteries got ripped off.

This is the first time this has ever happened to us perhaps because of the high return for lead at the scrap yard or someone with a truck needed a good set of batteries? Who knows but it's the sign of the times so a lock will be going on both of our sports run battery doors. The service call cost $800.00 in total so a couple of $20.00 hinge locks is a solid investment.

Getting back to the Vandalock system...when we talk to our drivers over the radio we can usually run them through the steps to check all of the exits to see if the latches are either locked or unlocked. One of the students could have very well kicked the latch closed since it's in the perfect spot on the side exit door as seen on the video.

The buzzer will stay on with the ignition key on with no engine crank until the latches are disabled. Vandalock systems are great to have as long as everybody is trained properly.

International School Bus Vandalock 


The International school bus vandalock is the same principle as Thomas buses but designed totally different. The conventional models have the entrance door and the rear door set up to lock out access and the engine start system. The video demonstrates how it works but the there is a minor flaw with the lever that activates the micro switch above the entrance door.

This micro switch has to be activated for the bus to start. Every year we have no start problems because of the lever dropping down while the bus is enroute. A rough road condition will cause this and the lever will drop down deactivating the switch causing an engine no start ... alarms will stay on while the ignition is turned on. One solution is to tighten the lever fastener to increase resistance but ever so slightly so the activating rod has enough push to move the lever.

Thursday, July 23, 2015

Cat 3116 Tune Up Steps

The 3116 Cat diesel engine tune up is quite involved because of the rack that controls the fuel injection system. The synchronization of the rack is the first step once the injectors are installed. The rack is mounted and torqued down on top of the head linked up to each injector rack.

The injectors must have hold downs installed on top of the return springs so the injector rack moves freely. The hold downs are included in the tune up kit. The #1 injector rack is non adjustable because it's calibrated at the factory. The tune up tools include a calibration fixture that has to be set up on #1 injector to enable the remaining 5 injectors to be synchronized.

After synchronization the full fuel setting is checked followed by injector timing and finally the valve setting. This is an extremely abbreviated explanation on setting up a Cat 3116 and without tools and some training it makes this job a tough one. The engine valve clearances can be checked but the rest definitely needs the tune up kit to complete the job properly.

Once going through the steps a couple of times setting these engines up it gets easier. Following the manual works it just takes time to get the calibration settings correct.

Tuesday, July 14, 2015

School Bus Photos 1997 Thomas Pusher

Thomas School Bus Photos from John Whelan on Vimeo.
Oh the memories....this 1997 Thomas school bus pusher is long gone but the photos tell it all. Back then our fleet had 13 Cat 3116 diesel engines. From new they were nice and shiny without any problems until suddenly several of them experienced an intermittent transmission shift episode.

We searched high and low for the fault and scratched our heads and even got the dealer involved thinking ...warranty?? Well what it ended up being was a corroded battery supply wire from the battery to the shift module and transmission control unit.

There was a butt splice half way down the frame which wasn't sealed with heat shrink or soldered at all. The crimped connector was blue with corrosion and caused the battery feed to cut in and out or it would totally cut out and our bus was dead in the water.

 The transmission shop would not give us warranty because the harness was OEM from the factory. So there was some discussion on who pays but it all came out fair at the end. The wiring was all hard wired (no multiplexing) and searching for problems in wiring took a lot of time.

If I had a second chance at this mishap the first thing I would check is "the source"! There was obviously a huge voltage drop between the battery and the TCU. I already mentioned that the ground and battery feed are fed directly to the TCU using #10 wiring and then they break down to #18 wires running into the interface module and TCU.

Step one is check for voltage drop... hindsight is easy after the fact but the time we spent along with the dealer on this issue was excessive. The problem always gets fixed it's a matter of how many hours it takes. In the video you can see the dash and interior layout.

The fit and finish was very good on these models. We've had Cummins power as well in these buses .... official model >>>> ER Saf T Liner. They handled nicely and gave us a lot of miles without trouble. However the Cat 3116 engines did have valve problems and required a few rebuilds. Normally our buses stick around our fleet for 12 to 15 years depending on the mileage.

If there is premature rust sometimes we retire them early considering the cost it would take to repair properly. Thanks for hanging out...please leave a comment and/or share this post if you liked it. Until next time take'er cool :)

Saturday, June 20, 2015

Cummins ISC Diesel Engine CAPS Failure

Cummins CAPS Assembly Repair from John Whelan on Vimeo.

This Cummins ISC diesel engine is in a 1999 Thomas pusher school bus. The engine died suddenly and eventually we found the drive failed in the CAPS pump assembly. Luckily the fuel injection shop we deal with had a core in the back room. We got lucky because the replacement of the pump assembly is around 4,000 dollars.

Most of the ISC diesel engines in our fleet have required a new pump. What happens is multiple engine codes that don't go away. There's a lot going on in the CAPS assy. It develops and controls the high pressure fuel that is distributed at the right time to each injector.

Running at 250 horsepower they are a great engine well suited for a school bus fleet. Other failures were injectors but not very often. The crank and cam sensors act up along with fuel leaks at the electric fuel pump. Our fleet only has 3 of these buses left and they are standing up very well for being thirteen years old.

The fuel pressure sensor in the CAPS accumulator was a regular failure through the years. Cummins did come up with a update on the sensor along with a replacement harness. It only takes 10 minutes to replace the sensor. I personally think Cummins has always been the leader in medium duty diesel engines.

I was an International DT466 fan for years until the emission and electronic version came around. Mechanical fuel injection can not keep up to emission guidelines and the old DT had to be scrapped. They were the best fleet diesel back in it's day but sometimes good things have to come to an end.

At present Cummins has the ISB which runs on DEF (diesel exhaust fluid) and besides the extra maintenance they are the most reliable engines in our fleet. They run seamlessly with the Allison automatic transmissions and the operators really like them for power and we like them for reliability.
Please comment and share this post and thanks for visiting my blog.

Thursday, June 18, 2015

Cat 3116 Rear Seal Installer For Sale

This seal tool has been sold....thank you for your inquiries.   If you're doing repairs on Cat 3116 diesel engines here's a rear seal installer tool that we're looking to sell. In a previous post I mentioned that we no longer have 3116 engines in our fleet. This tool does it all if you have to replace the seal.

I got a new price from CAT and they said $500.00 Canadian funds

This tool is used so we will sell it for $125.00  U.S. + Freight

Leave a comment below with your contact information.

I have a post on this blog that demonstrates how this tool works.  Check it out HERE 

Wednesday, June 17, 2015

Cat 3116 Fuel Solenoid For Sale

Since we sold all of our Cat 3116 engines a couple of years ago we have no need for Cat parts.

This fuel solenoid is new...never used out of the box. The last price that we had on it was $355.00 Canadian.

We will sell if for $100.00 U.S. plus freight. Contact me in the comments section below and let me know if you're interested along with your email address. I'll give the first response priority.

These solenoids are activated with the key on and the winding pulls in the piston to turn fuel linkage on in the governor housing. They screw in and are sealed by an o-ring.

 Here is more information regarding the Cat 3116 solenoid on a previous post. There you will find torque specs and operational details.

Check out this link which leads to all of the Cat 3116 related posts on this blog.

Thanks for the visit ... please comment and share this post.

Tuesday, June 16, 2015

Allison 3000 Automatic Transmission Turbine Sensor Replacement

Allison 3000 Automatic Transmission Turbine Sensor Replacement requires removing the bottom module of the transmission using a transmission jack. The module weighs around 50 pounds so it's much easier to lower it down easily while feeding the harness through the access hole in the transmission housing.

The turbine sensor is internal and is easily replaced once the module is exposed. This code is not very common but it was plain as day when hooked up to Allison DOC software. You can view a graph while road testing and the turbine sensor communication dropped out while on the road. There are 3 sensors on the Allison 3000 models. The engine speed sensor, output speed sensor and turbine sensor.

All these sensors have to be working properly for the transmission to shift properly. They can be tested using an ohm meter. Depending on the ambient temperature the reading should be around 300 ohms. The video gives you an idea on what the module looks like when removed from the main body and where the turbine speed sensor is located.

The 3000 series are very durable and most of the problems were in the wiring. The plastic convoluted loom that the harness is wrapped in is deadly on the wiring insulation. Through time vibration causes the loom to rub on the wiring and eventually expose the copper wire to the atmosphere. Years ago we would run new wiring to a sensor because of the resistance caused by exposure to the elements.

The special wire was twisted and shielded that fixed a lot of communication problems, Using the Pro Link was the first tool available for troubleshooting. Now Allison Doc software is the only way to go. Also I have to give a plug to synthetic transmission oil which in the past I refused to accept because of the price.

Believe me it's well worth the extra cost. Our mechanical failures are non-existent since using synthetic oil. It lasts longer and does not break down in the heat. Our services are 3 years between oil changes. You can't beat that when in our case we're running 77 school buses.

Getting back to our turbine sensor code repair. When removing the module I want to point out that you need to remove the 32 fasteners by hand. The aluminum threads in the housing wear out..... especially the filter housing retaining bolts. It isn't a fun experience heli coiling the threads on these units. We have a Kent Moore tool jig to re-thread the holes which is the only way to do it. I use a speed wrench to remove and replace the bolts.

I hope you enjoy the video and please make a comment and share this post. Cheers!  

Monday, June 08, 2015

Mechanics and Corrosion

The most difficult job when finding an electrical fault is when corrosion is involved. It's hiding somewhere in a connector or poking through the wiring insulation.

So what is the best way to troubleshoot corrosion in the electrical system? One way is to search and destroy the problem by opening the loom and exposing the green stuff but that is frustrating and  takes a lot of time. However it's necessary to make a proper repair.

Another method (when you know which circuit is faulty) would be to check for voltage drop in the circuit that is not functioning. If you can hook up a volt meter at each end of the circuit and see if there is a loss of voltage when the circuit is energized then you can be assured it's a bad wire. Checking the resistance is another check that works.

In our shop we've been using a load on the wiring circuit in question. A regular light bulb (non LED) hooked up to the one end of the wire will tell you if there is a lack of current when the light is dim after energizing with battery power. The wiring is either corroded or frayed restricting current flow.

If you have money to spend on tools you could use "diamond logic builder" software for International trucks to see the circuits working in a graphic form on a laptop. You can click on a circuit and actually see if the load is getting battery power. The pin outs on all the connectors are at your fingertips. I've used this software and it's a great tool to have compared to digging through wiring harnesses with a hope and a prayer.