CAT 3116 DIESEL ENGINE PROBLEMS AND FIXES

We have 13 CAT 3116 diesel engines in our fleet and there have been some problems so I thought I would share them with you. First of all I have to say they are unbeatable as far as construction goes. Heavy castings make this diesel engine hard to kill!
However, one weak spot are the exhaust valves, they break and make one big mess. The head must be repaired or replaced, we have been using REMANUFACTURED heads which cost us around $1200.
To prevent this exhaust valve problem we make sure the valves are adjusted every 60,000 KM. [ 36,000 miles]
The turbocharger must be checked as well as the cylinder and piston related to the offending exhaust valve. With flying valve debris there is no room for taking a chance!

Sidebar:
CAT 3116 diesel engines are fussy as far as setting valves and injectors. You MUST have the proper tools. The fuel is controlled by a GOVERNOR that moves a rack attached to each unit injector.
The 3116 tune-up: requires checking & adjustment of the fuel setting, synchronization, injector timing and valve adjustment. The tool kit has a digital dial guage that keeps adjustment tolerances within specifications. All tune-up specs are on top of the valve cover.

Another problem we've experienced is pressure in the fuel tank from compression blowing by the injector seats into the fuel system causing the engine to run very rough with no power. The injectors have to be removed and tested while the injector seats must be machined. If machining does not clean up the seats they must be replaced which can be done in-frame. When installing a 3116 injector you must use a special injector hold-down tool that seats the injector properly. We also use the o-ring seal on the injector tip even though it's not specified, it adds an even better seal.

These 2 failures are the most common we've experienced with the CAT 3116 diesel engine. There have been a few injector[they seize up] and governor failures but far and few between.

Cat 3116 Tune Up Tools and Procedures

CAT 3116 Diesel Engine Tune Up from John Whelan on Vimeo.

Cat 3116 Injector Adjustment

The video shows how the Cat Tuneup Tool Kit works on a 3116 diesel engine. When the injector is installed I find it's easier to place the dial contact on the injector by feel and then having a look to make sure it's seated properly. In the Cat tune up kit you need the dial indicator, contact point, timing gauge block and magnetic base.

On top of the valve cover is a data plate that has the factory timing spec. This is the reading that you need to stick to when the timing tool is all set up. First of all you need to preset the dial indicator on the timing gauge block and set it exactly to 62.00 mm.

Rotate the engine so cylinder #1 is on the compression stroke. Both valves will be closed and cylinder #6 will be on the exhaust stroke. Injectors 3 5 6 can be set in this position along with 1 2 4 intake and 1 3 5 exhaust valves. (Intake .015 in exhaust .025 in) The injector spec on the valve cover can vary plus or minus .020 mm.

Rotate the engine 360 degrees and adjust the remaining valves and injectors. The Cat tool kit comes with a manual and gives you a detailed step by step procedure for these adjustments. It's a fussy operation but once everything is set these engines run very nicely. Keep the valve adjustment on a regular schedule because of a weakness in the exhaust valve stems that blow apart if there running at high temperature and rpms.

I hope the video gives you a better idea what's involved with injector set up on the 3116. The entire tune up kit is pricey and the last time I checked it was up around $4000.00 Canadian. We had to purchase it however that was in the mid 1990s and we paid much less than that. You can not get away with setting up these engines (except valve adjustment) without the kit.

Cat 3116 Diesel Engines

I've been getting a lot of questions on 3116 Cat Diesel Engine problems. The one stumbling block is the tooling you need to repair these model engines. After the basics like fuel supply and electrical issues are taken care of the next step is replacing injectors and other related tasks.

The tools required for tuning up these engines come in a kit and costs over $2000.00 in my part of the world. These tools must be used to get this engine synchronized, timed and set up properly.

If you have access to the tools that's great, a manual accompanies the kit. There is a learning curve with setting up the 3116 but do it once and you'll understand the concepts behind the injection system.

There are glitches with the 3116 are usually the same and I have posted them as they happened on this blog. The exhaust valves are weak and it seems like #5 exhaust valve is a weak spot. Keeping the valves set is a good practice and prevents a tight valve and overheating.

If you use the search box above you can get more details on tune ups and repairs. There are specific rebuild procedures covered as well.

Or you can check all the posts out here:

http://schoolbusmechanic.blogspot.com/search?q=cat+3116

You might have to be more specific with your search i.e "cat 3116 oil pump"

You can always make a comment or ask a question and I will get back to you...

Cat 3116 Diesel Engine-Installing And Seating Injectors

Installing and seating injectors on a CAT 3116 DIESEL ENGINE.
http://schoolbusmechanic.blogspot.com/2006/05/cat-diesel-engine-model-3116.html
Once the injectors are installed {REFER TO LINK ABOVE - FROM A PREVIOUS POST} they must be seated properly.
Cat makes a seating tool that will do the job preventing compression from leaking past injector seats ino the fuel system.
Go to this previous post below and get detailed information on how to seat 3116 injectors.
http://schoolbusmechanic.blogspot.com/2006/04/diesel-engines-cat-3116-injector.html

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.

Cat 3116 Engine-Repairing Common Engine Oil Leak

The Cat 3116 Engine has a common oil leak that is very easy to fix. The first step is to remove the steering pump which is driven off the air compressor. The next step is to remove the rear housing from the air compressor, it's held on with 4 nuts on studs, there is a square o-ring that seals the rear housing to the main compressor body. The Compressor is a "Bendix 850 Model" which is a 2 stage [2 cylinder] unit.



The Cat 3116 Engine oil pressure guage and air compressor oil feed lines run off the housing pictured here bolted to the engine block which is connected to the main oil pressure gallery. There is an o-ring seal between this housing and the engine block.





This 2nd block is the air compressor rear support block that has an o-ring seal as well. This block also serves as an oil drain for the 3126 model which has a oil pump above that supplies high pressure oil to the HEUI system [Hydraulic Electronic Unit Injectors].




Pictured here is the oil pressure manifold housing removed. The heat is absorbed by these 2 o-rings and they become very brittle causing an oil leak. Diesel Engines run from the "heat of Compression" so you can bet the engine block is smokin' hot! when operating temperatures are met.





The manifold housing o-ring has been replaced and is secured with 2 M8 Metric bolts. These 2 areas are a common oil leak in both the Cat 3116 Engine & 3126 Diesel Engine .






Recommended: Diesel Engine Repair Manuals

Cat 3116 Diesel Engine - Installing Crankshaft & Main Bearings

Cat 3116 Diesel Engine Rebuild: Today we started assembling the Cat 3116 engine that failed back in June. It was put off until now for various reasons so when time permits and nothing else major happens the assembly process will continue.

The block has been machined and new sleeves pressed in the bores. The Cam Bushings were installed by the machine shop as well.

The first thing to do is install the piston cooling nozzles {as seen above} which get Main gallery oil pressure. They are held in by M8 fasteners and the torque is 18 ft lbs. + or - 2 ft. lbs.

Installing The Main Bearings:
The tang on each bearing makes it impossible to put them in wrong. The # 5 Main Bearing acts as the thrust bearing.
The other half of each bearing set must be matched up with the corresponding bearing cap.

Coat each bearing with a generous amount of Lubriplate grease {my favourite} or any other recommended engine assembly lube. Assembly grease is a good idea if the engine will be out of service for awhile.

Install Crankshaft: Very carefully lay crankshaft into block. Give the Crankshaft a slight rotation so you know it's seated properly in the upper main bearings.

Prepare Crankshaft Main Bearing Caps:
Make sure the main bearing caps are clean and install the bearings aligning reference tangs with notches in caps.





Install and Torque Main Bearing Caps:
Carefully install bearing caps, they fit snugly in block and don't need to be forced. Lubricate threads and between bolt head and flat washer of each main bearing capscrew.

Torque the cap bolt on the TANG side of the bearings first and then the other side to 45 ft. lbs. {Tang is the bent out portion of each bearing used as a reference when installing in the block or the cap}

Recheck torque and then turn each bolt 90 degrees starting at the non- tang side of each Main Bearing then move to the tang side.

Above you can see we are using a Torque Angle Guage from Snap-On tools.

Finally finish off by checking the end play of the Crankshaft with a magnetic base dial indicator which should read between .003 and .009 in.

More posts coming on our Cat 3116 Diesel Engine.

Cat 3116 Diesel - Engine Removal

This CAT 3116 Diesel Engine has failed because of an exhaust seat on #5 cylinder that collapsed and the fragments caused damage to the cylinder wall. The next operation is to remove the engine assembly and strip down the block so the cylinder can be repaired.





The Cat 3116 block deck surface has to be secured with a special plate fastened down with head bolts so the block does not warp while boring is performed.
Here you can see the scores running down the cylinder wall. Bits of broken metal that came from the exhaust valve seat lodged between the piston and cylinder. The turbo will have to be sent out for repair as well since the failure was on the exhaust side. Fragments will have went through the turbine wheel[exhaust side of the turbo] which runs on a very close tolerance.




Once the block is standing up resting on the flywheel housing the pistons are easily removed. All accessories have been removed including the oil cooler, governor, front gear housing ,camshaft and follower assemblies.
The cylinder head was removed while in the bus frame. We built a lifting bracket to fit over 2 head bolt holes and picked up shorter grade 8 bolts so the block could be hoisted out of the frame.



Once the pistons, flywheel housing and main bearing caps have been removed we used a fibre lifting strap to hoist out the crankshaft.





Out comes the crankshaft and the block will be sent to the machine shop for repair. They will measure the cylinder wear and see if they can machine damaged cylinder and press a dry sleeve bringing #5 bore back to standard.
They will hot tank the block and later press in new camshaft bushings.
Stay in touch with this blog as I reassemble our CAT 3116 Diesel Engine.

Cat 3116 Diesel Engine-Fuel Rack Synchronization

Cat 3116 Diesel Engine synchronization is the next step once the fuel injectors are installed. Each injector is seperate from each other and have there own fuel rack. So the main linkage which is controlled by the governor must be synchronized so each injector rack supplies the same amount of fuel into the cylinders. #1 injector is the only one that is not adjusted because it is factory set so the other 5 injectors can be set to #1.


So what we want to accomplish by this setting is to have exactly the same travel on each fuel injector as the racks move from no fuel to full fuel depending on engine demand.
There are calibration tools that have to be used on #1 injector so the right dimension is achieved when checking the other injectors. All these tools are found in the Cat 3116 Tune-up kit with instructions. There is a bit of a learning curve using these tools but if you want to save some bucks and do it yourself it's totally possible.
This was just a basic overview on Synchronization for the Cat 3116 Diesel Engine

CAT 3116 FUEL SHUTDOWN SOLENOID

The cat 3116 diesel engine comes with a electric fuel shutdown solenoid which is controlled by the key switch. It is located on the Governor/pump assembly [threaded in] with two wires controlling the electro-magnetic on/off function. The solenoid is energized at all times when the engine is running which means it can get hot and sometimes fail.

The Cat 3116 diesel governor has a fuel shut-off lever inside it's housing that the solenoid pushes against using spring pressure meaning there is no 12 volt power to the solenoid. When ignition voltage is applied the plunger retracts into the solenoid and another spring on the governor rack lever allows fuel to the injectors.

If you were to remove the solenoid the engine would run continuously until you physically reached into the governor housing and pushed on the shutdown lever. I've had a problem where the lever inside the governor has come loose and required disassembly of the housing and the mounting screws re-tightened. It takes an extra set of hands to get the housing back together! Care needs to be taken as there is multiple arms and levers that have to be re-engaged properly. I just replaced a fuel shutdown solenoid that got so hot it startd to seep engine oil, this is rare.
The Cat 3116 tune-up kit comes with a special tool to remove the solenoid [Tool #9U5120] the complete tune-up kit # 128-8822.
The fuel shutdown solenoid torque is 50 + or - 7 ft.lbs.
pull-in coil 22 ohms
hold-in coil 11 ohms with temperature @ 77 degrees farenheit

Cat 3116 Troubleshooting No Power

The problem with this 3116 Cat Diesel Engine was no power. The funny thing was it felt like someone stuck a banana in the tailpipe. There was no engine miss or hesitation what so ever. I checked for excessive back-pressure and that was normal.

One thing that seemed curious was the rpms in neutral went to the maximum without any problem but as soon as you put a load on the engine the rpms stayed at around 1200 rpm with no torque at all.

The Cat 3116 Governor controls the fuel rack which in turn decides how much fuel to allow to the injectors according to engine load and speed. The operator controls the throttle and the load is read off of the turbo boost pressure. The boost line goes directly to the governor air fuel ratio control. The more boost, the governor moves the rack for more fuel.

I tested the air/fuel ratio diaphragm with a regulator on the bus and it was leaking into the housing meaning the diaphragm had failed. Once I replaced the diaphragm it was a no-brainer to retest the new assembly and check for leaks. The new diaphragm was holding nicely.

NOTE: Don't test diaphragm over 20 psi

Here is a picture of the old diaphragm with a split in it. I remember the red flag that popped into my head when I called the Cat dealer for this part and they had 3 diaphragms on the shelf. Perhaps a recurring problem?

The 3 allen head screws are removed to pull the cover off to replace the diaphragm. This is an easy procedure once the governor is removed from the engine.

The governor linkage must be unhooked from the fuel rack before removing. Here you can see the pin which slides into the linkage and secured with a C clip.

The governor does not have to be timed and is fastened to the engine with 3 m8 bolts. Not much to it once all the fuel lines and piping is removed. This was a case of a smooth No Power situation. There was no white or black smoke, the engine did not miss or do anything really obvious. Testing the diaphragm with the air regulator is just another way for a diesel mechanic to troubleshoot a Cat 3116 Diesel Engine.

Diesel Engines-Cat 3116 injector seating tool

DIESEL ENGINES



Cat 3116 diesel engines require the proper tools when making any adjustments. One tool that is required is the injector seating tool. This diesel engine has unit style injectors that are seated into cups in the cylinder head.
If you don't properly seat the injectors when replacing or re-installing there is a possibility of compression blow-by which will pressurize the fuel system. I talked about this in a previous post, the fuel tank will build up pressure and your diesel engine will run verrry rough!
I experienced this first hand because I did not seat the injectors at all and relied on the injector hold-down clamps. This caused a lot of extra work, so our shop invested in the hold-down kit 'Cat # 173-1530'

Also when installing the injectors I use the sealing o-ring that fits over the injector tip [not specified for new injectors] this adds to the injector sealing capabilities.

The Cat 3116 seating tool is easy to use [it comes with an instruction manual] Just fit it over the installed injector [injector hold-down clamp torqued] then torque seating tool to 25 ft. lbs wait then retorque. Retorque injector hold-down clamp to 9 ft. lbs. [+ or - 2 ft. lbs.]

I highly recommend the seating tool for any of you doing your own repairs on a 3116 Diesel Engine.

Cat 3116 Engine Synchronization Video Tutorial

Cat 3116 Diesel Engine Setting Synchronization is a multi-step operation and requires the Cat Tune up Kit. Some standard hand tools will work but most of the setting tools are specially designed for this purpose. NOTE: Remove fuel solenoid before starting synchronization, this allows free rack movement.

Below is Step One:

Calibrating #1 Injector




Step Two:

Setting Up For Injector Synchronization



Step Three:

How To Adjust Injector Synchronization



This is the hardest step to get around {especially for the first time} but comes much easier with repetition. The Cat 3116 Diesel Engine is a fussy engine to tune up but it pays you back with great performance.

School Bus Engine Rebuild Video Cat 3116

Here's a video I put together going through the steps to rebuilding and installing a Cat 3116 Diesel engine in a pusher school bus. It's a big job and you can see it happen in a matter of minutes. It's much easier to assemble the transmission to the engine and use the trans jack for support and hydraulic hoist on the front end.

The whole works rolls right into the frame. Thankfully Thomas Bus allows the rear end frame to be removed. The Cat 3116 is a fussy engine to set up and you MUST have the Cat tool kit. There is no way to set up the timing, synchronization & fuel setting without the kit.

The valve train is the only weak spot on these engines, when they get too hot (in this case) the exhaust valve let loose requiring the major repair including a new cylinder head. Too avoid this keep the engine temperature down and check valve adjustment every 30,000 to 40,000 km (18-24,000 Miles). Enjoy the video....Please Leave a Comment


School Bus Mechanic Pictures..Exclusive! by jelletse

Cat 3116 Diesel Engine-Rear Seal Installation

The Cat 3116 rear seal comes with a plastic sleeve that should be left in the seal until installation, it helps the seal lip keep it's shape. The seal also comes with a wear sleeve that is pushed on at the same time with the seal installer.

The seal is installed dry, this is accomplished with Cat Tool # IU-7594

The seal installation tool is a 3 piece unit that bolts {2 allen head fasteners} to the crankshaft flywheel bolt holes.

The driver nut threads onto the stud that is bolted to the crank and pushes the seal and wear sleeve on at the same time. The driver bottoms out when seal is positioned properly in the flywheel housing.

Remove Seal installer and you see the seal and sleeve perfectly positioned. The seal installer is the only way to go in order to do this job right.
The front crank seal was previously installed in the timing cover using a proper driver. The vibration dampner then slides over crankshaft quite easily then the four fasteners are torqued to 120 ft. lbs.


Coming up: I'll be installing the cylinder head on our Cat 3116 Diesel Engine....

Cat 3116 Oil Cooler Repair

This Cat 3116 oil cooler was leaking oil so disassembly was required. On a Thomas Saf-t-liner school bus the complete air cleaner and piping can be removed to gain better access to the cooler and turbocharger. The turbo must be removed to get at all the fasteners on the cooler assy. Before removing the cooler parts the coolant must be drained from the block or radiator. There is a block drain (hex head) at the right rear of the engine behind the turbo.
Above you can see the oil cooler parts. The outer housing and the cooler itself are seperated by 2 gaskets which have hardened over time and became brittle.
Using guide bolts slide the first gasket and then the cooler bundle over the guide bolts. There are also to o-ring seals located at the bottom of the cooler.
Once the outer housing is installed the m8 bolts are installed and torqued to 20 ft. lbs. This isn't a major job but it still takes time and patience to get to the cooler. We have 13 Cat 3116 engines and the oil coolers have never failed as far as leaking oil into the cooling system.

Cat 3116 Diesel Engine - Install Oil Pump

The Cat 3116 oil pump is a positive flow gear pump which has an idler gear driven off the crankshaft gear.
The oil pump has sealing o-rings against the block and on the output housing.
The 2 mounting bolts are torqued to 45 ft. lbs. The pickup tube is bolted to the bottom of the block.
Install the oil pan {after the timing cover installation} with a new gasket and the bolts torqued to 18 ft. lbs.

Cat 3116 Diesel Engine Continued........

Cat 3116 Diesel Engine-Fuel Rack Installation & Adjustment.

Injector Synchronization
This is an over view of this procedure, you definitely need the 3116 tune up kit for this and any other adjustment. The kit comes with a very detailed instruction booklet and once you have gone through a couple of settings and understand exactly what is being accomplished with each adjustment it gets easier with experience.

Installing fuel Rack
The fuel rack has been bolted down with 4 allen head bolts torqued to 9 + or - 2 ft. lbs.
Remove fuel shutdown solenoid to allow complete rack movement.

Install injector hold downs so injector racks move freely. Don't force injector racks, this will cause damage. The hold downs come with the complete 3116 tune up kit. The hold downs slightly compress the injector spring allowing rack movement.

Synchronization Set Up
Injectors that have been removed must be synchronized and it's much easier with the rocker arms removed.

Place the 3.50 mm block[chain attached as seen in photo above] between injector rack stop rod and injector body on #1 injector. So the #1 injector rack is extended 3.50mm away from fuel shut off position [fuel shut off is when the rack stop pin is touching injector body]

Note: #1 injector is preset from factory and cannot be altered, the remaining injectors are set according to #1 injector settings.

There is also a synchronizer plunger adjustment that sets rack movement[for the synchronization adjusment only], this tool threads into two rocker arm mounting holes. Using the dial indicator [which is reading fuel rack movement] we can set the adjustable plunger to proper specs.

Once everything is set up you go to the injector that needs adjustment. Using our tool kit pliers we carefully clamp onto the fuel rack shaft and go to full fuel position, set dial indicator to zero and let rack go. The reading has to be 3.50 mm [there is a + or - allowed but I like to get it bang on] Now you can see why the 3.50 mm block is left in #1 injector for this adjustment.


Each injector has a seperate adjustment screw and once adjusted you'll have perfect synchronization and maximum performance out of your Cat 3116 Diesel Engine....

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.

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