Saturday, December 10, 2005


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.

11 comments :

Anonymous said...

hi JOHN.JUST WANTED TO SAY I'M GLAD I FOUND YOUR PAGE OF INFO. I'M A CONTRACT FLEET MECHANIC IN FLA,MOSTLY CHEVY VANS BUT A COUPLE OF TROUBLESOME BIG BOY'S WITH THE 3116 CAT DIESELS. WHICH I AM COMPLETELY ILLITERATE ABOUT.THE LOCAL CAT DEALER HAS BEEN GREAT ABOUT CHARGING US BIG BUCKS FOR WHO KNOWS WHAT? ONLY TO HAVE THE SAME PROBLEMS RE-OCCUR.WE ALSO HAVE HAD AN INDEPENDENT DIESEL SHOP TRY TO NO AVAIL.
AT THE PRESENT TIME I'M DEALING WITH A VERY INTERMITTENT 1995 KODIAK TRUCK THAT EVERY TWO OR THREE WEEKS GETS TOWED IN,ONLY TO START AND RUN JUST FINE WHEN IT GETS TO MY SHOP.
WHAT HAPPENS IS THE TRUCK SLOWS DOWN TO A CRAWL,SPEWS WHITE SMOKE,AND OCCASIONALLY WILL "CLEAR OUT" BY HOLDING THE ACCELERATOR TO THE FLOOR IN NUETRAL. THE DRIVER SAYS HE GETS A VERY STRONG "CITONELLA " SMELL AS THIS IS HAPPENING.I HAVE ADDED SOME INJECTOR CLEANERS AND FUEL TREATMENTS. BUT IT'S SO INTERMITTENT,I'M NOT SURE WHERE TO TURN NEXT.
ANYHOW I WAS TOLD TO CLEAN THE "SLIDING FUEL RAIL" AS THAT IS SURELY THE PROBLEM?..
ANYHOW THERE IS 100,000 MILES ON THE TRUCK.ANY SUGESTIONS WOULD BE APPRECIATED!
ALSO I SEE YOU PLAY ACOUSTIC,THATS MY OTHER PASSION,I'M NOT TOO GOOD,BEEN PLAYING ABOUT THREE YEARS NOW.......BUT I ENJOY THE HECK OUT OF IT!.....TAKE CARE AND THANKYOU AGAIN....BRIAN (brose007@tampabay.rr.com)

Dan Fortin/danfour10@msn.com said...

John,carefully check for fuel in coolant on the 3116 with any injector seating or cup problems.The injector seating tool group requires that you toss the o-ring if using this tooling.It will in time defeat the purpose of seating the injector into the (copper only)cup if an o-ring is used.No seat reaming is a welcome benefit when using the forcing bridge to "get 'er done"

Duane said...

John,
They changed the area of the seat angle on the injector, and in the literature sent with the new injectors tell you not to put the lower tip seal on the injector. The change in the injector seat area made a better seat in the sleeve, when the seating tool is used. The seal will decay from heat and tens to let the injector loosen. Have put many of these injectors in and have had no problems with leakage, when not puting the seal in. I also always ream the sleeve, after rebuilding cyl. head with new sleeves. Have found that when driving the sleeves in they have low and high spots, that show up when you ream them. Cat also added shims to the reamer group to control how much you remove from the sleeve when cutting.

Jean at Verns said...

John, our 95 cat. 3116 has an unusual problem, I hope you can help. It runs ok until the fuel tank uses 6 gal of fuel in it's 35 gal. step type tank. Then it barely runs at all. After the tank is full and a jug of STP diesel additive is added, it runs better. We changed to rubber fuel lines, cleaned the tank and sending unit, which was plugged. In the past six months we've changed the secondary fuel filter multiple times. Also the one on the engine. Also, is the overflow tube supposed to work in both directions? Please HELP if you can. Thanks, Jean at Verns

SKINNY said...

HELLO,
I HAVE A MED DUTY 95 GMC TOPKICK WITH A 3116 CAT IN IT!.HAS 225K ON IT.CAT JUST DID A UPPER END INSPECTION ON IT AT 190K AND ONLY REPLACED INJECTOR LINERS.

WELL TONIGHT MY BROTHER NOTICED THE OVERFLOW TUBE FROM RAD WAS LEAKING,WELL I CHECKED IT OUT THINKING IT WAS COOLENT,BUT NO ITS RAW DIESEL.SO WHAT DO I DO CHECK THE OIL ITS FINE,NEVER SAW TEMP CHANGE OR LOSS OF POWER TONIGHT.THEN I GO TO OPEN RAD CAP AND POOF IM COVERED IN DIESEL FUEL!.MY COOLENT SYSTEM IS FULL OF RAW DIESEL!.I NOTICED MY FUEL TANK ON DRIVERS SIDE GETS WARM WHEN I RUN OR DRIVE THE TRUCK,I FIG THAT WAS SOME KIND OF FUEL WARMER IT HAS FROM FACTORY?.(DOES IT HAVE FACTORY FUEL WARMER)?.PLEASE LMK IF U CAN POINT ME IN THE RT DIRECTION,ITS REALY BOTHERING ME WHAT IT COULD BE AND I CANT CALL THE DEALER OR CAT TILL THE MORNING!.THANKS FOR YOUR TIME AND HELP!.
GREG ELSER,IL..
SKINNYSBUICK@AOL.COM

SKINNY said...

HELLO,
I HAVE A MED DUTY 95 GMC TOPKICK WITH A 3116 CAT IN IT!.HAS 225K ON IT.CAT JUST DID A UPPER END INSPECTION ON IT AT 190K AND ONLY REPLACED INJECTOR LINERS.

WELL TONIGHT MY BROTHER NOTICED THE OVERFLOW TUBE FROM RAD WAS LEAKING,WELL I CHECKED IT OUT THINKING IT WAS COOLENT,BUT NO ITS RAW DIESEL.SO WHAT DO I DO CHECK THE OIL ITS FINE,NEVER SAW TEMP CHANGE OR LOSS OF POWER TONIGHT.THEN I GO TO OPEN RAD CAP AND POOF IM COVERED IN DIESEL FUEL!.MY COOLENT SYSTEM IS FULL OF RAW DIESEL!.I NOTICED MY FUEL TANK ON DRIVERS SIDE GETS WARM WHEN I RUN OR DRIVE THE TRUCK,I FIG THAT WAS SOME KIND OF FUEL WARMER IT HAS FROM FACTORY?.(DOES IT HAVE FACTORY FUEL WARMER)?.PLEASE LMK IF U CAN POINT ME IN THE RT DIRECTION,ITS REALY BOTHERING ME WHAT IT COULD BE AND I CANT CALL THE DEALER OR CAT TILL THE MORNING!.THANKS FOR YOUR TIME AND HELP!.
GREG ELSER,IL..
SKINNYSBUICK@AOL.COM

John Whelan said...

Skinny,
The injector sleeves are not sealing. They seperate the coolant from fuel (fuel is higher in pressure so it will mix with the coolant). This will also cause your fuel to get warm from the hot coolant. If you do a search (top left) on my blog for "3116" you'll get all my posts. There are a couple on seating injectors using the Cat tool.

John Whelan said...

Brian and Jean,
Sounds like an air problem or injector seating fault. If the return line / fuel tank is getting pressurized you are getting compression in the fuel from a bad injector seat.
Check your lines and supply (Jean) pick up tube in the tank.

freindly neighborhood logger said...

i got a 95 topkick same problem.i noticed oil or something all over the bottom of the truck. figured it was coolant but through mor inspection , found out it was fuel in the coolant .so much that when the motor runs it comes out the overflow steady like its being pumped in by a retun line.it being the first cat i owend .i wonder what kind of tuition im going to have to pay?

John said...

The fuel runs through the head gallery to the injectors and returns to the tank. Somehow you're fuel is seeping into the cooling system being that it's under pressure.
The first thing I would check is the injector seats which involves pulling the them.
Do a search on my blog for cat 3116 injectors for related posts.

overcomer said...

Hello John:
I found your site not long ago. Helpful info. on the 3116's. I have been working on one the last couple days and its my first. I have a governor problem. What is the max travel range the gov. shaft moves to control the rack, and when checking the fuel setting, what allows the rack to move (even by hand) if the governor shaft is anchored by the wedge and tooling that goes through the hollow pin? Oh, one more thing, which valve cover spec., full load static fuel 7.98 mm, other says fuel timing 65.01 mm.
thanks for your help in advance
Ed