Wednesday, January 25, 2006

One area that a lot of technicians don't check out on a low powered diesel is the charge air system. Any leaks and loss of turbocharger boost will limit engine power.
Besides checking clamps and hoses the AFTERCOOLER should be pressure tested. It's located in front of the radiator[picture shows upper piping that runs from the turbocharger to the AFTERCOOLER inlet] Our fleet has had numerous AFTERCOOLER failures so we finally ran a campaign repairing or replacing them.

Why cool the air to the engine inlet system? Because once the air is cooled it becomes more dense allowing a higher volume of air to enter the system increasing efficiency.

How To Test The Aftercooler:
Plug both ends and run 18- 20 p.s.i of regulated air pressure, check leaks with soapy water[We made plugs out of exhaust piping]. The aftercooler is made of aluminum and does not stand up to road salt and vibration. If you're stuck and need a quick fix[Patch Job] JB WELD will work temporarily. New AFTERCOOLERS are expensive around $1500 Canadian, we found a repair shop in Alberta that can re-core our units for half the cost.

In front of our school bus aftercoolers are shutters controlled by coolant temperature. In between the shutters and aftercooler is a steering cooler. All these are transversely mounted so a healthy cooling system is very important. The transmission cooling lines run through the radiator bottom tank.


Anonymous said...

Thanks for taking the time to photograph and write about your work. I do a fair amount of my own work on medium-duty diesels and find it helpful and inspiring

Patrick Keen said...

HI, ill try to make this short. My dad has a 95 chevy kodiak dump truck w/ 46,000 on it. it has the 3116 Cat. For some reason it will not start. it didnt give us any warning signs. we tryed the fuel filter and it still just cranks and cranks. He has talk to many people and no one knws the problem. i was wondering if u had any helpful hints. thanks for any info. email-

John Whelan said...

Check your fuel shutdown solenoid, it should click on when you turn your ignition on and while cranking. It needs 12 volts to energize and run the engine, with no volts a spring in the solenoid pushes the fuel rack closed and shuts down the engine. The solenoid will fail at any given time since it's an on off type electro-magnet.
Also check for a good prime[pressure] when using the priming pump. If not, check your fuel source.
Hope this helps!

Anonymous said...

3116 cat in a buggy.the engine was shutting down for no apparant reason and would start right back up no problem. other than shuting down it seemed to be running fine,no high temp or low oil pressure.changed the fuel shut off celleniod,oil pressure sender,water temp sender and water temp switch.still shut down every 2 to 4 hours.ran dirrect power to celleniod over riding shut down,this seemed to work for 2 days untill it shut down again in the morning.that afternoon the engine started to sound like it was missing on a cillinder. finning informed me that 2 injector seats were leaking and are currantly fixing that.would that be my problem or do you think i still have an electrical gremlin [problem].any insight would be appreciated.

John Whelan said...

RE: 3116 shutting down

I would have to agree with the CAT Dealer diagnosis. We have had the injector seat leakage problem happen a number of times.

What happens is the compression gases get into the fuel system and causes pressure in the fuel tank and aeration of the fuel.

If it takes awhile to shut down engine it would be a gradual thing with no power, like air in the fuel.

The engine miss is a tell tale sign of a mechanical problem developing.


jbrann said...

I have a m2 MBE 900 07 Model. How do you change the feul filter without getting air in the system? Can you just unscrew both caps and change inserts and top off with feul without having to do anything to prime system? My truck also has and Alliant feul water seperator with a priming button on it. I assume one can use this priming button to push feul to fill both bowls? Do you have to leave anything unscrewed to let trapped air out or does the engine take care of it on its own with a little cranking?

John Whelan said...

Here's a post on bleeding the Mercedes Diesel. The adapters are available from the dealer.
This set up works very well..

if this link does not work search my blog using the keywords "bleeding mercedes"

Wade said...

Have a Kodiak dump truck with the cat3116 in it. It will start up and run for a minute, then quit. attempted restarts will run for 1-5 seconds before quitting. I am not experience with diesels, but am guessing that I need to: 1) prime the fuel. 2) check the fuel solenoid (where is that located?)
I saw the reference to bleeding the fuel on the mercedes.
Any other ideas before we get a mechanic to come out?
It has sat for about 6months without running.
Appreciate you sharing your knowledge.

John Whelan said...

change the fuel filters [is there lots of contamination in them?]
Change the fuel completely if there is any water at all...
The prime pump is on the secondary fuel hsg.
Enter in the 'search box' on my blog "cat 3116" for more info.

Anonymous said...

I have a 1998 Chevrolet School Bus with a 3116 Cat engine. On cold mornings (40 degrees or lower) it has a bit of trouble starting and also after it shifts into 2nd it feels like it is not getting any fuel but after a second it catches and runs good. It does this several times and then it quits and runs well the rest of the route. I recently changed my fuel injector pump. What's up with that? I am afraid it will leave me on the route with special needs children on the bus! Help

J. E. Whelan said...

anonymous, Check your air intake pre-heater. It is supposed to aid in cold starts. You may want to check fuel supply as well. No power will cause a downshift in the trans.
The one thing these engines need is a good block heater or diesel engine heater especially in cold climates.