KW T300 W CAT 3126 engine... Stuttering & Losing Power

[KWcowboy]

Our 1996 KW T300 w/ CAT 3126 engine is a sweet puller with about 200K miles on it. Ran perfectly until husband changed oil ( used Rotella*ole Ford man...1st time), changed it back to Chevron Delo 15/40 W, but did not change filter again....

Now, the engine is losing horsepower intermittently, and cutting out like it is starving for fuel???? He has checked his fuel system and lines and all connections. Please help us figure this out. I am the slave that crawls in there and looks online 24/7.

We bought it to pull a 50' trailer after selling a newish F-350 4x4 dually that lost braking power at the worst possible time.... ( down a steep hill in Arkansas).

I am thinking IAP sensor???? any ideas?

Thank you in advance

Calamityj

[hermanmullins]

Calamity,

Welcome to the Forum.

Did you say you pull a 50 ft. Trailer???

Herman

[KWcowboy]

Hello Herman:

Thank you. Yes, we pull a 50' LQ RVIA/horsetrailer.... ( We have owned RV's in the past ( I have horses.. all my life), we are setting out to ride in retirement cross country. We have previously owned a Freightliner Showhauler, sold it to a Rodeo cowboy, bought a Ford F-350 new, but it did not feel secure when it started puking antifreeze and having weak braking power...

I hope we can resolve the issues we are having before cool riding season starts... several friends pull smaller bumper pull trailers with diesel pushers, however, I don't believe that they are framed for the tongue weight or pulling weight.?.

[huffypuff]

A 1996 Kenworth T300 w/ CAT 3126 with possible 22 foot box or larger. You are trying to tow a 50 foot trailer loaded with horses with unknown weight to us with a 260 - 300 hp engine. This forum is for motorhomes and we struggle enough with 40 foot pushing our own weight. I don't think we can help you as I believe that you need a over the road tractor designed for hauling more weight not a box truck or motorhome.

[wolfe10]

Agree, we don't know much about trucks. But many of us have that engine.

First, changing oil should not be an issue-- either Shell Rotella R 15-40 or Delo 400 15-40 is fine for your 3126.

You say he checked the fuel system for tightness.

But, with it acting like it is starving for fuel, first thing I would do is CHANGE the fuel filter(s).

If you have the Caterpillar manual primer pump on the secondary fuel filter, filters can be installed dry and the manual pump used to prime.

And, if the issue is air in the fuel system, turn off the engine and use the manual primer pump. If it is easy to pump, you DO have air in the system (air is compressible). If difficult to pump, no air in the system.

Anytime you unscrew (counter-clockwise) and pump the manual pump, be sure to push it all the way in and tighten it back up (clockwise).

[KWcowboy]

Thank you folks so much! Our truck is a daycab shorty with a hauler bed... weighs about 10k. Our trailer is aluminum, the LQ portion is much like your RV's only more leather, has kitchen/bath/closet/Tempurpedic bed... dinette...etc... weighs loaded to the gills with two horses, hay, 150 gallons of water, still UNDER 15,000 LBS... The 300 HP truck is rated GVWR at 33,000 LBS. We are in good shape. I was looking for experienced owners with CAT engines. Thank you.

[wolfe10]

See my post above-- let us know what you find on fuel filters/air in fuel system.

[DaveAtherton]

Kwcowboy, with what your saying sounds like the IAP sensor is going down or bad. What has happened Oil Sudge

Gets into the sensor and electronics cannot recieve a good signal. You can check the IAP sensor by unplugging the

Wire pigtail that feeds the sensor. With IAP sensor unplugged now see if engine will start and run. If engine does

Start and runs replace the IAP sensor it is bad Dave Atherton Retired Cat Mechanic

[KWcowboy]

We have changed both fuel filters, and oil filters. Again. Dave, we took the IAP off, engine would not start, so following your post, it could be OK... We also changed the speed sensors. No change..??? Should we replace the IAP? the wiring, the turbo, everything appears to be OK.?

[DaveAtherton]

KWcowboy, Making sure the IAP sensor is working correct you troubleshooting by removing the Wire Clip

and engine would not start tell you IAP sensor is working. Next sensor that is on lower side of HEUI Pump

is what we call Injection actuation pressure control regulator. ( what this does is regulate HIGHPressure oil

flow to actuate the injjectors and also can get sludged up. ) this is the only operation of the Heui Pump is

high pressure oil to injectors. there is also a little diesel fuel transfer pump connected to the heui pump but

is not with heui pump.

Going with things that you can do, I would sugest and remove the IAPCR valve ( remove wire clip than remove

solenoid, this gives room for a 1 1/8 wrench to remove the solenoid.) You can check the solenoid for ohms

and if reading is at 10 solenoid is good. than take and shake the regulator body back and forth should hear

a clicking noise of little plunger sliding back and forth. if you cannot hear any noise after trying several times

than the shifter plunger is stuck or sticky while running. This is a $ 275.00 part , and the IAP sensor is $ 185.00

aprox so this is why having you troubleshoot will remove someone else putting on parts on your nickel.

going back to the regulator, cannot hear any noise inside while shaking. You can take apart valve, hold hex end in

vice and channel lock pliers turn off barrel that screws into body. put a clean grease rag under this barret a

very sall needle can drop out and get lost. ( that is the only small part to worry about ) than take a flat blade

screw driver and turn out slot in housing ( behind that screw in the shift plunger ) will come out last part. look

over and can see tracking on one end or other if possible sticking. but in most cases just sludged up. as long

as electric solenoid test out for 10 ohms you can uuuse brake and clean plunger housing and all parts removed

put back together. again make sure the little needle is in the barrel on last part thet screws into regulator housing.

this seems like a lotof work but you have control of the repair not repair shop. there is one more update that

may be causing the problem but working away from heui pump is best direction to take and not costing money

Dave Atherton Retired Cat Mechanic ( 42 years )

[KWcowboy]

Sir; thank you so much! My husband has done all this with exception of the Injection Pressure Control Regulator... he will find it on bottom side of HEUI?? He will check it out in the AM.

[KWcowboy]

To all on this forum;

We were SO fortunate to have caught Dave Atherton on the road within traveling distance of our home! He and his wife, Pat, were within an hour! nested in a truck stop. My husband drove his limping truck up and Dave scanned it on his laptop for codes.... after speaking with Myron a couple of times, he already had a pretty good idea what our problem was. We got a sensor, they put it on and made other adjustments, and test drove it. PERFECT!!! It is running like a new one! By being honest about what we don't know, we put our trust in his knowledge and experience, and it worked. I will sing his praises when I recomend his service. I hope you all realize what an asset they are to your organization.

Myron & Jane Lake

SW Missouri

KW T300/Cat 3126 300 HP

( pulls RV 5th wheel and 48'+ LQ horsetrailer)

2000 Blue Bird Wanderlodge 43 LXI Motorhome

[wolfe10]

EXCELLENT! That is the only word for an FMCA member (Dave) going to the extra effort to help a fellow RV'er.

Thanks, Dave.

[wildebill308]

Good job Dave. Small world in that you were close enough to help in person.

Bill

[jleamont]

Nice job Dave!

[dickandlois]

Ah yes, Dave is a little like Merlin ! When you turn him loose on a Diesel engine.

He hooks up his equipment, mixes up one of his potions and the engine does not stand a chance.

May he and his wife have many more miles on the road together !!

Thanks Dave and give Pat a hug from us.

Rich and Lois

[KWcowboy]

Just wanted to check in and let you all, and esp Dave & Pat know that we are happily traveling with our KW thanks to your help!!! We hope you are all enjoying this beautiful fall also.

Myron & Jane Lake

[KWcowboy]

We finally dug in and took everything apart from the Exhaust manifold to the Turbo/ turbo wastegate/exhaust.... found leak/bad gaskets on exhaust manifold... bolts were not tight... cleaned it up, checked everything out. Getting new exhaust manifold gaskets and bolts in AM... will have the Turbocharger checked out too.. we threw enough parts at it.... so hope we don't run into any other terrifying challenge. 

[manholt]

KW, great to hear back from you again!

Safe travel

Carl

[KWcowboy]

To all Cat engine people here.... we have ((I hope), completed our saga of $$$$ drain from changing parts, putting in new gaskets, hoses,a fuel boost pump, checking turbo ( it was fine).. then, after they said there was an air leak from the turbo to the engine.. took off all pipes. Found elbow with huge rupture he could stick his hand into under the air filter. Wow. That hole was probably the whole problem! Dave Atherton told him it sounded like an air leak. Mechanics up here didn't find it *$$$. Finally, after he crawled up in there and felt around. there it was. After he got it back together.... we had to put in three new batteries... Now it is running great.. 

 

[wolfe10]

Ya, no modern diesel will run with boost leaking out.  They need all that extra air to make power.