Cat engine 3126

Since: Jul 08

Location hidden

#229 Feb 27, 2009
Ben sampson wrote:
My problem is the engine 3126 sending diesel to radiator and lost of power
i assume your engine is a mechanical 3126...
if so then theres three things that may cause fuel in coolant. from the most likely to the unlikely:

- A cracked fuel injector sleeve. the sleeve is replaceable and it would be wice to replace all six sleeves at the same time. the sleeve replacement procedure requires special tooling. this will affect output power because fuel pressure in the leaking injector sleeve is lower than required and the crack may leak coolant inside the sleeve causing a failed injector.

- A failed fuel cooler (if equipped). if the cooler is installed in the fuel return line it will not affect engine performance directly. if installed on the fuel suction line a failed fuel cooler will leak both ways and will affect engine performance because cooland is being drawn into the fuel system.

- A crack in the cylinder head itself. this is very unlikely since the fuel gallery bore (passage) is the highest chamber in the head casting. if a crack would reach as far as the fuel gallery it would also cause serious coolant and combustion leaks thus leading to reduced engine performance, hard starting etc.

Remember that each and everytime an injector has been removed the bottom sleeve must be machined before assembly!. this also requires a special reamer tool.

hope this helps, cheers!
Als Towing

Catawissa, PA

#230 Mar 12, 2009
DynPro wrote:
<quoted text>
<quoted text>
I'd start by measuring the fuel tranfer pressure (from 55 to 90psi under normal operating conditions), and installing a sightglass to the fuel return line. this because:
Only 3114, 3116, and 3126 mechanically controlled engines have a copper/bronze injector seat that needs to be machined before re-installing an injector, other cat engines with unit injectors dont need seat machining since either the seat is part of the cyl head casting or a separate steel sleeve. but since theres allways a theoretical possibility of combustion gasses leaking past the bottom sealing, it would be wise to install a sightglass to the fuel return line. if the fuel return flow contains a small amount of tiny air bubbles in relation to the flow during loading the engine, it is acceptable. if the flow contains up to one third of air, you will experience poor engine performance, hard starting, intermittent shutdowns and reduced injector life.
if the fuel pressure is within the range and theres no or relatively little air in fuel, i'd proceed to measuring the actual injection actuation pressure directly from the cyl head. Caution!!! the high pressure rail contains a maximum of 23500kPa (3400psi) of pressure!. the normal operating pressure varies between 15000kPa (2170psi) and 21000kPa (3040psi). the pressure should remain relatively stable during steady idle or steadystate max rpm, if not theres a problem on either the injectors or the load sensing spool on the pump itself. also the IAPC-valve may have failed, but that usually causes continous active symptoms. there are many variables that may cause the problems your engine is experiencing, it would be wise to contact you dealer for an indepth check if everything seems ok with these tests.
regarding the valvelash measurement: dial measurement can be performed and indeed is the most accurate method for setting valve lash, but should only be used when the engine has undergone an sufficient break-in. once the engine has been in operation for approx 500 hours the valve stem and rocker arm contact faces have worn to match eachother and the wear rate reduces to allmost nothing. at this point dial measurement can be used. measuring during break-in and the first valve lash setting after overhaul should be done by feeler gage since the lash will increase. measuring and setting valve lash after 500 hours of operation is a recommendation.
thanks for the compliments, such are rare here lol.
hope this helps. for more info just ask.
Dyn Pro:
Re-ran fuel lines and checked fuel pressure - within
parameters @ 65/70lbs. sq. in. No/or few bubbles.
Now looks like I have oil in coolant!! Drained engine coolant and flushed detergent and used CRC green
Nanotechnology block sealer - Voodo mechanix in a
bottle - I hate that I did this. This stuff never works.
Still blows white smoke. This is just great! Caterpillar.
I am looking for another motor. GGRRRR!!
in a a bottle
tferg

United States

#231 Mar 15, 2009
tferg wrote:
I have a 2003 Chevrolet C8500 with 3126E with 86000 miles.I bought the truck a month ago, ran fine until recently when one morning it would not crank immediately. Started after cranking for a few times. Next morning it was fine. The next morning it would not crank. Changed both fuel filters, still not starting. Got a mechanic to come over and look at it. He could not get it started with ether. After he left I went out and tried it with no ether, cranked right up. Drove it several miles,ran fine, and it stared next three mornings. Won't start at all now. Any ideas?
oil pressure sensor was the problem if anyone needs to know.
Jeff

Scarborough, Canada

#232 Mar 19, 2009
Rafter B Farms wrote:
Anyone with a LEMON peterbilt WITH AN ACERT MOTOR PLEASE CONTACT ME
I've got a 335 Pete with a C7 that won't start. new huey, injector rings ,check valve, etc...
Seems to start only when plugged in or when warm
Catman3

AOL

#233 Mar 23, 2009
I Also have a hard starting 3126. We have replaced the HEUI Pump and the fuel transfer pump. Checked all fuel lines for restriction none there. Also replaced the ICP. Still will not crank . Only two things left the crank sensor (which appears okay ) and the ECM?
chris t

United States

#235 Mar 24, 2009
who has the best price on injectors, the number on them is 1317150? thanks in advance
Benito

Bozeman, MT

#236 Mar 24, 2009
2ooo 3126 excessive cranking before start OTC Genisis reads codes 22 and 253 ihave no code info
caloinc

AOL

#238 Mar 30, 2009
have 96 pete 330 cat 3126 heat pump light keeps coming on after truck is warm. making truck run bad, and idling high
Dennis Berry

Houston, TX

#239 Apr 1, 2009
Hey I have a 3126b engine, it will not start but it cranks over. I have taken the valve cover off check for injector o'ring leaking back, check fuel lines for collasped, check computer for active codes none, check icp pressure, running out of options here can someone please advise me want is the next step.
tferg

United States

#240 Apr 1, 2009
Dennis Berry wrote:
Hey I have a 3126b engine, it will not start but it cranks over. I have taken the valve cover off check for injector o'ring leaking back, check fuel lines for collasped, check computer for active codes none, check icp pressure, running out of options here can someone please advise me want is the next step.
I have c8500 with 3126. Was having the same problems. On my engine there is a oil pressure sensor on the back of the engine right under the doghouse. It was cracked. My opinion was cracked before I got it when someone removed the doghouse. It would not let the engine crank because the ecm was reading no oil pressure due to the sensor not working. Had no codes and tried everthing else. hope it helps.
bodog

Mexico, Mexico

#241 Apr 6, 2009
JRA wrote:
<quoted text>bad injectors will pump engine oil in the fuel causeing high oil consumption
also the check the copper seats under injector.cat recuts in the engine and puts grease on tool to keep filings from cylinder.what a joke
Jerry

Henderson, NV

#242 Apr 13, 2009
Dave in Peoria,
I put a set of 6" straight stacks on my 2000 FL 60 Sport Chassis...its loud! My guy put an after market muffler, steel pack, between the engine and the Y pipe to take some of the "bark" out of it. It does sound nice though.
Jerry in Henderson NV
shawn

Netherlands

#243 Apr 25, 2009
Have a cat 3126 that started to run a little rough, changed all filters and seemend to clear the problems. Now it wont start, pulled the codes and found that it had a high voltage on the air itake sensor, also had replaced the speed timing sensors. Still wont start. Showes oil pressure on the gauge when attempting to start, ruled that out. Running out of options we more like ideas' Shawn in Iraq
cat3126

United States

#244 Apr 26, 2009
have a cat 3126. its throwing a code. just flashing once every 2 or so seconds. how do u read the codes?

[email protected]
Drew

Hermosa Beach, CA

#245 Apr 29, 2009
Have a Cat 3126A in a '98 Dutch Star RV. Looking for a manual for servicing pumps, injectors, hydraulics, hoses, etc.

Any suggestions or advice on what I need?
ben

Gilbert, AZ

#246 Apr 30, 2009
Stevie wrote:
I work in a corp fleet department every 3126 we have has giving us problems they has giving us job security. I need some info on the wiring and fuel systems. I have one that will start on either and run at 1000 R.P.M but goes dead at anything under [email protected]
check your huey pump presure sounds like not enough presure at idle
roz

Surrey, Canada

#247 May 8, 2009
i have cat 3126 and replaced all 6 injectors a month ago and now the engine runs rough ( makes the whole cab shake)while on idle at around 7-8 rpm or even on drive at same 7-8 rpm but as soon as you go over 1000 rpm its fine. anyone any ideas?
TEXASBLADE2006

Cherry Hill, NJ

#248 May 11, 2009
is this a heui pump 3126?
Hobbers10

Grantsville, UT

#249 May 12, 2009
shawn wrote:
Have a cat 3126 that started to run a little rough, changed all filters and seemend to clear the problems. Now it wont start, pulled the codes and found that it had a high voltage on the air itake sensor, also had replaced the speed timing sensors. Still wont start. Showes oil pressure on the gauge when attempting to start, ruled that out. Running out of options we more like ideas' Shawn in Iraq
Well, if you have high voltage at the air intake sensor it means you have an open wire. If you had high voltage it would mean you had a short. I'd fix that little issue first then move on. I'm assuming that since you are talking about a 3126 it is a HEUI engine. With a HEUI engine always check for oil pressure, like you said you did. Next very simple check is to unplug the Injection actuation pressure sensor and see if it starts with that unplugged. If it starts then you know you have a bad sensor. If that doesn't fix it then move on to the valve. If that doesn't do it, take the valve cover off and check the cross over tubes for cracks. I'm not sure what you knowledge on this engine is so I hop I'm not talking down to ya. Anyway. If you need more help, let me know.
Hobbers10

Grantsville, UT

#250 May 12, 2009
I just noticed you are in Iraq. You wouldn't be working on the Stryker would ya?

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