Cat engine 3126
Hobbers10

Pahrump, NV

#251 May 12, 2009
Also, meant to say if you have high voltage at the sensor, it means you have an open and if you had low voltage you have a short. Anyway, I just typed it wrong before.

Since: May 09

Pahrump, NV

#252 May 12, 2009
I'm guessing you mean the engine will crank but doesn't start. You really went all out by replacing the HEUI pump. You have nailed quite a bit. I would pull the valve cover off and check the cross over tubes for leaks. Do this by holding some stiff paper over the valves while cranking the engine for a sec. turn the paper over and look for oil spray. This will tell you if you have a crack. Be careful and don't look directly at the tubes while cranking. Oil may spray. Also, does the engine start when the oil is cold? Cold oil will have a harder time squeezing through a small crack in a cross over tube and may run till the oil heats up..
roz

Surrey, Canada

#253 May 12, 2009
TEXASBLADE2006 wrote:
is this a heui pump 3126?
no just regular 3126.
cherry124

AOL

#254 May 26, 2009
have a 2000 model 3126...its leaking diesel behind where the clutch fan bolts to the front of the block. can't see any fuel lines or anything else that would have diesel there....
randy

Minneapolis, MN

#255 May 29, 2009
eric wrote:
i have a 3126 cat in a forestry truck.problem is i am losing oil, cannot see any visual leaks and no smoke out exhaust. any suggestions?....ive gone thru 6gal of oil in 1 1/2 weeks
The oil is probly going into the fuel system. They can leak aroud the injector orings, check fuel in tank to see if it is getting dark
yankee

Pioneer, TN

#256 May 31, 2009
CatTech wrote:
any electronic Caterpillar engine questions i can help
I have got a 3126 98 model that will not start it was having intermittant problems with not starting like it isn't getting fuel where can i start besides a large lid crusher
Charley

Steamboat Springs, CO

#257 Jun 3, 2009
I have a cat 3126B in a motorhome with 47000 miles On my last trip there was an alarm that went off intermitentl but no dash light. Just before i got home the check engine light came on for a few seconds then went out. climbing the pass i noticed lower than normal oil pressure and if i steped on the breaks the pressure dropped. the engine quit at the bottom of the pass and would not restart. added 2 gallons of oil and it started but was hard. got it home but oil pressure still low and goes down with breaking. Idle is low now also which i assume is causing the presure drop and not the actual breaking. I also seem to have more blow by than previosly. Any one have any ideas?
Tech_JR

Portland, OR

#258 Jun 5, 2009
Rich wrote:
I am in the same market. I am looking at a Kenworth T300 'bobtail' truck. It is a 2002 Cat 3126 and it has an Allison 3060, six speed auto trans, 4:63 rear end. They rate the motor at 275 hp. I need to pull a 12,000 pound trailer (not 5th wheel). Do you think this cat has enough to do it> I am presently using a 2500 Dodge with a 5.9 cummins,,,,,,I am really putting the hurt on it.
No problem, they only show 275hp but they test out at 863 lb/ft which is about twice what your 5.9 will put out stock.
Tech_JR

Portland, OR

#259 Jun 5, 2009
yankee wrote:
<quoted text> I have got a 3126 98 model that will not start it was having intermittant problems with not starting like it isn't getting fuel where can i start besides a large lid crusher
The first thing to check is to make sure your fuel filters aren't plugged and that you are getting fuel supplied to the head. If you have fuel supply to the head at the right pressure then you'll want to check the pressure from the HEUI pump, too low pressure would prevent you from getting injection or at least good fuel atomization. A good check to see if the HEUI pump is damaged is to pull the plug from the high pressure oil galley at the back of the head and check for particles, if they are present then the pump is junk and your injector will need to be replaced as well.

Since: Jun 09

Iowa

#260 Jun 8, 2009
Purchased a 2002 Freightlinger FL80 with a 3126 motor last year (125k miles). From day one we have had problems with loss of power going down the road. Speedometer falls as well as rpm and volts. All other gauges remain and fan kicks on. This lasts for 2-5 seconds and them power returns. It is very unpredictable when it will occur. Sometimes serveral times per day or some days with no problems. The local Freightliner dealer has replaced the heui pump, the fuel acutator, and some other item I can't recall right now. They say they can't figure it out, in the meantime it is costing me a fortune. It seems to do better with clean oil, but it still acts up regardless. Vin j72493. Thanks for any suggestions.

Since: Jul 08

Location hidden

#261 Jun 8, 2009
tmorgz wrote:
Purchased a 2002 Freightlinger FL80 with a 3126 motor last year (125k miles). From day one we have had problems with loss of power going down the road. Speedometer falls as well as rpm and volts. All other gauges remain and fan kicks on. This lasts for 2-5 seconds and them power returns. It is very unpredictable when it will occur. Sometimes serveral times per day or some days with no problems. The local Freightliner dealer has replaced the heui pump, the fuel acutator, and some other item I can't recall right now. They say they can't figure it out, in the meantime it is costing me a fortune. It seems to do better with clean oil, but it still acts up regardless. Vin j72493. Thanks for any suggestions.
sounds like a wiring harness failure. either the vehicle interface or the engine & sensory harness has a defect or you have poor engine grounding.

usually these intermittent cutouts are caused by a failed ground point or bad harness so i suggest you start by checking all your engine related groundings starting from the engine ECM ground strap. the strap grounds between one of the ECM mounting bolts and the cylinder block itself.
if that all groundings clear test all engine related harnesses or replace them.

hope this'll help, cheers

Since: Jun 09

Iowa

#262 Jun 9, 2009
They say they checked the grounds. I was told by another mechanic it is probably a bad ecm. Does this sound accurate? Is there a way to test the ecm without having to buy a replacement first? I just don't have a lot of confidence in the local dealer and from what I have seen on this forum, you seem to be very knowledgable. I greatly appreciate the help.

Since: Jul 08

Location hidden

#263 Jun 9, 2009
tmorgz wrote:
They say they checked the grounds. I was told by another mechanic it is probably a bad ecm. Does this sound accurate? Is there a way to test the ecm without having to buy a replacement first? I just don't have a lot of confidence in the local dealer and from what I have seen on this forum, you seem to be very knowledgable. I greatly appreciate the help.
do you have similar engines in your fleet or do you know anyone who you could borrow an ecm from for a couple days?
if so you should try installing a similar ecm (with somewhat similar configuration) from the same engine serie in order to see wether the symptom remains or disappears.

once you install a new, blank ecm a cat tech can activate a certain "test ecm mode", which last
24 hours. after that the ecm goes blank again and can be returned. BUT since its an intermittent problem the 24 hour interval may run out before one can be sure it really was a defected ecm or not.

there have been some but rare cases with defected ecm's, but in my opinion replacing the ecm itself is the last thing one should resort to. an in-depth step by step check for the electronics system should be performed before jumping into conclusions that may prove expensive and fruitless.

please let us know the results.
hope this helps, cheers!

Since: Jun 09

Iowa

#264 Jun 9, 2009
I actually had to go to the dealer today for an unrelated problem and they hooked my truck up to the computer after I told them the engine problem was still there. It was maxed out on code 164-11 which is actuation pressure. This is the same code that has been coming up from the beginning and that was the first part replaced. They still have no explaination. I do not have any other cat motors and I have been trying to locate another ecm to test if I can. Just very frustrating.
adbdrvr

Pelham, GA

#265 Jun 14, 2009
We recently purchased a 2000 fl50 with the 3126, claims to have 275hp but doesnt have enough power to pull itself up a hill with an empty 30ft travel trailer behind it, truck has 488k miles and have taken it to diesel shop and they said that the 3126 engines are just week and that they cant turn it up, have put a power programmer to it but it did nothing. What could be wrong if anything? turbo???
JUANCHO

Louisville, CO

#266 Jun 16, 2009
HI DYNPRO...Is been a while..allmost a year ready..Well...My truck the compresion is very bad...i bearly jump in the freeway and i don't have power at all.if i have a load is more dificult.but went it take off i can easely drive crusing at 75mph.Do you remenber last time we did all the overhaul on the engine( changing the o-rings and the piston thah was bad)? Well my friend i really don't what to do because the mechanic last time say this truck will last for one more year and here we are.....Qestion? I'am looking to get a new truck well used( 2005). One is a Peter 330 with 230HP CAT C7http://www.truckpaper.com/li stings/detail.aspx?OHID=191113 3&GUID=4e1879c65bbf46528da c67945de82710&dlr=1 And the other one is a International D466 2005 as well 225HP.http://www.truckpaper.co m/listings/detail.aspx?OHID=20 56256&GUID=4e1879c65bbf465 28dac67945de82710&dlr=1 WICH ONE DO YOU THINK WILL DO BETTER...THANK'S

Since: Jul 08

DENVER/COLORADO

#267 Jun 16, 2009

Since: Jul 08

DENVER/COLORADO

#268 Jun 16, 2009
#U44812 AND #U45079
roz

Surrey, Canada

#269 Jun 17, 2009
i have a cat 3126 in a gmc t7500 cube van and have changed all injectors, tightened all engine and cab mounts, had dyno done and cem tested and no one figure out why my cab will shakes or gets rough when i come to a stop. rpm is at 750 at stop. as soon as you give speed and the rpm goes to 850 its smooth. drives well and has power. any ideas anyone??
Sail boat Captain

Newport, RI

#271 Jul 16, 2009
We have a CAT 3126 300hp in our 82ft yacht. We are consuming 3 gallons of oil for every 250gallons of fuel. I have had sea trials done and CAT are telling me that the we have an oil blow by problem caused by the engine being underloaded! Is this common on the 3126? Is it a technical fault? I need to find out as much info as possible before we decide to re-build or repower the yacht? Anyone have comments on this? Thank you. Oyster Captain.

Tell me when this thread is updated:

Subscribe Now Add to my Tracker

Add your comments below

Characters left: 4000

Please note by submitting this form you acknowledge that you have read the Terms of Service and the comment you are posting is in compliance with such terms. Be polite. Inappropriate posts may be removed by the moderator. Send us your feedback.

Caterpillar Discussions

Title Updated Last By Comments
The new C15 acert engine (Jan '06) Tue DeAcert king 864
cat accert (Jul '12) Apr 24 Tom 61
Caterpillar C15 Engine TPS error code (May '09) Apr 21 Steven 71
CAT C15 help!! (Jun '08) Apr 21 Bullet 7 164
I have no power no boost c15 bridge (Jan '14) Apr 20 04 C15 Mike 17
Fuel issues Apr 20 Dfitz 1
Engine swap Apr 13 Drainman44 1
More from around the web