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Thread Title:

CAT 3126B

Created On Sunday July 18, 2010 10:15

bobbinalong

Posts: 32
Joined: Jul 2010

Sunday July 18, 2010 10:15

In my motor home I have a 1996 CAT 3126. I got the home all packed up for a trip and was ready to go. Started the engine for warm up. Set the idle at 1050 rpms. Waited for engine temp. to reach 90 degrees. Put the Allison transmission, MD3060, 6 speed, in to 1st. gear. Well she would move but very slow. I cannot get much more than 900 rpms. Went back to neutral, stepped on the pedal and the rpms went to 2500 rpms with out hesitation.
The oil pressure is above 30 psi. and the dip stick indicates full and no trouble light. So I decided to replace the air filter, no luck there. I had to order the fuel filters and waiting for them to arrive but the current ones only have 900 miles on them. I REMOVED THE OIL FILTER AND THE FILTER IS DRY. This is something that I have never seen before. The mount that the oil filter is mounted on is also dry.

Does anyone have any idea in what the heck is going on. Thanks for any advice.

-------------------------
God -> Men -> Government.
Proud member of the Tea Party.
“In God We Trust;” in Liberty we thrive.

Edited: Sunday July 18, 2010 at 12:52 by bobbinalong

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desertstormboy

Posts: 372
Joined: May 2008

Sunday July 18, 2010 13:21

when you say the oil filter is dry, do you mean on the outside or had no oil in it? well, when the engine is in neutral and goes to rpm without hesitation, then there is a problem with putting a load on it. first check fuel pressure. could be possible problem with transmission. those allisons are a great transmission, but all things mechanical has their problems. you say its a '96 model? didnt know they had em that early, but if it is it is designed like a 3116 except has the crossover tubes design for the heui system. still by coming up on rpms bare with no hesitation, i wouldnt suspect any problems there. when is the last time the motorhome was put in service? sometimes after sitting some time, a lot of things can happen. i have seen wasps build nests internally, and even clog up the vent tubes on the fuel tanks. need to do some initial troubleshooting first. i seen that you have got new filters coming....keep us informed.

-------------------------
IT WENT BING BANG BOOM!

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bobbinalong

Posts: 32
Joined: Jul 2010

Sunday July 18, 2010 13:58

Yes, the oil filter inside was dry. Well not true. It was less than 1/4 full and like I said the mount was bone dry. After I pull the oil filter it always drips for awhile. Not this time, nothing. The last time I had her out was last March, 2010. Seemed a little sluggish at the time but not enough to worry. Man was I wrong. You are saying that bees can get into the tank and plug the line. Wow!! I do have pressure in the tank. By this I mean that when I take the filler cap off it always depressure. So I am assume the tank is sealed. I always use Donaldson filters. Are they recommended or should I be using another brand? Hey, thank you for your reply.

One more thing. Allison had me do a Stall test. Started at 750 rmps, hard throttle for 25 sec's, top rpm = 850. After the 5th test top rpms = 900. Allison is pointing the fingure at CAT. There is no slippage and the transmission is grabbing. Needless to say, this is not my field. I do feel that the HEUI is not getting enough oil pressure. Am I on the right path. Yes I will change the fuel filters and will let you know. Thanks again.

I have been thinking about what you said on the fuel tank vent. I am getting pressue built up in my tank. Is this telling me that the vent line could be plugged. Like I said, when ever I remove the filler cap I always get a boost of air comming out of the tank. Is this some what normal or not????

-------------------------
God -> Men -> Government.
Proud member of the Tea Party.
“In God We Trust;” in Liberty we thrive.

Edited: Sunday July 18, 2010 at 15:19 by bobbinalong

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desertstormboy

Posts: 372
Joined: May 2008

Monday July 19, 2010 04:37

remove the vent line from the tank and run something through it or blow air through it to make sure that it is clear. you need to have good heui pressure in the engine for it to perform properly. but that is something that needs to be checked with the laptop. you can use a manual gauge in the top of the head to read it yourself if you are capable of doing that. the pressure can be around 3000 psi so be careful with the engine running at high rpms. usually at idle it is around 850 psi. the donaldson filters are not the worst filters and have seen lots of people use them along with baldwin, fleetguard and luberfiner. In your case since it is a motorhome and it doesnt get used on a regular basis like an over the road truck, i would recommend putting the more expensive filters from cat on there. but that is just my opinion. good luck.

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IT WENT BING BANG BOOM!

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Mobiletech

Posts: 94
Joined: Jun 2010

Monday July 19, 2010 06:09

The first thing you need to know is fuel pressure at the secondary filter. If you suspect the tank vent line plugged the engine should have full power right after you have had the fuel cap off and vented it so I doubt that is a problem.
Can you hear the turbo spool up when you try to move. you may need someone listening at the back to hear it. If you take the air pipe from yhe filter to the turbo off you should be able to spin the turbo by hand without it running.
I have also seen the muffler plug and cause this problem. Make sure it is ok.
The oil filter being empty is weird but if you have 30 psi oil pressure I can't see that there is a problem with the low poressure oil system.
If there is a leak in the high pressure system it should be hard to start.
I would suspect possibly a fuel filter problem. Fuel will go bad if it sits too long and will plug up the filter.

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bobbinalong

Posts: 32
Joined: Jul 2010

Monday July 19, 2010 10:52

To many parts and pieces. I am an Instrument Tech and have no problem connecting gauges as well as making sense of what the pressure readings are telling me. However, from what you two are saying, I believe, is that I need a computer with the CAT software or I could be chasing my tail all day. I think at this point I should stop treating the motor home as if it was the old "57" chevy and take it to CAT. Thank you both for your time. I will come back and let you know what CAT finds. Maybe it will help you help someone else. Thanks again. -Steve

-------------------------
God -> Men -> Government.
Proud member of the Tea Party.
“In God We Trust;” in Liberty we thrive.

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bobbinalong

Posts: 32
Joined: Jul 2010

Monday July 19, 2010 17:13

Ok for all who wants to know what is going on, I can now give you what I know. The "Injection Actuation Pressure Control Valve" is putting out to much pressure to the "HEIU" pump. The computer sees this high pressure and puts the engine into lock-out mode. The fuel and air flows are fine. Now for what they do not know.... Why is the oil filter not getting oil?? This one has them stumped. So when I know the answer to that I will be back.

At least it is not an Allison problem. Well at least not yet.

Thanks to all for their input.

-------------------------
God -> Men -> Government.
Proud member of the Tea Party.
“In God We Trust;” in Liberty we thrive.

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bobbinalong

Posts: 32
Joined: Jul 2010

Wednesday July 21, 2010 23:00

While the Motor Home is being repaired at the CAT place I would like to have them boost the horse power from 275 up to 300. CAT is saying that the turbo and the cooling system will handle it. So no new hardware just a software change. I would like to have your input before I decide. Thank you.

-------------------------
God -> Men -> Government.
Proud member of the Tea Party.
“In God We Trust;” in Liberty we thrive.

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desertstormboy

Posts: 372
Joined: May 2008

Thursday July 22, 2010 05:36
what they gonna charge to up it 25 horses? used to be real expensive. so think about the cost versus 25 horses. ------------------------- IT WENT BING BANG BOOM!

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bobbinalong

Posts: 32
Joined: Jul 2010

Thursday July 22, 2010 07:50

$150.00 Plus $1k for the new IAP control valve and sensor. They should do it for free.

Well eight hours later the cost has gone up. Cat is now charging $250 for the software upgrade and I would also need to do an "iscaan" test for the Torque converter. So the total cost would be close to $500.00. I have decided not to do it. I have only needed more hp while climbing some of the hills in the Cascade Mountains. But this does not happen enough to justify spending $500.00. This is something I can do at a later time.

-------------------------
God -> Men -> Government.
Proud member of the Tea Party.
“In God We Trust;” in Liberty we thrive.

Edited: Thursday July 22, 2010 at 18:06 by bobbinalong

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desertstormboy

Posts: 372
Joined: May 2008

Friday July 23, 2010 19:23
i think you have made the right decision bobbin.. ------------------------- IT WENT BING BANG BOOM!

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bobbinalong

Posts: 32
Joined: Jul 2010

Saturday July 24, 2010 15:55

For you who want to know, here is the scoop. I had to have the "Injection Actuation Pressure Control Valve and Pressure Sensor" on the HEUI pump replaced, and a new modified spring and O ring on the oil filter mount installed. The motor home is running like a champ. It just cost me my left arm and my right hand. The parts cost where not bad but the labor killed me. Oh well what can you say. Next weekend we will be on the Columbia River then on to Ravensdale. I want to thank you all that give me advice. Most appreciated....

-------------------------
God -> Men -> Government.
Proud member of the Tea Party.
“In God We Trust;” in Liberty we thrive.

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desertstormboy

Posts: 372
Joined: May 2008

Sunday July 25, 2010 06:58
well bobbin since we are talking labor costs,,,,i just took my 08 dodge grand caravan to the dodge dealer to find a voltage draw. after days of troubleshooting cost me $702 to find out the heater control module was shorted out causing it to drain my battery. thanks for the update. ------------------------- IT WENT BING BANG BOOM!

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bobbinalong

Posts: 32
Joined: Jul 2010

Monday July 26, 2010 16:02
<< i think you have made the right decision bobbin.. >> Would you please tell me why you think I made the right decision. From reading some of your posting's I feel you have the knowledge to give me an accurate answer. Thank you. ------------------------- God -> Men -> Government. Proud member of the Tea Party. “In God We Trust;” in Liberty we thrive.

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desertstormboy

Posts: 372
Joined: May 2008

Monday July 26, 2010 17:37

paying $500 bucks for 25 horsepower to me just isnt worth it. if you dont have to change injectors, turbos or major components for the upgrade, takes like 20 minutes to program the ecm with a new flash file. the cat dealers love doing this because it is easy money. after working with a cat dealer for 7 years, they would charge a minimum of 30 minutes ($50) just to connect to the ecm and check and make changes to parameters for the customer. it takes like 5 minutes to do.

-------------------------
IT WENT BING BANG BOOM!

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bobbinalong

Posts: 32
Joined: Jul 2010

Tuesday July 27, 2010 19:24

Other then being ripped off, is there a down side to increasing the horse power? Why I ask, when I am climbing the mountain passes here in the Northwest I run in the 215 to 220 degrees on water temperature. I have been told that with the increase of horse power I would not reach these high temps. I always clean the radiator after each trip and have it flushed every three years. My transmission stays around 160 to 170. I have also been told that if I had a radiator problem the transmission would be running hotter at the same time.

-------------------------
God -> Men -> Government.
Proud member of the Tea Party.
“In God We Trust;” in Liberty we thrive.

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desertstormboy

Posts: 372
Joined: May 2008

Wednesday July 28, 2010 06:04

what makes you think if you have more horsepower the temp goes down? just the opposite, the more horsepower the higher temps. thats why you have to have a larger radiator with larger engines. more horsepower will let you climb the hills better that is true, but i dont think you would have been satisfied with 25 horses for the amount of money you would have had to pay.

-------------------------
IT WENT BING BANG BOOM!

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bobbinalong

Posts: 32
Joined: Jul 2010

Wednesday July 28, 2010 11:33
10-4 I got it. Nice to get a straight answer. Thank you. ------------------------- God -> Men -> Government. Proud member of the Tea Party. “In God We Trust;” in Liberty we thrive.

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