Author Topic: does not start my cat 3126b  (Read 1420 times)

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Offline español

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does not start my cat 3126b
« on: February 14, 2018, 12:32:51 PM »
good afternoon and
   sorry for my english
I bought a boat with 2 cat engines 3126b 450 hp and loscar engine engines were disassembled, we recostruido cylinder heads, segments, injectors, turbos, etc.
now the motors are mounted and it is very difficult to start in cold.
all the injectors are recon, the diesel pressure is at 2 bar, and the oil pressure without start is about 85 bars and when it starts it is set at 125 bars at the minimum speed. I have changed valve and IAP sensor and the problem is the same, the engine turns well, the injectors are heard, it smokes but it does not start and when it starts it seems to have little power.
what problem can I have
I have tested the return of diesel and good gasoil flow and without the presence of air, I even put a new valve.
in the mornings it starts well, but after a while it makes a slowdown of revolutions and stops, afterwards it is impossible to start.
  sometimes it turns and makes white smoke, but it does not start and sometimes it starts more or less fast, but it remains at 500 revolutions and it goes down little by little until it stops and if you give it a start again, you do the same.

Offline Ken Carpenter

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Re: does not start my cat 3126b
« Reply #1 on: February 14, 2018, 04:21:34 PM »
This request was originally posted under the AskDave, I’ve Got a Problem Board. Dave Atherton has posted his reply there. Here’s a link http://forum.dieselrvclub.org/index.php/topic,7607.msg19226.html#msg19226
« Last Edit: February 15, 2018, 10:32:19 AM by Ken Carpenter »
2005 Winnebago Journey 39K, C7 350HP
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Offline español

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Re: does not start my cat 3126b
« Reply #2 on: February 15, 2018, 01:51:28 PM »
The problem persists, the engine starts well in cold, but now when it warms up a bit, and I stop it, then it does not want to start, it turns to 25oce h0 revolutions when it starts, it smokes (it is injecting) but it can not start
« Last Edit: February 15, 2018, 02:22:14 PM by Ken Carpenter »

Offline David.e.atherton

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Re: does not start my cat 3126b
« Reply #3 on: February 15, 2018, 04:56:10 PM »
espanol, you indicated engine will start when cold after warm up engine and stopping
engine warm will not start along with white smoke. First did check all your injectors
power connections making sure there is power to all injectors ( this area where white
smoke is coming from.) with engine running install a clear plastic hose to the return
fuel pressure regulator and run fuel into a catch pan. The white smoke is telling me
you have air within the fuel system and fuel transfer pump cannot provide enough fuel
after engine warms up. Think fuel is not being pulled into engine at correct pressure. Last
Question, you indicated engines are putting out 450 hp, is this with both engines running
together or each engine is putting out 450 hp. Can you give me your engine serial
number of each engine so I can pull up builder spec as to Rated hp. Think that building
up engines may not fall within builder spec’s. Ask Dave. Dave Atherton Retired Cat
Mechanic

Offline David.e.atherton

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Re: does not start my cat 3126b
« Reply #4 on: February 16, 2018, 06:12:22 PM »
espanol, reviewing the test results on your engine time when it was shipped. Your
spec on test results ( spec number OK-2787 ) Engine arrangement number assigned
to your engine 164-7858. What concerns me is the diesel fuel pressure from fuel transfer
pump on engine, which requires a constant fuel pressure of 87 psi. at 2800 rpm. The engine
slowing down than stopping when warm along with white smoke tell me your fuel transfer
pump cannot maintain correct diesel fuel pressure. Again install a pressure gauge at secondary
fuel filter and pressure at this point should be 87 psi at high rpm of 2800 rpms.  Installing
a clear plastic hose ( hose where you can see through ) at end of fuel,pressure return
regulator on rear of engine head. This action should take you into the problem. Note:
you mention of lot of work preformed on your engine. Do you have a paper work on
all work done and was it done by a caterpillar trained mechanic.  Ask Dave Dave Atherton
Retired Cat Mechanic.