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CATEGORY LISTINGS > CATERPILLAR > 3406 PEEC 8TC/Boost Problem

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Thread Title:

3406 PEEC 8TC/Boost Problem

Created On Sunday August 20, 2006 09:15

phantomlord

Posts: 21
Joined: Aug 2006

Sunday August 20, 2006 09:15

I have this old 3406 PEEC and have a boost problem. Only 11psi boost, loaded or empty. Been to ring power and was told nothing wrong. Then they r&i the transducer/boost sensor, still @ 11psi. Checked turbo, air charge cooler & replaced broken studs on exh. manifold. Fuel psi is low and varies. Fuel transfer pump replaced. Timing, rack & bmt are supposedly ok. There is a small fuel leak from #4 line leading into head to nozzle, but Im told that shouldnt be a power problem. Ring power even hooked up the laptop while i ran down the road, and Im told everything is perfect, just getting 11psi boost. One other thing. While at ring power, the O-ring on bmt was replaced, after I drove 70 miles, stopped at a light, it threw a code, and was acting weird, reving itself up and down, up and down upto 1600 rpm. I stopped at the store and checked the plug to the bmt, i pulled it apart and it was dirty, when i put it back together it seemed to smooth out.Then when I started down the road it again reved to 1600 at red lite, when i took off, it started boosting to over 17psi bob-tail, and ran like a race truck. So I figured dirty connections. So I got a can of electric cleaner, and cleaned all connections and blew out with air. Put back together and test drove. Back to 11 psi boost. I am pulling my hair out with this thing. I know I can make it all mechanical, but I'd rather get it right this way before I do that. Any info anyone can give me, I would be very thankful. Thanks

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catmech

Posts: 326
Joined: Nov 2005

Friday August 25, 2006 20:19

you had it working after after playing with the wiring, try taking an ohm meter and checking the wires for resistance. the power has to be off or you'll fry the ohm meter. you may have a bad wire that is making a connection but not a good one. could be broken under the insolation. or run engine and wiggle the wires and see if there is a rpm change. seen engine that stop running because of metal stuck to the speed sensor.

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phantomlord

Posts: 21
Joined: Aug 2006

Sunday August 27, 2006 06:54
Thanks for your reply. That's where I'm leaning also. I tried to wiggle wires but got no change. I need an ohm meter yes. I did use my 12v test light and had connection on both ends of BTM wires, but light is weak. But I was told 8volt system, so I'm not sure about that part.

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catmech

Posts: 326
Joined: Nov 2005

Sunday August 27, 2006 08:05
you have a 8 volt and a 5 volt system depends on if their analog or digital. the volt ohm meter helps alot in checking out the systems, so it can be a great tool, want it in digital form.

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phantomlord

Posts: 21
Joined: Aug 2006

Sunday August 27, 2006 08:29
do you happen to know what my readings should be at the btm?

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catmech

Posts: 326
Joined: Nov 2005

Sunday August 27, 2006 15:26
I am sorry never worked on a peec. seen them talked to people about them, but never worked on them. so I don't know the voltage to the btm, but known it is constantly changing with load and rpms.

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HurricaneMech

Posts: 13
Joined: Sep 2006

Friday September 01, 2006 08:10

Remove the rack BTM from the governor housing. Look in the hole it came out of and see if the harness from the transucer module is hanging down, these wires will typically be covered with a yellow covering, should be two seperate harnesses located here.. There is very little room between the governor housing and the end of the rack BTM so if the harness is not pushed up out of the way the BTM can pinch the wires between the housing and can become cocked causing the arm on the BTM to bind in the sleeve on the rack control. In regards to your low boost problem, did the dealer check the rack sensor callibration? Is the rack position moving when the dealer was monitoring the engine on their service tool? The rack sensor is attached to the rack arm by a magnet, which allows the sensor to follow the rack position. If the sensor has become detached from the magent, it will no longer follow the rack position and can cause a low power complaint.

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phantomlord

Posts: 21
Joined: Aug 2006

Friday September 01, 2006 13:45
BTM doesn't seem to be hanging due to harness. CAT did check rack sensor and I was told it was ok. One thing I haven't posted yet, because I just found out. Is there is fuel getting in oil. and fuel leaking from where the six lines lead to head up to the nozzles. Haven't pulled cover to inspect yet.

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catmech

Posts: 326
Joined: Nov 2005

Friday September 01, 2006 19:09

those adapters that go through the head have a hole that is drilled in to it, lets fuel leak out if the seat for the internal fuel line or out side fuel line are not sealing right in that adapter. I would pull the valve covers as soon as possible, fuel in your oil can cause low oil pressure very quickly. also causes lack of lube to your bearings. look at the internal fuel lines see if they are tight, or have a crack in them. also check to see if the fuel is coming up around the nozzles.

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phantomlord

Posts: 21
Joined: Aug 2006

Saturday September 02, 2006 09:46

Thanks guys for the input. Something that was just brought to my attention also. There are supposed to be some sort of fuel line clamps that tie those six lines together at certain points. I don't know how many it is supposed to have, but there is only two on the whole set, and they are located at the front behind the air compressor. None are at the back. And the back three are the ones leaking. Number 4 is leaking worse. 5 & 6 not as bad, but still see fuel in that area. I'm about to pull the covers today to get a better look.

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HurricaneMech

Posts: 13
Joined: Sep 2006

Saturday September 02, 2006 10:15

Best to get the fuel line clamps in place. Can cause the fuel lines to crack due to vibration, also wears the o-ring seal out on the through head adapter causing an oil leak. As stated, fuel dilution can cause serious engine problems very quickly. You should diagnois and repair it immediately. The layout for the position of the fuel line clamps is in the specifications section of the service manual.

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phantomlord

Posts: 21
Joined: Aug 2006

Saturday September 02, 2006 17:24
YEs i agree. fuel line clamps are a must. I pulled valve covers today and ran engine while looking. Don't seem to see any fuel leaking from lines or nozzles. All I can see is fuel leaking from outside of head at line connections.

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HurricaneMech

Posts: 13
Joined: Sep 2006

Saturday September 02, 2006 22:03

If you do not see any obvious signs of fuel leaking from the internal injection lines, then I would suspect that the bleed screw washer is leaking on the nozzle body. Use compressed air and blow into the holes in the injector adapter retainer cap and see if you get any fuel spraying out, this will usually tell you if the bleed screw is leaking. This area of the nozzle adapter is typically full of oil, so you should be able to tell the difference with compressed air. If so, you will have to remove the injectors to test and reseal them. If you are sure that fuel is leaking externally from the through head adapters and not oil, then inspect the sealing surface of the internal fuel line and through head adapter when you have the lines off for the source of the leak. Fuel will not typically leak into the crankcase at the through head adapter if the o-ring seal on the internal line is in good condition, the bleed hole in the through head adapter allows the fuel to leak externally and not into the crankcase. Did the fuel dilution start after the fuel transfer pump was repaired/replaced?

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phantomlord

Posts: 21
Joined: Aug 2006

Sunday September 03, 2006 06:57

are you talking about those two holes on top of the nozzle to blow air into? that's the only holes I see.
thing about the trans pump is. i was told that could be my power problem when this first came about. so i replaced it and didn't detect any change. then when i had some time running thru TN. i stopped at KW just to let them try to figure it out. they were busy and close to closing, but they determained that trans pump bad and replaced it. i told him it was less than 30 days old, so he didn't charge me. KW said that was the reason fuel in oil. so i changed oil. but i can tell that oil is runny again and smells and feels like fuel. plus oil level is getting higher on stick again, and pressure is dropping too fast. so it either wasn't trans pump, or the second one is bad again...??? also, KW said #4 nozzle or #4 inj pump bad. i don't know how they figured that, because another shop said they have to be removed and pop tested to know that. but the #4 outside line does have the worst leak.

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Caterlac

Posts: 23
Joined: Feb 2006

Sunday September 03, 2006 08:43

Take the fuel return line off of the injection pump and cap it ( the JIC fitting coming off of the inj pump) Then use the hand priming pump
to pump the fuel up....this will build pres quick because your actually dead heading the pump. Then inspect your entire fuel system for leaks. If any external
leaks are present this method will find them.

-------------------------
Don't be down-hearted I can fix it for ya sonny....It won't take too long it'll just take$$$$$$

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phantomlord

Posts: 21
Joined: Aug 2006

Sunday September 03, 2006 09:13
good deal Caterlac. i will do that asap.

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