Hi guys and gals. I'm new to the forum and am in need of some advice. Any help will be greatly appreciated.

Heres some history. I bought a used dump truck about 3 years ago. Its a 1997 Freightliner with a Cat 3406E with 250 HP (maybe 350 HP, cant remember). I know the HP sounds pretty low but whoever owned the truck must have had it tuned down. It does what I need it to do though. It had about 408,000 miles on it and it now has 436,000 miles. It used to have a fifth wheel but was converted to a dump truck (frame extended, hydraulics added, and a new dump bed).

Heres some recent history. For a couple of months I was having water in my fuel issues and rough starts in the morning when I first start the truck for the day (groggy with white smoke for about 5 seconds). Other than the rough first start, the truck ran well with clean exhaust (no smoke and no power loss). I thought I a had sucked up some bad fuel from a gas station during the heavy rains. So I thought it would clear it out with filter changes and fresh fuel. This happened to us once on another truck, so I assumed it was the same issue.

Well it just wouldn't go away. So I thought maybe someone didn't like me where I park my truck at night and was putting water in my tanks. But, one warm Friday afternoon driving in Los Angeles traffic for two hours, I get back to the yard and there is diesel fuel coming out of my overflow tube from my radiator reservoir.

So I thought it might be the fuel filter assembly because there is water lines running through it to heat the fuel. I pressure tested it with a water hose and it would not leak.

So I began to call some mechanics. They said it was a cracked injector tube and that the head needed to be rebuilt and it would cost about $2,500.00.

Well at least I finally know what the issue is and can get it fixed. So we take it to a shop and they get the head rebuilt ($2,800.00). I drive it home and realize that the coolant temperature gage isn't working and that my fan clutch is stuck on. I call the shop and they said to bring it back in.

I had jobs I needed to do so I ran the truck until I had some time to bring it back in. On the second day after picking it up an injector failed. The piece in the end of the rocker arm had turned sideways and jammed the injector valve open. Why would this happen??? Did they not adjust the clearance properly??? Does anybody know why this happened right after they rebuilt the head???

So I run to the Cat dealer and get a re-manufactured injector and other parts needed so I can get back to work the next day (about $550 for parts). They put it in and it ran good but we still had the temp gage not working and the fan stuck on. They tried to trouble shoot it, but it was like 7:00 pm and I had to get home and I had a job to still finish.

Within the next couple of days I buy a new temperature sending unit ($30) and now my temp. gage works again, but the fan clutch is still on.

Then I buy a fan clutch sensor ($100) and replaced it but it did not fix the fan clutch.

I tested the fan clutch solenoid and it works fine at 12.2 volts but the signal wire to the solenoid is only bringing 11.2 volts!

So, should the solenoid be able to function at 11.2 volts or is the ECM not putting out the proper voltage????? How do I fix this issue?

I checked the voltage on the fan clutch sensor that has 3 wires on it. One had like 6.5 volts, the other had like 4.3 volts, and the last one was a ground. Does this sound right?

Heres a summary of things I would like opinions on. Feel free to add anything else.

1. Is the shop responsible for the failed injector after the head rebuild?

2. Are they responsible for temp. the sensor and fan issues?

3. How can I trouble shoot and fix the fan staying on constantly issue?

 

the electrical path for the fan is involved with the electrical path for the a/c. i had some a/c problems last month and while i was effin around with the wiring for the a/c drier i noticed that when i severed one of the wires coming from the driver side plug the fan came on and stayed on until i re-established the connection. maybe that path was damaged or severed while they were doing the head work?

 

That is an interesting theory I will look into, but why am I only getting 11.2 volts to the air solenoid? Something is trying to turn the fan off but isnt allowing enough volts to do do. Where does the hot wire for the fan solenoid come from?

 

Well I found out why the fan was staying on.

Thanks to tankyanker for pointing me in the right direction.
I just love the internet and forums.

My truck has an APADS ( http://www.indexsensors.com/products/apads.php) air conditioning controller. Well looking at the controllers blink code, it was telling me it had low voltage which means the default action is to run the fan. The APADS website had great trouble shooting guides and manuals to help diagnose issues. So I began running through the trouble shooter and was trying to figure out why the APADS had no main voltage and no ground.

Well the mechanics plugged the APADS into the only possible wrong plug for the system power and ground. There just happens to be a spare plug coming out of the firewall near the APADS that appears to be for a unused device. The actual plug they needed was coming from the other side of the engine.

Thanks for your help guys. I hope this helps someone in the future.