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Thread: Fan Problems

  1. #1

    Default Fan Problems

    I just dropped a 5.3L into my truck. I had problems with my old engine over heating before because the fans weren't kicking on and now its doing it with the new engine. I noticed that my temperature gauge in the cluster is off. I have my bully dog set up to read engine temp and it reads like 220 and my cluster gauge reads less than 205. I think the fans aren't coming on because my gauge cannot read something right. Does anyone know what that problem could be and how it could be fixed. I have another question as well, would my running hot make me get less mpg and horsepower??

    I have one more question. I just got that engine put in and the oil pressure is at like 20, is that bad or average or what? My old 4.8L was at 40.

    Please and thank you!
    -Chad

    P.S. sorry if i posted this in the wrong thread.
    '07 Chevy Silverado Classic

    PERFORMANCE
    -K&N Intake
    -Air Raid Throttle Body Spacer
    -Thrush Muffler
    -Bully Dog Triple GT Programmer
    5.3L V8
    LOOKS
    -3" Spindle Lift
    -Tint
    -Blacked Out Rims
    -Blacked Out Taillights
    SOUND
    -2 Kicker CVT 12s
    -Rockford Fosgate 6.5"
    -500 Alpine Mono Block
    -Pioneer 6.5" Touch Screen
    -2 Boss Tweeters
    SOON!
    -3.73 gears

  2. #2
    Sr. Engineer
    Join Date
    Oct 2010
    Location
    Indianapolis, In
    Posts
    487

    Default

    I am not sure if the computer looks at the same sending unit as the gauge but my experience is that there is a seperate coolant temp. sensor that is for engine management. Does your Bully dog get its info from the ECM, if so it is seeing what your computer is seeing and it probably wants the fans to run. First, do the fans work? Are the fuses good? Is the fan relay good? Is the ecm sending power to the relay? The first "no" answer you get is where to start looking for your problem.
    2000 GMC YUKON SLT, 5.3L tow pkg, G80 rear/w 3.73 gear

  3. #3

    Default

    Definitely sounds like a variance in what the sending unit/ computer are seeing. Also agree with @dpeter on the above issues to start looking for and troubleshooting.

    "If you're not living life on the edge, You're taking up too much space"

    "Truck Norris"
    - 2008 TX Edition Silverado
    - McGaughy's 4/5 Drop Kit
    - Apline Type R 10s & Amp
    - Pioneer 6 Disc Touchscreen Deck
    - Nightmare Breed Motorsports custom tune
    - Custom 3" dual exhaust through x-pipe dumped at axle
    - Airaid CAI
    - Badges and molding removed, roll pan, Truxedo roll-up cover (compliments of GMTC!), 3pc billet grille, factory fogs upgrade
    "Kristine" - 1991 Nissan 240sx
    - Cut to pieces, LS build pending

  4. #4

    Default

    That's the problem. My mechanic hooked his scanner up to it and turned them on low and high and they worked on both modes. he turned on the ac and they run when the ac is on. I think it has something to do that my cluster gauge is not reading right. the gauge is not reading right so the fans are not turning on, but i have no idea that just makes sense to me.
    '07 Chevy Silverado Classic

    PERFORMANCE
    -K&N Intake
    -Air Raid Throttle Body Spacer
    -Thrush Muffler
    -Bully Dog Triple GT Programmer
    5.3L V8
    LOOKS
    -3" Spindle Lift
    -Tint
    -Blacked Out Rims
    -Blacked Out Taillights
    SOUND
    -2 Kicker CVT 12s
    -Rockford Fosgate 6.5"
    -500 Alpine Mono Block
    -Pioneer 6.5" Touch Screen
    -2 Boss Tweeters
    SOON!
    -3.73 gears

  5. #5
    Sr. Engineer
    Join Date
    Oct 2010
    Location
    Indianapolis, In
    Posts
    487

    Default

    If you can operate the fans Via a scan tool then all is working and that is a good thing. What exactly leads you to believe you are overheating? I cannot recall but I think my owners manual suggests that 220-230 is normal if towing and nothing to get excited about. I'll check and get back to you.
    2000 GMC YUKON SLT, 5.3L tow pkg, G80 rear/w 3.73 gear

  6. #6

    Default

    When it starts to get hot it feels as if I'm driving with my e brake on. it seems like its hard to accelerate and when i let off the gas it is like I'm engine braking. my old engine ran at 204, i don't see why it wouldn't with this engine because it is the same computer.
    '07 Chevy Silverado Classic

    PERFORMANCE
    -K&N Intake
    -Air Raid Throttle Body Spacer
    -Thrush Muffler
    -Bully Dog Triple GT Programmer
    5.3L V8
    LOOKS
    -3" Spindle Lift
    -Tint
    -Blacked Out Rims
    -Blacked Out Taillights
    SOUND
    -2 Kicker CVT 12s
    -Rockford Fosgate 6.5"
    -500 Alpine Mono Block
    -Pioneer 6.5" Touch Screen
    -2 Boss Tweeters
    SOON!
    -3.73 gears

  7. #7
    Sr. Engineer
    Join Date
    Oct 2010
    Location
    Indianapolis, In
    Posts
    487

    Default

    Checked my manual, says gauge will read 210 or less most of the time, going up hill or towing it may reach 250 and that would be normal, if it reaches 260 or more then it is working beyond its capacity. From what you describe, I would be looking for dragging brakes. Maybe transmission selecting wrong gear. Does not sound like motor issue to me.
    Do let us know what find out. Good luck.
    2000 GMC YUKON SLT, 5.3L tow pkg, G80 rear/w 3.73 gear

  8. #8

    Default

    Yeah that's the thing. It shouldn't be at 220 in town. That's too high when it says it should be less than 210 most of the time. I just got a new Tranny put in like 5k miles ago so I doubt that would be the problem.
    '07 Chevy Silverado Classic

    PERFORMANCE
    -K&N Intake
    -Air Raid Throttle Body Spacer
    -Thrush Muffler
    -Bully Dog Triple GT Programmer
    5.3L V8
    LOOKS
    -3" Spindle Lift
    -Tint
    -Blacked Out Rims
    -Blacked Out Taillights
    SOUND
    -2 Kicker CVT 12s
    -Rockford Fosgate 6.5"
    -500 Alpine Mono Block
    -Pioneer 6.5" Touch Screen
    -2 Boss Tweeters
    SOON!
    -3.73 gears

  9. #9

    Default

    Drove it today on the freeway and it seemed like it was working really hard to stay at 80mph. it was jumping into 3rd gear then back into 4th. it does that sometimes on inclines or with strong wind but there was neither today. the temperature read anywhere from 210-221. I don't know how but i think that the fans not turning on is making it lose power because of pressure. Its starting to make me mad because my truck hasn't been right for the longest time and I'm getting tired of having to keep putting money into it. Does anyone know anything about any of this stuff??
    '07 Chevy Silverado Classic

    PERFORMANCE
    -K&N Intake
    -Air Raid Throttle Body Spacer
    -Thrush Muffler
    -Bully Dog Triple GT Programmer
    5.3L V8
    LOOKS
    -3" Spindle Lift
    -Tint
    -Blacked Out Rims
    -Blacked Out Taillights
    SOUND
    -2 Kicker CVT 12s
    -Rockford Fosgate 6.5"
    -500 Alpine Mono Block
    -Pioneer 6.5" Touch Screen
    -2 Boss Tweeters
    SOON!
    -3.73 gears

  10. #10
    Sr. Engineer
    Join Date
    Oct 2010
    Location
    Indianapolis, In
    Posts
    487

    Default

    220 degrees by itself is not a problem but when you add to it that the motor is larger than original so the radiator may not be big enough and you have oil pressure on the low end, (used motor?) with bearing issues. You could have several issues contributing to the problem..Water pumps can go bad, thermostats go bad, radiators plug up, could have straight ani-freeze in it. Are the part numbers the same for both engine's coolant temp. sensor? You mentioned same ecm used for 5.3 as the 4.8, could there be a mismatch of components causing you problems? Now I'm just guessing.Hopefuly someone will chime in with something more useful.
    2000 GMC YUKON SLT, 5.3L tow pkg, G80 rear/w 3.73 gear

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