Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

k3500 3 + 3 big block "seems" to run hot.. what now????????

Discussion in 'The Garage' started by camiswelding, Oct 22, 2003.

  1. camiswelding

    camiswelding 1/2 ton status

    Joined:
    May 25, 2003
    Posts:
    2,545
    Likes Received:
    0
    Location:
    Redding, CA
    k3500 3 + 3 big block \"seems\" to run hot.. what now????????

    my new k3500 big block bone stock with 37k original miles on it seems to run hot.... all systems are go and truck runs excellent.. truck has had a new water pump and obviously has low miles,,,everything is like new on the truck ... runs at 210/215 degrees per guage..does go up and down a little... original owner said he felt the thing was always hot as well..hot enough you cant rest your hand anywhere near it.... dealer checked out ok when under warranty.. has a monster radiator...hasnt boiled over but in traffic needs the backup electric fan to keep it cool,, the radiator burbbles (air)occasionally
    Im at a loss.... any ideas
    pressure test it? under load?
    thanks
    cam
     
  2. burbBoy

    burbBoy 1/2 ton status

    Joined:
    Feb 4, 2002
    Posts:
    358
    Likes Received:
    0
    Location:
    WI
    Re: k3500 3 + 3 big block \"seems\" to run hot.. what now????????

    Check the thermostat. Chances are if its running that hot its got a 195 in it. Change it to a 180 and it should help quite a bit. Also check the timing to make sure its not advanced a little too much.
     
  3. mudjunkie 82

    mudjunkie 82 1 ton status GMOTM Winner

    Joined:
    Dec 27, 2002
    Posts:
    11,449
    Likes Received:
    0
    Location:
    Cleveland Ohio
    Re: k3500 3 + 3 big block \"seems\" to run hot.. what now????????

    I'm with burb, replace the t' stat
     
  4. nvrenuf

    nvrenuf NONE shall pass! Premium Member

    Joined:
    Jan 7, 2002
    Posts:
    13,075
    Likes Received:
    245
    Location:
    Mobile, Al.
    Re: k3500 3 + 3 big block \"seems\" to run hot.. what now????????

    Fan clutch ok?
     
  5. BlueBlazer

    BlueBlazer 1/2 ton status

    Joined:
    Feb 15, 2001
    Posts:
    1,940
    Likes Received:
    0
    Re: k3500 3 + 3 big block \"seems\" to run hot.. what now????????

    Changing the tstat to one of a lower opening temp is just a bandaid fix. Check things like the plugged radiator fins, slipping fan belt, bad fan clutch, quality and ratio of coolant mixture, and other things that would cause a lack of cooling.
     
  6. camiswelding

    camiswelding 1/2 ton status

    Joined:
    May 25, 2003
    Posts:
    2,545
    Likes Received:
    0
    Location:
    Redding, CA
    Re: k3500 3 + 3 big block \"seems\" to run hot.. what now????????

    thanks for the tips...
    I cant stress enough that this truck is showroom new under the hood
    timing is set to specs, passed smog without even registering on the machine so I know cat etc is good
    fan clutch operates to specs
    belts are new
    radiator is like new inside.. I drained and filled it with specd mix when I got the truck last month
    like I said Im at a loss.... never had a truck run hot like this that didnt have something detectable wrong with the cooling system...
    never owned a big block... thought maybe they run hot...
    the only thing not changed is the thermostat... but Ill test it next (and last) and replace it.....
    cam
     
  7. GMCLegacy

    GMCLegacy 1/2 ton status

    Joined:
    Jan 24, 2002
    Posts:
    620
    Likes Received:
    0
    Location:
    Grand Haven, MI
    Re: k3500 3 + 3 big block \"seems\" to run hot.. what now????????

    i have always just replaced clutch fans, what are the "specs" that a fan clutch operates at?

    things i would check...
    when idling, with the hood closed, can you feel air being pulled in through the grille?

    what temp t-stat are you running?

    is there a fan shroud on the radiator?

    how many blade fan is on the truck?

    most of the questions are not worth checking if you are running a 195 or so t-stat already. since your temp gage isnt at the same spot in the cooling system as the t-stat, you will never get the exact same reading.

    good luck
     
  8. yellowK20

    yellowK20 Well Lubricated Premium Member GMOTM Winner

    Joined:
    Dec 26, 2002
    Posts:
    7,602
    Likes Received:
    554
    Location:
    Wasilla AK,
    Re: k3500 3 + 3 big block \"seems\" to run hot.. what now????????

    mine runs on the warm side as well about 205-210 under load but I've heard TBI trucks tend to run hotter than carbed motors
     
  9. HarryH3

    HarryH3 1 ton status Author

    Joined:
    May 31, 2000
    Posts:
    10,384
    Likes Received:
    2
    Location:
    Georgetown, TX
    Re: k3500 3 + 3 big block \"seems\" to run hot.. what now????????

    First verify the temp with a known-accurate gauge. Modern EFI engines are designed to run right at 195-205 degrees, so 210-215 isn't really that hot at all. /forums/images/graemlins/eek.gif Also, if you are running the a/c, the engine should still run at about the same temps, but the underhood temp will increase dramatically. The a/c condensor creates a LOT of heat, making everything under the hood too hot to touch. /forums/images/graemlins/shocked.gif
     
  10. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

    Joined:
    Feb 17, 2000
    Posts:
    7,385
    Likes Received:
    0
    Location:
    Atlanta
    Re: k3500 3 + 3 big block \"seems\" to run hot.. what now????????

    My 88 454 Burb was doing the same thing. Ended up being radiator. I had internal corosioin and the fins were packed full of bugs. I ended up dropping in a Modine 4 core and I only hit 210 with A/C on stuck in traffic with mid 90temps with a 195 degree thermostat. I was having to shut the A'C off and having a hard time staying under 220.
    I also added some CRC Tow Kool from Napa.

    I have heard that the factory radiator in the late 80's was restrictive of air flow. The WWWWWWW stuff is really packed in and the cores are small. The modine has less of the WWWWWWW and larger cores. Been doing fine since.
     
  11. camiswelding

    camiswelding 1/2 ton status

    Joined:
    May 25, 2003
    Posts:
    2,545
    Likes Received:
    0
    Location:
    Redding, CA
    Re: k3500 3 + 3 big block \"seems\" to run hot.. what now????????

    thanks everyone... all good info
    Ill re-look at everything
    and yes I was going do much of what has been suggested this weekend....
    operates to specs means working like the factory states
    i.e fan clutch cycling properly.... radiator is clean/clear
    etc etc etc... this one still has me baffled...
    you cant touch the hood when the engine is hot... neither of my other rigs are that way at all...
    if I have to aftermarket radiator to cool it I will
    cam
     
  12. nvrenuf

    nvrenuf NONE shall pass! Premium Member

    Joined:
    Jan 7, 2002
    Posts:
    13,075
    Likes Received:
    245
    Location:
    Mobile, Al.
    Re: k3500 3 + 3 big block \"seems\" to run hot.. what now????????

    For camparison of another TBI truck, I have a 91 crew cab with a 350 and when the motor is hot I cannot touch the hood either. Typically, with the a/c on, my truck runs dead on 210. Mine never goes over 210 but it will run at about 195~200 on a cool day with the a/c off.

    FYI - I have a 4 row (Modine) radiator, a severe duty fan clutch, 7 blade fan, fan shroud and a 50/50 coolant mix (no additives). I have yet to change the thermostat so I have to assume it's an OE 195* piece.
     
  13. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,979
    Likes Received:
    189
    Location:
    Roy WA
    Re: k3500 3 + 3 big block \"seems\" to run hot.. what now????????

    I'm not going to say it IS your problem, but to ever think the radiator is NOT the cause because of age or visible condition, is somewhat foolish.

    Wish I knew the link, guy had a Camaro with a 2 year old radiator that was overheating. He swapped EVERYTHING (and I mean everything, to include intake and heads) and it still overheated. Radiator "looked" good. Guess what the problem was, after 1000's of $$?

    I'm fairly lucky, I can get radiators flow tested for free locally, so if I was in doubt (and I have been) I'd take it there. Had a bad radiator myself that "looked" good, but more often than not, the corrosion at the bottom is ten times worse than what you can see from the top.
     
  14. chubbybob

    chubbybob 1/2 ton status

    Joined:
    Oct 18, 2002
    Posts:
    730
    Likes Received:
    0
    Re: k3500 3 + 3 big block \"seems\" to run hot.. what now????????

    I have the same engine and back when the truck was my tow rig it always ran at 210 that is what they run at so dont worry about it. I turned the truck into my wheeler a couple years ago and moved to vegas. in the summer its about 120 degrees out and the thing over heats in about 5 minutes after starting the engine. the truck sat for about a year while building it so I pulled the radiator and had it boiled that made a huge difference but it would still get hot after a while. so then I got rid of the clutch fan and added a flexalite blue 10,000 RPM fan and now the thing can idle at 195 degrees when its 120 degrees outside it never even gets close to heating up now.
     
  15. DesertDueler

    DesertDueler 1/2 ton status

    Joined:
    May 23, 2001
    Posts:
    3,106
    Likes Received:
    0
    Location:
    Phoenix, AZ
    Re: k3500 3 + 3 big block \"seems\" to run hot.. what now????????

    I would have that radiator checked/replaced. That truck came from AZ, so most likely the radiator is full of calcium ( Our tap water is full of calcium out here). I always replace the radiator when I but an older chevy. My old burb run warm, and it only had 57,000 miles on it. I put in a new radiator, and never got over 185 degrees, even in traffic with AC on.

    Dan
     
  16. camiswelding

    camiswelding 1/2 ton status

    Joined:
    May 25, 2003
    Posts:
    2,545
    Likes Received:
    0
    Location:
    Redding, CA
    Re: k3500 3 + 3 big block \"seems\" to run hot.. what now????????

    great advice everyone,, thanks again
    cam
     

Share This Page