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Chevy 454 overheat

Discussion in 'Truck & Equipment Repair' started by CK82, Jan 29, 2006.

  1. CK82

    CK82 Senior Member
    Messages: 189

    Can anyone help!?!? I have read every forum to exist about overheating and I am still not sure what to do first in order to cure my overheating problem of my Chevy 2500 with the 7.4 liter 454. There is no problem without the plow on, everything stays right in the middle at 210 degrees. Soon as the plow is on and traveling over 40mph the temp goes up to about 240 within minutes. I have flushed the system, and removed the clutch fan spring from its slot to keep the fan engaged even at highway speeds. Removing the spring helped somewhat but the temp still sits about 240 at higher speeds. Is there any quick fix that has actually worked??? Please help, Chris
  2. dj&sonplowing

    dj&sonplowing Member
    Messages: 47

    454, first thing i was goning to say was fan clutch, i gotta 350 it was doing the same thing i had a after market heavy duty fan clutch put on, it solved it totally ,i try to block all the air off with plow on a warm day highest i get it is 175 now,, totall with labor was like185 not bad:rolleyes:
  3. clark lawn

    clark lawn PlowSite.com Addict
    from NE ohio
    Messages: 1,233

    is the fan shroud in good shape. also when you flushed it did you wash the outside of the rad. they get plugged up alot if you wash it use LOW pressure so not to damage the fins.
  4. justme-

    justme- 2000 Club Member
    Messages: 2,138

    Well obviously the addition of the plow is the problem, and always is. Are you carrying it as low as you can, and straight to minimise the effects of air flow around it.?

    Try a heavy duty service fan clutch, try a bigger radiator. Odds are you have a 2 row core and you want to look for a 4 row core. the big block puts out alot of heat so you need a big radiator.
    Do you have an aux tranny cooler (besides the in radiator one)? Adding one MAY help by reducing the transmissions effect on the coolent temp, as well as an engine oil cooler may help lower engine temps.

    Oh, and you do know you're really not supposed to be traveling at highway speed with a plow on right? the blade deflects alot of air and there is really little that can be done at high speed to correct it. Keep the blade straight across and as low to the ground as you can, the Rams I have noticed actually get better flow with the blade angled to one side because of the grill design.
  5. CK82

    CK82 Senior Member
    Messages: 189

    The fan clutch spring is out of its slot so the fan runs non-stop, it helps some, but things are still getting way too hot. Would a heavy duty fan clutch actually help considering the fan is already running non-stop I had the radiator backflushed, not sure if it got cleaned out inside, everything works fine without the plow on, so I'm assuming its ok. I guess it could be partially plugged and its only effected when the plow is on. The fan shroud is in good shape and the fan blades are also. I am pretty sure it has an aux tranny cooler, which would be the smaller sized radiator next to the actual radiator. I'll have to check and see if its a 2 or 4 row radiator. If you guys have any more suggestions, please let me know! I would like to get this fixed without spending an arm and a leg.
  6. CK82

    CK82 Senior Member
    Messages: 189

    Forgot to add, that I also have an electric fan which sits on the outer side of the radiator. I know it works, just not sure when it works or at what speeds and what not.
  7. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    I had a 1990 454 K-3500, and know what it means to overheat with the plow on. What year is your truck? Depending on the year, is it possible it has the incorrect water pump on it? The serpentine belt equipped trucks use a different waterpump than the V-belt trucks. I've heard of many old syle pumps being installed on newer trucks making the impeller go backwards. Worked OK until the heat started.

    First off, I've never heard of the fan clutch spring trick. Are you sure your getting full lockup of that viscous clutch when you do this?

    You could always try a fan spacer and make the fan direct drive w/o the viscous clutch. This would only be good for winter low RPM use though.

    I would get a new OEM fan clutch from GM. Make sure you specify HD, as I think there was a severe service one available for fire/amublance/tow truck etc.

    Also, on the OEM aux. fan out front....I never witnessed mine come on. I wired mine to a relay that came on with the ignition. This way, it was always on. Seemed to help some. The newer 454's got better cooling in the engine. Once again, not sure what year you have.

    You likely have the biggest radiator there is, but if you want to do some tweaking, you could get one for the 6.5 diesel....it's much bigger (thicker, taller, and wider). While your robbing 6.5 parts from the junkyard, grab it's bumper and shrouds, the holes in the bumper are for better cooling, and every bit will help.

    I also went with a 180 degree stat....again, not sure of your year, but some computers won't do well with a colder stat.

    So, anyways....what year is the truck? :help:
  8. bugthug

    bugthug Senior Member
    from Pa
    Messages: 268

    I have a 98 gmc with a 454. I removed the rubber gasket on the back side of the hood and I noticed about 10 degrees cooler the next time I plowed. I was toying with the idea of removing the insulation from under the hood we will see.
  9. Yaz

    Yaz PlowSite.com Addict
    from NH
    Messages: 1,061


    Please add a signature with all your info, it helps us help you..

    I would like to know the year, is it lifted,mods to engine, ever rebuilt, if so how much bored over, size and type of plow, size tires.

    And what temp was it out side when this happens? If you put the heat on will the temp drop? by how much? If you angle, raise or lower the blade does it change temp? by how much?

    And I also have never heard of locking a clutch fan up. If you did I'm sure it will rob power and be very loud.
  10. CK82

    CK82 Senior Member
    Messages: 189

    Its a '95 Silverado 2500, 454 7.4 liter. The first time removed the clutch spring from its slot the truck was really loud, but the fan did run constantly and it did help, then I replaced it after flushing the system thinking it would be ok. This didnt work so I removed it from its slot again and this time the engine didnt run as loud, each time helped the temp somewhat, but it still runs about 245 to 250. I've tried the plow down up left right, all over the place it doesnt help. Temps outside ranged from 10 degrees to 35 degrees, despite it ran hot. I think I will try some of the recommendations starting with the fan clutch. Any other info please let me know.

  11. Acmemechanic

    Acmemechanic Senior Member
    Messages: 137

    Hot Hot Hot

    I agree the severe duty fan clutch solved all problems on my 94 Former City Truck.They wear out and don't respond to temperature like they should.Add a blade and you actually have a Negative Airflow to the grill {Vacuum} I could be Wrong but don't believe the spring trick would work.:yow!: :yow!: :yow!:
  12. Yaz

    Yaz PlowSite.com Addict
    from NH
    Messages: 1,061

    CK82 If it stopped making noise it it can't be turning as fast.. I agree with Acmemechanic there is a vacuum. I would try the new fan and wiring the electric one up as well. I'm a little puzzeled as to why the electric wouldn't kick in on it own when the temp came up...
  13. dj&sonplowing

    dj&sonplowing Member
    Messages: 47

    id get rid of that elec fan, its probally blocking more air than doing good? if you put a hd { one made for pulling trailers} doesnt have to be chev one either, and id bet your gonnna hear them blades a singing a song, solved mine ;)
  14. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    The factory aux fan is about a 10" fan. It's controlled somehow to come on at certain times. I don't know what triggers it, but it's NOT the A/C. Switching mine to full on all the time helped my A/C and the Auto Trans cooler. Just wire it to a full on position and you won't hurt anything.

    As for the overheating.....if you somehow were able to LOCK the fan with pulling that spring, and it didn't help your problem, then ALL our advice on replacing the clutch won't help a bit. Something is causing the overheat.

    You likely do NOT have the original water pump. (certainly NOT with running full fan lockup for any period of time). I would go and check P/N's on it to make sure it's the correct one. There was a company called Stewarts who made a real good waterpump. I'd look into them. Do that, and get that radiator rodded out or replaced with a better one. I was serious about the 6.5 diesel parts, they would help, and it would make fitting a 6.5 radiator possible. Check with a good radiator shop. After 11 years, that radiator is likely shot. What temp thermostat are you running?
  15. lumberjack49

    lumberjack49 Junior Member
    from Mi
    Messages: 5

    Everybody is talking about the fanclutch its just my .02 cents worth are we sure that the gage is reading right is it the factory gage that you are relying on or an aftermarket one
  16. justme-

    justme- 2000 Club Member
    Messages: 2,138

    What about that t-stat? how old is it? They do fail, and they do start failing long before the completely fail- if it's the original stat change it.

    I would not remove the elec fan- they never block more than they pass- often guys drop the mechanical fan and replace it with a pair of electrics one on each side.

    You probabily have the biggest radiator they offered, but that doesn't mean it's a 4 row core. you said it runs 210 w/o plow, that's winter temp- how hot in the summer? IMO 210 is too hot anyway- should be under 200.
    It is possible the guage is going, but not likely.
  17. douglasl330

    douglasl330 Senior Member
    Messages: 356

    I'm with TLS if you can find a used diesel radiator cheep throw it in! We are all forgetting that the temp sensor is on the engine and not the radiator! Can you tell when the t-stat opens--you will see the gauge drop down when cooler coolant enters the engine! If this is what you are seeing and you use the truck just for plowing this time of year--you may just want to yank the t-stat and fab a restrictor plate for plowing. The truck will suffer when cold(sluggish), but won't see the high temps. your cab heat won't be so hot! It takes about 5-minutes to swap out so you could do this when putting the blade on!--This is just an alternative and not a fix to your problem! Is there any chance that the bypass hole for the waterpump is restricted? This would cause the truck to run hot, then adding the blade sends it to 240. You do need to make up the air flow if that is the only time that you see the overheat problem! Hd fan and maybe an additional switched electric fan!

    Think Snow!
  18. KingDuramax

    KingDuramax Senior Member
    Messages: 226

    I had a 95 1ton Dually with the 454. Even in the summer pulling the racecar trailer(32foot gooseneck) I wouldnt get that hot. Sounds like you need to look into it a little further. One thing noone has mentioned...
    Is the coolant level full??
    Change the T-stat thier cheap
    Make sure the clutch fan is working properly
    Make sure the electric fan is kicking on when it gets hot, Not sure what temp that is. Call your Chevy dealer and ask them.
    If this dosen't help it. You could always build a custom air dam to direct air up to the radiator from the bottom.
    Hope this helps.
  19. CK82

    CK82 Senior Member
    Messages: 189

    The truck runs at 210 which is directly in the middle all year round, the only problem comes when the plow is on. Is that too hot for a 454 to run? The coolant is full and has been backflushed recently. If 210 is hotter than normal, then I have a different problem, as it is running hot without the plow on then. I just assumed that 210 was where it should be at. The electric fan works, I see and hear it on when I first start up the truck, I'm not sure when it comes on after that and am curious to find out? I feel thats odd that the electric fan runs when the truck first starts up, but thats just me. The radiator and t stat are factory and then over 10 years old from what I know, I think getting the rad. rodded or boiled or whatever they do would help. The truck will heat up somewhat quickly at 20 degrees outside temp and will go right to 210 and hover there, it seems the longer I drive without stopping and the warmer the fluids get, trans, oil, etc thats when the temps rise up to 240 or so. Is the t-stat failing if it keeps the engine from overheating (210) during normal driving? I think I'll start with the rodding/boiling of the radiator, then the fan clutch. I would just like to not have to try every suggestion in order to get this solved, even though I know its trial and error somewhat.

  20. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    You still haven't mentioned the water pump. When your doing all this, if it IS still original, REPLACE IT! Either get a new GM or a Stewart's as they know how to rebuild them right. Plus their under $100 shipped. Make sure you replace the bypass hose too.


    If thats the original radiator, you'd likely benefit from a new one.

    New HD clutch fan.

    New waterpump.

    New T-Stat

    New hoses/gaskets

    New or Rebuilt radiator

    New coolant

    And you should be all set.