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Discussion in 'Chevy Trucks' started by jrm123180, Nov 6, 2004.

  1. jrm123180

    jrm123180 Senior Member
    Messages: 156

    Ok, heres my problem....

    I have a 1979 chevy truck K10 w/ a rebuilt 350. Since my rebuild, I run cool; when my plow is on and I have it up, I over heat while driving. In order to cool down, I have to stop and idle for a few minutes. I'm sure this is happening due to the fact that the plow is blocking my radiator. Does anyone have any suggestions as how to help, or even fix this problem?

    Thanks for the help...
  2. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    There are a few 'standard' answers to this sort of question:

    Are you driving with the blade straight or angled? If angled to the side you will have more airflow than if it is straight. For certain models (and home made for the rest!) air deflectors are available to direct air over the plow towards your radiator. Speaking of air deflectors, some cars and trucks have a little 'air-dam' that bolts to the bottom of the rad support which redirects air thru the rad instead of under it.... maybe you can add one. I'm not talking about the fancy molded ones more for 'decorative' purposes, I'm talking about the (usually much smaller) one thats about the same width as the rad directly under the support--looks kinda like a piece of plastic angle-iron usually! :p for lack of a better description....

    Check that your fan clutch is in good working order.

    Do you have a shroud? Do you have a multi-cored rad? Consider adding each of these, as cooling capacity is greatly increased with these.

    Do you have a proper mix of antifreeze/water? There is an optimal mix, read the bottle carefully. There is also a product called 'Water Wetter' that someone reported helped alot too. Also be sure you don't have an airlock somewhere (often happens around the thermostat housing) but usually this will show up without a load too. Make sure the rad cap is in good shape.

    Being that it doesn't overheat without the plow, I doubt it is thermostat related. Do you know what temperature thermostat it is using?

    If I understand right, this is only since the rebuild, correct? Did you raise the compression ratio? That, or even the tighter fit of a fresh motor can cause overheating. Consider an auxillery oil cooler if necessary.

    Hope this has been helpful. You can search under the word 'overheat*' and you will find many people have had the same problems with various trucks, its not uncommon. There may be more info to read there too that may be useful.

    ps. Don't let that motor overheat! With the tight fit of the new pistons to the bores, you can scuff the skirts and kill your rebuild easier than an older engine...
    Last edited: Nov 6, 2004
  3. lawnmedic

    lawnmedic Senior Member
    Messages: 703

    Just to let you know my experiences with overheating on my '89.
    Bought it with a bad main bearing. I rebuilt engine and found a cracked head. I decided to put a 180 degree thermostat in instead of the factory 195 degree one thinking it would let the engine run cooler.
    The truck would run hot when driving several miles between plow jobs( also would get hot when pulling landscape trailer in summer with air on) but cool off as soon as I started plowing.
    Threw a lot of parts at the problem over 3 years
    water pump
    3 thermostats,,180 degree
    3 fan clutches
    auxiliary fan(electric)

    Finally along with another with another water pump(#3 counting the new one with the rebuild) I put a factory temp (195 degree) thermostat back in and no more overheating.... Even made a 20 mile highway run in 80+ degree weather and the gage never went above 205. It now runs at 200 when just driving it.....
  4. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    I'd say to get a new clutch fan. If it's original its definatley BAD. Some mid 70's GM trucks just had a simple 4 blade fan without a clutch. They were horrible. You need airflow, if the plows blocking natural air, you need a big sucker of a fan on there to get it through.

    Check your ignition timing and your carb mixture.

    Is it an automatic tranny? What do you have for coolers on there?

    Could also get a radiator for a big block or diesel. With new mounts you could really get a big radiator in there.

    If it's a non A/C truck the rads are quite small 2 row jobs.

    Also, make sure you have the correct water pump rotation.
  5. jrm123180

    jrm123180 Senior Member
    Messages: 156

    Thanks for all you input.

    -I haven't reinstalled me fan shroud yet
    -this truck doesn't't have a fan clutch, but does have an aftermarket fan
    -the engine is rebuilt and a 195 thermostat
    -new H20 pump
    -no a/c
    -original radiator, but I sent that out to be cleaned...I do need to replace it.

    I will get a fan clutch, and put the shroud back on and see if that helps at all. I have an automatic tranny so I will get an additional cooler to see if that helps at all. Thanks for your help. Hopefully I can get it to run a bit cooler (out of the red zone)

  6. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    Get that shroud on ASAP! And make sure it fits the fan with enough but not too much clearance.

    Make sure that the fan your using is sufficient to pull a large amount of air. If your not going to use a clutch actuated fan, do NOT use a FLEX-FAN. You need air flow at ALL speeds.

    195 is warm for a non computer engine. I'd think about a 180.

    Get at least a new 4 row radiator to fit your mounts. For as cheap as they are, getting yours rodded out is probably a waste of money.
  7. jrm123180

    jrm123180 Senior Member
    Messages: 156

    A flex fan was installed by the last owner. Would that be ok along with a clutch and shroud? The thermostat is the stock temperature.

  8. JMR

    JMR Senior Member
    Messages: 567

    I would agree that the fan shroud is very important, but it is EXTREMELY important as to where the fan blades sit in the shroud. Just shrouding the fan doesn't mean it will work. The blades of the fan should only be 1/2 shrouded. The fan will work most effectively if only 1/2 of the fan blade is extended into the shroud. The flex fan should also work without a clutch. You probably won't find a clutch to work with your exsisting flex fan. Properly set up and spaced the flex fan will probably draw more air than a conventional fan with fan clutch.
  9. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    One of the hot rod mags had an article a few years back testing various fans for flow and efficiency.

    The flex fan did not even flow as much air as the stock five-blade GM clutch fan, let alone the HD seven blader...

    IMO ditch it and get the seven blade clutch fan, GM knows what they are doing. The flex fan may be lighter but I doubt you are revving this truck to 8000rpm where it may make a difference.
  10. jrm123180

    jrm123180 Senior Member
    Messages: 156

    where could I get one of these fans?
  11. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    Junkyard trucks and vans etc. with the heavy duty cooling option.
  12. jrm123180

    jrm123180 Senior Member
    Messages: 156

    I was wondering if adding a reverse direction fan to the outside of the radiator to push the air through would be worth it?

    Thanks again,
  13. raptorman03

    raptorman03 Senior Member
    Messages: 333

    why dont you put and electric fan on it with a togle switch
  14. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    The same article said that an electric fan in front will actually hinder the flow of a engine-driven fan because it doesn't turn as fast.

    Seems like a band-aid fix anyways.

    Fan and shroud seems to be where it is at.

    For comparison, my '82 has the seven blade fan with a worn-out clutch, a shroud that is a little too short (I need a fan spacer), a stock two-core cheapie rad, and a high-compression 383 engine. Runs very cool even with the 195 degree thermostat. I haven't had the plow on since the engine swap but the 305 it replaced always ran cool too.