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Cooling Systems -- Problems & Solutions (Radiator, Fan, etc)

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  • OK You have helped alot. Just 2 questions, How hard is it to change head gasket?
    How can you test the lower hose for integraty?

    Very thankful for your input
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,179
    Feeling the hose is one technique. If uncertain, taking it off and looking at interior is best. By then it's cheap just to go ahead and replace it.

    Does it overheat driving at speed along the highway or roads? Overheat sitting idling?

    Head gasket requires careful diagnosis and checking pressure inside cylinder with compression tester to see if a particular cylinder doesn't maintain as high pressure as next one. It requires removing the intake manifold, valve covers, and then the head bolts. Head needs to be inspected for cracks, etc., that might cause leaking.
  • Just went out and started truck for 2 minutes, let it get to operating range, no change in resistance on fan but let it run idle, not highway. It heats up at highway speeds, not on idle. Felt top and bottom hoses, top felt hot and bottom did not.
    Suggestions on the "Cheaper" way to check for sure?
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,835
    Okay, if it heats up at speed but not at idle you have a coolant circulation problem, not an air circulation problem.

    By the way, a chemical flush of the radiator is a pretty lame procedure---you could still have a clogged radiator.

    MODERATOR

  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,179
    Agree with shiftright. Now that you've said it's an overheat at higher speeds, it's back to the radiator and or lower radiator hose.

    The cheapest is to take the radiator out yourself and take it to shop for proper cleaning.
  • just ran it at speed for a few minutes (Actually went on highway for a few miles) The gauge never mooved but after coming back, I felt no resistance change in the fan, is that a correct way to see if the fan clutch is bad or going bad?

    Any idea whats the best way to make sure radiator is not plugged? (No more LAME testings)
    Thanks for your input.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,835
    You'd have to pull it out and have it flow-tested.

    Again, if you have high speed overheat, this is probably not a fan problem (air problem).

    MODERATOR

  • oldfarmer50oldfarmer50 Posts: 6,461
    Ok let's see how smart you guys are.

    1984 Corvette 5.7L with 100+K miles runs hot at lower speeds. Gets up to a 235 temp before radiator fan kicks on and cools things off. Runs normal at highway speeds.

    Am I looking at a sticking thermostat or a defective fan switch or something major?

    2009 PT Cruiser, 2008 Eclipse, 1995 Mark VIII, 1988 GMC Van

  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,835
    If you overheat at lower speeds but not at higher speeds, you have an AIR circulation problem, not a coolant circulation problem.

    MODERATOR

  • bolivarbolivar Posts: 2,316
    Your car may be running correctly.

    Does it hit 235 before fans with the AC off? Or is your AC dead and not running? The Cadillac referenced below will not let the AC turn on if the AC pressure is low or high.

    In other words, for Cadillas Northstars, if you are running the car with the AC off, it is set to let the temp hit about 225 before it turns the fans on. That's just the way they programmed it.

    If you have the AC working and on, the fans run all the time (above 195 or so??).
  • oldfarmer50oldfarmer50 Posts: 6,461
    "...you have an AIR circulation problem..."

    That's interesting. This is a car my son is considering so I have not driven it myself. I'm being told that for some reason the fan does not kick on until about 235 and then it does come on. The present owner say the AC does not operate as it needs some sort of valve. Not sure if one has anything to do with the other but any thoughts would be welcome.

    I'm trying to let my son make his own decisions but the urge to "protect" him is still very strong even though he's 25.

    2009 PT Cruiser, 2008 Eclipse, 1995 Mark VIII, 1988 GMC Van

  • oldfarmer50oldfarmer50 Posts: 6,461
    edited May 2010
    "...Does it hit 235 before fans with the AC off?..."

    Can't say for sure. As I just posted to Shifty, the owner says the AC does not operate. As I understand it, when driving in the city at slower speed the temp reaches 235 and the fan comes on and the car cools to "normal" whatever that is ( for most cars I've owned that would be around 195).

    Remember, this is and OLD Corvette so I don't know if the computer in it is very fancy. That's why in my original post I was wondering if it could be so sort of mechanical switch which was the problem. If this is typical of all GM cars that would be fine. I just don't want my son to buy this and find out it's a money pit.

    2009 PT Cruiser, 2008 Eclipse, 1995 Mark VIII, 1988 GMC Van

  • obyoneobyone Posts: 8,065
    With an '84 vette you might want to check the body out closely since the frame wasn't the best leading to a lot of flexing causing the fiberglass to crack. If I were looking to buy a used vette, I'd look at a C5 or newer as the C5 has hydroformed rails which means a much stiffer suspension and no creaks or body cracks. Just my opinion of course.
  • bolivarbolivar Posts: 2,316
    84 Corvette will be a money pit.
  • kiawahkiawah Posts: 3,666
    As was my '75.
  • oldfarmer50oldfarmer50 Posts: 6,461
    edited May 2010
    Now you guys are scaring me.

    Then again I would think any corvette could be expensive to repair.

    The kid has got the hots for this car so the money pit thing may be a moot point. I'm just hoping it's a smaller pit.

    Any other thoughts on the cooling issue? The owner suggested installing a manual fan turn-on switch but I was wondering if there might be some other way of fixing such a problem.

    2009 PT Cruiser, 2008 Eclipse, 1995 Mark VIII, 1988 GMC Van

  • bolivarbolivar Posts: 2,316
    Repair the AC. The fans will probably then run all the time, as designed.

    A Corvette is nothing but a top-of-the-line GM. It's a Chevy motor and transmission and Cadillac electronics.

    Here is the life line of many Corvettes.
    -The first owner babies it. Probably doesn't put many miles on it. It's the car 'he always wanted', or 'it's the 4/5/6 one he's owned'. After about 3/4 years the toy goes stale. Or, if he's a multi-owner, it's time to buy the new model. The car has excellent maintenance from this owner.
    -The second owner always wanted a Corvette but never had enough money to buy a new one. He drives it a lot. He keeps it about 3/4 years and then a baby comes, so he has to get something more practical. Usually maintained pretty good. If some small stuff fails, it might not get repaired quickly, if at all.
    -The following owners see the car as a 'hot rod', and treats it like one. Maintenance is slipped. If the car starts and gets down the road, all is good. A 'check engine' light is ignored. The AC doesn't work, just roll the window down. The dash display fails, and it's going to cost $1,000 to repair, just keep up with the other traffic for speedometer, and those other displays aren't actually needed.

    This is an 85, right? 25 years old. Had about 6 previous owners, at a minimum? It's probably been 'hit' at least one time. It's going to be a money pit if you try to get everything working and keep it that way. If your son just wants it to 'get down the road', it might manage to do that.

    P.S. I've owned 4.
  • oldfarmer50oldfarmer50 Posts: 6,461
    edited June 2010
    "...Repair the AC..."

    Now that sounds like a plan. If the fan and the AC are interconnected as you say that might be all it needs. Thanks.

    As to the typical Corvette history all I can say is LOL. This one was supposedly owned by a doctor in Kingston NY from 1984 until around 2006 when the current owner, a guy in his 70's bought it. I ran a Carfax on it and it came back clean for accidents (at least back to 1996 when Carfax started). I get the impression that the current owner doesn't want to sell it but his wife doesn't want him putting any more money into it.

    As I said, my kid has hot pants for it so my opinion isn't worth much. Thanks for the advice on the fan.

    2009 PT Cruiser, 2008 Eclipse, 1995 Mark VIII, 1988 GMC Van

  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,835
    Since the subject has come up, I would agree that a 1984 Corvette is not a good choice. It has CFI injection, which is not the best and hard to tune and fix right, and very difficult to modify.

    IIRC, the '84 Vette had a thermostatically controlled fan that only worked UNDER 35 mph.

    If he likes C4s, he'd be much better off shopping for a later 80s model. Better in every conceivable way.

    MODERATOR

  • oldfarmer50oldfarmer50 Posts: 6,461
    "...better off shopping for a later 80's model..."

    Too late, the 84' is now sitting in my driveway. At least he had a mechanic check it out and there seems to be no major mechanical problems.

    So you are saying that the fan situation may be a thermostat switch problem? That was what I thought might be the problem.

    I least we now have a couple of directions to go. Thank you all for your comments.

    2009 PT Cruiser, 2008 Eclipse, 1995 Mark VIII, 1988 GMC Van

  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,835
    Oh the '84 is good enough but if he has dreams of modifications on that CFI system or any future "collectibility" he can forget it. He'd best find himself someone who understands CFI injection, too.

    Yeah the fan might be a thermostat switch. That's how it works.

    MODERATOR

  • burdawgburdawg Posts: 1,524
    Is that CFI fuel injection similiar to the Bosch mechanical system that was on my Mercedes 280?
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,835
    Methinks not. The Bosch system is a Tuned Port Injection, debuting in 1985. So that's called TPI, whereas CFI is the older cantankerous system designed by captives held deep in the GM prison system. :P

    MODERATOR

  • burdawgburdawg Posts: 1,524
    edited June 2010
    No, I meant the very early mechanical FI that was on the late 70's and early 80's cars. If you remember, they had fuel distributors with diaphragms built in to regulate the flow of fuel based on demand (some later ones had crude electrical controls also), but the flow was continuous to the cylinders. I can't remember the actual names, but things like "Bosch J Tronic" come to mind. I used to have a manual for them, but it's long gone. It was very helpful at the time though I remember. I seem to remember that it first appeared on the 280 sedans around 1975 or 1976, I'm not sure when on the V8's but probably about the same.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,835
    Oh I see. Yeah, Bosch did a lot of licensing. Didn't the 1975 Cadillac Eldo use some form of Bosch FI? In any event, whatever GM did to the early C4 injection, it wasn't an improvement.

    MODERATOR

  • burdawgburdawg Posts: 1,524
    Now that I think about it, the name was Bosch CIS, for continuous injection system.
  • We must take care of ac be it residential ac or car ac.
    Air conditioning Florida is dedicated to provide air conditioning maintenance, ac repair and, air conditioning services at affordable price.
  • bolivarbolivar Posts: 2,316
    What's the price for a service call to northern Oklahoma?
  • nise188nise188 Posts: 3
    Some guy told my husband to drop efferdent tablets into the radiator to clean. My radiator overflow tank and cap is getting a real fine silty build up that looks like clay. Engine runs great. Car has overheated twice. Once last summer. Once last winter, from freezing I am sure. When the winter overheating occurred, I pulled over, turned the car off, and "snap, crackle, pop." Then, I put anti-freeze/ coolant in it. Car still runs great. The car is a 1995 Cougar, with over 200,000 miles. Odometer quit at 178,000. It has used oil and water since I got it at about 160,000 miles. We live a mile down a dirt road. But, the car just keeps going and going. I drive it to work 5 days a week, 20 miles each way. Will efferdent work or harm?
  • kiawahkiawah Posts: 3,666
    Auto parts stores sell radiator cleaning solution, made for cleaning out the coolant system.
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