If I had a head/head gasket issue, how long till overheat?

Discussion in 'Small Block Tech' started by 72skylarkconvt, Sep 23, 2019.

  1. 72skylarkconvt

    72skylarkconvt Well-Known Member

    If I have a head gasket issue, bad head, bad intake gasket how long would it take for my car to overheat?
  2. Briz

    Briz Platinum Level Contributor

    Usually the bad gasket will let cylinder pressure into the cooling system and push coolant out of the radiator even if the coolant is not boiling. You may or may not see steam with a sweet smell coming out of the exhaust. Water could be getting into the oil and oil getting into the water. After the car has run and the cooling system is pressurized let it sit until cool then remove the plugs. see which are wet or rusty looking also bump the starter over to see if any coolant comes out of the spark plug holes.
    Orphan and Donuts & Peelouts like this.
  3. 72skylarkconvt

    72skylarkconvt Well-Known Member

    Well since all my overheating issues I have not, nor did my shop when they did my timing cover, oil change see water and oil mixed anywhere it should have not been. I have done the "sniff" test of the exhaust and has not smelled sweet. Only thing I have not done is pull plugs and look at them. I am not losing coolant from driving it. I have not done that combustion gases test on the radiator yet. I have a new clutch for the cooling fan coming and a heater core bypass kit if I find that clogged. If those last two things are not a fix I must have a LARGER issue with head/gaskets.
    EVERYTHING in the cooling system has been replaced with new parts.
  4. 72skylarkconvt

    72skylarkconvt Well-Known Member

    i had overheating issues and thought I had it licked. It was overheating on the HWY. Radiator fixed that. This weekend in 86 degree weather I took it out, staying cool driving around surface streets, all good, I take on HWY and it running about 195 maybe a little higher (leave reading error a degree or two either way since my gauge is a cheapo??). I get off HWY and noticed on redlights it was 210 to 220 by the time I got it home. Got it home, no boiling over to over flow tank, just hot AGAIN. I am hoping that my clutch on the cooling fan is just old and fatigues out once it is hot hot, slipping maybe, not engaging well enough. If I up the RPM's it will cool a few degree.
  5. Mart

    Mart Gold level member

    You don't need a bypass 'kit', just take one heater hose and run it from intake to water pump.
  6. 72skylarkconvt

    72skylarkconvt Well-Known Member

    I would just think if this were a head issue/gasket that this thing would overheat like right away.
  7. TrunkMonkey

    TrunkMonkey Well-Known Member

    A cracked head, block, leaking head gasket, intake gasket or cracked intake can be anywhere from "car will not run" to, "every once in a while, things are just not right but I can't put my finger on it" and everywhere in between.

    Overheat can be within a few minutes to randomly occurring over a wide range of operation.

    Stop chasing ghosts.

    Systematic and logical troubleshooting is the best (and yes, time consuming), but the time effort and money spent doing it right will save you lots more of those things as well as aggravation.

    Even if you have changed everything out, is it the correct parts, installed properly and is all things in the "system affected" properly configured and adjusted?

    Have you done test to see if you have combustion gases in the coolant?
    If not, do that. It will tell you if there is a breach into the coolant system via cracks or gasket issues.

    What T-stat are you running, (who made it, part number would help). You could pull it and put it in a pan with a thermometer and test it to see when it starts to open and when it is fully open to determine if it is bad.

    How far from the radiator core is the fan blade? Are they parallel to each other?
    Do you have the correct shroud?
    Is it sealed around the radiator?
    Is the fan blade 1/2 in and out of the shroud opening?

    What is the initial timing with vacuum advance disconnected and the line plugged?
    What it total timing?
    What is the advance curve?

    Are you running lean or rich?
    At all running conditions?

    Are the heater hoses routed correctly to the heater core (not reversed)?

    Have you run water through the system cool and verified no obstructions or blockages?

    Scope the water jacket to see if core plugs have been knocked in and are obstructing flow?

    Have you run a piece of nylon stocking in the inlet (top) side of the radiator to catch rust or scale?
    (this will tell if you have issues with a radiator getting plugged. It will not take long to stuff up a new radiator).

    There are more things.

    Stabbing at this or that, especially after doing as much as you have, will really begin to frustrate you.

    So, make a list of all you can, and post it. Folks here can help with any of the steps to do the various things to narrow this down.

    Lastly, I realize that often these issues(threads) can cover a lot of what I posted, if you have done many of those things, it is only because I did not read or recall reading of them. (or others). Nobody is born with knowledge, we all learn from others.

    Hope this helps. :)

    STAGE III Lost Experimental Block

    Excellent advice Brian! I just copied your instructions in case I have a similar situation and get turned around in it.
    Best of luck with getting her fixed Tim & as one personal bit of advice, if any new parts that could affect your cooling are involved, don’t trust them till tested, just because they are new these days . Have seen lots of new junk over the years.
  9. 72skylarkconvt

    72skylarkconvt Well-Known Member

    Heater control valve
    All new hoses
    Timing chain cover/oil pump from TA perm.
    Radiator fluid has been clean since when I got the car and it had a old radiator in it.
    Shop that did my TC/WP repair saw nothing in the oil that would be a sign of an issue, likewise for the rad fluid, though no test for combustion gases in rad thus far.
    The shop that worked on my car are all old timers that know a way around a motor like this one like most of you guys that do here. They said that the fluid from the motor was clean.
    I am not using any radiator fluid when I drive the car, it stays at the same level.
    They set the timing to what I was told what I was told here to do.
    I strongly feel that the car has flow, no obstructions that would make it overheat. I may be wrong, we will see if I have to go that route.
  10. 72skylarkconvt

    72skylarkconvt Well-Known Member

    And yea the fan is an inch inside and outside the shroud which is flush with the rad. I noticed this as I was taking the fan out last night.
  11. TrunkMonkey

    TrunkMonkey Well-Known Member

    Then testing for gases is a must. That will help eliminate a lot of "what ifs" regarding several things that can result in those gases being present in coolant.

    Old timer or not, you cannot (always) tell by looking for "oil film" in the coolant. Exhaust gases entering into the coolant system via a crack in the head, will likely be void of oil as it will have been burnt off during combustion, and only the gasses will make it into the coolant.

    Again, that is not an "in every case", but more likely than not.
    A blown head gasket, might allow oil into the coolant, and one might see a slight sheen.
  12. alec296

    alec296 i need another buick

    Probably weak fan clutch. The cooling system on hiway shows everything else seems to be working.
    Is that running hot with air conditioning on? Thats a entirely different issue.
  13. 72skylarkconvt

    72skylarkconvt Well-Known Member

    When I do the test for gases in the rad and I doing the test with the car hot and via the overflow tank or letting the car cool enough to open the rad cap and test it there? I have seen two diff video where one test was done with car cold, the other running temp.
  14. BuickV8Mike

    BuickV8Mike SD Buick Fan

    I thought it increased temp by 20* on the freeway, but I could be wrong. What kind of radiator did you buy? More is not better with respect to tubes on an Alum one from what I understand.
  15. 72skylarkconvt

    72skylarkconvt Well-Known Member

    At one point it was running 200. I got the radiator recommended from a few folks here. And when I did I checked for the compatibility for the car and it was the right one for the car. Off the top of my head I don't recall which one it is. The AC does not work in the car, belt removed from the unit even.
  16. 72skylarkconvt

    72skylarkconvt Well-Known Member

    FWIW the car starts and drives fine all the time during any drive. No loss of power, no motor missing issues if that means anything.
  17. TrunkMonkey

    TrunkMonkey Well-Known Member

    The gas test can be done hot or cold, but I would do it both hot and cold.

    It is possible to have a crack that passes cold, but then seals up hot, and vice versa.

    It takes so little time to run both tests.

    First. When the car is cool enough to pop the cap, then drain the radiator to give about 3 inches of headroom for the rubber stopper to fit into the radiator cap opening and stay well below the bottom of the stopper.
    If you get any coolant into the test tube, it will negate the test.

    You can use a vacuum source from the engine, or a tube with your mouth. You only need to draw enough vapor into the tube to get some bubbles. (it's how I've always done it).

    In some cases, enough gasses will intrude into the cooling system and pressurize the tube without a vacuum source.

    Color change from blue to yellow should occur within a minute or two.
  18. 72skylarkconvt

    72skylarkconvt Well-Known Member

    if the car is cold, the minute I pop open the cap won't the gasses escape and not give a test result? Can i try it from the overflow tank?
  19. TrunkMonkey

    TrunkMonkey Well-Known Member

    The gasses are "dissolved" (solution) and present in the coolant, so the test will reveal them as they are released (they never leave the gas phase) from the coolant continually. (The gasses just take a ride in the coolant). So, the test will be valid .
  20. 72skylarkconvt

    72skylarkconvt Well-Known Member

    May as well check so I did. I pulled the heater core hoses at the motor and flushed them with a garden hose with some pressure back and forth through both hoses. First came coolant of course then clean water with a very good amount coming out each time I put water to them. The core is not blocked I would think based on this.
    TrunkMonkey likes this.

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