Overheating Issue

Discussion in 'The Bench' started by 79Bonneville, Jul 21, 2015.

  1. 79Bonneville

    79Bonneville Member

    Ok, I have been reading several threads that describe a similar problem as I am having. I have a 79 Bonneville (obviously) and it has the 350 Buick in it. This car gets warm at highway speeds. I replaced the head and intake gaskets. Running around town she stays at about 210. I have a 190 degree thermostat in it. It seems to build a lot of pressure in the upper hose, and not so much in the lower hose. There is about a 30 degree difference in temperature between the two hoses (190 upper 155 lower) the block is registering at 250 plus. I'm having issues seeing the timing mark, it seems that unless the distributor is completely retarded, the timing mark doesn't come close to 15* btdc. I also replaced the vacuum advance thing on the distributor. I'm lost, is it a timing issue, carb issue, radiator issue? It does everything the same as it did before the gaskets were changed. No I didn't have the heads checked as it never got over 250ish... like I said I'm lost!
  2. Junkman

    Junkman Well-Known Member

    Sounds like a coolant flow problem with the radiator. But hard to say without "hands on"
  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    You probably have an old radiator in it. Once they get scaled up, there isn't much you can do to clear them short of re coring them or buying a new one. Also, you can't expect the engine to run cooler with that thermostat in it. A 190* thermostat will not be fully open until 210*. Beyond that, it has no control over the coolant temperature. If you have a dial back advance timing light, you don't need the mark to be on the scale. Read my Power Timing thread for more info.

  4. toymobile

    toymobile Retired knuckle buster

    The timing mark might be moved because of a bad balancer, if the rubber is soft the outer ring can turn and thus move the timing mark. Just a though retarded timing will cause heating but the problem could be with the radiator. NEED HANDS ON AS JUNKMAN SAID.

  5. Briz

    Briz Founders Club Member

    The Riv had temp creep issues until I replaced the fan clutch. Stays at temp now under all driving conditions. make sure you have your fan shroud installed.
  6. 79Bonneville

    79Bonneville Member

    Thanks guys, definitely good stuff here. My plan for today is to check the radiator because I forgot to mention that prior to the new gaskets the car had the same problem Even after I pulled out the thermostat. Great article on timing Larry, I'll have to read it a few more times to fully get it. Thanks much! I'll keep everyone posted just in case anyone has a similar problems..
    Last edited: Jul 22, 2015
  7. 79Bonneville

    79Bonneville Member

    So I put in a new radiator and wa la, problem solved! Now my timing issue is still weird... following all the instructions for setting the initial timing, my mark is on the opposite side of the timing marks. Could the chain jump a tooth?
  8. DeeVeeEight

    DeeVeeEight Well-Known Member

    Pull #1 spark plug and set the piston to top dead center (TDC) on the compression stroke, then take a look at your timing mark, it should be at or close to zero.
  9. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    What kind of light do you have? What is the specified initial timing? What happens when you rotate the distributor? Does the timing mark not move? You aren't explaining your problem well enough.
  10. 79Bonneville

    79Bonneville Member

    Well... the problem was that you had to smarter than what you are working on, which I was not. Long story short I thought #1 cylinder was on the passenger side and was using that wire. You can laugh, because I sure as hell did when I figured it out!:Dou::Dou: I did manage to set the timing to 15* BTDC which is what the sticker stated under the hood. She still spits and sputters a bit at idle and low speed, so it could be the adustment on the carb.
  11. bhambulldog

    bhambulldog 1955 76-RoadmasterRiviera

    Number is determined by the most forward cylinder. On your car, the left bank of cylinders is forward of the right bank.
    Making front left number one

    Some cars have number one on the right. (
    mine for example, has the right bank forward. Number one is on the right
  12. SteeveeDee

    SteeveeDee Orange Acres

    One thing about this forum is that most people don't get all kinds of insulting about what people don't know. It is pretty refreshing- thanks, Jim! Just keep us posted on what you are doing, and hopefully you will have good results.
  13. Smokey15

    Smokey15 So old that I use AARP bolts.

    I noticed that as well. We all remember that we weren't born 'knowing it all' (I still don't) and we all asked (I still do) a lot of questions ourselves.
  14. 79Bonneville

    79Bonneville Member

    Thanks guys, I think the cooling issue is solved, although there seems to be a big fluctuation in temp between the thermostat opening and closing. Driving along it warms up to about 200 (it's a 190* thermostat) then cools down to I'm guessing what would be the 160 mark, heats back up... thermostat opens... cools down. Once it's warm these intervals take about 30 seconds each. I'm thinking of getting another new thermostat.
  15. yachtsmanbill

    yachtsmanbill Well-Known Member

    I put a new NAPA 185 in mine and it ran consistently at 220, and would creep up after a shutdown. I put the old 180 back in and she runs about 160 all the time with plenty of heat for defrosters etc. If yer not aware of the fan clutch, its filled with a viscous liquid that's pretty temperature sensitive. At idle and low speeds, the fan turns pretty fast (youll hear it moving air) but on the road the VL warms up and the fan spins much free-er, meaning like as much as 25 HP less to turn it at high speeds. I had a 70 that overheated on the E-way, changed the clutch and it was all good. Bill in TR
  16. rogbo

    rogbo Gold Level Contributor

    Old saying, "The more I learn, the less I know" is definitely true!

    For your info the GM generic engine program started in 1977, had beautiful 77 Estate wagon with 350 Olds engine.
    Lot of people got POed about it,especially if they got a Chevy engine, my 79 Bonne had a Buick engine also.
    Was a night mare for some people who didn't know and ordered wrong parts!
  17. bhambulldog

    bhambulldog 1955 76-RoadmasterRiviera

    190* seems a bit warm.

    I run 165* in mine (shop manual spec)
    I don't recommend you go as cool as 165*
    Maybe a 180* for your car ....
  18. 79Bonneville

    79Bonneville Member

    I think I had some air in the system, which I thought I removed... there is very little fluctuation now. It's 92 here today and she's never hit 220
  19. Smokey15

    Smokey15 So old that I use AARP bolts.

    Did you drill a 1/8" hole in the flat part of the thermostat to help alleviate air pockets? Seems to help.
  20. 79Bonneville

    79Bonneville Member

    No, I didn't know that! But it appears to be fine now, I've put some miles on he with no problems. But that's definitely good information to have.

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