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Thread: Fresh 020 322 Overheating ONLY at highway speed.

  1. #1

    Fresh 020 322 Overheating ONLY at highway speed.

    I've just finished my first Nailhead build for my '56 Buick Century! Everything was replaced, pistons, valve train, the lot. She runs and looks great but I've got a case of the dreaded overheating. Block was tanked and mag'd, rinsed out well. Rad was flow tested fine by an old boy here in Victoria, BC, caps were not removed. (Got quoted 6-700 to remove caps and replace) New 7lb rad cap. It's got about 400 miles on it so far. Great oil pressure and an aftermarket gauge to watch temps more accurately is being temporarily used. New H2O pump from Kanter. Timing is spot on as well as dwell. Took timing cover and bead blasted it to clean up water pump surface before reinstallation.

    It ONLY overheats on the highway ( + - 50mph) or at higher RPMs. Overheated (250) about 17 mins into initial cam break in, had to shut er down to cool for an hour +. Figured it was just really tight. Sits in traffic at around 200-210 which is higher than I'd like but still reasonable.

    My thoughts so far:

    Possible broken mechanical advance spring causing too much advance at 2000+ RPM
    New water pump vane clearance too far out from timing cover? What that's supposed to be I don't know, but I'm guessing the tighter the better...
    Maybe I had a bunch of missed crap move from out of the block? (drain rad and somehow try and get out?)

    It's terribly frustrating, it's summer and I can't drive to any shows

  2. #2
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    Fresh 020 322 Overheating ONLY at highway speed.

    In my experience, all of my Buick radiators had to be disassembled and recored. it costs a fortune and if I were to do it again, I would go aluminum.

    If you have gunk in your radiator that freed up (sounds likely), just drain the fluid into a clean bucket and you should find out pretty quickly. I would start with that

  3. #3
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    Check the temps with an infrared thermometer. Highest temp will be at the thermostat housing; lowest at the water pump at the lower rad hose. Even new aftermarket direct reading gauges will lie to you.
    It should not cost more that $150 to remove the top tank and rod it out.

  4. #4
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    Way back when I was working a real parts counter, I'd suggest you check the lower radiator hose. Collapsing hose gives the exact symptom you describe.
    Thanks
    Huntz

  5. #5
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    I'd check the rad first Many years ago I saw where the rebuilder put expansion (frost plugs) in the heads where they don't belong. Even though they fit. Caused the same type of problem. Maybe pull your intake and check to see if that happened. Also when I worked in the trade manga you years ago I worked on a Ford car. Same problem. Tried a lot of different things. Finally checked the timing. It was out a bit. Set it to where it was supposed to be. Cured the problem.

  6. #6
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    stubbe

    Hello Buickfriends.I had the same problems some years ago on my Nailhead.
    Some person before me was put new frostplugs in engine but dont get out
    the old plug,pushed it in instead.The engine get not hot under driving bad roads
    but in smooth roads its got hot.I have flushed my 322 several times and still get
    out a lot of dirt from inside.Clean also the cooler of Dyna,My was cloggled no
    circulation at all.The Dyna was owerheated.
    Stubbe in a Sunny Sweden.

  7. #7
    Join Date
    Jul 2009
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    Most likely your problem is a plugged radiator or heater core. Considering your block was tanked and all I doubt its sediment in the block or anything. Ive had this problem on a few of my Old cars that I daily drove over the years. What I am going to tell you may make some guys cringe but Im 5 for 5 with it so I can recommend it to anybody. First flush everything out with clean water. Take your thermostat out, and disconnect your lower radiator hose, then take the hoses off the heater core but leave them attached to the block. Stick your garden hose into one of the hoses that would be attached to the block. Kind of like the old Prestone flush kits. Now stick an extension or something that will fit into the other heater hose just to plug it. Now crank up the garden hose and flush any of the sediment or dirt that got into your block out. I also plug the lower hose some times to let the block fill more then unplug it so the water rushes out.

    Then hook the heater hose up to the heater core and use the garden hose to push water through it, you usually get a little crud that comes out. Next disconnect the garden hose from the heater hose, and put the other heater hose on. Now the heater core will have 2 hoses on it. No grab one hose and blow into one as hard as you can to blow out as much of the water as you can. Now get some ZEP Calcium, Lime, and rust remover, plug one hose off and fill the heater core from the other hose and let it soak for around 4 hours. Ive left it over night before, but 4 hours is enough. Then aim the hoses away from anything painted, Ive never had damage but still better safe than sorry, let it drain out. Now rush water through it using the garden hose attached to the heater hose. It will probably be sudsy and foamy, but eventually it will run clear, and your drive way will look like its covered in rusty gravel.

    Now flush the radiator by plugging up the lower hose filling it and draining it, you can also rig up something to fill the radiator through the lower hose and make everything flush upward to get the stuff loose, that usually works well to. Then when you feel like its as clean as its going to get. You can either take the radiator out and lay it on its back or just plug up all the lines and fill it with The ZEP Calcium Lime And Rust Remover and just Let it sit. If you want you can cut it like 60/40 with water using ZEP at 60%. Let that sit for about the same as the heater core. Then Flush it out. Once you do that look into the radiator youll be looking at some very shiny new looking Copper and Brass...

    Now hook everything up in the car except one heater core hose and the thermostat is still out, Leave the radiator cap off and run hose water into the block. You should get water flowing out of where the radiator cap should go and out of the heater core. Do that for a while to get any residual cleaner out of the block. Now pop the thermostat back in fill it with water take it for a ride around the block come home drain it. Then add your 50 50 mix of antifreeze and you should be good. If you have any trouble with air pockets, get a small drill bit like an 1/8 inch and drill one hole into the ring of the thermostat just out side of where it opens it will help you bleed the system as you fill it, and causes no problems with heat or anything else.If youre feeling really ambitious pull the block drain and try to get all the water out of the system and refill with 50/50 mix of distilled water and Antifreeze then you wont get new calcium deposits..

    Now I'm sure someone will say dont use the zep cleaner it will ruin everything. The acid thats in it is actually in most of the radiator flush you buy in the autoparts stores. The radiator guy I use is a good friend of mine. We were talking about the Idea of using the ZEP cleaner to clean a radiator, I had the same problem with overheating on the highway on my 77 Mustang so we tried it as an experiment figuring if it ate up my radiator it was garbage anyway. It worked and then the 2 of us started trying it on anything we could and so far it works. I did use it on my 55 Special's radiator and it worked very well. Anyway I hope it works for you. Let me know how you do.

    If you dont want to do all of that just rinse everything out to get the antifreeze out and fill it with a 60/40 mix of zep and water and drive it for 30 mins, that works too, but then youre circulating the junk instead of draining it out. Ive done both methods together on stubborn high mileage cars like my 74 Olds 88 and have had good results that way too. But I feel like the only difference is you remove the crud in the block by circulating the cleaner, and you really shouldnt have that problem because your block is fresh.

  8. #8
    Join Date
    Jul 2015
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    Same Problem

    I got the same thing goin on with my '62 401! it can idle or cruise at 60 seemingly forever but as soon as i step on the gas and get up to only 65-70, the gauge slowly climes up to 225 and will just sit there between 225 and 230, which is not good.

    dye test last summer showed a big maybe, turning the blue dye green after about 15 minutes of idling (w/o overheating). a baggie over the radiator cap didn't do anything, i put an air dam in the front, nothing. i've switched from the stock 4 blade fan to a 7 blader, nothing. i've drained and flushed both the block and radiator a bunch of times to no avail. the water just goes screaming across the top of my radiator when the stat (new 180) opens, my i.r. gun shows the radiator is much hotter at the top than it is at the bottom. the radiator shop put in a powder they swear by that seals leaks and that did nothing either.

    all i havenot done is a leak down test on the engine. c.r. check is pretty good across the board around 165lbs each. i did have retarded timing at first and when i set it correctly, it helped alot, but is still doing this thing. the advance weights seem to be working when i have my timing light on it. (btw 62 and 65 nailheads have different timing). i thought when i changed the timing i had fixed it as it would heat up sooner and at lower speeds, but like i said, this still overheats above 60mph with timing correct.

    i have also not put my i.r. gun on the bottom of the radiator either to see what the trans is doing to this whole thing. i have not checked either, to see if my lower hose has a spring in it or not. i see a new aluminum radiator from radiatorexpress (champion brand) is only about 250, but would hate to change it and see no improvement.

    OP, you out there? fix this yet? anybody else? thanks,

  9. #9
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    Quote Originally Posted by bullheimer View Post
    i've drained and flushed both the block and radiator a bunch of times to no avail.
    But did the radiator shop remove the top or inlet tank and rod it out? If they cannot or will not do that then the new aluminum radiator will probably solve your problem.

  10. #10
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    no but i am going back over there today to have them do the dye test again, i will ask them how much it is to rod it out but ****, a new aluminum radiator is only 225 from radiator express. i have one in my truck and it looks mighty fine, but my truck is a long long way from stock, this leSabre has everything original under the hood except the air cleaner and an alternator with an internal regulator. i dont suppose it matters tho on something like this, that is basically a rolling p.o.s., if the radiator is original or not. i also plan on taking it out and checking the tranny fluid temp this time and the bottom radiator hose having a spring in it. nice to have a day off when the sun is out. might get up to a balmy non-freezing temp.

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