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Overheating 235 in 1936 Chevy pickup

Discussion in 'The Hokey Ass Message Board' started by robertrj, Nov 24, 2011.

  1. robertrj
    Joined: Jun 13, 2007
    Posts: 64

    robertrj
    Member

    I have a 1936 Chevy pickup with a 235, Offy dual carb intake, Rochester model B carbs, and fenton headers. I had the original radiator and never had any problems with overheating.

    Two years ago I had a valve stick, bent a pushrod and broke a rocker arm. I had the head redone with hardened seats, guides and valves ground. The block was hot tanked and bored .30 over. I installed a new Howard’s solid lifter cam.

    While I had the truck apart I decided to add A/C, it came with a condenser that covers most of the radiator. While I was breaking in the motor it overheated even though I had never had problems before I thought it was probably caused by a combination of the bore job, hotter cam and the condenser.

    My solution was to replace the radiator with a new Walker radiator. This radiator is thicker and sets back closer to the engine so I was no longer able to run the mechanical fan and I had to install a pusher fan in front of the radiator mounted on the condenser. The truck still overheats if it just setting idling but it seems to be OK if I am traveling down the road.

    I have changed the water temperature gauge, sending unit, water pump, thermostat twice, checked the timing, and burped the system.

    I have put about 7000 miles on the truck since the rebuild it runs great but I always have to worry about getting caught in traffic because it wants to overheat.

    My next idea is going to be to take the condenser off the front of the radiator, mount a larger fan and install a remote condenser.

    Does anyone have any ideas? Thanks.
     
  2. 28dreyer
    Joined: Jan 23, 2008
    Posts: 1,151

    28dreyer
    Member
    from Minnesota

    Sounds definitely like an airflow problem.

    The condenser probably created the problem by restricting/reducing air flow through the original radiator.

    The new radiator while thicker, may also have more fins than the old and may be a further restrictor and the pusher fan is only pushing air through an area equal to it's diameter because it's not ducted while the previous fan may have been well shrouded, giving good air flow over the whole radiator surface.

    Relocating the condenser will probably solve the problem, and in fact the old radiator and fan (pulling air through the radiator is preferable) may function just fine, especially if that Walker radiator is a part of the airflow problem.

    So, start by removing the condenser and see if it cools. If not or marginal, put the old radiator and fan back in and see if the new core and pusher fan are the problem.
     
  3. Rickybop
    Joined: May 23, 2008
    Posts: 6,921

    Rickybop
    Member
    from Michigan

    ^^^Exactly correct...couldn't add a thing.
     
  4. grm61
    Joined: Oct 19, 2009
    Posts: 179

    grm61
    Member
    from Washington

    Never had a 235 apart...Just a couple thoughts...Had a street sweeper with a ford six down at work, a guy had replaced the water pump, when idling it would slowly get hot. I pulled the water pump off there was silicone pluging a small water passage about as big as a pencil between the block and pump, cleaned it out and no more problems.

    Also could it be possible the wrong head gasket was used, or flipped so its plugging a water passage?
     
    Last edited: Nov 25, 2011

  5. robertrj
    Joined: Jun 13, 2007
    Posts: 64

    robertrj
    Member

    Thanks for the input I'm treating it like an airflow problem.

    I'm pulling the fenders and hood so I can get to the radiator and grill shell. I'll pull the condenser off and see if that solves my problem.

    I didn't know if there was something particular to 235's that may have been related to the rebuild. There doesn't seem to be any sign of a head gasket problem that I can see.
     
  6. robertrj
    Joined: Jun 13, 2007
    Posts: 64

    robertrj
    Member

    I talked to the old timer at the machine shop that did the work for me. We looked over a 235 head gasket he had setting there the best we could tell you couldn't put it on backwards.

    I may check the head gasket, if moving the condenser doesn't solve the problem. I changed the water pump once, I am careful with the silicone, but once when working at dad's service station I changed a water pump and left a rag stuffed in the hole. Duh!
     
  7. grm61
    Joined: Oct 19, 2009
    Posts: 179

    grm61
    Member
    from Washington

    You wouldn't see it unless you pulled the head and gasket, good possibility its airflow....but if that doesn't get it, it gives you someplace to look next.

    Good luck

    EDIT I see you type faster than me :)
     
  8. F&J
    Joined: Apr 5, 2007
    Posts: 13,222

    F&J
    Member


    If you can put up a pic of the fan install, and how much of the radiator it covers...




    if going down the road gets it cooler, then it seems like more of the radiator is now being cooled by airflow beyond the edges of the fan..
     
  9. Rickybop
    Joined: May 23, 2008
    Posts: 6,921

    Rickybop
    Member
    from Michigan

    The tipper was that you said it does fine at highway speeds, but not so good in traffic.

    Airflow for sure.

    The only other possibility would be if there's another problem that's stressing the borderline cooling system. But I doubt it. No bubbles in the coolant when viewing down the neck of the radiator? The coolant isn't turning milky? No water in the oil? No smoke/steam/water out the tailpipe? No oil gettin' pushed out the dipstick tube? Runs good? Chances are that you head-gasket is fine. Do a compression check if you wanna ease your mind. Look at the plugs. Check for intake leaks by spraying around with carb-cleaner. Pay special attention to the mounting-surface at the base of the carbs. Be aware that carb-cleaner can screw up nice paint and poished aluminum. If you don't see or hear anything odd, it's probably all air-flow. Good luck.

    P.S. - If it runs good, chances are that you don't have an intake leak. But it occurs to me to ask anyway...esp if you detect an rpm change if you spray at the intake/head mounting surface. Did you install the intake? Did you watch it being done? Were the metal sealing-rings installed between the intake and the head?
     
    Last edited: Nov 25, 2011
  10. squirrel
    Joined: Sep 23, 2004
    Posts: 47,791

    squirrel
    Member

    send the radiator back to Walker....

    They probably don't sell any to guys with 235 engines, so they think they can make them any way they want to. Lame.
     
  11. robertrj
    Joined: Jun 13, 2007
    Posts: 64

    robertrj
    Member

    F&J

    I'll take a picture after I get it apart. The fan and condenser is behind the grill shell and they are all painted black. Its hard to see but here is a picture.
     
  12. robertrj
    Joined: Jun 13, 2007
    Posts: 64

    robertrj
    Member

    Pic of grill
     

    Attached Files:

  13. robertrj
    Joined: Jun 13, 2007
    Posts: 64

    robertrj
    Member

    Jim

    I'd like to tell Walker to take it back, if you can belive it I paid more that twice for the radiator than I paid for the truck.
     
  14. F&J
    Joined: Apr 5, 2007
    Posts: 13,222

    F&J
    Member

    Looks like a somewhat small fan mounted down low.



    It should be a bigger one mounted up higher where the radiator is hotter, or twin fans stacked.





    Fan blade dynamics? Too close, may/or may not cool as well


    but it sure looks like the fan does not cover nearly enough. I would not remove the condenser yet. Yes it will run cooler, but if you want the AC, try other things first.
     
  15. JohnEvans
    Joined: Apr 13, 2008
    Posts: 4,883

    JohnEvans
    Member
    from Phoenix AZ

    Adding the AC did the stock setup in. Using a pusher fan is your problem now being it cools going down the road.
     
  16. robertrj
    Joined: Jun 13, 2007
    Posts: 64

    robertrj
    Member

    Its kind of hard to tell but the fan is the same width as the condenser. I'll see if there is room to mount another fan above the current one after I get it apart.
     
  17. DrJ
    Joined: Mar 3, 2001
    Posts: 9,418

    DrJ
    Member

    Does you vacuum advance work and is it drawing manifold vacuum like it should be?
    If the timing isn't getting advanced enough at idle by the vacuum advance it will overheat for sure.
    Check your vacuum advance!
    And the radiator should fit what you bought it for, if you asked for one to run a 235 with it shouldn't be set back for a shorter V8.
     
  18. robertrj
    Joined: Jun 13, 2007
    Posts: 64

    robertrj
    Member

    DrJ

    The vacuum advance seems to be working, it is external on the 235 it seems to pull the distributor as I work the throttle.

    Walker doesn't make a different radiator for 6 or 8 but I did get the more expensive one. It said you needed it if your engine had been bored.
     
  19. fordcragar
    Joined: Dec 28, 2005
    Posts: 3,179

    fordcragar
    Member
    from Yakima WA.

    We have a 36 Chev PU that I used a radiator from a 1974 Ford LTD. The radiator is a crossflow, which is turned up on it's side and it works great. I bought the radiator from Performance Radiator, part number 401CBR. Sometimes while waiting at a stop light, the temperature might raise a little. Then I'll just crack the throttle and the temperature will come back down. This radiator has been in there over ten years and doesn't over heat.

    This truck has a slightly warmed over 350 SBC and uses a mechanical fan. I had a situation years ago with a electric fan and don't like them. The radiator that I mentioned, is also running in a friends 37 GMC with 454 in it. He doesn't have any problems either.
     
  20. outlaw256
    Joined: Jun 26, 2008
    Posts: 2,023

    outlaw256
    Member

    you need the more expencive one if your engines been bored? ive sold parts and built performance engines for 40yrs and i have never heard that one!what about people that buy reman. engines that have been punched?they gotta but new radiaters too?sorry man but that burns my balls for some reason. ive run mean built 327s and 350 hell even 454s in 55 chevys with a cleaned up stock rad.and never had problems.ive run pusher fans on a few cars that i built and i always try to get the biggest they make. i want to cover as much of the radiator as i can.i only had problems once and that was because i wired it up to pull and the damn thing was blowing out the air instead of blowing it on the rad. lol duh.
     
  21. sqhd
    Joined: Sep 9, 2006
    Posts: 71

    sqhd
    Member

    This may sound like a stupid question, but have you checked to see if the fan is running in the right direction? I've seen it on a couple of installations where I've walked past a car and the air was being pushed out the front while it was parked!

    Carl
     
  22. richie rebel
    Joined: Oct 8, 2007
    Posts: 1,184

    richie rebel
    Member

    the pusher fan is the worse of the 3,mechanical is the best ,then the puller,then the pusher,you need at least a puller,just my 02 cents
     
  23. brad chevy
    Joined: Nov 22, 2009
    Posts: 2,627

    brad chevy
    Member

    Just from the pictures of the frontend,your problem is fan location and size. Mostly location. Its not cooling but one part and at a stop in traffic you have no airflow at all to most of the radiator.
     
  24. richie rebel
    Joined: Oct 8, 2007
    Posts: 1,184

    richie rebel
    Member

    o yes, way to small of fan,double them or stack them
     
  25. robertrj
    Joined: Jun 13, 2007
    Posts: 64

    robertrj
    Member

    Outlaw256

    Here is what Walker's website says I had never heard of this before either.
    I guessed that a 235 would be easier to cool than a V8 but I went ahead and got the Z series

     
  26. robertrj
    Joined: Jun 13, 2007
    Posts: 64

    robertrj
    Member

    I pulled the grill off and removed the condenser. I installed a 16" fan in front as a pusher and a 12" fan on the back as a puller. Not enought room in front to go with a larger fan or to put two.

    It seems like it may cool a little bit better but it still seems hotter than it should be.
     

    Attached Files:

  27. 28dreyer
    Joined: Jan 23, 2008
    Posts: 1,151

    28dreyer
    Member
    from Minnesota

    Should be a simple matter to now remove the front fan and try it with just the puller realizing that these two are possibly bucking each other.
     
  28. brad chevy
    Joined: Nov 22, 2009
    Posts: 2,627

    brad chevy
    Member

    As suggested take the pusher fan off the front,its just cutting the air supply off to the puller fan. And be sure your puller fan is turning the right way to pull not push.
     

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