Cooling problem Ford 302

Discussion in 'Propulsion' started by san, Oct 21, 2004.

  1. Frosty

    Frosty Previous Member

    You say it does'nt overheat if you run the engine on land with the leg in a barrel of water and feed the engine with a hose but will overheat if you let the pump in the leg do the job.
    Gotta be the pump or the feed from the pump????

    I would pull the pump out again and check it out. I would check to see if the brass centre bush of the impellor had not lost its bond with the rubber impellor. Make sure you twist in the impellor blades the right way to rotation, they should right themselves but!! maybe it tried to do that and bust the bond,--could have been an old impellor ie past its shelf life.
     
  2. san
    Joined: Oct 2004
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    san Junior Member

    I pulled out the engine, cleaned and inspected it (lots of dirt). The head gaskets didn't look good, the "metal rings" around the cylinders had corroded and the gaskets had separated so compression should have been able to get into the cooling system. I was happy and thought this was the problem. The heads are now milled. No visible cracks. Everything on the upper half of the engine is inspected and looks good now. I've replaced the exhaust manifolds and risers since they didn't look OK.

    Now I am able to run the boat at about 3200 rpm without any problems. If I pull full throttle it works fine for about 20 seconds with temp gauge at 150 F but then instentiously the temp rises to maximum.

    Is it needed to pull the heads with tourque wrench after running the engine warm once? It seems to me that it must be exhausts in the cooling system since the temperature rised so quickly. Can a lean running engine behave like this? I ask this since after my restoration of the engine when I gave full throttle the rpm went up and down, like it didn't get enough fuel. This behaviour disappeared after the first run.

    San
     
  3. gonzo
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    gonzo Senior Member

    Modern gaskets don't need to be retorqued. A lean mixture will make the engine heat up, but usually not that fast. Do you have access to an infrared thermometer?
     
  4. san
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    san Junior Member

    Thats a smart idea. I suppose you mean that you would find the heating spot making the problem? Am I able to find for example a crack in a head with this method?
     
  5. travis912
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    travis912 Junior Member

    restrictor plates.

    I am having the same problem with my 302 marine engine i took it to a boat place to be worked on becaues it was over heating it is a new engine the boat place put in they took manfolds off and found the restrictor plates in it and said that was the problem so they took them out i ran it and it did the same thing overheated so i changed the water pump on engine did not make much difference changed thermostat still the same so wondering if the restrictor plates need to be back in. My restrictor plates only had a pin hole in it LET ME KNOW WHAT TO DO !!!!!!!!
     
  6. san
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    san Junior Member

    If you have the "octopus" cooling system where water from exhaust manifolds goes back to thermostat housing and then out through the risers you must have the restrictor plates. The pin holes are there to let air out of manifolds directly to risers (for instance when the boat has been on land and engine is drained of water), but water flow should go back to thermostat housing.

    My problem was not the engine, but a gasket in the drive. My exhausts goes through the drive and the gasket between plastic plate you put the impeller house on and drive was ruined. With this the impeller tried to pick up water but with more throttle the pressure from exhausts overtake the pick up of water and the engine was filled up with gases. With less throttle the engine was able to get rid of gases but the more throttle the bigger the gas bubble in intake manifold became with less circulation of water. This was the reason why the temp gage rise that suddenly. When gas bubble grew and got to temp sensor the needle rised in a few seconds.

    This was what I did to find the problem and what I recommend you to do. Put a transparent hoose between drive and engine (that is before cooling water gets into engine) and make sure you dont have bubbles of air in water when running engine. If you have bubbles the problem isn't in the engine but the problem is before the engine. (I have asked dozens of experts but no one has even mentioned something like this)

    I wish you all luck and hope this is your problem as well. Easy and cheap to fix.
    Stefan
     
  7. travis912
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    travis912 Junior Member

    hello again I took one of the hose off that goes to the thermostat then to the exhaust manfold and there seems to be alot of exhaust fumes coming out the hose could this be caused from a crack in a exhaust manfold. engine runs fine when not being ran at high speeds over heats about 2 min after you get out of the water.
     
  8. gonzo
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    gonzo Senior Member

    There should be a lot of water coming out of the hose.
     
  9. san
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    san Junior Member

    Do as I told you. Put transparent hooses both before and efter engine and take your boat for a run. If you only have bubbles getting out of engine, then you have a crack in one head, blown head gasket or leak in exhaust manifold. Do your spark plugs corrode (leak of water)? Is the engine easy to start? As written earlier in this thread you can check for cracks in heads or blown gaskets with air pressure. Exhaust manifolds can be tested in same way with air pressure. Risers are a little more tricky to check due to water and exhaust getting together inside riser.
     
  10. travis912
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    travis912 Junior Member

    if crack in head or blown head gasket shouldnt the engine run like crap or mis
     
  11. san
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    san Junior Member

    Doesn't have to do that and depends on how big crack you have. What happens is that exhausts from combustion chamber is pushed into cooling system and circulation stops. If you have a big crack or leak then water can get into the cylinder and either fill up the cylinder with water or corrode in cylinder. Then the engine wont run on startengine or becomes hard to start. That's why I asked about if your boat is hard started. If you have a small crack neither of this have to happen. The crack grows and let exhausts through when engine becomes warm but doesn't make any error when engine is cold. Easiest way is to check with the transparent hooses to surround the problem.
     
  12. Frosty

    Frosty Previous Member

    Hang on a minute guys, i think your going down the wrong road. When you took the hose off the thermostat housing you say a lot of exhaust was coming out of the pipe, you now assume that the exhaust is cracked. Well its never going to be cracked big enough for exhaust to be coming out.
    What you've got is exhaust pressure coming back throught he exhaust injection holes back up through the manifold and out through the cooling system simply because it the easiest way to go because you have the pipe off!!!!--- if im following your story correctly?
    Now Gonzo says there should be a lot of water coming out of the hose, he is talking about the hose from the thermostat, it depends on wich end of the hose you are looking at. There should be alot of water coming out of the thermostat hose going down to your manifold as gonzo says. if you dont you have weak pump pressure. Pheeeeeww

    I am assuming you've checked the thermostat or take it out ????
     
  13. gonzo
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    gonzo Senior Member

    You are right, it depends on which hose end it is. If you mean the end from the manifold, it will be dry and exhaust gas will come out.
     
  14. travis912
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    travis912 Junior Member

    I have the log style exhausts manfolds with end risers there are two hoses on the end risers a top hose and a bottom hose the top hoses are blowing exhausts back to the thermostat housing which is blowing exhaust into the engine could this mean that the riser could be cracked or busted on the inside
     

  15. san
    Joined: Oct 2004
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    san Junior Member

    Maybe I'm misunderstanding what you mean. Attached is log style manifold and riser (poor quality). On this you have one hoose on riser and one hoose directly below riser on exhaust manifold.

    When engine is cold most water goes directly through top hoose on riser. When engine becomes warm water goes through engine, to manifolds, back to thermostat housing via lower hoose on manifold directly below riser and then out through upper hoose on riser.

    I have also tried doing what you've done on my engine with this setup, and there should come water whatever hoose you pull. The easiest way for exhausts is through the stern if everything is in order.

    If you pull the top hoose on riser which should drain water FROM engine and you get exhausts from riser (does water come from engine in this case?), then there is a plug somewhere that makes easiest way for exhausts through top hoose on riser. Can be the flip flops in lower part of Y-tube.
     

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