408 Stroker Runs Hot!!! Help!

Discussion in 'Fox 5.0 Mustang Tech' started by Stonerboys, Jul 1, 2013.


  1. Stonerboys

    Stonerboys Member

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    Hey guys I'm in a bit of a dilemma with my 89 Lx drag car that has a 35 windsor based 408 stroker motor. I cannot get it to cool down! It has a meziere elec water pump (52gpm) and has an electric fan and shroud. I tryed putting a thermostat in it both 160degree and 180 degree ones and a restrictor plate with a 1" hole and a 5/8" hole. I put a water hose in the top radiator hose to check the flow and it flows fine. I ran it with the rad cap off and tryed a new cap (16 lbs) and still didnt solve it. I even lowered the top radiator hose and changed the bottom rad hose because it sucks shut over night. I tried a new water temp gauge, pulled the water pump. The guy I bought the car from said the water pump was new when I bought it. I checked the water pump on a bench and it runs clockwise and seems to be working fine. This motor will run 10 minutes with fan and water pump running and will get up to 180 degrees then with 5 more minutes of running willclimb to 210 beforeI shut it off. WhenI shut it down it coolds down at a normal rate. This is a fresh 408 stroker with the best of everything I could buy in it but it runs too too hot which scares me! I don't want to blow another motor in this car its getting too $$$$!!! It has copper head gaskets. I noticed the cooling holes on the heads are only 5/8" and both jegs and summit told me they're factory tested and I should not cut the holes bigger. Is this the problem with the Victor JR. heads? I also tried a radiator and fan from my buddys mustang and still had the same problem! Any info or help would be greatly appreciated! This car has me, all of my car guy friends, and jegs and summit tech guys stumped! Its like christine! I swear this car hates me!!!
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  2. clement

    clement Founding Member

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    what fan is on it? it could be that there is scale in the blocks water jackets. I would flush it completely. it could be sucking air because of the copper HGs. they are kind of a pain in the ass to seal. and the stuff you seal them with clogs the radiator. is there a spring in the lower radiator hose? or does it heat up like that idling?
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  3. autopart101

    autopart101 New Member

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    I have a 428 stroker with the same heads. What radiotor are you usieng? Stroker motors make lots of heat . You need a aluminum radiator. I went with a thick Griffin and 180 stat. Car never gets over 190.
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  4. 2000xp8

    2000xp8 Mustang Master

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    If there are no leaks and holds pressure properly, just sounds like a cooling capacity issue.
    I'd suspect the radiator, fan or maybe both are undersized.
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