Do I have a blown head? And should I replace my motor? 93 Sedan Deville 4.9L V8
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HT4100 4.1, 4.5, 4.9 Discussion, Do I have a blown head? And should I replace my motor? 93 Sedan Deville 4.9L V8 in Cadillac Engine Technical Discussion; I have a 1993 Sedan Deville w/ a 4.9L V8. I thought that I had a cracked/warped head gasket so ...
  1. #1
    truggenberg is offline Cadillac Owners Member
    Automobile(s): 1993 Cadillac Sedan Deville
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    Do I have a blown head? And should I replace my motor? 93 Sedan Deville 4.9L V8

    I have a 1993 Sedan Deville w/ a 4.9L V8. I thought that I had a cracked/warped head gasket so I purchased a product off the internet called "STEEL SEAL," which has a lifetime warranty and I have heard good things about it. Today I was preparing to run the STEEL SEAL through the radiator/engine so I drained all the old coolant and flushed my radiator w/ distilled water. I then mixed my antifreeze with water 50/50. When I poured the coolant in the radiator I had my engine running and the heat turned up to 90 with the fan on full blast. I didn't even pour a gallon of coolant in the radiator and it started to spew back up and spit out (radiator cap was off). I also noticed that my heat didn't work and the only vent in my car that was working was the one on the floor (and it was blowing out cold air). I was worried that if I used the STEEL SEAL that it wouldn't circulate through the engine and I would have wasted $115 on my purchase. Does the coolant bubbling back and spitting back out sound like a broken head on my motor? My thought is that I need to replace the motor. Any feedback that I can receive would be very much appreciated, because I need to know what direction to head in.

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    daniel58 is offline Cadillac Owners Fanatic
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    Re: Do I have a blown head? And should I replace my motor? 93 Sedan Deville 4.9L V8

    It has been my experience that you cannot run an aluminum eng while adding coolant, it will boil over in your face before you get it full. Add coolant to a cold eng, then warm it up a bit, let it cool and add coolant as needed. This will take a while but its the only way I have found to do it. I hope you didn't run it hot or you could have messed it up. The bigger question is why did you need the additive in the 1st place?

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    truggenberg is offline Cadillac Owners Member
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    Re: Do I have a blown head? And should I replace my motor? 93 Sedan Deville 4.9L V8

    The reason that I needed the STEEL SEAL is because I have been told that I have a blown head gasket, and the STEEL SEAL is supposed to fix that problem. So if I understand you correctly what you are saying is that when I am adding coolant I should not have the car running? Should I keep the radiator cap open, or should I close the radiator cap to increase the chances of having the coolant/STEEL SEAL circulate through the radiator and the engine? Also, why wouldn't the heater be working, I have electronic climate control and had the heat at the maximum setting of 90 degrees w/ the fan on high. Why were my interior vents, besides the one on the floor not blowing out hot air? The defrost vents near the windshield on top of the dash were also slightly blowing air, but again it was cool and not hot. I checked all the fuses and they were fine so that is not the problem. I also need to swap out the transmission on my caddy because none of the gears work. I am thinking that I should replace the tranny prior to circulating the STEEL SEAL through the engine. If it doesn't fix the head gasket problem then that will mean I have a problem with the actual head and I will need to drop a new engine in her. Does this logic appear to be sound? Assuming the worst case scenario will be what I am facing...does anybody know what engines are compatible w/ my 93 Deville? Also, what type of transmissions are compatible w/ her? I know I have a lot of questions, but I finally have a little $ saved up so I can make the necessary repairs and I want to make sure I do everything as efficient as possible. Any information or input from you guys would be very beneficial and appreciated.

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    HUF's Avatar
    HUF
    HUF is offline Cadillac Owners Connoisseur
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    Re: Do I have a blown head? And should I replace my motor? 93 Sedan Deville 4.9L V8

    Who told you that you had blown head gaskets? Blown headgaskets are extremely rare in 4.9 engines. It is not Northstar! What were the symptoms of blown headgasket? If that magic STEEL SEAL worked so great that would everybody spend $3,500 to replace blown headgaskets in Northastars?

    Fill the 4.9 with proper mix of water and coolant. Drive the car around the block (radiator cap is closed of course) so that the thermostat opens. Let it cool down. When the engine is cold, open the cap, add coolant. In a couple of heating/cooling cycles the system will get rid of air pockets.

    The heater will only work when there are no air pockets. The core might be clogged as well and needed backflushing and flushing. Why did you turn it to 90 while you were filling the system? It does absolutely nothing to cooling system since it only opens or closes air mix door under the dash.

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    daniel58 is offline Cadillac Owners Fanatic
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    Re: Do I have a blown head? And should I replace my motor? 93 Sedan Deville 4.9L V8

    Do you have coolant in the oil? Air bubbles in the coolant, bad compression? Those are signs of a blown headgasket among others. My 90 Deville 4.5 is recomended to have seal tabs added to the coolant, that is one thing. Those magic fix all block sealers are usually a waste of money.

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    the recluse is offline Cadillac Owners Connoisseur
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    Re: Do I have a blown head? And should I replace my motor? 93 Sedan Deville 4.9L V8

    The problem with that stuff is the engine design. The pistons sit in sleeves that have a minimal contact surface, unlike a 350 or what not. Then it'll probably clog your radiator or bypass houses anyway. Don't bother with that stuff and take it back.

    Run through the list of tells for a blown head gasket and properly diagnose it, then fix it right.

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