90' 4.5L Deville Head Bolt Leaking
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HT4100 4.1, 4.5, 4.9 Discussion, 90' 4.5L Deville Head Bolt Leaking in Cadillac Engine Technical Discussion; Hi Guys, I started a thread "High Eng Temp Light" before I knew the issue, but I stopped at my ...
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    Cristofo's Avatar
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    90' 4.5L Deville Head Bolt Leaking

    Hi Guys,

    I started a thread "High Eng Temp Light" before I knew the issue, but I stopped at my mechanics today and he walked me through the leak.

    So while under the car, you need to look up between the transmission and the engine block. Here you'll see the LONG head bolts that connect the head to the block. The bolt closest to the driver side tire is leaking at the threads that go to the block. Also this is the right side of the engine closest to the firewall.

    My question: Is it possible to replace or tighten the head bolt from above the engine? My guy tends to believe there is no way to get to the bolt with the engine in the car. He told me since I have nothing to really lose, to get a really good bars leak type sealant for the cooling system and see if this works. Also to temporarily get a lower PSI radiator cap while I run the bars leak.

    Thanks for the help and guidance.

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    Cristofo's Avatar
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    Re: 90' 4.5L Deville Head Bolt Leaking

    Well I guess you can never tell how a car is by upkeep, appearance and the way it drives. This leak is driving me crazy. The weird part about this leak is, my radiator is about 1/3 or less full, when I pour antifreeze in it starts to leak immediately and the engine does NOT have to be on. So there is no way the fluid is going through the UPPER Rad hose and then leaking. Fluid is going through the lower hose and leaking from this area. The leak is not a minor one, it comes out freely almost like a hose burst.

    Im glad I got to drive my "MINT" condition car for 3 months i guess. This sucks.

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    quins90lac's Avatar
    quins90lac is offline Cadillac Owners Enthusiast
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    Re: 90' 4.5L Deville Head Bolt Leaking

    If you could get a picture of where its leaking it would help a lot.

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    Re: 90' 4.5L Deville Head Bolt Leaking

    Quote Originally Posted by quins90lac View Post
    If you could get a picture of where its leaking it would help a lot.
    Thanks, I will definitely try but I will need to put it on jackstands or get it on the lift again. This is just very bizarre to go from no leak to full blown leak from 1 day to the next and it NOT be an obvious heater/rad hose.

    Im still having trouble locating any engine diagrams or pictures of this engine. If I was able to find a picture of this engine from the bottom up, It would help.

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    the recluse is offline Cadillac Owners Connoisseur
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    Re: 90' 4.5L Deville Head Bolt Leaking

    Quote Originally Posted by quins90lac View Post
    If you could get a picture of where its leaking it would help a lot.
    Agreed.

    The ONLY way the bolt would leak is if you had a cracked head, blown head gasket, or a cracked block; two of which would give you crappy drivabililty issues and the last one is not one you would want to tackle or try and fix. Well, the intake manifold gasket may be possible, I'll check on that.

    The possibility lies more with the bypass hose around the backside of the engine. If you look under the exhaust manifold you'll see a 5/8 steel line that wraps around to the front of the engine and loops down to the harmonic balancer and back up to the firewall. There it turns into soft line with a couple of "T" unions, also possible leaking locations. Reach all around there and see if you can feel anything.

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    Cristofo's Avatar
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    Re: 90' 4.5L Deville Head Bolt Leaking

    Quote Originally Posted by the recluse View Post
    Agreed.

    The ONLY way the bolt would leak is if you had a cracked head, blown head gasket, or a cracked block; two of which would give you crappy drivabililty issues and the last one is not one you would want to tackle or try and fix. Well, the intake manifold gasket may be possible, I'll check on that.

    The possibility lies more with the bypass hose around the backside of the engine. If you look under the exhaust manifold you'll see a 5/8 steel line that wraps around to the front of the engine and loops down to the harmonic balancer and back up to the firewall. There it turns into soft line with a couple of "T" unions, also possible leaking locations. Reach all around there and see if you can feel anything.
    Thanks guys, I really appreciate this info. Ill keep looking, my next step is to jack it up or take a wheel off to get a better view of the leak.

    Another thing I guess I didnt really mention yet, my mechanic told me and showed me that the cylinder head was DRY and no fluid was leaking from the head gasket.

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    Re: 90' 4.5L Deville Head Bolt Leaking

    I'm going to delete this post, because I have a more successful thread going in the Deville ALL FWD forum 1985-2005. I posted it here because I wasnt sure what was the correct approach.

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