4.5 intake manifold gasket progress
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HT4100 4.1, 4.5, 4.9 Discussion, 4.5 intake manifold gasket progress in Cadillac Engine Technical Discussion; Some of you might remember last fall I started replacing the intake manifold gaskets on my '90 Eldo. I got ...
  1. #1
    drewsdeville is offline Cadillac Owners Master
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    4.5 intake manifold gasket progress

    Some of you might remember last fall I started replacing the intake manifold gaskets on my '90 Eldo. I got it tore down, then got sick with pneumonia. with an additional school load from getting sick, then just plain getting lazy, I left it sit all winter. Today I took advantage of the weather and got back on it.

    I'm done for today to celebrate St Patty's with my girlfriend. Slow process as everything needed to be re-cleaned from sitting all winter and also I'm slowly remembering how everything goes back together...

    Enjoy

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    Sevillian273's Avatar
    Sevillian273 is offline Cadillac Owners Connoisseur
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    Re: 4.5 intake manifold gasket progress

    Wow.. so the rods go through the manifold? What a strange design. I took apart a ford 5.0L once and the lifter valley was covered in wax and sludge. Turned out the previous owner use nothing but quaker state oil. Yours looks nice and clean. Its a shame you have to remove the rockers and stud girdle just to change the intake gaskets. Ive read alot of threads about the girdle cracking after re-installation. Apparently its very sensitive to its torque specs. If you need any info from the FSM let me know as I have have the same engine. Same body color too it appears.

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    drewsdeville is offline Cadillac Owners Master
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    Re: 4.5 intake manifold gasket progress

    Yeah, it's not that bad though. In fact, the thing that makes it the easiest is the rocker support. Just have to remove the support bar rather than removing each individual rocker.

    The design is similar to the GM 2.8, 3.1 and 3.4 engines. The design allows for better packaging since the engine doesn't have to be as wide, externally. However, it doesn't allow for very good breathing heads, which is the 4.X's downfall when it comes to performance, especially high RPM.

    The rocker supports usually crack from incorrect install and removal. You can't just remove each nut one buy one. You have to cycle through them all, tightening/loosening little by little as the valvetrain is compressed. If you remove one nut completely without the others, the force of the corresponding valve spring will crack the support in that spot.

    I torqued the main rocker support nuts to 37ft/lbs. What does the FSM say? Hopefully nothing wildly different as I already put the rear valve cover on, as you can see from the pictures.

  5. #4
    Sevillian273's Avatar
    Sevillian273 is offline Cadillac Owners Connoisseur
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    Re: 4.5 intake manifold gasket progress

    From the FSM in FT. LBS.:

    ROCKER ARM PIVOT TO SUPPORT SCREWS - 22
    ROCKER ARM SUPPORT TO HEAD BOLT NUTS - 37
    ROCKER ARM SUPPORT TO HEAD - 7

    Looks like you're good to go.

  6. #5
    drewsdeville is offline Cadillac Owners Master
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    Re: 4.5 intake manifold gasket progress

    Cool, thanks.

  7. #6
    steelybill is offline Cadillac Owners Enthusiast
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    Re: 4.5 intake manifold gasket progress

    Don't know about the 4.5, but the 4.1 oil drain-back from the top of the heads is a bad design. It drains alongside the head bolts into the lifter valley. Had to fool with mine, blow them out etc. Sludge seems to collect there, and bakes in there.

    I was afraid to remove any head bolts to clean it better. I visualized a heli-coils nightmare

  8. #7
    drewsdeville is offline Cadillac Owners Master
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    Re: 4.5 intake manifold gasket progress

    No problem on the drainbacks for my 4.5 or 4.9. Never had a 4.1 to compare to.

    The engine was really clean and I'm doing this is at 170,000 miles.

  9. #8
    ehall's Avatar
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    Re: 4.5 intake manifold gasket progress

    That does look clean. My 4.1 has some gritty baked oil. I'm going to do an ATF treatment before the next oil change.

  10. #9
    the recluse is offline Cadillac Owners Connoisseur
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    Re: 4.5 intake manifold gasket progress

    Quote Originally Posted by steelybill View Post
    Don't know about the 4.5, but the 4.1 oil drain-back from the top of the heads is a bad design. It drains alongside the head bolts into the lifter valley.
    When I had my heads off, I ported and polished them but also ground out the drain-backs and got rid of the casting imperfections.

  11. #10
    steelybill is offline Cadillac Owners Enthusiast
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    Re: 4.5 intake manifold gasket progress

    That sounds like a good fix. I don't plan on any head work at this point. Did your head bolts come out OK?

  12. #11
    the recluse is offline Cadillac Owners Connoisseur
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    Re: 4.5 intake manifold gasket progress

    Quote Originally Posted by steelybill View Post
    That sounds like a good fix. I don't plan on any head work at this point. Did your head bolts come out OK?
    No, I had to heli-coil the block, an aggravating endeavor in itself.

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