Thread: Lower intake manifold gasket

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  1. #1 Lower intake manifold gasket 
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    Well, I fixed the tensioner elbow fittings (in another thread.) Today I got out of the car and smelled coolant. When filling the system I forgot to reinstall the bleed screw so coolant did spill out onto the engine. That stuff stinks and takes a while to go away. So I did an inspection, and I can see a small puddle of oil? (can't get my finger down there to find out) on the intake manifold behind the alternator.

    I was just reading about the LIM gasket failures (why on earth did they use plastic gaskets???? It looks plastic...)

    I strongly suspect that the LIM gasket on the car is the original one, as the coolant elbow was replaced six years ago.

    After searching around on RockAuto, I see they have a redesigned LIM gasket set that has all the bits you need, and it looks like it's a metal gasket, not a plastic one. That's the one I ordered. Even though i don't see any evidence of coolant etc out the tailpipe or in the oil, I'm thinking this would be a good preventative maintenance type of deal.

    Are there any gotchas with this job? The supercharger is obviously in the way, I ordered a new supercharger gasket (OEM.) As far as mechanical aptitude, I've rebuild engines in my carport before. You do what you have to sometimes...
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  2. #2 Re: Lower intake manifold gasket 
    GT Level Member mguzzo's Avatar
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    the key is keeping coolant out of the lifter valley. remove the t-stat housing and use a shop vac to suck all the coolant out of the LIM before you lift it off.

    there are a lot of write up on this, so you should be able to do it in a day
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    Current '98 GTP Coupe: Still stock and rust free. That will change.
    Old '98 GTP Coupe: VS Cam, 3.0, S2IC, 42.5#, TOGs, N*/LQ4, Corsa. it once ran a 13 flat
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  3. #3 Re: Lower intake manifold gasket 
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    I have a small hand pump that I can use to pump out the coolant, thanks for the tip. I think I'll also remove the front knock sensor (next to the rad) to drain out as much coolant as I can.

    I also plan to fix the leaking AC compressor at the same time (I read elsewhere they have a big o-ring in them that fails and causes them to leak.) Because it's been leaking for a while (the damn compressor is covered in green dye) I'm replacing the condenser and receiver/dryer too. I contemplated replacing the compressor only, but I only want to do this job once! I also discovered a squeaking radiator fan (the passenger side one) so I'll change that too. That squeak was driving me crazy as it was somewhat intermittent and I never clued in that it was squeaking only when the right side cooling fan was on!
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  4. #4 Re: Lower intake manifold gasket 
    GTP Level Member FriboRage's Avatar
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    Even with pumping/draining all the coolant, there's going to be some pooled in the LIM you wont get out that'll likely spill as you try to lift it and break the seal with the heads...

    Most people just get a quart of motor oil and use it to wash down the lifter valley, just pour the oil over top to wash away any coolant that got left there... then do an oil change when you're all done with the LIM. It's really better safe than sorry.

    When I did it, I drained the oil before I started, then I got some cheapo oil to wash the lifter valley and then fill with after I was done, ran it for 5 or 10 minutes... drained and filled with my preferred stuff and went from there.
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  5. #5 Re: Lower intake manifold gasket 
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    I agree with all said above. Make sure you look up a how to. The intake is easy to do. Just tedious. I would get GM o-rings for the coolant elbows or use a bit of RTV on them when you reinstall. The Dorman o-rings are known to fail within a few years. Sometimes a year. The aluminum elbow is fine just the O-rings have issues. There are great guides and have all the ins and outs. Make sure to follow torque and tightening sequences. Use a good dab of rtv in the corners of the intake. Change oil when done! Also a good time to change supercharger oil while you are messing around with it. Make sure to use the right oil. Intense sells the right kind and perfect amount.
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  6. #6 Re: Lower intake manifold gasket 
    Turbo is the way to go. BillBoost37's Avatar
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    Make sure you retorque the knock sensor to the proper spec if you take it out.
    I drink..so consider that when reading my posts.

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  7. #7 Re: Lower intake manifold gasket 
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    Quote Originally Posted by BillBoost37 View Post
    Make sure you retorque the knock sensor to the proper spec if you take it out.
    Yep, I've had it out before to drain the block.

    I also have the factory manual for 1997, so that helps when looking some things up.
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  8. #8 Re: Lower intake manifold gasket 
    Turbo is the way to go. BillBoost37's Avatar
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    Sooo on that FSM, likely the LIM bolts are calling for approx 11ft lbs of torque. Once GM redesigned the plastic lims with metal sleeves around the bolt they upgraded to ~13lbs. When they came out with all metal gaskets, I used 15lbs on each car I did with no issues at all. Just something to keep in mind
    I drink..so consider that when reading my posts.

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  9. #9 Re: Lower intake manifold gasket 
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    Well, I'm going to attempt changing the gaskets and fixing the A/C all in one shot over the next week or so. I just transferred the tags to another car for now so I don't have to worry about getting it back together in a hurry.

    Hopefully not too many surprises when I start getting into it. I actually think the A/C repair is going to be more work than the intake gasket.
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  10. #10 Re: Lower intake manifold gasket 
    GT Level Member mguzzo's Avatar
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    what part of the AC are you repairing? orifice tube is a ***** to get at under the brake booster. evap core inside the car needs the whole dash to come apart. but dryer and condensor replacement are easy.
    --
    Current '98 GTP Coupe: Still stock and rust free. That will change.
    Old '98 GTP Coupe: VS Cam, 3.0, S2IC, 42.5#, TOGs, N*/LQ4, Corsa. it once ran a 13 flat
    Older '98 GTP Sedan: Pullied, rockered, SSIC, etc. Stock 14.33 @ 96.5 / PB: 13.89 @ 101
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  11. #11 Re: Lower intake manifold gasket 
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    Quote Originally Posted by mguzzo View Post
    what part of the AC are you repairing? orifice tube is a ***** to get at under the brake booster. evap core inside the car needs the whole dash to come apart. but dryer and condensor replacement are easy.
    The compressor went, it's leaking everywhere. Surprisingly, it still cycles but it's incapable of cooling. I've got a new compressor, receiver/dryer, and condenser plus o-rings etc for it. The PO had it charged and dye added. The compressor is covered in green dye. When I went to my usual shop to have them suck out the little bit of gas that was in it, they said the when that model of compressor goes it's quite often the seals. They do a lot of A/C work, so I believe them.

    I did get a new orifice tube but if that's a real PITA maybe I won't bother. Or maybe as I've removed the supercharger/throttle body/intake tubing I should do that first before I reinstall the intake. Right now there really isn't much of anything in the way, the whole top half of the engine is gone...

    That fuel rail is the only damn thing that gave me problems. I have an old (cheap) plastic fuel line removal set but I think the plastic was distorting when I was trying to remove the feed line. I now have anodized aluminum ones ($$$), and it popped off on the first try.

    Lucky for me I don't see any sludge inside the engine. I know the PO gave it regular fluid changes, but I have no idea about before that.
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  12. #12 Re: Lower intake manifold gasket 
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    Well darnit, I think I found out why the cooling system was very slowly losing pressure under a pressure test.

    The lower intake has some pitting around some of the ports.

    I see RockAuto shows a lower intake for the L67 but it's made by Dorman, are these any good? I'd be surprised if GM still makes these... and if they did it'd likely be a few limbs.
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  13. #13 Re: Lower intake manifold gasket 
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    Well, I did look and GM doesn't make them anymore. I guess the Dorman one is likely the only option...
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  14. #14 Re: Lower intake manifold gasket 
    Killa Bee Scottydoggs's Avatar
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    you can smear jb weld in the pitted areas, let it dry and sand it smooth with sandpaper and a block of wood.

    98 Buick Regal GS, F body brakes, Caddy STS wheels, tinted tails L36 bottom end, lightly ported heads, 1.95 roller rockers, headers, gen 5 N* 3.0 pulley, FSIC, 42 lb injectors, a BrandonHall rebuilt trans, DHP tuned and AEM water/Meth injection https://goo.gl/gpV5kW
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  15. #15 Re: Lower intake manifold gasket 
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    Quote Originally Posted by Scottydoggs View Post
    you can smear jb weld in the pitted areas, let it dry and sand it smooth with sandpaper and a block of wood.
    Hmm. After using some Google-fu, I discovered that while mine is pitted it's not nearly as bad as some I saw on youtube, those were craters, lol. My only problem is I don't have a way to clean the pits out, it was recommended to use a media blaster or something and then clean it really well. I think I'm going to have to get the Dorman one, hopefully it's not a piece of junk. I've seen some used ones on ebay etc but they only have a picture of the top side and none of the bottom, so good chance they're pitting as well.

    And of course now I just caused myself another problem. I was taking the lower seals off of the fuel injectors, and one of the plastic retaining rings that hold the seal in place snapped off. I'm going to guess that means I have to buy a new injector now. Bah!
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  16. #16 Re: Lower intake manifold gasket 
    Killa Bee Scottydoggs's Avatar
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    post a pic of said pitting. maybe its not as bad as you think.

    98 Buick Regal GS, F body brakes, Caddy STS wheels, tinted tails L36 bottom end, lightly ported heads, 1.95 roller rockers, headers, gen 5 N* 3.0 pulley, FSIC, 42 lb injectors, a BrandonHall rebuilt trans, DHP tuned and AEM water/Meth injection https://goo.gl/gpV5kW
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  17. #17 Re: Lower intake manifold gasket 
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    It's getting dark now, so I've come inside to make food. I'll do that first thing in the morning.

    As I mentioned above I had problems where a cooling system pressure test was lowing pressure, but slowly. I found a couple areas around the LIM where some oil and coolant had puddled. And there was so much rat poop on the intake it was unbelievable. There's must've been a cup of oily/watery rat poop that I cleaned off. I guess the coolant most likely attracted them...

    Weirdly enough, it wasn't going in the oil pan and it wasn't going out the tailpipe either (I checked that a couple months ago when I noticed I was leaking a bit of coolant.)
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  18. #18 Re: Lower intake manifold gasket 
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    I meant when I noticed I was losing coolant, not leaking coolant. I can't see a way to edit my post lol.
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  19. #19 Re: Lower intake manifold gasket 
    Killa Bee Scottydoggs's Avatar
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    what year and engine you working on? if na the upper intake fails and leaks coolant inside the engine. if you caught it early enough maybe before the hydro locking could happen.

    98 Buick Regal GS, F body brakes, Caddy STS wheels, tinted tails L36 bottom end, lightly ported heads, 1.95 roller rockers, headers, gen 5 N* 3.0 pulley, FSIC, 42 lb injectors, a BrandonHall rebuilt trans, DHP tuned and AEM water/Meth injection https://goo.gl/gpV5kW
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  20. #20 Re: Lower intake manifold gasket 
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    1997 L67, Supercharged. I don't have a plastic plenum.
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