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  1. #1

    Default 5.7 L Vortec, intake manifold??

    Please let me know if the intake manifold is a good candidate for the problems I'm having.

    Truck: 1997 suburban K1500 4X4, engine: 5.7L Vortec

    First off, NO coolant leaks. NO Loss of coolant!
    I do have oil consumption, Plugg #3 fouls constantly.
    High idle, idles at 1K

    Huge amout of vacuum at the breater (hose that goes from intake tube to valve cover) Way too much vacuum for the crank case in my opinion.

    No oil mixing with coolant ect..

    Engine seems to ping inder hisgh load at 2K rpm. (ok after that)

    getting code 507, IAC, high idle. (iac is fine)

    Thanks in advance! hope it's not intake gasket.. :P However I'm worried about an internal vacuum leak.
    Last edited by fierodough; 08-09-2007 at 06:38 PM.

  2. #2

    Default

    Have you replaced the pcv? Might be plugged up and not allowing air to flow through properly.
    Gary

    99 K 1500 Suburban
    78 Silverado Big 10 w/factory 454
    00 S-10 Blazer
    1976 Trans Am
    1980 Honda CB900 Custom

  3. #3

    Default

    Hi Eric. What was your mileage again?



    Jamie

    2007 Ford E250(Work van) (Ya, Ya, shut up!)
    1996 GMC Sierra SLE 1500 5.7L/4L60E

  4. #4

    Default

    Quote Originally Posted by Cableguy View Post
    Hi Eric. What was your mileage again?

    220K now. :(

  5. #5

    Default

    Ahh crap!

    Found out how to test the intake for a vacuum leak... Just for further reference in case someone has the same problem...

    Disconnect the breather and disconnect the pcv. cover both valve cover holse with your thumbs. Feel some vacuum? not good.. .

    I was quoted a 7 hours job to change the lower intake gasket. I think I may attempt to do this one myself.

    Cheers!
    Eric

  6. #6

    Default

    The intake gaskets are not too tough to do on your own. Just take your time and bag all of your bolts and nuts so you know where they go back.
    Gary

    99 K 1500 Suburban
    78 Silverado Big 10 w/factory 454
    00 S-10 Blazer
    1976 Trans Am
    1980 Honda CB900 Custom

  7. #7

    Default

    I did my intake manifold gaskets last fall on my '98 5.7. It wasn't too difficult, but it took some time (spread out over three days for me). I don't remember where, but I know there is at least one good write up on the internet that I found that really helped, in addition to the information I got from the Haynes, Mitchell, and Motor repair manuals.

    I would recommend the FelPro gasket set (98000T I think).

    I think the hardest part for me was getting the manifold back on. The manifold was heavier than I expected and, with wires and such in the way, I had a hard time setting the manifold straight down so as to properly set on the RTV along the valley ends. Other than that, it was mostly the painstaking process of removing everything.

    The only question I still have on the job involves disconnecting the fuel lines. I disconnected them on top of the intake manifold, but the o-rings that came with the gasket kit didn't fit those fittings. I wonder if they intended you to disconnect the fuel lines farther back.

    Anyway, as noted, take your time, pay atttention to where things came off, and you should do fine.

    Oh, one other thing: The seals in the heater hose quick disconnect fitting broke when I disconnected the fitting, so I had to replace that fitting. A lot of people report breaking this fitting off whenever they take it apart, I guess I got lucky because the fitting didn't break on me. So it was pretty easy for me to replace, but be aware that you may not be so lucky, if you end up needing to replace that fitting.
    '98 K1500 Suburban LS 5.7 L 4L60E NV246 ARB
    '92 Ford Explorer XLT 4x4 4.0 L A4LD BW13-54 Trac-loc rear
    "My toys were the greasy cogs and springs and pistons that lay around all over the place, and these, I can promise you, were far more fun to play with than most of the plastic rubbish children are given nowadays." Danny in Roald Dahl's Danny The Champion of the World

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