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Thread: Intake Manifold O-rings

  1. #1
    Junior Member
    Join Date:  Feb 2017

    Location:  Madison, MS

    Posts:    20

    Intake Manifold O-rings

    I've taken the plunge and started a VOD cleanup. All said, it's not too bad in there. I found a few copper sealing rings and an old grill clip from the engine cover. I found the air filter box bolt I dropped the first week I owned it, as well as what I believe is the bolt it had replaced I will have to replace the heater pipe and a few hoses and clamps, but overall it could have been a lot worse.

    I ordered the intake o-ring kit from DMC, and my assumption was the 6 rings go between the block and the intake manifold. They're the right size, but the existing rings appear to be flat instead of rounded and fill the entire recessed area perfectly. Is that because the rubber flattens over time under pressure, or does it really not matter? Or am I missing something altogether and these rings go somewhere else?

  2. #2
    Not a DeLorean Guru
    Join Date:  May 2011

    Location:  Rochester, NY

    Posts:    1,888

    My VIN:    01049

    The new o-rings will get squished down when you re-install the intake.
    -Mike
    1981 DeLorean, heads/cams/exhaust, EFI
    1999 Corvette, heads/cam/exhaust, 440 BHP
    2005 Elise, stock
    2016 Chevy Cruze

  3. #3
    Senior Member NckT's Avatar
    Join Date:  Jun 2011

    Location:  Yorkshire UK

    Posts:    120

    My VIN:    No. 4068

    Yes, they flatten over time.

    My personal preference on reinstallation is to use clear silicone sealant to hold the new O rings in place and create a guaranteed seal between the cylinder heads and inlet manifold.

    On my car I also used a heat gun to dry the "valley" area, vacuumed any remnant dirt/ dust, and then used motorbike air cooled cylinder engine black paint to protect the top of the alloy of the engine to help prevent any future rot due to any water ingress.

    Take your time in removing the long bolts that hold the V coolant pipe to the cylinder head. I tapped the head of the bolts a few times with a small hammerr to help shock loose the threads before undoing them as they are prone to snapping.

    Good luck with it all, it's not as bad as people make it out to be.
    Last edited by NckT; 10-12-2017 at 01:27 PM.
    RIP Rob van de Veer Top bloke

    I say Sir, I must be mad, one loves fixing K-Jet !

    Make sure there's plenty in the tank for the weekend chaps....

  4. #4
    Senior Member Jonathan's Avatar
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    Location:  Ontario, Canada

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    My o-rings were squished flat when I took them out too.

    IMG_1417.jpg
    One damn minute Admiral...


  5. #5
    Not a DeLorean Guru
    Join Date:  May 2011

    Location:  Rochester, NY

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    Quote Originally Posted by Jonathan View Post
    My o-rings were squished flat when I took them out too.

    IMG_1417.jpg
    Dang dude, those have to be some of the flattest I've seen!
    -Mike
    1981 DeLorean, heads/cams/exhaust, EFI
    1999 Corvette, heads/cam/exhaust, 440 BHP
    2005 Elise, stock
    2016 Chevy Cruze

  6. #6
    Senior Member Jonathan's Avatar
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    Location:  Ontario, Canada

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    Quote Originally Posted by opethmike View Post
    Dang dude, those have to be some of the flattest I've seen!
    Oh yea. For this and 100 other reasons just like it, the car thanks me for finding it and making her like new again.

    In other news... we still have at least one thread on the forum here today that hasn't been overrun by BOTS. Whaddupwiththat?
    One damn minute Admiral...


  7. #7
    Junior Member
    Join Date:  Feb 2017

    Location:  Madison, MS

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    Quote Originally Posted by opethmike View Post
    Dang dude, those have to be some of the flattest I've seen!
    This is why I was in doubt:

    IMG_6353.jpg

  8. #8
    Senior Member mluder's Avatar
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    Location:  Happy Valley, OR

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    My VIN:    4456 - Owner since March 2011

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    Quote Originally Posted by NckT View Post
    My personal preference on reinstallation is to use clear silicone sealant to hold the new O rings in place and create a guaranteed seal between the cylinder heads and inlet manifold.
    Plus one on this - Top tip is to use clear silicone on all the engine o-rings when you reinstall.

    Cheers
    Steve
    Cheers
    Steven Maguire
    #4456


    IT'S A TRAP!!!!!

  9. #9
    Junior Member
    Join Date:  Apr 2017

    Posts:    11

    Always replace the intake O rings?

    I had a coolant leak on the back of the water pump (cockeyed hose), and pulled the intake manifold to get to the hose. I did not replace the intake O-rings. I didn't think they were that old since I had replaced them 3-4 years ago. Now I've got an apparent massive vacuum leak. I tried a smoke test and all I could see was a bunch of smoke from 'somewhere' under the manifold. I bought a cheap borescope camera, thinking I would try the smoke test again this weekend to pinpoint the leak sources.

    Should you just always replace those O rings when re-installing the manifold?
    Robert
    1981 DeLorean #1890
    1976 Datsun 280Z
    1968 Pontiac Le Mans convertible

  10. #10
    Young Padawan With The DeLorean kings1527's Avatar
    Join Date:  Jun 2012

    Location:  Oak Park, CA

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    My VIN:    6575

    Quote Originally Posted by DMC1890 View Post
    I had a coolant leak on the back of the water pump (cockeyed hose), and pulled the intake manifold to get to the hose. I did not replace the intake O-rings. I didn't think they were that old since I had replaced them 3-4 years ago. Now I've got an apparent massive vacuum leak. I tried a smoke test and all I could see was a bunch of smoke from 'somewhere' under the manifold. I bought a cheap borescope camera, thinking I would try the smoke test again this weekend to pinpoint the leak sources.

    Should you just always replace those O rings when re-installing the manifold?
    I've removed the intake probably about eight times or so and that's what I've done with the exception of one or two times. Cheap and easy to do and prevents stuff like what you're describing from happening.

    Alex Abdalla
    6575

    Late 1981, Grey 5-speed, 61k miles. Built 11/11/81

    DPNW Toby Fans, DPNW Wings-A-Loft Elite, DMCMW Fan Sequencer, R12 AC, Full LEDs, DMCH Digital Door Lock Module, DPNW Door Lock Actuators, DMCH 140A Alternator, Infinity Kappa 3.5"/5.25", JL XD700 Power Amp, Alpine CDE-HD138BT, DMC CA 8" Sub, Dave McKeen RPM Relay, DMCH Replica Carpet Set, NOS Seat Covers

    A full restoration with step-by-step "what I did" is in progress at www.delorean6575revisited.blogspot.com

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