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Intake manifold gasket leaking? (1/8)
 12/7/17 11:34pm
Tony B
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Massapequa, NY - USA

Vette(s):
1990 Dark Red Mettalic convertible


Joined: 10/29/2017
Posts: 10

Noticed antifreeze laying in a well on the left rear of the intake manifold. Cleaned it up and it returned. Is that indicative of an intake manifold gasket leak or could it be something else.
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Re: Intake manifold gasket leaking? (2/8)
 12/8/17 11:29am
Atchafalaya
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Atchafalaya Basin, LA - USA

Vette(s):
Black 1979 L-82 Black 1996 LT1 Black 1999 Coupe


Joined: 3/20/2009
Posts: 507

Tony B said: Noticed antifreeze laying in a well on the left rear of the intake manifold. Cleaned it up and it returned. Is that indicative of an intake manifold gasket leak or could it be something else.



At the minimum...leaking gasket.
Was the bolts checked for tightness?
Re: Intake manifold gasket leaking? (3/8)
 12/9/17 9:48pm
Tony B
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Massapequa, NY - USA

Vette(s):
1990 Dark Red Mettalic convertible


Joined: 10/29/2017
Posts: 10

Didn't check the intake manifold bolts for correct torque. Just picked up the vette in October.
Re: Intake manifold gasket leaking? (4/8)
 12/11/17 3:18am
Hot Rod Roy
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Mission Viejo, CA - USA

Vette(s):
Yellow '84 Coupe


Joined: 3/18/2015
Posts: 74


How does your oil look?   A leaky intake manifold gasket could also allow antifreeze into your oil . . . not good!



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Re: Intake manifold gasket leaking? (5/8)
 12/12/17 11:05am
Tony B
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Massapequa, NY - USA

Vette(s):
1990 Dark Red Mettalic convertible


Joined: 10/29/2017
Posts: 10

No anti freeze in oil. Oil is clean.
Re: Intake manifold gasket leaking? (6/8)
 12/12/17 1:49pm
Atchafalaya
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Atchafalaya Basin, LA - USA

Vette(s):
Black 1979 L-82 Black 1996 LT1 Black 1999 Coupe


Joined: 3/20/2009
Posts: 507

Tony B said: No anti freeze in oil. Oil is clean.



If it was me....I would loosen intake bolts, then tighten and torque in proper sequence.
Wipe any residuals and monitor for another leak.
 
If it leaks again, plan to remove intake to properly diagnose where it's leaking from.
 
Very simple to do.
Re: Intake manifold gasket leaking? (7/8)
 12/17/17 12:09pm
The Car Whisperer
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Andover, MA - USA

Vette(s):
1986 Coupe


Joined: 3/22/2009
Posts: 50

I have never seen a torque wrench that you can use to access any of the intake manifold bolts on an L98 without removing the entire fuel delivery system.  It's not a simple task to properly torque the manifold on these engines.  FSM  recommends 35 lb. ft. I just tightened my leaking intake manifold by hand using whatever I could get to the bolt head with., using best judgement as to tightness.  It was quite loose. The leak hasn't re-appeared for three years now.  Just go in and try to tighten it by hand.  A 1/4" box wrench with the proper sized torx insert bit can get to most of the bolt heads on the intake without removing anything.  The wrench is short so you can't get in much trouble over tightening.  Use your experience!!!




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1986 "Bright Red" COUPE - Aluminum Heads,
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Automatic, Bilsteins - "Mostly Original" otherwise.

Re: Intake manifold gasket leaking? (8/8)
 12/27/17 8:49pm
djsroknrol
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Guthrie, OK - USA

Vette(s):
1984 L83/MD8 coupe


Joined: 2/7/2011
Posts: 124

It could be a number of things: A heater hose or radiator hose, heater core leaking (you would see something like this in the passenger well...not fun) and like the other guys are saying, an intake manifold leak...take a good look at everything coolant related. These things run on the hot side, so don't shortcut anything when it comes to cooling......


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