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96 Chevy Pickup Intake Leak?



 
 
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  #1  
Old December 13th 04, 03:26 AM
bob
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Default 96 Chevy Pickup Intake Leak?


"aarcuda69062" > wrote in message
...
> In article >,
> "bob" > wrote:
>
> > I can see (or could see) coolant leaking down the passenger side of the
> > engine near the front on my 96 chevy pickup with 5.7 Vortec. Doesn't

look
> > like the water pump nor heater hose. I have read of problems with the
> > intake on these. What is the typical problem and where do I look to

verify.
> > Cannot see where it is coming from right now and I messed up as I was
> > loosing about 1/2 gallon of coolant every 6 weeks or so so I decided to

put
> > Bars Leak in rad. Of course, when I started motor to mix in the Bars

Leak
> > is when I noticed that I could actually see the coolant dripping off of

the
> > motor. Of course not it stopped but would like to fix permanently if

there
> > is a known problem on these. Truck has 130K miles on it.
> >
> > Thanks,
> > bobby

>
> Gm V engines of this era use an intake manifold gasket that is a
> plastic backbone with silicone inserts. Eventually from
> expansion and contraction, the plastic backbone begins to to
> fracture and the silicone sealing insert gets displaced allowing
> coolant to leak.
> If you are seeing an external coolant leak, there is certain to
> be an internal coolant leak as well, the internal leak is into
> the lifter valley and coolant contamination of the engine oil is
> sure to happen. The leaking gaskets are also certain to allow
> air intrusion into the cooling system which will cause the
> DexCool coolant to turn into a jelly like mass (mess). Definitely
> NOT a good thing. You want to get this fixed ASAP or risk having
> the engine damaged severely.
> There is no guess work here, they all fail in this manner...
> Get the gaskets replaced, the cooling system flushed thoroughly
> to remove the Bars Leaks and new Hybrid OAT (gold colored)
> coolant installed in place of the OAT DexCool (orange) that came
> from the factory.


aarcuda69062,

Your diagnosis was correct. Nove I've been digging for a couple of answers.
I picked up new gaskets but cannot find out if you put RTV on the gasktes at
the coolant ports or install dry? They have the plastic backbone with
silicone insert as was described. Also, cannot find specs for base ignition
timing (gotta get rid of Haynes and get a real book). I assume you align to
TDC as there is only 1 mark on the damper and a single notch on the little
plate on the block Assuming I align to the notch but is there anything to
unplug (used to be vacuum advance, "spout" connector, etc.) to disable the
idle advance?


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  #2  
Old December 13th 04, 04:41 AM
aarcuda69062
external usenet poster
 
Posts: n/a
Default

In article >,
"bob" > wrote:

> aarcuda69062,
>
> Your diagnosis was correct. Nove I've been digging for a couple of answers.
> I picked up new gaskets but cannot find out if you put RTV on the gasktes at
> the coolant ports or install dry? They have the plastic backbone with
> silicone insert as was described.


Install the gaskets dry.
Run a bead of good RTV along both end rails of the block, run the
bead 1/4 inch up the cylinder head, install the gaskets and then
put a dollup at each corner to meet the bead you ran on the block.

> Also, cannot find specs for base ignition
> timing (gotta get rid of Haynes and get a real book). I assume you align to
> TDC as there is only 1 mark on the damper and a single notch on the little
> plate on the block Assuming I align to the notch but is there anything to
> unplug (used to be vacuum advance, "spout" connector, etc.) to disable the
> idle advance?


Your 96 doesn't have adjustable ignition timing, that is
controlled by the PCM based upon a signal from the crankshaft
sensor. The distributor contains a camshaft position sensor
which determines the sequence of injector pulse, adjustment of
the distributor is accomplished with a scan tool under the
function of "camshaft sensor offset."
Hopefully, you marked where the rotor was pointing, the
distributor base to the block, and can re-install everything
lined up as it was.

One more tip....
The manifold bolt torque values are very low, please use a torque
wrench suitable for low torque measurements, i.e., definitely not
a 1/2" drive!
  #3  
Old December 13th 04, 02:57 PM
bob
external usenet poster
 
Posts: n/a
Default


"aarcuda69062" > wrote in message
...
> In article >,
> "bob" > wrote:
>
> > aarcuda69062,
> >
> > Your diagnosis was correct. Nove I've been digging for a couple of

answers.
> > I picked up new gaskets but cannot find out if you put RTV on the

gasktes at
> > the coolant ports or install dry? They have the plastic backbone with
> > silicone insert as was described.

>
> Install the gaskets dry.
> Run a bead of good RTV along both end rails of the block, run the
> bead 1/4 inch up the cylinder head, install the gaskets and then
> put a dollup at each corner to meet the bead you ran on the block.
>
> > Also, cannot find specs for base ignition
> > timing (gotta get rid of Haynes and get a real book). I assume you

align to
> > TDC as there is only 1 mark on the damper and a single notch on the

little
> > plate on the block Assuming I align to the notch but is there anything

to
> > unplug (used to be vacuum advance, "spout" connector, etc.) to disable

the
> > idle advance?

>
> Your 96 doesn't have adjustable ignition timing, that is
> controlled by the PCM based upon a signal from the crankshaft
> sensor. The distributor contains a camshaft position sensor
> which determines the sequence of injector pulse, adjustment of
> the distributor is accomplished with a scan tool under the
> function of "camshaft sensor offset."
> Hopefully, you marked where the rotor was pointing, the
> distributor base to the block, and can re-install everything
> lined up as it was.
>
> One more tip....
> The manifold bolt torque values are very low, please use a torque
> wrench suitable for low torque measurements, i.e., definitely not
> a 1/2" drive!


Thanks for all the advice. I've read so much about how common this failure
is. Are the new Felpro gaskets any better than the original or will they
have similar lifetime ? I just don't remember ever hearing of intake
gaskets failing until recent new designs. Is this plastic/silicone insert
design really better than the old paper ones? To answer my own question, I
assume the aluminum intake is the real culprit as they were cast iron on old
daze.


 




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