2002 SL1 intake gasket

[hubops]

My friendly neighbourhood Saturn dealer is saying
that my intake manifold gasket is faulty.
I was in for routine oil/tranny fluid change.
No symptoms - that I can tell. yet...
What symptoms should I be looking for ?
Will it likely fail suddenly or gradual ?
120,000 km on the car.
Thx. John T.

 

[Bob Shuman]

Generally a leak in the intake manifold gasket will result in an elevated
idle and possibly set a check engine light code. Does your vehicle have
either of these symptoms?

Bob

 

[hubops]

Thanks for reply - no symptoms yet.
I just - last month - got my bestest mileage yet
51 mpg (Imperial gallon) on a tankful - ideal driving conditions
for the complete tankful - and a 42 mpg prior.
So average ideal maybe 46.
This same dealer wanted to do a head gasket
and motor mount - when I bought the car -
at 4 years 70 k km .. I declined - so far so good.
He said that the motor mount was "after market"
so I asked why the factory one lasted only 3 years
for the original owner... no good answer there !
jt

 

[Bob Shuman]

Sounds like the dealer is attempting to lighten your wallet. I'd find
another place to provide service if it were me.

Bob

 

[Joe Blow]

Aside form the aforementioned high idle & SES light (which occurs in
the late stages of bad gasket), you may notice the following in the
early stages of bad intake gasket :

1) better mileage (I got 51 miles per imp gal highway)
2) slowly disappearing engine coolant
3) hotter burning cylinder (indicated by spark plug color)

One way to test for leaky gasket yourself is to spray some WD-40
around the intake gasket while idling the engine. Do this for each
cylinder. And if you hear the engine speed up, you have a leak.

Based on personal experience, early stages of this can be ignored if
the leak isn't bad enough. But once the idle RPM goes out of control,
bring it in for service because you won't pass the smog control test.

 

[Private]

Aside form the aforementioned high idle & SES light (which occurs in
the late stages of bad gasket), you may notice the following in the
early stages of bad intake gasket :

1) better mileage (I got 51 miles per imp gal highway)
2) slowly disappearing engine coolant
3) hotter burning cylinder (indicated by spark plug color)

One way to test for leaky gasket yourself is to spray some WD-40
around the intake gasket while idling the engine. Do this for each
cylinder. And if you hear the engine speed up, you have a leak.

Based on personal experience, early stages of this can be ignored if
the leak isn't bad enough. But once the idle RPM goes out of control,
bring it in for service because you won't pass the smog control test.

Both the temporary increase in fuel economy and the hotter burning spark
plug are due to the over lean mixture resulting from the intake leak. This
over lean mixture can cause engine damage due to detonation and overheating
of the piston crown particularly in high load situations. IIRC there are no
coolant passages in the S series engine but ICBW. IIRC failed intake
gaskets have become quite common in engines with aluminum manifolds and
heads and are caused by repeated thermal cycles and gaskets that are
designed for easy assembly at the factory, These leaks commonly show up at
around 100,000 km.

Changing an intake gasket is not a difficult job for a driveway mechanic,
but may require the purchase of a special wrench or two. IMHO the key to a
successful repair is to carefully and completely clean the old gasket
without damaging the soft aluminum and to use a top quality silicone gasket
glue. IMHO the best glue is the grey sensor safe silicone sold by GM, it is
a little pricy and its thick viscosity makes it harder to spread but it
works well when carefully applied. IMHO the bolts should be lubricated with
thread lubricant suitable for aluminum, and torqued (at least) to the higher
side of spec and then retorqued after silicone has compressed, again when
warm and again after cool down. I suspect the factory gaskets fail because
of lack of this retorqueing.

Good luck YMMV

 

[hubops]

Both the temporary increase in fuel economy and the hotter burning spark
plug are due to the over lean mixture resulting from the intake leak. This
over lean mixture can cause engine damage due to detonation and overheating
of the piston crown particularly in high load situations. IIRC there are no
coolant passages in the S series engine but ICBW. IIRC failed intake
gaskets have become quite common in engines with aluminum manifolds and
heads and are caused by repeated thermal cycles and gaskets that are
designed for easy assembly at the factory, These leaks commonly show up at
around 100,000 km.

Changing an intake gasket is not a difficult job for a driveway mechanic,
but may require the purchase of a special wrench or two. IMHO the key to a
successful repair is to carefully and completely clean the old gasket
without damaging the soft aluminum and to use a top quality silicone gasket
glue. IMHO the best glue is the grey sensor safe silicone sold by GM, it is
a little pricy and its thick viscosity makes it harder to spread but it
works well when carefully applied. IMHO the bolts should be lubricated with
thread lubricant suitable for aluminum, and torqued (at least) to the higher
side of spec and then retorqued after silicone has compressed, again when
warm and again after cool down. I suspect the factory gaskets fail because
of lack of this retorqueing.
Good luck YMMV

Many thanks !
I think I'll be looking to deal-off the Saturn - they seem like good
cheap cars - for the guys who like to work on their cars.
I'm more used to just driving them for 250,000 or 300,000
km ... without the "working on them" part ..
.... 2 Taurus's and a Mazda in the last million km.
... never a wrench on the motors or transmissions.
John T