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