Rust where is should not be

The "first cylinder closest to the synergy drive" is cylinder #4.

If you wish, you can upload a photo file by "Go Advanced", and look for the file attachment utility.

The usual reason why a spark plug would be rusty is because water entered the spark plug well. You've probably noticed that only one small bolt holds each spark igniter to the valve cover. The rubber O-ring around the igniter does not form a perfect seal.

Water can drip down from the cowl onto the engine. Or, if you wash your engine, this provides another possible way for water to appear on the valve cover, then enter the spark plug well.

What does the spark igniter look like? Is it also corroded? Are there any burn marks upon, or cracking of the plastic body? If so, then the igniter should be replaced.

If your extended warranty plan was provided by Toyota, then it should expire when your odometer reaches 100K miles. I'm not aware of an extended warranty plan that provides coverage beyond that mileage. If yours really does so, please scan the terms of the plan and post as a .pdf file.

 

A blown head gasket would not cause the rust shown in your pictures. If a head gasket leaks, the coolant will either leak into the combustion chamber, into the crankcase, out between the cylinder head and block or some combination of the three.

I agree with Patrick that the rust is due to water getting into the spark plug well.

 

Now that you've provided photos, I suggest that you replace the four spark plugs with the correct NGK or Denso iridium plugs (see owner's manual for the correct model numbers), and clean off the igniter that was in the photo, using a couple of paper towels moistened in paint thinner. Since the igniter produces high voltage, do not use water, and make sure the igniter is perfectly dry before reinstalling it.

You should also clean out the spark plug well the best you can, using more paper towels and paint thinner. Not too much paint thinner - you don't want liquid to enter cylinder #4. Make sure the spark plug well is dry before you reinstall the spark plug and the igniter.

What does the high voltage terminal in the bottom of the igniter look like?

If you cannot remove the rust stains, if the high voltage terminal is corroded, or if you find cracks or burn marks in the plastic, I suggest that you replace the igniter now so that you won't have a misfire problem later.

 

The dealer should have done this, but confirm with a dealer or with Toyota USA (they have a toll-free number; have the VIN handy when you call) that all applicable TSB (Technical Service Bulletin) repairs and modifications were performed on this car. Some early versions needed to have the hood gasketting replaced to prevent water entry.

It's also possible that a previous owner was a nutcake who washed the engine with a garden hose.

 

would that earlier version include for 2004 prius? ill look

 

2004 at 160,000 mi...
gasket replaced.

 

2004 with less than 100K miles?! Wow!

 

Thread is from 2008