Main water pump leaking, now oil in spark plug

1. Was the engine coolant pump replaced? Hard to imagine a gallon of coolant could leak out via its bearing weep hole. Any other leaks?

2. The plug closest to the passenger-side fender is the cylinder 1 spark plug.

3. Yes, certainly an aluminum engine can be easily damaged due to overheating. You would need to have a cylinder leak-down test performed to determine if cylinder 1 or any other cylinder has a problem.

 

Is the oil on the boot or ceramic of the plug or on the tip that goes in the cylinder?

 

I hope it is your water pump but it sounds like you lost a head gasket. that can cause oil in cylinder and loss of coolent. If you drive it you may cause damage to the engine. It is easy to have a lot of water go out the exaust. If there is no water in the oil it is a good thing. One thing you often see with a blown head gasket is steam in your exaust, it will look like white smoke. It is not a cheap fix, will probably need head shaved and new gasket installed and this cost a fair amount. I would take it to have it checked out. if the stealership says its a water pump I would take it somewhere else and see if they have the same opinion.

 

Re: Your water pump. A couple of years ago Toyota had a recall to replace one of the water pumps on the 2004 model... I do not recall which one of the two water pumps it was. If you have not had a water pump replacement, I suggest that you have your dealer track down that recall and replace the subject water pump. Hopefully it is the one you are having a problem with.
BTW... My 2004 Prius with 135,000+ miles was recently given a full inspection and the dealer's service manager was a bit upset as all they could recommend was new wiper blades. I have approximately 5,000 miles left on my original break pads... both front disk and rear liners. I have yet to have any repairs, other than those performed on a recall or as a function of routine, scheduled maintenance.

 

Re: Your water pump. A couple of years ago Toyota had a recall to replace one of the water pumps on the 2004 model... I do not recall which one of the two water pumps it was. If you have not had a water pump replacement, I suggest that you have your dealer track down that recall and replace the subject water pump. Hopefully it is the one you are having a problem with.
BTW... My 2004 Prius with 135,000+ miles was recently given a full inspection and the dealer's service manager was a bit upset as all they could recommend was new wiper blades. I have approximately 5,000 miles left on my original break pads... both front disk and rear liners. I have yet to have any repairs, other than those performed on a recall or as a function of routine, scheduled maintenance.

 

Re: Your water pump. A couple of years ago Toyota had a recall to replace one of the water pumps on the 2004 model... I do not recall which one of the two water pumps it was. If you have not had a water pump replacement, I suggest that you have your dealer track down that recall and replace the subject water pump. Hopefully it is the one you are having a problem with.
BTW... My 2004 Prius with 135,000+ miles was recently given a full inspection and the dealer's service manager was a bit upset as all they could recommend was new wiper blades. I have approximately 5,000 miles left on my original break pads... both front disk and rear liners. I have yet to have any repairs, other than those performed on a recall or as a function of routine, scheduled maintenance.

 

Did you notice this oil on the actual spark plug electrodes after removal, or are you just referring to oil being present around in the spark plug well before removal.

- If it's the former case then please post photos of the spark plug in question.

- If it's the latter case then it's merely due to spillage sometime during an oil fill. Not a big problem.

 

Sounds like you've got a handle on it. Looking at the pics of the plugs, if you didn't overfill the oil, just keep an eye on oil consumption and your exhaust. If there's no smoking or rough running, probably not any problem in that area.
Might check posts on water buildup on the cowl below the windshield. That could have caused water to run on and pool around the one rusty plug.
At 125,000 miles I would also recommend changing the inverter coolant and transaxle ATF if they haven't been done in the last 30,000 miles. Had one guy changed the ATF at about that miles and MPG went up 9 MPG, not typical. It really extends the life of the transaxle. Both the inverter coolant and transaxle ATF are fairly simple drain and fill procedures any DIY-er can handle. Lots of posts here about both.

 

Adding to the recommendation regarding changing the coolant for the inverter. I'd recommend changing the inverter cooling pump. I was let down by this pump failing at about 180,000km (about 115K miles) which was very inconvenient. Pump isn't super expensive but if it breaks in the middle of nowhere it is a pain. You will see a big nasty warning triangle then the car starts shutting down systems to protect the inverter (Cruise control, A/Con, 12 volt charging system, etc) then the car will stop and damage to the inverter may occur if the inverter overheats. It's unlikely to overheat on short journeys, but on a long one, very inconvenient. Mine went out in the middle of a 3,500km journey in the Australian outback, fortunately near a town with a Toyota Dealer. Car was off the road for a week, used a hire car to complete part of the journey.

 

Not a bad idea. On 2004-2007 there was a Limited Service campaign A0N to replace the inverter coolant pump at no charge.
Don't know if there was a similar LSC for 2008.

 

Not sure if we had that in Australia.

 

Yep that's an overfill right there.

3.5 quarts is a pretty safe fill, as long as you've properly drained. Just check the dipstick, anything near to full but not overfilled is perfect.

 

I would be angry if my oil was overfilled. I think that can cause damage to engine, and could start an oil leak. Im not sure if .5 quart is going to hurt this engine but it is not the correct amount.

I guess you could keep one of the empty quart btls and fill it half way with new oil and give him that along with three full ones. I check my oil after it is changed to make sure it is right.

 

Yeah, it's using oil, that's why your plugs were oily. When it's overfilled it seems to use that excess oil relatively quickly. That's what actually causes the problems.