Greetings, I have 2011 Prius II with 125K miles on it. All routine maintenance by the dealer per manual. New spark plugs and new transmission oil, as well as inverter. Synthetic engine oil every 10K miles. Do not drive it hard at all. Original owner. About 6-7 month ago, started hearing pinging noise when accelerating uphill. Faint but real. Not every time but quite often. Use Costco gas for the last 4 years. Once tried premium (93 around here) gas, which seemed to have solved the issue, but it is back again with regular gas. Any ideas/advises? Wanted to keep the car for a bit longer, hoping for 200K miles or so. Will take it to the dealer again, but want to know what to ask and expect. Thanks very much.
I do not check manually. Never had warning signal come up. Never have been told the levels were low at the dealership. But pinging happens even right after the oil is changed. Usually change the oil twice/year. Certainly can check tomorrow. Should not take long..
I’d make checking the oil a regular thing. If it does get low, it can cause all sorts of noises and things that you don’t want to have. Good luck and keep us posted .
Watch your coolant level. Pinging is a subtle sign of overheating/low coolant. My 2010 did that when I got it. Found a slight coolant leak that I stop leaked. It lasted 3 months or so, then it went all at once. And I'd go with a 5k or 7500 mile oil change interval given the mileage on the car. That puts you(or your technician) under the hood more often. You need to be proactive on this one.
If that is the infamous "Knocking" noise you are hearing, I don't think it has anything to do with your oil change or the gas you use. The typical follow up question would generally be "Are you losing coolant?"
Carbon buildup? Consider hotter plugs for your personal driving habits, else drive it a little bit harder.
So my engine coolant is low. Taking to the dealer tomorrow. Thanks for tips. What brand and where can I get it myself? Diluted or no? Thanks
Sophie, While filling up the coolant reservoir would not hurt, it may be irrelevant at this point. Because the reason you are hearing what you are hearing isn't because you are low on coolant. It is because where that coolant is getting to. I am hoping I am wrong but if it is what I think it is, it will be a costly repair job. Don't immediately go with the dealer offer if they say it is the leaky headgasket. Anyways, hoping for the best and let us know...
@iskoos Interesting... So I filled the coolant tank. While the pinging is better, it is not completely gone (30mi and 40min driving, mostly highway). How much does it cost to replace head gaskets? Worth it? What are the options? If the head gaskets are leaking, should I try to get a private mechanic to look into it? Is that a known issue with this model? Something I did or did not do with the maintenance? Thanks
Head gasket replacement is 90 percent labor. The “official” Toyota way says pull the gas motor to change it. This video is the shortcut, still pretty expensive though. Toyota way is about $3600 if I recall correctly. These guys do it with the engine in the car.
Just a follow-up. Took the car to the dealer. They did not charge anything but also did not find anything. Pinging/knocking noise was not reproducible. I also cannot hear it any more. No leak was found in the coolant system. They did pressure test and said it was normal. They confirmed coolant was changed at 90K mi (2 years/35K mi ago). I do not see any spots on the garage floor under the car. For full disclosure, I did move the coolant tank about a year ago to swap the headlight bulb. Just removed the 2 bolts and moved the entire assembly. Did not disconnect the attached hose. Cannot remember if the tank was full or not at that time. Will be checking the coolant weekly for now, but still have no explanation where it all went. When I opened the tank to add coolant, pressurized air did come out with a hiss. The engine was a bit warm, as I had to drive about 2 miles to get to the store. Tried to use battery as much as possible to keep it cool, but it was also a hot day. Thanks
Hi Sophie, first thing first, please check on the coolant and oil level every week as many has suggested. But before jumping into the head gasket, let's take one step back into the original post. Problem: I think you had already described the symptom and had tried a low cost diagnostic to confirm the problem. Pinging under load (you said accelerating uphill) may have something to do with carbon deposit, clog injectors, clog EGR system, low grade fuel, etc. Solution: Easiest and least expensive would be dump a bottle of Techron fuel additive into your gas tank at the next fuel up and start using brand name fuel (I may have opened up a can of worm for argument as some members don't believe in brand name gas and fuel additives LOL). Also recommended by many members here is cleaning of intake manifold, EGR circuit -cooler, valve, and pipe (should get these done periodically anyways), replace PCV valve, and install oil catch can. Depends on your skill level, DIY (or know a good friend) can be very inexpensive as you provide your own labor.
Thanks. Already got a pack of Techron fuel additive. Hope it does not damage the engine. Will try to use it with 93 octane once every 3k or so. Cosco generally sells brand name gas. I tried Shell 87 but that did not seem to make a difference. I am not that eager to do DIY stuff, but will ask the dealer or private mechanic about doing what you suggested. Thanks again.
Screw a compression tester style hose (with the valve removed?) into each cylinder, and connect to compressed air, see if you get bubbles in the engine coolant reservoir. Somebody posted a video on that today, can't recall which thread though.
Techron won't hurt your engine. Note that the manufacturere recommends limiting the treatment to twice per oil change, as the product can dilute your oil via leakby through the rings. 'To keep the entire fuel system clean, use Techron Concentrate Plus, Complete Fuel System Cleaner, every 3,000 miles (4,800 km) or at scheduled oil change intervals, not to exceed twice per oil change." Costco always sells Top Tier gas, as far as I know. There is no name brand other than Costco - they buy it from a distributor mixed to their specs.
