What I Learned From Fixing The Headgasket On My 2010 Toyota Prius

Has the Check Engine warning for Insufficient EGR flow gone away? A CEL illuminates only after a failure occurs several times. The light may be a remnant of an older problem, although you could use TechStream to cycle the EGR value to make sure it's opening and closing.

Hello!

Great articles about EGR, 3 signs of head gasket failure and this one. Very helpful. I have 1/3 of the symptoms as described in the 3 signs of a head gasket failure article. Very occasionally I get the aggressive rattle in the engine. This has happened 10 or less times over 2 years. A previous mechanic said it happens when the oil gets low. I check the oil more often, add some if needed and that seems to stave off the rattle/knock.They last a short bit of time or I turn it off and usually starts up okay after that.

Would this still be a head gasket problem or something else? Coolant levels are good and oil change last weekend showed normal color oil.

I'm doing my research now on how to change a head gasket but want to make sure it's the right move to make. I'm not real experienced with cars I have a desire to learn and have been helping friends recently which inspires me to take that roll. I have a trusted and experienced friend who is and agreed to help.

Any advice would be welcomed! Thank you!

Two things I regularly see on the gen 3s are coolant pump not functioning correctly and egr coolers that are plugged up. These are the contributing factors in the head gaskets letting go.

Thank you much. Just purchased the 2010 prius solar. I have the strange misfire at start up. After the plugs, the misfire was gone until tonight. It has 192000, oil changed every 5000 or less, documented on carfax. Crystal clean valve train to include the entire car. This thing was well cared for. It runs smooth except for the start up misfire rattle. I have no milkstake or reduction in coolant, however, there is a coolant odor inside the cockpit. After reading all of the head gasket issues, I feel this would be a good subject for a head gasket. Do these engines live on after a head gasket or are they done at 200000? I've heard everyone replacing them. What do you think? Also, this will be my first engine with that cam phaser. Is there anything special to that, or just line everything up to TDC like usual? Thanks for any insight.

Peter, the mechanics that discouraged you from replacing the head gasket the gen 3 Prius sound like alarmists. If the engien runs fine at any time during your test, the main components are still good. A problem like a bent rod doesn't come and go. I've never seen a bent rod occur on startup. If enough coolant has leaked into the cylinder (hydrolock) to cause this kind of damage. The engine simply won't crank. It will just stop when it reaches the hydrolocked cylinder with its valves closed. The only time hydrolocking will bend a rod in a Prius engine is if a copious amount of coolant enters the cylinder while the engine is running and the piston has the momentum of the spinning crankshaft. And if a head gasket leak is so severe it could fill a cylinder within a few milliseconds, I doubt that engine would have been able to run at all. The only time this amount of coolant can enter the cylinder is while the engine is stopped and it slowly fills the cylinder. But again, the engine won't even crank. There are lots of mechanics who are afraid of head gasket jobs because of lack of confidence in their own ability. For some, it takes several dozen to gain that confidence. Some will never get over it. It's just easier on the brain to cover your butt and recommend an engine replacement. I've had old-timer mechanics who are so uncomfortable doing them, I'd have to reassign jobs.

It does happen more often than you'd think that the coolant causes the piston to break. I have one in my shop now that broke the piston then the rod punched out the block front and back. You can look straight through the engine.
Once that morning miss begins I wouldn't waste time getting the gasket replaced along with cleaning out the EGR heat exchange. I,ve gotten to where it's better for me to keep a few cleaned EGR coolers on hand and just exchange them when doing the head gasket job or....replacing the engine.

As an avid used Prius buyer from auction almost all Prius from 2010-2016 will Experience this head gasket failure. I am shocked no one has rattled Toyota corporate for this well known issue. Toyota doesn’t care as it’s out of warranty and gives two shits about it. I wonder if it’s happening to gen 4 as well and wonder when we will see a flood show up with the issue. You can fix the head gasket only and it will survive everyone I’ve done has worked great. My plugin is at 245k and my V is at 299k both with new HG. The main freaking issue you will have after this is oil consumption. Every dealer knows about the old xb rav4 Recalls for oil burning and the Prius is also one of those. You will have to fill you’re Prius every 3 days depending how bad you’re low tension rings are. Shame on you Toyota for not fixing such a simple issue. Then again I almost have 300k lol

As an avid used Prius buyer from auction almost all Prius from 2010-2016 will Experience this head gasket failure. I am shocked no one has rattled Toyota corporate for this well known issue. Toyota doesn’t care as it’s out of warranty and gives two shits about it. I wonder if it’s happening to gen 4 as well and wonder when we will see a flood show up with the issue. You can fix the head gasket only and it will survive everyone I’ve done has worked great. My plugin is at 245k and my V is at 299k both with new HG. The main freaking issue you will have after this is oil consumption. Every dealer knows about the old xb rav4 Recalls for oil burning and the Prius is also one of those. You will have to fill you’re Prius every 3 days depending how bad you’re low tension rings are. Shame on you Toyota for not fixing such a simple issue. Then again I almost have 300k lol

I have a question Peter.... My "NEW" 2010 JDM engine with 50k miles on it is due any day here... I am thinking about replacing the head gasket preventatively. Is the quality of the original head gasket the issue here on why I would replace it or is it something else? And what would I gain by changing the head gasket? Thanks for any advise you might offer.

Wish I read your article a few months ago. Just purchased my second Prius (2013). Had it for approximately two months and now it's just sitting in my yard because I am not certain what to do after the dealer told me that it's leaking coolant in the Engine and they can't tell if it's the Eng valve ($2000) or in need of a new engine ($6000). I only paid $5000 for the car, so I just can't pay $6000. My problem sounds exact to your 3rd gen issue. Any advice on how to find someone in Pittsburgh WO can do the work. Dealer price is way too much!

I have a 2010 Prius with 185K miles on it, and after recently replacing the spark plugs, coils, fuel injectors, and servicing the EGR I still manage to have some miss firing going on. I noticed when's taking the spark plugs out of cylinder one that it was wet and my coolant level was lower. I am assuming my head gasket needs to be replaced. Where can I get a good set of instructions on changing out the head gasket as what's you followed? Thanks in advance

I did the gen 3 head gasket and really thought it was pretty straightforward. The internal combustion section of the power train is found in many Corollas and a number of other similar cars. Unfortunately, the owner continued to drive it after the gasket failure for some time and complained that randomly, initial startup in the morning was difficult. And, coolant was being burned. Depending on the piston position in the affected cylinder, whether the piston was on the compression stroke, and amount of coolant, engine rotation can begin but then be abruptly halted. This, combined with the fact that electrically generated torque is well above what a normal car starter produces, IMHO could radically stress the piston rod. I'm not an engineer though. The affected cylinder had significantly higher compression than the other three. And, there was polishing in two areas instead of the cross hatching found elsewhere. This was caused by the bent rod and that eventually led to the break. My suggestion would be to inspect cylinders for any polishing and toss then engine if any is found. Also, compare all pistons at TDC and if there are any differences, toss it. I think a piston could also likely be replaced with the engine in the car but would require removal of oil pan, likely the oil pump, etc. Unfortunately, I didn't know enough to toss this one so wasted some time and effort on the gasket replacement.

Thanks for the article Peter. Wondering if you (or anyone following this article) has a parts list covering everything required for a full head gasket replacement job on the 2010 Prius so I can properly cost it out before setting out to do this on my own? Also, looking for recommendations for the best place to purchase reliable parts for a job this intense. Not looking to do this a second time because of inferior parts :) Thanks in advance.

Jesse, I'd suggest you look through all the relevant info on priuschat.com. If the car was producing which exhaust smoke, then coolant was being burned and there's a possibility of hydro locking where coolant enters a cylinder after engine shutdown. This can bend a piston rod and I'm not sure how to easily check that except when cylinder sidewalls have been made shiny/polished. Maybe measure piston height at TDC? If you do the head replacement, cleaning head bolt threads and properly torquing and de-torquing head bolts will be much more important than the quality of parts you use. I like FelPro gaskets and bolts. I'd suggest a water pump and/or a timing chain, depending on the mileage your car has. You can always get Toyota parts or you can get the cheapest ebay or amazon stuff you can find. The cars I work on are usually 10 or 20 years old so I focus on the cheaper parts. I also like to take pictures after each part I take off and put bolts and nuts with each part in a plastic shopping bag or ziploc bag, You might want to consider row52.com or used motors as it's really not that much more difficult to pull and replace the motor. You do need an engine hoist that you can rent or borrow though. Also, keep in mind you may need to surface the cylinder head, although I wouldn't if it has a flat surface. Also, make sure to get all the bolts and nuts holding the coolant tube on the driver's side of the cylinder head. I forgot one and the locating pins caused some scratches in the cylinder head face as I was trying to remove it. If you leave the exhaust studs in the head, you need to pull it off pretty much straight forward.