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Coil Bolt?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by R_W, May 31, 2024.

  1. R_W

    R_W Junior Member

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    A few years ago, when I replaced the coils in my 2010, the head of the bolt holding the first coil down broke off.

    I did not have a bolt extractor at that time and all the stores were closed, so I just ignored it because everything seemed to work right. The next day, I bought a bolt extracting bit, but since I could see no issue, I just continued to ignore it and did not do anything about it the next time I changed the coils too. (PSA: Cheap coils apparently only last a few years.)

    Lately, I have noticed a little oil on top and figured it was where one of the kids had spilled some. (My 2010 uses about a quart between oil changes, which I have been chalking up to it being a 2010.)

    Today, the car was up on a lift and you can see where oil has trailed down from the top and has blown on parts underneath. None of it is reaching the ground because it is not on my driveway or my wife's parking spot at work, so I interpret that to mean that maybe oil is leaking while the car is running and not while it is parked.

    As I start spitballing what might be happening and before I've done any research of my own, I thought I might ask here for opinions about whether the coil not being fastened down could be the source of the oil?

    Apologies for being lazy and just asking the experts, but it strikes me as something somebody might know.

    Thanks.
     
  2. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    The coil assembly doesn't include any oil seals.

    The oil is probably leaking past one of the valve cover gaskets. There's a big one around the perimeter, and then an "island" for each of the four coil tubes. It's probably leaking at that tube gasket.

    Coil not fastened down can give you a misfire when you hit a pothole, that's about it.
     
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  3. Tombukt2

    Tombukt2 Senior Member

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    Chain tensioner or oil sending unit
     
  4. R_W

    R_W Junior Member

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    Thanks.

    @Leadfoot J. McCoalroller: That is kind of what I thought, especially since the bolt head has been broken for years.

    It looks like it could come from the gasket. Though since it is in line with where oil would seep down if spilled when pouring, I thought the oil had been from it. Like I said, there's none on the driveway and until this afternoon, when a mechanic decided to yell at me and send me away without him doing any billable work, I didn't know that the leak was more than just that little visible smudge.

    (Semi-long story. I guess he was having a bad day and is pretty much an a-hole.)

    Again, thanks. I guess I'll do the wheel bearings myself (or take them to a McGarage) and I'll look into the valve cover gasket issue because now that I know the bit I'm seeing is probably not a spill, yours seems like the most logical explanation.

    (I guess it's also good news in that maybe my 2010 isn't burning a quart of oil every 10k.)
     
    #4 R_W, May 31, 2024
    Last edited: May 31, 2024
  5. R_W

    R_W Junior Member

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    @Tombukt2: Thanks for the suggestion. I'll look into those.

    Right now, considering that I didn't know there was an oil leak, my focus is on the wheel bearings because my wife is taking her Girl Scouts on a trip next weekend and had been wanting to use that car.

    Though, now that I know there's a problem, I've added it to my list.

    Thanks
     
  6. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Any backstory on the broken bolt? There is a gotcha in the repair manual: the torque value is in inch/pounds, which are 1/12 of foot/pounds.

    the bolts are just to keep the coil from somehow rattling loose, need no more than a good snug. But there’s been several reports, DIY’rs see the inch/pound torque value, get out the 1/2” drive torque wrench, set it to a value that’s 12 times too much (wheel lug nut territory), and snap off the head.
     
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  7. R_W

    R_W Junior Member

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    @Mendel Leisk: I don't remember whose video I was following -- as you know, the Prius is very different than my old Fords, so the first time I followed a video -- but I went to Harbor Freight and bought the small torque wrench special for the job.

    I don't know if it was the inexpensive torque wrench or the fact that I had never used one, so I was inexperienced, but as soon as that first bolt sheared-off, I remember dashing to this forum to verify the setting they gave in the video and to confirm that I really didn't need to torque it. As you say, they are really just holding the coils down and I've never had any ill effects from having one unbolted.

    (Though this new, previously unrecognized oil leak made me wonder. So I did as I've always done when researching a repair, I went directly to PriusChat. Today, it wasn't five minutes after the garage clerk had fired me as a customer.)

    BTW: Special thanks to you, @Tombukt2 and all the other experts who have helped me over the years. Whenever I see someone asking a difficult repair question in another forum, I send them here to PriusChat.
     
    #7 R_W, May 31, 2024
    Last edited: May 31, 2024
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  8. R_W

    R_W Junior Member

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    I know this is off-topic for the title and when I'm ready to do it, I will make a new post -- right now, I guess it may be leaking, but not enough to be a priority.. Apologies for asking a follow-up question.

    I cleaned the area on top, right in front and saw what looked like could be a bulged-out gasket, which was actually broken or nearly broken outside of the valve cover. I assumed that could be the leak, but later when watching a video that was mostly how to remove the valve cover, when the YouTuber showed the final product, it looks like he might have the same bulge

    My part is dirty, so I took a couple of clips of his. The first is an isolated shot of what looks like I see, slightly enlarged, followed by a an overall view. (Focus is the white "goo string"above the empty bolt hole.)

    upload_2024-6-1_3-5-32.png

    upload_2024-6-1_3-4-16.png

    If anyone would like to confirm this is normal, it would prompt me to look for something else.

    (I have wiped down the area, run the car for a bit and will keep an eye on it and everything else I can see.)

    Thanks.
     
  9. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    That’s normal.
     
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  10. Tombukt2

    Tombukt2 Senior Member

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    That's just Fipg place gasket oozing out at assembly . That's exactly what you're looking to have happen when you assemble one of these engines correctly That's just permatex gray Toyota's equal of that material It's in a tube they use that now a lot instead of gaskets when they can. You want to clean off your engine with something like super clean anything that's not silver like around where you put the oil in you'll see black residue that looks like it's taken on dirt that's where people have spilled oil when they're trying to get it to hit the hole and it runs down and then dirt sticks to it and anything else that the fans blow around under the hood so after you shut the car off when it's hot good and warm you let it sit about 30 minutes or so so the exhaust manifold gets reasonably cooled off and that sort of thing maybe the hood up semi in the shade You don't want the sun beating down on it after the exhaust manifold gets cooled down enough to where you can touch it literally You don't have to grab it with your whole hand but putting a finger on it doesn't produce a blister instantly then it's safe to spray the engine off with a mixture of super clean and a little bit of water You do that let it soak in well if you're spraying the super clean on the engine and it's steaming and drying immediately you're too warm anyway when you get this right you let that sit on just a couple minutes and blast it off with the hose your engine should be silver and everything else should be black Black rubber silver aluminum after you get that cleaned up nicely then you want to start running your engine and driving and looking all around it with a flashlight after every run I don't care if you're making runs out in front of your business or street up and down the road and you just keep looking until you start to see the beginnings of seepage from somewhere timing cover valve cover that sort of thing usually head gaskets don't pour oil out of them. Then when you find the vapor in the leak usually around oil sending units are popular timing chain tensioners are popular that sort of thing penetrations of components.
     
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  11. R_W

    R_W Junior Member

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    Thanks.

    I had thought about getting some Gunk brand something -- I have some Speed Perks to burn-off over the next few days -- but the engine isn't really that dirty, so I started by wiping down the spot on my car that is shown in the screencap with a (singular) disinfectant wipe.

    As I said in my initial post, I have been adding about a quart between oil changes every 8 to 10k or so and have been chalking that up to it being a 2010 with over 300k.

    I'll certainly wipe everything down from the top and keep a check for where the oil might reappear, but it really isn't using a lot and there is none on my driveway. (Though the mechanic tried to call it a "massive" and got angry when I was surprised, what he showed me looked like someone had sprayed that bit of the underside with a coating of Pam. It was nothing anywhere near like the underside of my aways-leaking Ford trucks.)

    (I should add that I pulled the bottom cover off years ago, so there's nothing to prevent the leaking oil from reaching the ground.)

    Again, thanks to everyone for the help and I'll keep a check on this post.

    When I know where it is leaking and are ready to do something about it, I'll definitely search the forum and maybe make a post of my own, but the stuff I wiped off has been there for at least a year and the amount of oil usage has only incrementally changed over the years. (And, right now, I have to concentrate on getting the bearings done, plus I've never even looked at my rear brakes and my wife just knocked-off her third passenger side mirror -- she doesn't like trash days.)

    Again, thanks for the help.
     
  12. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Ours, for comparison.
     

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  13. R_W

    R_W Junior Member

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    @Mendel Leisk: Mine looks like yours, except mine had a light coating of dirty oil and I didn't get too deep into cleaning around the white goo, in case it was a gasket leak. Thanks for the pic.
     
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  14. Tombukt2

    Tombukt2 Senior Member

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    Yeah it sounds like your oil sending unit or timing chain tensioner or something like that is letting some vapor out and then it's getting blown around by the fan settling down wherever it does
     
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  15. R_W

    R_W Junior Member

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    Thanks. I'll definitely check it out.

    (I assume they are in the not-hurting-anything-until-it-throws-a-code category?)
     
    #15 R_W, Jun 2, 2024
    Last edited: Jun 2, 2024
  16. Tombukt2

    Tombukt2 Senior Member

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    Probably not hurting anything even when the code is being thrown Just make sure that you generally keep your oil between the dots on the dipstick is your best bet Make sure when you check your oil you're on semi-level ground in the engine's been off for say 5 minutes so you're not overfilling never overfill better to be a tad under than ever over.
     
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