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BMW 3-Series (E90 E92) Forum
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Broken valve cover bolts (N52)
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10-17-2009, 01:26 AM | #1 |
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Broken valve cover bolts (N52)
Hey all, first time I ever posted but a few weeks ago the fact that my valve cover was leaking was brought to my attention. I figured this is something I could do myself and save a few hundred dollars as I'm way over the warenty mileage (I've heard quotes as high as $900 for this job). Anyway, my parts came in today (gasket & new bolts) and I started getting all that stuff on top of the engine out of my way. As soon as I got that engine cover thingy out of the way I discovered the source of the leak. Two of the bolts on the valve cover were snapped. Needless to say I'm pretty pissed off and I guess I'll be spending a good amount of time tomorrow trying to get those things out. Are there any good ways of getting those things out? Anybody else have this problem? A friend of mine who's a mechanic gave me some ideas (unfortunately he's busy for the next couple of weeks).
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10-17-2009, 08:28 AM | #2 |
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Not being able to see the situation, I'm just guessing here. Since your engine is relatively new the bolts shouldn't be too hard to extract since they are probably not corroded in. First off remove all the other bolts and remove the valve cover. Then apply some liquid wrench or PB Blaster to the studs to break any corrosion bonds that may be present. Also, I’m not sure the bolts are aluminum or steel. There are a lot of aluminum bolts used on the N52 due to the use of the magnesium block. The head is aluminum though.
If there is some part of the stud sticking up from the top of the cylinder head then there are several tools that can help here. One is a stud extractor. There are cheap ones that use a cam lever against the stud. The tool looks like a fat disk with a hole in the outer edge that fits over the broken stud. Most NAPA stores will have it in the special tools section. The problem with this tool is it needs room, as the disk is about 1.5 inches in diameter. There is a better stud extractor, which looks like a drill chuck, and works much in the same way, but in reverse. They are expensive. Another tool is a bolt extractor, which looks like a socket, bit with deep cutting flutes in it. You'd have to find a set with one small enough to grad the bit of stud. Finally, a good set of visegrip pliers might work considering the studs should backout easily since there is no pressure on them. If the studs are broken off flat to the cylinder head, then you need to use a screw extractor, which is a funny looking drill bit with left-hand cutting flutes on it. This tool requires drilling a hole in the center of the stud, then screwing in the extractor left-handed (counter clockwise) until it bites and starts removing the stud. |
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10-17-2009, 01:54 PM | #3 |
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doing the job is kind of a PITA. getting the valve cover out of car is the hardest part. the bolts break constantly thats what always causes the leaks. they will turn out by hand or with a pick if the bolt is recessed into the hole still. however, getting the valve cover out around the valvetronics portion of the head is difficult. also, be sure you have a torque wrench that goes to 7nm and you will also need to replace the bolts and angle torque them to 90 degrees...
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10-18-2009, 04:42 AM | #4 |
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Hey all,
I started getting the valve cover off and yup, getting around that valvetronic motor was turning into a nightmare. At that point I took a second look at the broken bolts and decided to take a shot at getting them out with the cover still on. I know just replacing those bolts isn't as proper as replacing the whole valve cover, but much much easier. They were only recessed about a 1/4" from the surface of the valve cover. I decided to use left-handed drill bits to drill them out and then use one of those bolt extractors to finish the job. I was quite nervous this being an aluminum head and all. Anyway, they ended up popping out in the process of drilling the holes (left-handed bits are awesome). The bolts are now replaced (torqued 7 N-m & angle torqued 90 deg). I really wish I had one of those plastic covers and steel bolts the newer models have. Are the covers compatible? I got lucky this time with the bolts breaking in the front but if it happens again and its at the back of the engine I'm going to be very unhappy. |
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10-18-2009, 09:06 AM | #5 |
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had this happen to me a month or two ago, pulled out the driveway and see the aluminum broken bolts on the floor! WTF
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05-18-2010, 10:15 PM | #7 |
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Yup this sounds like every other valve cover gasket job on the N52 engine. I did mine last october and had one broken bolt on it. I said f*** it and I took it to my Indy shop and had them do it.
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05-20-2010, 12:09 AM | #9 |
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Just changed my VCG today... It definitely is a PITA, but if you have the right tools and patience its doable. One bolt in the front lower bottom corner was completely missing and the bolt next to it was broken in half.
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05-20-2010, 01:56 PM | #10 |
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I had the same problem. Stealer quoted $3000+ for the fix. Lucky, it was covered by warranty.
Good to hear that you could have everything done by yourself. Does anyone know how often those bolts are likely to break? |
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10-26-2010, 08:18 PM | #11 |
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can some one quicly explain to me how do i take off the cover and valve cover? because mying broke over the weekend and i really need my carand im out of warranty soo DYI TIME LOL so please help me out..
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10-27-2010, 10:53 AM | #12 |
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This is not a type of diy that someone can explain quickly. Invest in a bentley manual.
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If no codes are being thrown use Chevron Techron fuel injector cleaner (concentrate). It solves rpm fluctuating upon cold start-up. Also, for most BMW problems start off by scanning your car with the Peake Research Tool. It contains the actual BMW codes. If you want to register a newly installed battery for free (just buy a $10 cable) and google/download BMWLogger
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11-02-2010, 10:48 PM | #13 |
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You can just pop the plastic covers off and replace the broken bolt(s)... that's what I did... seems to be working just fine so far.
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03-30-2011, 12:40 PM | #14 | |
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Did it work?
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06-09-2011, 11:42 AM | #16 |
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FWIW, I had 3 broken Al bolts on my valve cover at 85k miles. 2006 325i (E90 car, N52 engine). Dealer replaced the gasket and bolts under CPO warranty. Dealer also replaced some other gasket (?) where they noticed oil leaking in the vicinity of the oil fill.
Warranty on the repair is said to be two years from the date of repair, with unlimited mileage. |
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06-09-2011, 06:19 PM | #19 |
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Just replacing the bolts is one thing, but if you open it up and replace the gasket, you need to replace all the bolts regardless of the fact that they look fine. They break when they're new so a reused one will almost certainly brake at some point. If the gasket didn't over saturate with oil, it should be fine. I paid $500 to get mine fixed, but I had several broken bolts and it was leaking quite badly.
I had a tech tell me that that the parts are actually not that bad. BMW over-torqued them from the factory and that's why the brake. I have no clue what the old or new torque specs are. He said, he's never seen one with broken bolts again after they have been replaced. Then again he worked at a dealership, so maybe they just never came back to him. I have 60,000 miles (160,000 miles total) on my new bolts and they haven leaked yet. Only time will tell.
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06-09-2011, 07:27 PM | #20 | |
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06-27-2011, 10:43 AM | #22 |
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