05-28-2017, 06:04 PM | #231 | |
Relic
Join Date: Oct 2003
Location: Bethesda, MD
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Quote:
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2011 M3 2006 Sierra 2500HD 4WD LBZ/Allison 2004 X5 3.0i 6MT 1995 M3 S50B32 1990 325is 1989 M3 S54B32 Hers: 1989 325iX 1996 911 Turbo |
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05-28-2017, 06:40 PM | #232 |
No more BMWs
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They all have to be drilled out. Not looking forward to it
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05-29-2017, 10:19 AM | #233 |
No more BMWs
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Matt had complained about stalling and some lumpy power delivery at low RPM which is almost always a sign of failing VANOS seals on these cars. BMW used o-rings that tend to get brittle with age and they don't seal well, causing oil to bypass the pistons and not actuate the cams properly.
With the VANOS unit off you can see the covers that retain the pistons. With the covers removed, the pistons come out. You can see the o-rings, which are a square cross section. There is also a spacer beneath these that takes up some of the depth in the piston groove. When the seals are bad it's very easy to tilt the piston in its bore, not a good sign. The only way I've found to remove the seals is to cut them with an X-acto. There are aftermarket kits to replace the seals with a more resilient material, so as soon as those come in I'll replace them. |
05-29-2017, 04:44 PM | #234 |
No more BMWs
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Carmudgeonly Ride: Ram, MS3, CX-5, RX-8
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Next fun task, exhaust stud replacement. These are a bitch and a half. They always corrode and seize in the manifold flanges. They are made of some ungodly hard material so they are very hard to drill out. I've tried heat in large quantities and they don't budge.
No in progress pics here, but I cut it flush with the flange, center punched it, then drilled it straight through with a 1/8" bit. Then I drilled it most of the way through with a 1/4" bit and punched it out. Only three more to go... |
05-29-2017, 08:43 PM | #235 |
Mugwump
Join Date: Oct 2003
Carmudgeonly Ride: E46 330i, Chevy Colorado, Tesla Model 3
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Sweet!
After seeing those pictures I just spent 30 minutes trying to better understand how vanos works. I get that it uses a helical gear to rotate the intake and exhaust camshafts slightly to alter the timing. Youtube animation But which parts are spinning at engine speed, and which are not? If the piston is pushing on something that is rotating at engine speed there must be a bearing somewhere right? |
05-29-2017, 08:47 PM | #236 |
Mugwump
Join Date: Oct 2003
Carmudgeonly Ride: E46 330i, Chevy Colorado, Tesla Model 3
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05-30-2017, 05:31 AM | #237 |
No more BMWs
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We either need new ones or to replace them with stainless bolts. I need to give that some thought.
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05-30-2017, 08:45 AM | #238 |
older fart than ZBB
Join Date: Oct 2003
Location: On the road again
Posts: 8,900
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What is the exhaust manifold material? Stainless can react poorly with some materials
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05-30-2017, 08:54 AM | #239 |
No more BMWs
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They appear to be stainless steel. I've never had any problems using stainless bolts with them.
John |
05-30-2017, 12:26 PM | #240 |
older fart than ZBB
Join Date: Oct 2003
Location: On the road again
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stainless to stainless is fine. While working at Fastenal I had to take an online test about dis-similar metal reactions. Some stuff doesn't play well with stainless
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