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Old 05-28-2017, 06:04 PM   #231
Nick M3
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Quote:
Originally Posted by John V View Post
Hmm... Main thing holding me back is I need to drill out all four studs on the manifold outlets. Then the trans can go back in, the exhaust back on, and the car can go on the ground.

I did the motor mounts and the air /oil separator today as well as cleaned the throttle body. Need to do the vanos seals, then get the valve cover back on and power wash the engine. Cooling system, then onto the interior stuff. But as far as being able to drive it, it's really close.
Cool. Good luck on the studs. I hope you can get them out without having to pull the manifolds off.
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Old 05-28-2017, 06:40 PM   #232
John V
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They all have to be drilled out. Not looking forward to it
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Old 05-29-2017, 10:19 AM   #233
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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.

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Old 05-29-2017, 04:44 PM   #234
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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...

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Old 05-29-2017, 08:43 PM   #235
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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?
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Old 05-29-2017, 08:47 PM   #236
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Quote:
Originally Posted by John V View Post
Then I drilled it most of the way through with a 1/4" bit and punched it out. Only three more to go...
Get 'em all?

Speaking of those exhaust studs...... don't we need to order 4 new ones? Or do you have some already?
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Old 05-30-2017, 05:31 AM   #237
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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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Old 05-30-2017, 08:45 AM   #238
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What is the exhaust manifold material? Stainless can react poorly with some materials
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Old 05-30-2017, 08:54 AM   #239
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They appear to be stainless steel. I've never had any problems using stainless bolts with them.

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Old 05-30-2017, 12:26 PM   #240
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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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