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Old 08-17-2008, 07:23 PM   #1
el maestro
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Oil Pump PROBLEMS! m20 2.7

I was removing my oil pan to replace the oil pan gasket and i accidentally dropped the oil pump drive shaft and it had two plastic like washers or stoppers .... well they both broke so i was wondering if there was any where i could buy these stoppers separately or if i would have to buy the whole oil pump drive shaft.

Oh and while im at it does anyone know the torque specs for connecting rod bolts on a M20 2.7 ?

Any input would be great.
Thanks in advance
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Old 08-17-2008, 07:25 PM   #2
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check realoem.com then take the part numbers to bma
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Old 08-17-2008, 07:40 PM   #3
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btw don't try to "retorque" the con-rod bolts, they are torque-to-yeld
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Old 08-17-2008, 07:41 PM   #4
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^^ Tried it and and theres nothing on those damn stoppers also know anything on the connecting rod torque specs?
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Old 08-17-2008, 07:43 PM   #5
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Im not trying to retorque them, i took the cap of the end of the rod too check the bearings and i dont see anything in the chiltons manual i have.
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Old 08-17-2008, 08:12 PM   #6
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I think he meant they are one time use.
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Old 08-17-2008, 10:04 PM   #7
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So if they are one time use there is no way to put them back on and id have to get new bolts?? Because i just took the cap of the end of the rod to check for bearing wear

Last edited by el maestro; 08-17-2008 at 11:57 PM..
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Old 08-18-2008, 05:39 AM   #8
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As mentioned above those are torque to yield bolts and can only be used one time. You'll have to get new bolts for that rod cap.
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Old 08-18-2008, 08:06 AM   #9
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so does anyone know what to torque them to?
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Old 08-18-2008, 10:28 PM   #10
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So i went to a local shop that specializes in Bimmers and he looked it up and said that you can re-use the connecting rod bolts and that torque specs go as followed.


Torque wrench settings (continued) Nm
Connecting rod cap bolts/nuts
M10 and M30 engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
M20 and M40 engines
Stage 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Stage 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Angle-tighten an additional 70


Just wanted to get other opinions or experiences. Thanks to those who tried to help and i posted the specs for anybody that might be doing the same as me.
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Old 08-18-2008, 10:50 PM   #11
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Quote:
Originally Posted by el maestro View Post
So i went to a local shop that specializes in Bimmers and he looked it up and said that you can re-use the connecting rod bolts
This is why most 'BMW' shops are nothing more then hacks, you do not reuse the M20 connecting rod bolts.

A quick lesson in TTY bolts. If you look at the specs for the M20 you will see it has a initial torque, this seats the cap and bolt to a even clamping load. Then you will see it says to 'angle' tighten 70*. When you pull this 70* angle you are stretching the bolt, not only are you stretching it, you are placing it into a 'elastic' state. Once removed the bolt is stretched and elasticized and is no longer considered usable.

If you try to torque it again all it will do is continue to stretch until it snaps.

I have built many successful BMW engines, M20's, M42's and a M30, thats why my shop is called 'E30 Motor Werks'. I build BMW E30 engines. Also ASE certified with 20 yrs of automotive repair experience.

Or you can trust your 'local bmw specialist', The same one who appearantly did not mention the specs he gave your are in Nm. So 20Nm plus a 70* pull, or for the US crowd, its 15ft lbs plus a 70* pull. Makes me wonder if this shop wasn't trying to set you up for the kill. Figure they might get a engine build or replacement out of you. That or they are just dumbass's

I once tried manually torquing a brand new rod bolt to 55ft pounds, it just kept stretching. After I pulled it out, it was 3mm longer then a stock unused rod bolt.

Quote:
Unlike a conventional bolt, TTY bolts are tightened beyond their elastic range past their yield point from which the bolt material can recover to its original length, and into the plastic phase of the bolt material. The bolt is permanently stretched and for this reason should not be reused. The reliability of these bolts once stretched is greatly reduced. If they are reused, they are permanently stretched further a second or third time. It is also for this reason why you should never retorque a torque to yield bolt.
http://www.robbos.com.au/myweb/Tech_Bolts.htm

PS: the oil pump rod is about $10 new from the dealer.





Quote:
Originally Posted by el maestro View Post
So i went to a local shop that specializes in Bimmers and he looked it up and said that you can re-use the connecting rod bolts and that torque specs go as followed.


Torque wrench settings (continued) Nm
Connecting rod cap bolts/nuts
M10 and M30 engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
M20 and M40 engines
Stage 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Stage 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Angle-tighten an additional 70


Just wanted to get other opinions or experiences. Thanks to those who tried to help and i posted the specs for anybody that might be doing the same as me.

Last edited by peerless; 08-18-2008 at 11:01 PM..
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Old 08-18-2008, 11:23 PM   #12
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^ So do i just go to my local bmw dealer and order the connecting rod bolts?

Is there a place online that sells connecting rod bolts for the m20?

Let me know and thanks for the useful information

Im gonna go ahead and buy the bolts just to make sure.
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Old 09-14-2008, 03:46 PM   #13
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You only need two, go for it.
I'm not going to thow my buddy down, but he is a certified ASE mechanic and has made his way to foreman of a dealer shop, like 15 years exp, I trust him. He said shops frequently reuse these typs of bolts. Heck, it's someone else's car.
Anyway, he explaned to me it may stretch futher but will still torque to spec. It's not going to fail 10k miles down the road, if it's going to fail, it will fail when you torque it. $100 for 12 bolts? $4 for a cup of coffee, Who knew? There's a BMW owner born every minute. (I'm still conidering replacing mine for my build but leaning toward not.)
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Old 09-14-2008, 05:30 PM   #14
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no, they definately will not torque to spec. These arent being used in a small block or something like that where you can reuse the bolts till they rust out or pull through, they are totally different fasteners.

The manufacturer of the bolt calculates the exact amount of stretch in application of torque to apply the correct clamping force. When you get real serious in motorsport applications, torque figures are actually meaning less and you use a bolt stretch gauge which indicates length. You can compare it once tightened to make 100% sure it has stretched just that right amount. Have a look at companies like ARP, they will provide stretch measurements and clearly state this is the first method reccomended to check for correct fastener torque.

Not all rod bolts are torque to yield, certainly not where the rod has a threaded rod attached for nuts to bolt the end cap down on to. However, anything at all that is torque to yield must be replaced the minute pressure has been released from the fastener. It doesnt matter if they have only been installed 5 mins, once they have stretched, they are only designed to more so far to apply the correct clamping force. Outside of this, its all over the place and will mean the difference between a rod bolt walking out (does happen), sheering clean off (does happen quite a lot as bolts are a weak point) or not applying correct torque and allowing the cap to move.

TTY bolts are cheap (a whole $8 ), they are throw away items for a reason. a pair of $8 bolts or a junk engine? because, believe me, if the rod bolt lets go, it will munch the rod, destroy the piston, score up the bore, possibly damage the crank, break a couple of valves and try really hard to exit the piston out the top of the head (cracking through the cam bearings in the process) or out the side of the block (and blow a huge hole out the side).

You are a dick if you build a new motor and dont use replacement bolts. BMW owners arent born every minute you moron, these are bolt manufacturers who dont give a shit about bmw telling you the way it is. Believe whatever you want, but this shit has been standard practice for 50+ years.

Do a websearch for torque to yield and you will find a whole bunch of results from bolt manufacturers. There is a specific science to fastener production, its not just as simple as a bit of thread on some rod and away you go.
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Old 09-14-2008, 07:33 PM   #15
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Wow, I especially like the moron comment. I've been doing this for 25 years so, half of whatever you say these bolts are being used. None of my engines have let go.
Really, I do understand the concept. Are you an engineer or a metallurgist? I'd understand the moron thing if you've spent any time pull testing these bolts. The fact is, torque over a given number of fasteners does not always give a consistant tension or pressure. Friction during torquing plays a part in this. Engineers use the angle torque method to try to achieve this equal tension.
If these bolts aquire so much fatigue in the initial pull that they can't hold or achive the same or similar tensile strength for a second pull then I dont want the damn things in my engine in the first place. I don't think the engineer would design the torque to turn procedure that far into the plastic range of the bolt, but I'm not afraid to admit I could be wrong.
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