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Subject: M70 re-ring writeups with photos Author: cheung1 as Patrick C 88 750 160K New piston rings : member since March, 2004 : 1168 posts Posted on: 2007-11-14 22:26:26

Any quick way to upload the photos to bimmerboard? That way I can do a global edit of photo URLs in my RF posts and repost on bb. Roadfly allows uploading six photos at a time so it was easier for me to do the writeup there first.
The main tasks I went through have been covered with photos in chapters in either e38.org/e32 or Johan's masscom.net. My photos below focus on some shortcuts I have found useful.

Another thing I found is that in the BB forum if I replied to a message on Page 2, that message will rise to the top of Page 2, not Page 1.

With no particular order.

1) Drop and remove the front stabilizer bar and attaching cross member before detaching exhaust components. That opens up much more working room. Bolts are of odd sizes, 18 mm and 15 mm.



2) Mark new headbolts with a white dot at 12 o'clock positions. Much easier to track the first and second stage of 60 degree torquing. The above photo doesn't have the resolution to show dots on all headbolts at 120 degree position. These have finished the second stage torque.
Second photo is a close up on the dots. Also, a 1/2 inch breaker bar made torquing much less strenuous.



3) After the piston slots are cleaned and new rings installed (I used bare hands only to install rings), used an ARP tapered bore piston compressor to prepare piston to be put into the bore. Crank had to be rotated in two positions to fit all pistons because at any given position some conrod bolts were blocked; also, when crank was at the highest position for a cylinder, it was difficult to line up the piston so the other side mate with the crank (unless you have a helper ) so the piston might not clear the ARP compressor.



4) Use a $10 motorize driver and swivel link like in photo to drive all the hundreds of M6 (10-mm) bolts, then use 1/4-inch torque wrench to reach 89 in-lb. The swivel link is especially good for upper timing chain cover bolts that face the radiator.



5) When placing the two small horizontal gaskets below the upper timing chain covers, use bolts to affix the gaskets otherwise they will shift position as you torque down the covers.



6) Good new here is that one (or two) of the coolant bridge bolts on the driver side can be tackled from underneath. A workable sequence:
1) Install driver side head with bridge. Torque headbolts.
2) Loosen two bolts on bridge, driver side, with Gearwrench wrench; one from above, one from below. Now bridge can jiggle somewhat.
3) Install passenger side head. Insert three bridge bolts by hand and start some threads.
4) Torque down headbolts for passenger side head.
5) Hand tighten all five bridge bolts as close to 89 in-lb as you can.





7) When lifting engine from mounts, use a stick like in photo and mark original height at the radiator as a reference.



8) Use multiple vise-grips ($3 each harborfreight) to grab the long exhaust manifold to downpipe bolts. There is a spec in Bentley but I just got the nut flush with the bolt bottom, then turn 3 complete turns.



9) Use a short wood dowel pin or (in my case) metal pin to tie parallel to the gas strut to keep hood from slamming down. Vise grip works too but I don't like the teeth marring the rod.



10) To gain access to the upper pan bolts by the torque converter holes had to be drilled at the pan section that faces forward. Only on e hole of size larger than your swivel 1/4-inch 10-mm socket is needed. My largest drill bit was 1/2 inch, a bit too small, so I used this step drill bit to enlarge the bore. Use electrical tape on the socket and extension so the former won't fall loose past the hole. You can see the bolt through the center 2-inch diameter opening. No need to put the two bolts back when re-install.



11) To renew the Center engine cover I ordered new bolts and spring washers and two nuts, plus a gasket. The old bolts were difficult to come out; five of them broke off. See photos where I circled Red. The Rectangular circle was where a protruded feature was casted so I could insert a pry bar to lift the cover. There was another protrusion at the rear but I was too impatient to know it existed. By lifting only on the front I eventually chipped off a small piece at the rear around a broken bolt; not show stopper but hope no one need to repeat that mistake.
So wait until both heads are removed to tackle this cover; and don't fret about the broken bolts because by the time you have the cover lifted, the broken bolts will have 7-10 mm above the block, and you can ground the sides of the bolt with a Dremel tool then grab and turn the bolt out with a vise grip.





12) At TDC (pin through drive plate) try to rotate the camshaft so that if you lightly pressed on the alignment tool with one hand and slide a small piece of paper through the top and bottom gaps, paper should not slide through neither of both gaps. Otherwise it is hard to rely only on eyesight that the tool bottom is absolutely parallel to the head surface.



13) The cross member is bolted on on both sides by 6 17mm long bolts. To re-install (which I did a few times because of the need to rotate the crank) line up the dowel cylinders as well as the mounting flanges for the steering box (Red rectangular box).



14) Rusty exhaust manifolds were spray painted with Dupli-color high temperature paint with Ceramic that claims to withstand 1200F. The paint fumed and smelled badly in the first few days of driving but the paint seems to stay well now. I made no preparation--just sprayed on the rust and called it done.



15) The steering box was hung down by wires while the cross member was removed. To anchor the wires I temporarily replaced mounting bolts for the oil filter canister and Pentosin reservoir with longer bolts.



16) Again on the steering box, the big (19 or 22mm?) nut and washer hide behind the engine mount and are difficult to access. However, if the lower oil pan is removed, one can gain access from sideway. A long nose plier with long handles is handy here.



17) Exactly what had to be removed underneath to remove the upper oil pan:
Crossmember
stabilizer bar and attaching cross member
a 13mm mounting bolt of the Pentosin pump
hose clamp of a oil return hose near the oil filter canister
What need not move:
pair of transmission pipes (I loosened at the radiator because the pan refused to move and later on I found it was the oil dipstick 10mm nut holding the pan back)
Pentosin line to LAD (just drop the hose sections)
center tie rod balljoints (drop the idler arm and therefore the passenger side of center tie rod is tilted down. I loosened the ball joint nut as in photo but eventually didn't find it necessary to pop the balljoint at the pitman arm)
engine mounts stayed with the engine block



18) I now have the section of rubber weatherstrip cut and removed (Red outline) to allow a 1 cm air gap so no heat traps under the hood to degrade old plastic or wires. The strip section is placed in the trunk and can be reinstalled (like when you don't want to smell the fumes of silver paint).



19) To prepare the valve cover for painting, this time I used different sizes and types of wire brushes mounted on drill and finished the preparation in much shorter time than last time when I used a powered sander.



20) I panicked when I first saw the original conrod bolt heads were not the torx type like the new bolts. Since I could not take a bolt sample with me I didn't know exactly what to buy, only know this bolt head has 12 points. Spent two hours hunting different stores and eventually at Sears bought an assortment of sockets. Turned out this bolt can simply be removed by a Craftsman 12-point 10mm socket. Get the 3/8-inch not 1/4 inch socket.





Patrick C 88 750 159K

• M70 re-ring writeups with photos (pic) - Patrick C 88 750 160K New piston rings 2007-11-14 22:26:26 (772 views)
  • Odd sizes ... - kharon8 2007-11-20 12:57:41 (93 views)
  • Outstanding work! Thanks for sharing! (nt) - DavidC 2007-11-16 19:46:36 (89 views)
  • Finally passed CA smog check (pic) - Patrick C 88 750 160K New piston rings 2007-11-15 16:23:52 (546 views)
    • Really impressed with your re-ring spread. Thanks - beezer02 2007-11-17 23:37:38 (94 views)
    • Great Day!!, Congrats Pat!!!! (url) - shogun 2007-11-15 21:52:11 (141 views)
      • Glad to see you're back on the road, Pat. - Rich 1990 750iL 2007-11-15 22:52:01 (108 views)
      • Congratulations Patrick! - bcweir750 2007-11-15 21:57:51 (98 views)
        • Thanks. Yes, feel good giving back to the Internet - Patrick C 88 750 160K New piston rings 2007-11-16 18:25:19 (110 views)