Zero Oil Pressure?

#21

First get a replacement valve cover gasket. Don’t skimp get a good one. Remove spark plug wires, blow out plug holes and remove spark plugs. Check the gap on them them put them back in their respective holes but don’t thread them; just leave them loose. This allows compression to release and makes it possible to turn the motor. Remove intake manifold brace and vent tube from valve cover. Take off nuts in reverse order of Bentley tightening order to prevent warping. Lift off cover and remove gasket. Make sure all gasket material is off of the head.

To adjust valves, start with cylinder 1. With trans in neutral take a long 21 or 22 (?) and turn Jesus nut on front of crank until cam lobes on cyl 1 both point down and the rocker arms are at the lowest point on the cam shaft. Slide the feeler gauge under the rocker arm where it meets the valve. Rock the rocker arm (ha) back and forth. It should not move. If it does, loosed the 10mm bolt on the rocker arm eccentric and rotate the eccentric with a 2.5 mm Allen wrench until it touches the feeler gauge. Tighted the bolt slightly and check again. The feeler gauge should slide in and out with just a hint of resistance ad the rocker arm should not rock until the gauge is removed. Tighten bolt firmly. Repeat for the other cyl 1 valve and then do 5,3,6,2,4 by turning Jesus nut towards passenger side (I think).

Put gasket on and tighten nuts according to Bentley order and torque (don’t forget plug wire rail). Tighten plugs to torque, fasten vent and brace to cover, put on plug wires, wash hands, open beer and enjoy your quiet motor.

#22

Thanks for the writeup!

#23

Remove plugs and valve cover. Turn crank with a wrench until both the intake and exhaust valves on a cylinder are both fully closed, i.e. when both cam lobes face away from the rocker arm. Adjust. I usually mark the ones I adjust with a felt tip pen. Rotate crank with wrench until another cylinder looks the same. Repeat 4 more times. Re-install valve cover and plugs (good time for a new set of AR53) and enjoy.

#24

Yes good call on the AR53’s. Gotta gap em.

#25

Well uhhh that’s an issue.

#26

Dang, sorry man. It’s possible that’s salvageable if you take the head to a shop that is used to welding AL heads. Chuck Baader would have a better prognosis than I.

The same sort of thing happened to AR Hoshmandy at CMP weekend before last, except his was at #6 intake. Hard to know for sure what caused it. My guess is that it got weakened by something in it’s history and then the cumulative stress took it out. Tightening the bolt down too tight is a possibility but the turbo guys tighten their bolts down much tighter then us and the heads seem to survive? A valve could have hit a piston and pushed up the rocker, but I’d think that the valve would just bend before the rocker arm retaining shaft would break the head.

The good news is that a head R/R is pretty easy. Scare up a replacement head, have a shop do a refresh on it for $400ish, consider new cam ($200) and rockers ($25ea), and you’re back in business.

#27

All of the above are possible, the engine had who knows how many miles when I bought it (guessing around 190k). If you look in the very bottom right of the picture, you can see that the next one over is cracked as well.

What are your thoughts on trying to find something like this and put my current hardware into it? Better to get a complete head from a pull a part?
http://www.ebay.com/itm/bmw-e30-m20b25-885-bare-head-/301235865458?pt=Motors_Car_Truck_Parts_Accessories&hash=item46230e8772&vxp=mtr

#28

Also - are all “i” heads the same? As in, could I get an i head from any year to go with my '89 engine?

#29

Don’t buy a head w/o being able to examine it’s cam journals. Those are the big holes in the head that the cam rotates in. Those holes often have grooves worn in them. The grooves make the cam a loose fit in the head. A tight fit is necessary to maintain oil pressure.

The engine’s oil has 4 routes. Each of these routes need to be restrictive in order for oil pressure to stay high. If one route is loosey goosey, all oil pressure is low.

  1. To intermediate shaft bearing.
  2. To crank and rod bearings.
  3. To head’s cam lobes.
  4. To head’s sprayer bar.

My perception is that worn cam lobes are the #1 thing that turns a head into a doorstop.

Get the guy to send you a close up pic of the cam lobes. Have him run a fingernail across the surface to detect grooving. If you can’t feel it with your fingernail, it’s probably ok.

#30

If you don’t know what u need, the best thing to do is buy a refreshed head from someone on this forum who knows what they are doing (Richard Bratton, Chuck Baader, Ranger or Jim. Others?). Machine shop guys tend to say “yep, it’s right” and have no idea what they did.

#31

All OEM i model heads are the same. There’s some aftermarket oddball heads out there, and occasionally you’ll find someone that thinks they have an i part and it’s not. I once bought a motor from a well respected BMW parts recycler only to find it had a 323 head on it.