This section contains special information on the engine that is not found in the Service or the Bentley manuals. It may have clarifications on the content of these manuals as well.
All information contained in this FAQ is provided by BMW enthusiasts who are not typically fully trained in the art of BMW maintenance. As such, all information in this FAQ is provided "as-is". Any use of this information is strictly the responsibility of the using party. The supplier of the information and the Webmeister assume no liability for incorrect information or use of this information.
The Final Word on Engine Idle
Alternator Bushing Replacement
Spark Plugs--Bosch Silbers
Fuel Injectors and Cold Start Injector
Temperature Gauge/Warning Light Sensor
Starter Removal - Alternative
Starter Replacement That Beats All
M6 Idle Control Valve and Throttle Switch
Oil Pressure Delay
Replacing the Cam Shaft Seal
No Start Problem Troubleshooting
Alternator Bushing Replacement - Michael_J._Fagan@SterlingPulp.com
This is a step by step detailing of the removal and replacement of the alternator bushings in my 1985 635csi. Wherever required I will include the reason why I did something in a particular way. If it is possible, use the urethane bushings instead of the rubber ones from BMW. Read the directions through a few times before you begin. The job took me 2 hours, most of which was spent cleaning the old bushings out of the alternator. As I am a DIY hacker and in no way a certified mechanic I must add that the usual disclaimers apply.
slip-wrench (to remove fan)
13mm wrench selection of metric and SAE sockets (see steps 17-20)
large vise (opens wide enough to span the alternator, with several inches to spare)
various screw drivers
C-clip pliers (a must).
1. Disconnect the battery.
2. Remove the alternator belt. This is accomplished by loosening the backside nut on the upper mount, and then turning the front side bolt head such that the toothed mechanism moves the alternator toward the engine block. When the belt is loose enough, remove the belt.
3. Turn the large bolt head such that the alternator moves back to its original position. This may seem unnecessary, however I found it makes it easier to perform the next step (no obstructions).
4. Remove the bolt through the upper mount by removing the backside nut and then sliding the bolt out of the mount. Note that the large front side nut is not really a nut but a cogged wheel which slides on to the bolt. Make sure you do not drop this cogged wheel or any washers when you remove the bolt.
5. In order to make some room, move the slotted arm to which the upper mount was attached, out of the way (toward the engine block). If it is anything like mine was, IT WILL BE STIFF. You may wish to spray some penetrating oil on the bolt point to help.
6. This step is optional, though it may save some skin from you knuckles. Remove the fan assembly and the radiator fan shroud. Note that the fan shroud may interfere with removal of the lower mount bolt if it is not removed.
7. Using a 13mm wrench on the backside nut and a 13mm long socket on the front bolt head, remove the bolt from the lower mount, taking care not to loose any washers.
8. Gently pull the alternator from its position and twist it such that the back of the unit is facing up. Place it carefully on the top of the power steering pump. This allows easy access to the wiring connections on the back. Pry back the rubber boots, and remove the connections. Mark the connections where necessary to ensure proper assembly later on.
9. Take the alternator out of the engine bay and take it to a well lit work area (this makes it easier to find the C-clips when they are inadvertently launched, I speak from experience)
10. Using C-clip removing pliers (HIGHLY RECOMMENDED), remove the C-clips from both the upper and lower bushings. Be careful as they can easily fly off the pliers. Put these in a safe place along with the new bushings and the flat washers which are below the C-clips.
11. Remove the bushings by tapping and/or prying out the metal sleeves. This may or may not be easy depending upon the condition of the rubber bushings. My upper sleeve came out with not much effort, but the lower sleeve was a lot more difficult due to the gooey nature of the rubber bushings.
12. With the sleeves removed, remove the rubber bushings or what is left of them. I used a hardwood dowel, slightly smaller in diameter than the inside diameter of the mount bore, to scrape out the gooey remnants. It is very important that the inner walls of the mount bores and the outside surfaces of the metal sleeves be clean and smooth. Believe me, this may take some work.
13. It is now time to reassemble the unit.
14. In order to ease assembly, coat the inside of the mount bores, the rubber bushings and the outside of metal sleeves with a suitable lubricant which will not attack the rubber. I used a liberal coating of graphite.
15. Starting with either the lower or upper mount (both are assembled in the same way), insert the rubber bushings into the mount bores. Push the metal sleeve back in, inserting it from the front side of the alternator. It is only necessary to get the sleeve partially inserted into the back bushing.
16. Place the alternator in a vise (or use large slip-pliers), being careful to protect the surface of the metal sleeve and the rear rubber bushing. Slowly compress the vise until the metal is inserted as far as it can go (ie. sleeve is hitting the back jaw of the vise).
17. Open the vise very wide. Now place a socket of such a size that the inside of the socket just clears the metal, on the rear rubber bushing. Close the vise again (gently). This should insert the rubber bushing far enough that approximately 1/4" of metal sleeve is visible.
18. Once again open the vise. Over the exposed part of the metal sleeve place the flat washer and, using the C-clip pliers, place the C-clip on the sleeve.
19. Carefully place the socket back on the sleeve (it should be making contact with the c-clip, if not, use a smaller socket). Using the vise, compress the bushings until the c-clip snaps into the groove in the metal sleeve. One mount is now finished.
20. Repeat for the other mount.
21. Once this is finished, re-attach the alternator by reversing steps 1-8.
Starter Removal - Chris Wright <firstname.lastname@example.org>
I posted a cry for help on removing a starter from a 635csi a couple of volumes back and have since pulled together enough information and secrets to finish the job. I pass this along FYI and for the FAQ on the web page.
1. Disconnect negative battery cable
2. Drain engine coolant- (small plastic plug in lower Rt radiator elbow)
3. Remove the heater hose that runs from solenoid across the top of the bell housing to access the top starter mounting bolt
4. Loosen heater hose from fitting on fire wall and flex out of the way
5. Disconnect starter wires
6. Remove the 2 bolts (17mm) that hold the starter to the bellhousing. The lower out side bolt also carries a small bracket that supports a wire bundle; mark and unplug this bundle from bracket on intake manifold and push aside. The bolts are slightly recessed and there is not enough space to get a socket on the bolts: nor can you see them. A small mirror helps. You have to use a box end wrench and worry them out an 1/8 of a turn at a time.
7. Remove the oil filter by loosening bolt on top of filter housing and drop it down through the access space (have something underneath to catch it).
8. Work starter forward between base of dipstick tube and ABS controller bracket. The starter should pass under the oil filter housing and turn and drop down through the oil filter access space. It may be necessary to loosen and reposition the brackets on the dipstick tube and move the starter cable to accomplish this.
Tip: pass a small cord thru a starter bolt hole to help support the starter while you wrestle with it!
Spark Plugs--Bosch Silbers - "Gene M." <MClan@postoffice.worldnet.att.net>
Credit to Don Eilenberger < email@example.com>
The owner's manual for cars prior to 1988 with the M30 big 6 engine call for a particular Bosch spark plug, either WR9LS or WR9DS (according to Bentley's on the 5 series, only the 1983 3.210 litre engine uses the WR9DS). The "S" stands for the Bosch Silber plugs, ather than their normal "C" copper plug or "P" platinum plug.
The Silbers are ONLY spec'd for the big-6 engine (if you look in a Bosch reference book).. meaning that Bosch made them especially for the engine. Although other plugs will cross-reference as replacements for the Silbers, you may find that your car may not idle or run as well as with the appropriate Silber plug. It may have something to do with the Motronics unit or the heat range and heat transfer properties of the Silber. The Bosch web page does not have any information on the Silbers.
Silbers are substantially more expensive ($9.00 retail/each range) than copper or platinum plugs, but you should be able to be find sources in the $5.50-$6.00/each range. The Silbers, however, will last way longer than copper plugs.
Don Eilenberger states that it is important that (1) they go in dry - no antiseize [it screws up the heat transfer - so you need CLEAN threads in the head..] (2) they get torqued in (again, heat transfer, plus it keeps you from stripping out the threads in the head). Makes a difference - especially at idle.
Bentley's specifies a light amount of oil on the threads to help avoid cross-threading and a tightening torque at 15-22 ft-lb.
On the spark plug gap, Bentley's specifies a gap of .027 +- .004 in. Don E. recommends a .032 gap and an increase in valve clearances about 0.002" (from stock 0.012 to 0.014) if you are interested in a smoother idle.
Spark plug brands in many applications
may not make a noticeable difference in the running of your car.
However, if you are not running the Bosch Silber spark plug specified
for your car, you may want to consider trying the Silbers if you
are experiencing idle problems, "drop outs" during acceleration
or general poor running. How well your car runs is somewhat subjective,
but if you are spending a lot of time troubleshooting idle or
running problems, a variable you may want to eliminate is your
plugs and several 6 owners have reported their cars run noticeably
better with the Silbers.
Fuel Injectors and Cold Start Injector - "Gene M." <MClan@postoffice.worldnet.att.net>
Credit to Don Eilenberger < firstname.lastname@example.org>
If you suspect that you may have a bad fuel injector, put in a clean set of sparkplugs and run the car hard for 15 minutes, kill it and "read" the plugs - if you have a dead injector or a leaking one - the plug reading should indicate it.
The general rule of thumb used by a mechanic friend is - if you can hear the injectors - they're probably OK. When the injectors gunk up they start to get quiet. The fact that they seem to get noiser at higher engine speeds may indicate that they are being called upon by the Motronic for longer duty cycles When one injector is not firing, the other ones are pulsed longer to make up for it.
You can have the injectors cleaned/flowrated, but there are many vendors in the Roundel with reasonable prices on injectors and this may not be a viable economic option.
My experience with this has been the cold-start is the injector which generally seems to go bad and you may want to check it first. When it fails - it seems to like to dribble, maybe because it's the lowest point in the injection system.
In order to access the cold start injector, you're going to need tiny hands and tiny wrenches to get it out - and a length of 8 mm fuel injection hose long enough to get it to a jar.. it is a royal PITA to remove and install on the big 6. Once you're done - I'd suggest replacing the fuel line with new BMW fuel line - it will handle the pressure and heat - regular fuel line WILL NOT. The fuel line to the cold start injector runs from the fuel rail down through an opening in the intake manifold and it is very difficult to visually check the line. It is subjected to a lot more heat than most of the fuel lines. A leak in the fuel line to the cold start injector can be very dangerous since it may spray fuel in the area of the exhaust components.
Temperature Gauge/Warning Light Sensor - "Gene M." <MClan@postoffice.worldnet.att.net>
There are several temperature sensors on the thermostat housing of a M30 big 6 engine. The temperature gauge sensor is the taller, 2 pronged one (one prong is larger than the other) that usually sits back behind a shorter temperature sensor toward the driver's side (depending on your year vehicle). It will have a temperature rating stamped on it (usually 117 or 118 degrees), which is the temperature that it will close and light up your temperature warning light.
On one of the terminals (larger one), the connector will have 2 wires with the same color (brown/white on my 83 633), one will go to a connector on the back of the instrument cluster and eventually to the temperature gauge and the other will go to pin 4 on the diagnostic connector.
On the other smaller terminal, the connector will have one wire that may appear to be a brown ground wire because of weathering. It is not. It is a brown/violet wire on my 633 (85 schematic shows brown/gray), which goes to the temperature warning light. When you turn on your ignition, 12+ volts will be sent down this wire.
This temperature sensor for the
gauge is GROUNDED TO THE BLOCK--not to the gang of ground wires
that attach below the fuel rail. If you suspect a bad ground,
clean your threads. When testing the sensor, the larger prong
will show an increase in resistance as the temperature increases
to feed the signal to the temp gauge. The other smaller prong
will show infinite resistance until the rated temperature is reached,
closing the switch.
Starter Removal - Alternative - Jim Houts <email@example.com>
Having just removed my starter,
let me tell you the fast & clean way to take it out (Norm,
this may be good for the FAQ).
Before you pull the starter: Make sure that if the starter is continuing to spin after you release the key, that you are not getting any voltage to the small wire that goes to Pin 50 on the solenoid. If you are getting voltage with the key in RUN (not START), then you likely have a bad ignition switch, not a bad starter or solenoid.
Anyway, on with the show: After getting my engine back together (9 month job), I went to crank it over, and zip - nothing. After Steve Haygood suggested I had the wrong pin connected on the solenoid, I checked it and it was connected to PIN 5a, not PIN 50. I changed it, and still nothing.
I read the FAQ on starter removal, and thought there had to be a better way than removing hoses and draining coolant & oil (I had just, 30 minutes before, finished putting all of that in). Here's how to get the starter out in a hurry:
Buy a 3/8" drive, 17mm SHALLOW swivel socket, a 3/8" standard swivel and a couple of long extensions (long enough to reach near the water pump, or there abouts). Disconnect the battery & remove all of the wires from the starter. Remove the Idle Control Valve, and the throttle cable bracket from the intake manifold. Between the intake ports, under where the ICV was sitting, you can use a flashlight to see the inside starter bolt tucked down inside. Take your new swivel socket and an extension, and run it between the ports to the bolt. It won't slip on the bolt easily, you'll need to take a hammer and drive it on to the bolt (its a tight fit). Once on the bolt, remove the 3/8 extensions and flip the swivel part of the socket down so that it faces the front of the car.
Now take one of the 3/8" extensions and slide it in along the top of the starter. You'll need to tip the back end of the extensions up a little to engage the 17mm swivel socket.
Tip: You should be using fender covers. If you don't have them, buy 'em, theyB9re cheap.
If you're having problems lining up the extension & swivel socket, lie over the intake manifold (from the drivers (left) side). and look down at the socket until you can line up the extensions.
If you can comfortably get a long ratchet on the extensions (I couldn't) you may want to give the bolt a try. If not, connect the 3/8" swivel and the next extensions to the first extensions. You should now have a 17mm swivel socket, extension, swivel, extension and a good size breaker bar or ratchet at the end. If you don't have enough clearance to turn the assembly, you may want to add an additional extension to get past the intake manifold.
Now, go ahead and turn that sucker loose! Yeah, it IS on tight!
After the inside bolt is out, you can easily get the outside bolt out with a 17mm end wrench.
Pull the starter out of the hole, turn it point down with the solenoid facing the front of the car. You can now wiggle the starter straight up past the brake bomb & regulator (it does fit) and out of the car.
Installation is reverse of the preceding, except I used a 12mm allen bolt for the inside, much easier.
I bench tested my starter with a pair of jumper cables and verified that the solenoid was bad. The solenoid would eject the drive gear, but it wouldn't turn. The starter worked fine when the solenoid was bypassed. A new solenoid at BMW was $170 USD. I found a Bosch unit down the street for $40 USD. It said Made in Germany, but the quality was more South East Asian (Malaysia is my guess).
I installed the new solenoid and all was well in my world. Cranked over the engine to circulate the oil, installed the main relay, and it fired right up. More on this later.
Ignition Upgrade for Idle Improvements - "Gene M." <MClan@worldnet.att.net>
Your 1982-1984 U.S. model 633 (also applies to 533 and 733) may have had an upgrade performed by the dealer to address idle problems. Technical Service Bulletin TSB 13 07 86 (1162) discuss these changes.
The major components of the upgrade were to:
(1) Replace the ignition system (coil, cap, rotor, wires) with the 30 kv components (the type in the 635) and adding a rotor adaptor;
(2) Install a 35 degree C thermotime switch;
(3) Replace the idle control unit with the green unit (or may be a black unit with green tape);
(4) Install a purge control module;
(5) install an external resistor in the wire for the temperature sensor that feeds the Motronics (should be the one with the light grey connector) Resistor type is 270 ohm, 1/2 watt, "Gold Band" metal film resistor for Motronics Control Units with a Bosch code date of 342 or higher (production date after 9/83) and for Motronics 341 and lower (9/81-9/83 production dates), it is a 560 ohm, 1/2 watt "Gold Band" metal film resistor .
This upgrade was performed at no charge, but may not have been done on your vehicle. If you have the slip on rotor instead of the bolt on type, the full upgrade was not done, but you may still have the external resistor installed under TSB 11 11 84 (920), which was only added to address a complaint of "hesitation/poor throttle response" during several minutes of operation after starting a cold or warm engine at an ambient temp above 75 degrees F.
A few things on these model years because of these changes.
First, when replacing ignition components, make sure you are getting the correct coil, cap, rotor and wires, depending on whether your car has the upgraded components. If the upgrade was not done, a rotor adaptor (PN 11 31 1 718 761) is still available if you choose to upgrade to the 30 kv components.
Second, if your car is not running right and you have questions, make sure to specifiy whether your car has had the upgrades.
Third, the external resistor may be the source of a "no run" condition, if the solder connection breaks from handling the temperature sensor connector. This resistor is usually soldered just behind the connector and may be concealed under the rubber boot. A broken or bad solder connection will mean that your car will not start or run, and this could be an intermittent problem because of engine vibration. In an emergency, you can disconnect a wire to the short 2 prong temperature sensor that feeds the idle control module, and the car will run, but the idle will surge hard. It may be better to carry a short wire with small insulated alligator clips on both ends in your tool kit to do a roadside repair.
Starter Replacement That Beats All - Samuel Abbasi <SamuelAbbasi@aol.com>
I posted brief information as to the easiest way I discovered to replace a starter on the 6er forum. I received e-mail responses asking that I forward my full experience to you as an FAQ. I read the two existing postings on how to change a starter and this method is MUCH less of a headache, and it works in a fraction of the time! I hope it's worthy.
To remove a starter on a 635 CSI, first gather the following tools:
1. The 17mm wrench from your trunk's toolkit (a must). Reason - the standard 17 mm Craftsman wrench, or the like, has too thick a wall to use the tool. The BMW wrench's wall is thin enough to use for this application;
2. Flat head screw driver;
3. The wrenches appropriate to remove the bolt for the oil filter, nut from starter solenoid and for loosening the battery connections;
4. An oil pan;
5. A jack (jack stands if you prefer);
6. Small flashlight with an adjustable beam; trust me you'll need it (MagLite works well);
7. and, a broom handle.
Plan for a total job time of approximately 1.5 hours.
Start the job when the engine is cold.
Jack the car and place the oil pan underneath where the oil filter housing will be removed. You know, like you've done a hundred times before. When removed, lower the car.
Remove the battery connections, negative first. (Remember, when you disconnect the battery, you will need the radio code to use your radio after the job is complete. No code, no radio).
Place the new starter in a place where you can see it easily while you work. This will help guide you as the job progresses as you will sometimes be using your fingertips as your eyes.
There are only two bolts (starter mounting bolts) and one nut (from the solenoid) to remove. Both bolt-heads and the nut face forward, nothing should be loosened from the rear.
Starting from the drivers side, disconnect the cables coming from the solenoid. There are only three of them and two go to the same post. Keep a mental image. This is a no-brainer, you'll see what I mean when you get to it.
Find the lower outside mounting bolt. You're fingers are your eyes here. Using your 17 mm wrench, remove the lower outside bolt first. It will be a bit tight but work with it. This is the easy one, but watch your hands and be careful of wrench slippage.
Now, using your screw driver loosen the o-ring of the hose at the very top-rear of the engine block. It's about 1" in diameter and it's the end that leads to the engine. Move the hose back (towards you) and tuck it somewhere so that you don't have coolant spillage. If you do it right, you won't spill a drop of coolant.
Now move to the passenger side of the car and take your 17mm wrench and your flashlight with you.
Lean over the engine block and look through the 3" square opening just below and to the left of the air flow meter. From the view you now have, the opening is above the #1 piston (closest to the firewall) above the valve cover. You'll be looking sort of through the engine's head. Using your flashlight's narrow beam, look for a 17 mm bolt. It's the only one you'll see and it's right there. This is the second starter mounting bolt. This one was the pain.
Now, slide and guide your 17mm wrench from the far-left of the valve cover, near where you disconnected the hose earlier. Use one hand to guide the wrench and the other to hold the flashlight allowing you to see where the wrench-head is. You will only be able get the wrench onto the head in one position, and it's a good one. You now know the importance of the thin walled wrench. Now that you have it on, go to the drivers side and bring your broom handle with you. Brace the butt of the handle on the neck of the part of the wrench that you can see. Push firmly and slowly! Once it gives, go to the other side of the car and work the wrench in small increments to get the bolt off. Remember, the starter is heavy. It may help to have someone there to support the starter, from the drivers side, while you remove the last bolt from the passenger side. One person can do this, but it's much easier with someone on both sides of the car.
Once the bolt is off, the starter will be in the hands of the person that is supporting it for you. Be careful not to drop it, you may damage assorted hoses and/or cables. Ease the starter towards the removed oil filter housing. You have to turn it in different ways to get it through opening created when you removed the oil filter. Once the puppy is out, you may want to take a break.
Do the opposite to get the new starter back through the opening. The replacement procedure is similar to the removal with the following exceptions:
Once the new starter is hand-held in its mounting position, put the outer bolt on first. This was the first one you took off during removal. Don't tighten it yet. Go about half way, then work on placing the second bolt. This is a one person job. Work from the DRIVERS side. Use your left hand to support and jiggle the starter so that your right hand can work the last bolt into position. Slide and guide your right hand into the position where the wrench was when you were removing this bolt. This procedure can be a bit time consuming and unnerving. Be patient, it will happen. Once it grabs, hand tighten as far as you can. This makes the wrench tightening procedure shorter. Now from the passenger side, use your wrench to tighten as far as you can. Once that's done, use your broom handle to tighten it even further.
Home stretch now.
Reconnect the coolant hose from earlier, the no-brainer solenoid wires, oil filter, battery and YOU ARE DONE!!!
Start her up, and you will notice that... SHE SOUNDS GOOD!
By: Samuel Abbasi 85 635 CSI
M6 Idle Control Valve and Throttle Switch - Dick Bargeron <firstname.lastname@example.org>
M6 IDLE CONTROL VALVE
On close examination, the M6 has its idle control valve tucked in under the first two throttle bodies. The ICV used on this engine is a very nicely made item, having a steel outer case and die-cast aluminum valve parts - unlike the mostly plastic units used on most other engines.
To remove the ICV for cleaning, first remove the intake manifold by removing the 12 nuts holding the 6 necks to the 6 throttle bodies. Use a magnet to get the washers off so they don't get lost. Loosen two hoses, one from the valve cover, the other from the ICV. Disconnect the large flex boot to the airflow meter (don't need to loosen the throttle body boots). As the manifold with boots and necks, is lifted up and out, pull off the tube at the bottom running to the crankcase. The connector is barbed so it may work better to cut the first 3/4" off this tube if it won't cooperate.
With the manifold out of the way, unplug and take the ICV out of it's rubber holder and disconnect the hoses. By looking into the ports you can tell right away if this valve is free or gummed up. It can be cleaned with carb cleaner - but don't soak the electrical end. If you have compressed air, blow it out afterward. Shake the valve (twisting motion) to check that the internals move freely. Installation is straightforward. As the manifold is put back, check the o-rings at the necks and wipe all mating surfaces clean. Use care in reattaching the throttle/cruise control cable bracket. Check that the linkage returns to the full rest position.
M6 THROTTLE SWITCH
The throttle switch on the M6 is at the top and front of the engine, at the end of the throttle shaft. The switch has a three-wire connector ( 3 18 2 ). Take off the plug and measure ohms between the center (18) and the bottom (2) terminal. It should be 0 ohms at closed throttle, and should go to open circuit as the throttles start to open. If this switch does not connect terminals 2 and 18 at closed throttle, the ICV doesn't get the right signal so idle will hang and come down slowly instead of dropping normally. (The other function of the switch is to connect 3 and 18 at high throttle opening - but this is obviously unrelated to idle performance)
With the engine off you can hear the microswitch mechanism as the throttle linkage is moved on and off the rest. But it may sound ok and still not be making contact. Use an ohmmeter to be sure. The switch can be removed and taken apart for cleaning (which I did ), this is tricky - the case is glued together and the inner switch is soldered in.
If you take the switch out, be sure to adjust it for proper function when putting it back. The closed circuit between 2 and 18 at rest should open very soon on opening the throttles.
Oil Pressure Delay - Don S. <DIS933@HOTMAIL.COM>
Oil pressure light stays on for 5-10 seconds after engine is started from cold.
This problem does need attention as soon as possible to prevent catastrophic damage to the engine.
The cause could be due to several items:
1. Oil pressure sender
2. Banjo bolts on the valve train lubrication tube
3. Oil pump
The easiest place to start is the oil pressure sender - you can just purchase a new one for about $5 or test the one you have with a bicycle pump which has a pressure gauge. Just attach ohmmeter leads to the terminal and sender body, apply air pressure to the hole in the sender with the plastic inflating needle (usually provided with the pump) and observe the ohmmeter needle. If it opens the circuit at 3-5 psi, the sender is OK.
Check the banjo bolt under the valve cover. There are two of them holding the oil distribution tube to the valve train. (One of mine bolts was totally out of the threaded hole, just lying next to a valve spring.) If they are still there, and are torqued adequately you are OK. You may want to consider removing them, and applying locktite, or use oversize aluminium washers under the head, and peen one side over the bolt head and the other over the tube (suggested by Bill & Shirley Proud, 34 yrs with no bad banjos...).
Finally, if both above items are OK, you may consider changing the oil pump. But first attach a pressure gauge to where the Oil pressure sender is threaded into and observe your oil pressure. You should test and observe how long (seconds) it takes for the pressure to come up to 60 after a long cool down (8 hrs). If it takes 2-3 seconds your pump is OK. If you get 60 psi at cold idle, you are possibly OK as well.
You should also observe how long it takes for the oil pressure to drop below 10 psi once you shut down the COLD engine -- 4-5 seconds is good. You can repeat the test with everything hot, but I do not have the time, but I believe that 2-4 seconds is OK as well. If the time is very short, it suggests loose engine bearings, or ........
If the above tests do not indicated any anomalies, maybe replacing the sender will give you better indications.
Replacing the Cam Shaft Seal Behind the Distributor Rotor Adapter Kurt Ryan Eckholdt <email@example.com>
This procedure was done on a 1985 635CSI registered in California.
Loosen the two screws at the top of the fan shroud on the radiator. Remove fan, I used a 1 &Mac185;" open end wrench, also it has left hand threads. Take the fan shroud out. Remove the spark plug wires from the distributor cap. Remove the 3 screws holding the distributor Cap onto the housing and lift off the distributor cap. Then remove the rotor using a 3mm Allen
wrench. Then remove the rotor adapter using a 8mm Allen wrench. The bolt is located in the center of the adapter. Then you can take the cover off, that black dish thing behind the adapter. Then you can get to the Cam Shaft Seal.
I heated and bent a screw driver and used it to pry out the old seal, it was crisp and broke into pieces. Clean out the housing with lacquer thinner. Bought a 2" O.D. thick fender washer with an I.D. of the Allen bolt that holds the adapter in place. Then by hand started the new seal into the seal bore. Thread the Allen bolt, with the fender washer on it, into the cam shaft and torque it down pressing the seal into place. The seal should be flush with the outside diameter of the seal bore.
Take off the bolt and fender washer and reassemble distributor.