©Copyright, 2014, R. Fleischer
INTRODUCTION & HINTS, OIL PAN & GASKET; ENGINE CASE HOLES & THREADS FOR THE PAN:
HINT #1: A VERY high percentage of the time when a pan gasket seems to be leaking, it is NOT the pan gasket, but the leak is from someplace else. When the gasket does leak, it is usually due to OVER-tightening and/or IMPROPER tightening (sequence) or damaged sealing surfaces. Leaks from the timing chest, head gasket, cylinder base area, and pushrod seals, ETC. are often found to be the cause with careful inspection.
HINT #2: If you DO need to replace the pan gasket:
The early cork gaskets are no longer available and tended to leak anyway. The presently available gaskets are a fiber material, and are much better. Supposedly they have a side with writing on it, that is SUPPOSEDLY coated with a heat-activated glue. That side is normally UPwards.
HINT #3: Gaskets have apparently been seen that do not conform....so just install the gasket in the correct fitment direction.
HINT #4: Stuck pans can usually be released by a wood or plastic mallet, do NOT break fins!, after you HEAT a corner. I usually try to remove a pan after a ride, so the entire engine and, of course, the pan, are HOT. DO NOT PRY WITH A SCREWDRIVER!
the pan and engine
surfaces VERY THOROUGHLY. You may need to use chemical cleaners to remove whatever glue,
adhesives, etc., are there. Use a fine file if you have to on the
EDGES, on an angle, if any have metal nicks sticking up proud of the surface....I
have seen people use screwdrivers to get a stuck pan off, and gouge the metal, so
clean it up if need-be. If any deep gouges are found that are really BAD,
clean them and apply a two-part epoxy and when fully cured, file very carefully to be
flat. This is particularly important if any of the gouges are over
50% across the surface. If you have serious nicks, you can clean them up,
fill them with high temperature epoxy, and after that stuff cures, file/scrape/sand,
etc....until dead flat. Use a mechanics flat rule, on edge, if needed, or other
means to ensure flatness. Flatness and no nicks is critical. You only
want to do this job once.
HINT #6: I am NOT a believer in the aftermarket-available soft silicon rubber gaskets...too many problems...although SOMETIMES they do work. I do not use silicone pan gaskets....nor ANY type of sealant, silicone or otherwise, on the pan gasket surfaces (that means engine and pan metal surfaces), unless absolutely necessary. I make sure the pan is flat, nick-free, and I install a STOCK STANDARD BMW pan gasket.
HINT #7: There have been instances of annoying leaks from the bolts in the general area of below the oil canister area. Use NON-hardening Permatex Form-A-Gasket on the bolt threads and on the bolt washer.
HINT #8:I suggest the pan gasket work be done at the same time you are scheduled for a regular oil change, with or without an oil filter, A/R. HINT #9: Do NOT!! use a big torque wrench like we use for swing arm locknuts or for the cylinder stud nuts. BE SURE you do not confuse foot-pounds, inch-pounds, Nm, etc.
HINT #10: Read HINT at
#13, in next section.
1. At the next oil change, drain the hot oil. If the drain plug is frozen and cannot be removed, try heating it and CAREFULLY using a Vice-Grip pliers. If no luck, find a Torx bit that is just a bit bigger than the hex hole. Hammer it into place and then unscrew. A hot pan can help here. AVOID any type of screw extractor, they are hard, brittle, and will cause a considerable problem if they break in the drain plug.2. Check that all of the 14 bolts CAN BE tightened to 78 INCH POUNDS minimum (maximum, in my opinion, is 85 for this test); if any are stripped, fix with Helicoils after pan is removed. If your FEEL is OK, using a SMALL offset 10 mm box end wrench (4 inch length?);or...better... a SMALL square drive wrench with a 10 mm socket on a torque wrench, try tightening the 14 pan bolts, but not over 85 INCH-pounds. If any of the bolts have bad threads, note which ones, mark the case (felt tip pen or pencil, or make sketch?), so you can fix them after the pan is off. You don't want to replace the pan gasket and then find you have bad threads at any of the 14 threaded holes.
3. Put a large and soft towel or other item on the floor, as the pan MAY fly off the engine. The pan may have been put on with a sealant, which is WRONG!....the pan may be difficult to remove. Occasionally even a pan that does not have sealant applied will prove difficult to remove. Check that every pan bolt is removed! There are 14. HEAT a corner area of the pan if not already hot from riding. Use a block of wood and a substantial hammer & give the well-placed piece of wood a substantial whack from the hammer. Do NOT bust fins, ETC. DO NOT allow the pan to fly across the area & be damaged. I usually have an assistant, wearing gloves (Pan is HOT!) grab the pan so it cannot fly. DO NOT use a screwdriver to try to pry the pan off. You will leave nicks and depressions that are difficult to seal against leaks.
4. With the pan removed, VERY thoroughly clean everything. Some gasket remover products work pretty well, if you are leery ...and I suggest you be VERY careful about using sharp tools in cleaning off any old gasket and sealant residues.
It is critical that you do not nick the pan and engine mounting surfaces. Any projected nicks you find should be dressed flat. Rarely you may find a nick that needs filling, you can use one of the metal epoxies for that, then after curing, make it dead-flat. To remove the old gasket, if need-be, use a sharp blade on a very flat angle (nearly flat to the surface) to remove any old sealant or other substance found. Use a strong commercial gasket remover, if you wish. The crankcase surface absolutely must not have ANY old gasket material and no nicks that have metal proud of the surface. Clean the area very well! Final cleaning of the crankcase surface should be by a good solvent that does not leave residue. I am particularly fond of acetone or MEK for this. If you have gouges and nicks that are serious, repair them. Metal-containing epoxy will work OK!5. Bad threads are best fixed by installing Helicoils. You will want the M6 x 10 Helicoil kit. You will need a 1/4" drill bit, unless your kit comes with the drill bit. YOU MUST drill and tap at 90 degrees to the surface. USE A DRILL GUIDE AND a TAP GUIDE. If you drill and tap on an angle the results often are 'it leaks, forever...'. Check the threaded holes in the engine case....any been drilled through into the oil area and Helicoiled...or? Is the bottom engine area FLAT?..... not been dinged by someone?...looks good around the threaded holes? Are any Helicoils (or?) BELOW the surface...they should be! Are the internal Helicoil tangs, used when installing the Helicoil, removed? They should be!
BMW has shown various specifications for the pan mounting bolts. Some literature shows 8.7 FOOTpounds (don't!!!); some 6.5-8.0. Use MY figures!!! For the final torque: Torque to 65 inch pounds minimum to maximum 74 inch-pounds.
OVERTIGHTENING or failure to do in stages, cross-patterning....will cause LEAKS!
11. Install a FRESH drain plug crush washer (or the later
solid aluminum washer BMW now sells), and refill the crankcase. DO NOT FORGET TO INSTALL OIL!!!...yes, folks HAVE done that!
13.HINT! If you find any leaks at any bolt, you can remove the bolt and apply some common gasket NON-permanent sealant at the BOLT threads and under the bolt (and washer) head. I prefer the Permatex NON-hardening Form-A-Gasket #2 product. This is what I have mentioned above. DO NOT use #1, it is much too hard and permanent. ANY decent non-permanent sealant will be OK. The most common THREADS leaking problem (but can be at other areas) is at the pan bolt holes below the oil filter area. Use a flashlight or stiff solid wire to investigate those holes, before you button-up the pan and gasket. Such THROUGH-HOLES are always suspect for leaks.
Torque Wrench Conversion Factors:
While there are articles on this website with full information about torque readings, wrenches, conversions, values, etc....here are some conversion factors:
ONE Inch-Pound is the same as 1.1525 CmKg and also same
as 0.1129 Nm....and 1/12th of a Foot-Pound. Use an inch-ounce torque
wrench if that is what you have. DO CONVERT PROPERLY IF YOU NEED TO CONVERT.
Common torque wrenches with maximum's of 75 or 100 foot-pounds are NOT ACCURATE
for the pan bolts.
Foot-pounds multiplied by 1.356 is Nm.
Nm multiplied by 141.6 is inch-ounces; divide that by 16 if you want inch-pounds.
Nm multiplied by 0.7376 is foot-pounds
PERSISTENT OIL LEAKS:
IF...and only IF...you have had oil leaks that you have been unable to fix
by replacing pan gaskets in the past and after paying careful attention to the
surfaces, including checking for old gasket, nicks, flatness, etc:
Pan and pickup differences (and some other stuff):
The oil pans were not the same over the years, and some
aftermarket ones were also available, supposedly to improve cooling, which they
do much of...really!
Early pans were flat. In 1976 the pan was lowered a bit, it was a bit deeper, which gave more room for crankcase pressure, and reduced oil consumption from oil mist through the breather due to that extra air space. The breather was also modified a bit later.... it was still the round disc at that time, but added in 1978 was a tiny hole in the bottom of the oil condensation chamber in front of the breather....to drain oil back into the engine. That teeny hole MUST be clean and clear, if not, you will use oil more rapidly. When the pan was lowered half an inch or so in 1976, BMW now had to, and did, add a spacer in the oil strainer pickup tube, at the 2 bolts. Early spacers were phenolic, then later were aluminum. Two small paper gaskets are used when the spacer is used. I prefer to use a tiny amount of evenly spread sealant like Form-A-Gasket non-hardening #2 on both sides of the paper gaskets, using my fingertip...remember, THINLY......and Loctite BLUE on the threads of both bolts. The spacer surfaces need to be flat and nick-free, and the two bolts need to be evenly tightened back and forth. Some folks have used red Loctite, and I am OK with that.
You can't use the one piece
cast part on the early pans; that part is used only with the 1981+ pans. The
one-piece casting versions eliminated the need for the spacer and the extra gaskets.
In 1981, BMW made the pan a fair amount deeper, adding more oil capacity, and a slosh baffle in the pan construction, so the engine would not momentarily run out of oil on very hard braking. Also in 1981, the pickup became a cast aluminum item, no longer was a sheet metal steel pressing.
There were 3 types of oil pickup assembly bolts used, all M6, but of various lengths depending on the bike's oil pickup items. There may have been 4 types, not sure, I seem to remember one of the bolts had two head styles....one had more taper under the head. My memory might be faulty in this matter. This is hardly anything critical...the bolt must simply be long enough to fit the items properly.
NOTE: Mystic, Roadster, G/S, and GS models use a shallower pan. The pans have threaded holes for mounting a bash plate. These shallow pans are the replacement for the original NLA /5 pans. The GS pans were slightly deeper from 1991; and GS pans have a rear wall drain. There were special pans for the GS in, I think, 1988....with a large capacity.
1970-1975 center-stands do not work
with deep oil pans, unless you modify the center-stand (or, change the stand).
There is even more confusion with what dipstick to use, see below.
I am NOT in favor of NON-BMW aftermarket 'oil cooling' extension items, that give a larger oil capacity and have tubes in them running for and aft. Rare, but they have been known to give serious problems. They don't add much cooling at all.
Anton Largiader has a considerable amount of information
with photos of pans and dipsticks. He also covers some aftermarket pans at the
end of his article. Dipsticks:
BMW has used two 'styles' of dipsticks on the airheads. The early style was silvery, metal top, and used a metal crush-ring type of gasket (which was not tightened so tight as to crush it!). The later style has a black top, which stays cooler to the touch, and uses a rubber O-ring in a groove in the top handle.
The only good way to identify a dipstick is by the top style AND by the measured distance from the bottom flat area of the top part, to the minimum and maximum marks...and the tip.
HINT!...When removing or replacing the dipstick, AVOID bending the left carburetor throttle cable!
|YEAR and model||
to min. mark
to max. mark
|1975 R60/6, R90/6||11-5/16"||11-3/16"||10-5/16"|
|1979 R100RT, 1982 R100RS||10-15/16"||10-3/4"||9-3/4"|
|1983, 1984 R100RT||11-3/8"||11-1/4"||10-3/8"|
I did the above 1983, 1984 R100RT myself,
have not personally confirmed the others.
These were the only ones measured so far.
Note that these measurements apply only to stock dipsticks.
Note: just because there is information here on measuring dipsticks, does not mean, necessarily, that you have to replace yours, if, for example, you install a later oil pan. Simply note the actual level, when you do an oil change; making sure you have the correct amount of oil for that pan.
The 1982 R100RS and the 1983-4 bikes really should be identical. I have no explanation, yet. I've not yet removed pans and checked pickup heights and oil level heights with standard oil quantities.
Following is courtesy of information from John Falconer, and taken from a posting on the Airheads LIST on 09/06/2003 (and corrected from mm to cm). All John's corrected measurements are in cm,from the sealing lip to the indicated mark. Note that in the table, above, all measurements are from the flat area under the dipstick top, that is, bottom of the threads flat area.
Engine oil quantities:
Note that Anton Largiader's site also measures the dipstick from the underside of the threaded area
BMW offered a temperature gauge dipstick for late models. AFAIK, there is only one length, ~290 mm, so it won't work with every pan. $$$ too. 11-43-1-337-542
Engine oil quantities:
1.Review Anton's website article: http://largiader.com/tech/oilpan/
Excessive windage causes more than just problems with breathers and oil losses, it also causes horsepower losses from all sorts of frictional... and other effects. There are various types of friction happenings with the oil cloud.
Just one one is that the oil at the surface of the crankshaft parts is moving at a
different speed than the oil a bit away from the crank
surfaces. That in itself is a power-robbing bit of friction, much more than you may think! Think of it as multiple friction layers. Additionally, the oil flow piles-up at various places on the crankshaft, and thus creates FRICTION, which additionally ROBS THE ENGINE OF HORSEPOWER....and UNbalances the crankshaft, if not compensated-for. Besides oil piling up here and there, the oil is not regular and smooth at the crankshaft surfaces, and so there is even more friction, with multiple layers of clouds.
9. Besides these things, the frothy pan oil does not pump and distribute nicely. The PUMP finds it harder to deal with frothy oil, with is full of air bubbles, which compress, and the oil pump does not like compressible air. Put simply, lubrication CAN BE MUCH LESS. The pump was designed to suck up & distribute OIL as a liquid, not an aerated froth. An aerated froth is also compressible, and just that alone reduces volume in circulation, quite considerably actually; and the cooling provided by the oil, let alone the lubrication, can suffer. Quality oils contain anti-frothing additives, but there are limits to their effectiveness.
10. A small amount of lowering of the oil level in the pan has a goodly effect on all these problems. Theory...or, common knowledge.... and 'common knowledge' is always suspect :-)..... has it that BMW added a forward baffle (1981?...see Anton's article), because under some circumstances the oil pickup 'unports', which means it isn't in the oil and so doesn't pick up oil,... if you brake quite hard. Some have said that happens more easily on quite steep downhill's. All of this is not really fully accurate, that is, it is not the full story, but IS adequate-enough for here.
11. It is 'common knowledge' that if you fill to the max fill line on the dipstick, you will 'burn off' (dumped through the breather mostly unless the engine wear is enough) the initial first half quart (approximately), much faster than any of the rest of the oil. There are multiple reasons for this, including the mentioned things; but also there are changes in the oil itself over time/miles. Note also that the size of the engine determines crankcase pressures, and that the early bikes, with a round breather disc, had two positions possible on a breather post clip, and so were adjustable for the engine size. The adjustment controlled the pressure of the spring above the breather disc, and more pressure (lower clip setting) was used with the larger engines which had more air movement with the pistons movements.
12. There is a quite small condensed oil return hole in the breather area on later models...which should be checked for being open and not obstructed. There are photos in one of my articles of that:
http://bmwmotorcycletech.info/oilsketch.htm which will clear up confusion over where that hole is.
©Copyright, 2014, R. Fleischer
Return to HomePage
Last edit of THIS page: Tuesday, April 26, 2016