Pans; oil pan gaskets; oil pan threads, oil capacity; dipsticks; oil pickups
© Copyright, 2012, R. Fleischer
Trick/hint: Using a SMALL offset 10 mm box end wrench or a SMALL square drive wrench with a 10 mm socket, try tightening the 14 pan bolts, but not over ~75 INCH-pounds. If any of the bolts have bad threads, note which ones, mark the case, 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)
|This first section is a copy, edited, of a short
thread from the Airheads LIST. Please read this
section, and then read the rest of the article.
"I replaced the leaky oil pan gasket on my 1973 r75/5 with a high quality silicone gasket. I had a terrible time getting the original gasket off (stuck on the oil pan side). After getting the original gasket off I lightly sanded the oil pan with 400 grit sandpaper, cleaned surfaces, and installed. Well I still seem to have a leak (perhaps even slightly worse). I plan on taking the oil pan back off after I try to find the exact location of the leak with talc. I will get a better torque wrench and follow guide lines (6 ft-lbs) I found on other threads. My question: Are there any other tricks to avoid leaks? Perhaps something applied to the gasket besides adhesive?"
"This is a generic reply, for MY method of dealing with pan gaskets.
BEFORE removing the old gasket, I use my personal hand-feel on the 10 mm bolts (you can use a torque wrench) to identify any threads that are being pulled out. Finding out about a pulled thread is best now, and not after you start torqueing up the new gasket.
I NEVER EVER use silicone pan gaskets....nor ANY type of sealant, silicone or otherwise, on the pan gasket surfaces (that means engine and pan metal surfaces). I make sure the pan is flat, nick-free, and install a STOCK gasket, on very well cleaned surfaces (some gasket remover products work pretty well, if you are leery (and I suggest you be VERY careful anyway) of using sharp tools in cleaning off any old gasket and sealant residues.
Any sanding of pan surfaces MUST be done on a FLAT surface, such as an old piece of window glass or a real Surface Plate. I use even pressure, and figure-eights, varying my hand position, etc. Don't do sanding unless there is a problem! You can use a lamp or flashlight at the pan-to-flat-plate surface to see any problems...or, as I do, with a very thin feeler gauge (.002" happens to be the one I use).
After the pan is known to be flat and without serious nicks (DO NOT nick with your scraping tools!), and ALL old gasket crap is removed from engine and pan surfaces, and the surfaces cleaned (I use ACETONE on a rag), I install conventionally, I hold the pan and gasket to the engine, then fingering-in all the bolts first. Sometimes I hold a 10 mm socket in my fingers and just go finger tight. Then I tighten evenly, in a cross-pattern (very important), and for the first go-around, I use a quite low torque, just by feel, I'd guess at maybe 10 INCHpounds or so, never have measured it. I might use the socket and a 4" or so stubby square drive tool; or a box-end wrench..
Then, I almost always just use that small 10 mm box end, offset, wrench. If you do not have a good feel for torque, use a good INCH-POUND or equivalent torque wrench, after you get all the bolts evenly and LIGHTLY tightened. Always do any tightening in a cross-pattern...this is just plain good practice, and is IMPORTANT at the pan. It is very important to torque evenly, in a cross-pattern, and to do this in STAGES. That means any one amount of torque is done in a cross-pattern until all bolts are at that torque level, then increase the torque a bit, until all are at that next level. The idea is to NOT 'bunch up' that gasket. Of course, the idea is also not to over-torque the bolts and pull threads out of the engine!
Do NOT!! use a big torque wrench like we use for
swing arm locknuts or for the cylinder stud nuts.
After you have ridden the bike some, and have a few heat-cool cycles, you can re-torque the 10 mm bolts. If you find any leaks at any given bolts, you can remove the bolt and apply some common gasket NON-permanent sealant at the BOLT threads and under the bolt (and washer) head."
If you are replacing the pan gasket due to leaks,
first be sure that the leaks were from the pan mating
surfaces. I have seen pushrod seals leaks, leaks from the
oil sender switch, leaks from the high pressure galley, neutral
switch etc., all appear to be pan leaks.
You will need a brand-new 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. They have a side with writing on it, that is SUPPOSEDLY coated with a heat-activated glue. That side is UPwards. NOTE: Gaskets have apparently been seen that do not conform to this....so just install the gasket in the correct fitment direction.
Torque Wrench Conversion Factors
There is an article on this website about torque wrenches. It is article 71B. There is also an article on torque problems, etc., it is article 71A. Review them at your leisure.
For the purposes of the Pan bolts, you may have reason to
convert values for various types of torque wrenches.
ONE Inch-Pound is the same as 1.1525 CmKg and also same as 0.1129 Nm....and
1/12th of a FootPound. Use an inch-ounce torque wrench if that is
what you have.
In this article I generally use a value of 75 INCH-pounds for the pan bolts. That is only a bit over 6 foot-pounds.
use torques as high as 8 or 9 foot-pounds!....that is too high!!!
The old books said 6.5 to 8 footpounds, I deem that too much. Use an inch-pound or inch-ounce wrench, or by calibrated feel!
Common torque wrenches with maximum's of 75 or 100 foot-pounds are NOT ACCURATE for the pan bolts. 72 inch-pounds is fine (I don't go over 75), if you have an inch-pound torque-wrench. Trying to use a FOOT-pound wrench is usually BAD, as you are typically at the bottom of the wrench scale, even if it does go that low. Remember, 72 INCH-pounds is the same as 6 FOOT-pounds! Metric-reading torque wrenches are much more commonly seen in the USA nowadays. Small capacity metric torque wrenches are available, in various types of readings. One such is cm-kg, and 83 cm-kg is same as 72 INCH-pounds. Some wrenches read in both metric and American standard. Be cautious. A common 75 or 100 FOOT-pound wrench might have Nm scale readings, and the SAME problem occurs when trying to use small settings, whether metric or standard, that is, 72 inch-pounds is only about 8 Nm. I very much recommend you do NOT use a 75 or 100 foot-pound wrench to tighten pan bolts!
How to go about replacing the pan gasket, basics:
As noted at the very top of this article: If any of the bolts have bad threads, note which ones, mark the case, so you can fix them after the pan is off (You don't want to replace the pan gasket and find you have bad threads at any of the 14 threaded holes).
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 AND TAP GUIDE(s).
At the next oil change, drain the hot oil.
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!.. thus, the pan may be difficult
to remove. Occasionally even a pan that does not have
sealant applied will prove mildly difficult to remove.
HEAT a corner area of the pan if not already hot from riding. Check that
every pan bolt is
removed! There are 14. Use a block of wood and a substantial
hammer and give the well-placed piece of wood a substantial whack
from the hammer. Do NOT bust fins,
ETC. DO NOT be stupid and allow the pan
to fly across the area and be damaged. I usually have an
assistant to grab the pan so it cannot fly.
With the pan removed, VERY thoroughly clean everything. 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 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 for this.
Look upwards with a strong light and SLOWLY AND CAREFULLY inspect the oil pickup, etc. Be sure it looks OK and the bolts tight. This is a VERY good time to inspect that pickup, tube, casting area, for CRACKS!....some have been seen on extended pickup models. If you wish, remove the metal screen and clean it. If the two bolts for the pickup are even slightly loose, remove, clean with solvent, use new gasket(s) and apply Loctite BLUE to the threads before tightening (evenly!). If you absolutely INSIST on reusing the gaskets, and they look OK...that is, not torn, you can install them with a FAINT, but thorough, coating of NON-hardening Permatex form-a-gasket (type #2). It is preferable to install new gaskets, no goop. The reason to install fresh gasket(s) is that the gasket will not go back onto the assembly in EXACTLY the same position, and you might even have it reversed or upside down, as they fit any which way. That means that the raised area and non-raised areas no longer match-up, and you can get AIR sucking-in at that point. Thus, using an old gasket is a BAD idea, unless it is mandatory in some field situation.
Check the pan for ACTUAL flatness. Use #1 eyeball
with the pan on a piece of glass or a surface plate, and a strong
light...or a feeler gauge or both.
If necessary, place the pan on a flat piece of glass with a large piece of sandpaper, perhaps grit 320. Do careful figure eights, with evenly spread hand pressure. If you are good at it, use a long flat mill file carefully covering adjacent and cross-surfaces.... otherwise do the eights. Do just enough to be sure the pan is flat, smooth, and NO dinged edges that have protruding bits, etc. DO NOT round the pan edges, flatten unevenly, etc. It is NOT necessary to try to flatten the pan to remove every irregularity, but you want it flat.
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 the Helicoils (or?) BELOW the surface...they had better be! Are the internal Helicoil tangs, used when installing the Helicoil, removed? They should be!
HINT! I have found it sometimes necessary to use a gasket sealant on the pan BOLT threads & under the heads (and I ALWAYS use waverly locking washers). My particular favorite is the old tried and true Permatex Form-a-Gasket #2...(do NOT USE #1, it is much too hard and permanent when it dries). ANY decent sealant will be OK. The most common THREADS leaking problem (but can be at other areas) is at the pan bolt holes adjacent to the oil filter area. Use a flashlight or stiff solid wire to investigate those holes, before you button-up the pan and gasket. THROUGH holes are always suspect for leaks.
use any sealant on the gasket
surfaces! The gasket writing should be UPwards!...there
is a heat activated glue on that surface!..that is, if the pan
gasket was made properly (some are reportedly not).
I do NOT use silicone gaskets. However, to be truthful, many have used them successfully.
Hold the pan and gasket up to the engine FLATLY, and with fingers, get the 14 bolts installed. NOW...tighten the pan 10 mm bolts (with waverly washers) very carefully, in a cross fashion...bit by bit....I do this with a small 10 mm box wrench or 3/8 drive socket and short ('stubby') handle ratchet. I do it by FEEL, and I guess I do it to around 6 foot pounds...but I have seldom measured it. DO NOT go for full torque right off the bat. Do the tightening in STAGES, in a cross-pattern. Do one amount of tightening, then when all 14 bolts are at that tightness, increase the torque on one bolt, and start the cross-pattern tightening again. Continue until final tightness is reached. OVERTIGHTENING will cause LEAKS!...if you do not pull threads first.
Install a FRESH drain plug crush washer (or the later solid aluminum washer BMW now sells).
NOT FORGET TO INSTALL OIL!!!...yes, folks HAVE done that!
After a few heat-cool riding cycles, touch up the torque on the bolts again; again a cross-pattern....slightly.....same torque level.
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 not
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, 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 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 the bolts... BOTH in all instances. The spacer surfaces need to be flat and nick-free, and the two bolts need to be evenly tightened back and forth, and I use blue Loctite on them, some folks have used red Loctite. 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.
NOTE! 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 to cooling much 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.
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). 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
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.
1) Dipstick from an early /5 (metal cap, no markings) : 25.7 cm to full, 28.3 cm to low
2) Dipstick from an early '80s R65 (plastic cap with molded in "A") : 27.2 cm to full, 29.3 cm to
3) Dipstick from a '92 R100GS (plastic cap with molded in "C") : 26.6 cm to full, 28.4 cm to low
Note that Anton Largiader's site also measures the dipstick from the underside of the threaded area
There is sometimes confusion about how much oil an engine takes during an oil change. Your owner's booklet has the figures. Here are some guidelines, for stock oil pans:
Without oil coolers, up to 1980: 2.25 liters
With oil coolers to 1980: 2.50 liters
From 1981 without cooler: 2.50 liters
From 1981 with cooler: 2.75 liters
R80GS to 1990: 2.25 liters
GS from 1991: 2.50 liters
To fill the engine from the MIN to the MAX will take nearly a full liter....a quart U.S., except that after 1980 it was a bit less...about .85 Liter or .9 quart, approximately.
08/13/2006: emphasis on the glue and writing upwards
11/21/2007: WAS article 79. Minor changes in emphasis also.
01/15/2008: Move page position on Tech Index Page during re-organization of site; edit the article
for clarity during this process; add Pan Differences from the Engine Internals article.
MAJOR changes to this article.
07/07/2008: Add Anton's website link to pickups heading.
01/22/2010: cleanup, clarify some details.
03/19/2010: edit for clarity; include the LIST stuff.
02/24/2011: Changed to 50C
03/23/2011: Remove oil pan information from 50B, move here; revise this article for more clarity
04/05/2011: minor clarifications
10/18/2011: Another "C" anomalie?...make note
10/18/2011: Correct the discrepancies on the dipstick measurements, noting WHERE they are
10/12/2012: Add QR code; add language button; update Google Ad-Sense code; clean up article,
incorporate a table, etc.
© Copyright, 2012, R. Fleischer
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