Leaking oil pan bolts... again

[lmo1131]

My /5 is leaking oil from a few oil-pan holes. I've determined this by observation over a period of days. The push rod seals are leaking as well, but there is definitely oil getting past the bolt threads.

I know that the oil pan bolt-holes are "through" holes.

This started recently with a) an oil change, b) a new pan gasket, and c) installation of stainless steel bolts (sequentially torqued in three steps).

I strongly suspect that the new stainless fasteners are to blame; possibly a slight difference in "specifiation" allowing more major-diameter clearance(?).

Has anyone else experienced this situation (leak after stainless bolt installation)?

Two possible fixes:

a) drain the oil, drop the pan, clean holes, reinstall with new gasket using appropriate thread compound on stainless bolts.

b) replace with the original steel bolts (if I can find 'em...) WITHOUT thread sealant, to see if the leak stops with the carbon steel OEM bolts (indicating that the stainless bolts were indeed "out of spec").

c) implement total-loss oil system

d) none of the above

Comments?

[fracture]

I do not see how the fastener could be the problem. It sounds like oil is getting past the gasket then running down the threads.

My experience with a leaking oil pan gasket may or may not solve your problem. I put up with pan gasket leak for about a year. I finally dropped the pan and installed a factory gasket. A week later, I could see oil leaking from under one bolt head.

What did I do? I got a silicone gasket from Real Gaskets. Problem solved.

[robsryder]

I've found that use of the silicone pan gaskets sold by Rocky Point Cycle stopped all leaks about the pan on my bikes. Whatever pan gasket used (paper OEM or silicone) the sealing areas need to be cleaned and flat. Flatness of the pan can be checked with a piece of plate glass.
http://www.rockypointcycle.com/Merch...egory_Code=B10

Both the bottom of the engine case and the pan sealing surface should be thoroughly cleaned. I scrape the old gasket material off - gently so as not to gouge the aluminum! Then I use some ScotchBrite to further clean these surfaces. I use a wee bit of brake cleaner on a rag to remove the residual oil (if any) from the sealing surfaces.

Both the paper OEM and Silicone gaskets are to be installed dry. If stainless fasteners are used some anti-seize is recommended - stainless in aluminum can gall if anti-seize isn't used. Galling is a type of welding that can result in thread damage.
http://www.fastenal.com/content/feds...%20Galling.pdf
http://www.eng-tips.com/viewthread.c...=217587&page=7
http://www.ssina.com/view_a_file/fasteners.pdf

One advantage of steel is the fasteners are magnetic - seems like I'm always having to use my telescopic magnet to find a dropped bolt.

Matt Parkhouse has written about repairs to the pan threads. He recommends testing each threaded hole BEFORE removal of the pan. He has suggested slightly applying a tightening torque prior to loosening. If a thread is stripped then it can be noted as to the hole(s) that will require thread repair (e.g., heli-coil insertion). If the suggested tightening torque is 5 ft-lbs, then one shouldn't apply much above that (e.g., 6 ft-lbs if using a sufficiently precise torque wrench). Matt has illustrated the pan thread repair by leaning the bike upon the appropriate cylinder valve cover (an old piece of carpet beneath the valve cover is useful to keep the valve cover from becomming scratched).

I find that tightening the pan bolts in a criss-cross pattern (similar to the way one is to tighten head bolts) is useful to uniformly compress the pan gasket. I also approach the desired final torque in three steps. For example, if the desired torque for the M6 bolts is 5 ft-lbs (NOTE - the silicone pan gasket calls for a lower torque value - 3 ft-lbs as I recall), then the first step is insertion of the bolts in the criss-cross pattern to a finger tighteness. Then to about 1.5 ft-lbs (18 in-lbs - or one finger about 2 inches up the 10 mm open end wrench). Next to about 3 ft-lbs (or two fingers about 2 inches up the wrench). Finally to 5 ft-lbs (three fingers on wrench). It helps to have a torque wrench capable of distinguishing torque values in the range of 10 to 60 inch-lbs, or develop a self-calibration for your finger(s).

If the bolt won't tighten up, then the threads are likely stripped. It will then be necessary to remove the pan and gasket to repair the threads. A good M6 thread repair kit will be useful.
http://www.amazon.com/Helicoil-5546-.../dp/B0002KKPXK
http://www.helicoil.in/helicoil.htm