[Story Time] D**n you, upper pan bolts!

[bmwman91]

No, my gasket didn't shift and cause another failed oiling system.  It might, but it hasn't yet.

So, I was changing my oil the other day and decided to yank the lower pan to make sure the bolts were still in place from my rebuild like 15k miles ago.  The pan was clear of all debris, phew.

So, I proceeded to check the upper pan bolts that are threaded into the timing case.  All are good...EXCEPT the two directly adjacent to the oil sump inlet.  The bastards were both stripped and probably didn't provide more than like 10lbs of clamping force.  Poop!

Well, not having time to pull the upper pan and helicoil the timing case (which will need to happen at some point to let me sleep easier) I got "creative."  One was easy.  It seemed that one of my lower-pan bolts was like 1mm longer than the one that came out of the head.  So, I bet myself that there were a couple good threads beyond the ones that were now wrapped around the bolt I removed, mocking me.

Bam, it went in and I applied maybe 10ft-lbs to it and it didn't have that nasty "I am wrecking your life" feeling common to freshly stripping threads.  The other, well this trick didn't work on it.  The thing was badly gone.  Well, I didn't have any fancy M6x1 bolts with captive washers on them that were the needed 3mm longer than the existing ones.  I DID have a ton of pan-head screws though with the right threading.  So, I got a thin washer  and my trusty red Loc-Tite and attacked the stripped hole.  Naturally, it is the one that is up in the cavity, conveniently blocked by the dipstick tube.  A super long Phillips screwdriver got the job done.  I got that screw as tight as I possibly could with both hands on the screwdriver and it didn't tear out.  Phew.

So, hopefully my upper pan gasket won't be slipping and killing my motor now.  This certainly won't qualify as the "right" way to fix it, but it works.  I am sure that after thermally cycling over the next month and the aluminum pan/timing case expanding more than the steel fasteners, the threads will be thermo-mechanically torn from the timing case.  Nevertheless, I am willing to bet that I am safe for now.  Excessive cynicism would be easy here, but I prefer to be optimistic and think that I'll be OK now.  After all, optimists may be seen as fools from time to time, but a cynic is always seen as a cynic.

BTW, who has some sharp info on doing a really nice OEM rebuild for the M42?  As much as I want a Metric Mechanic motor, I don't think I can buy a Sport M42 from them and still feel responsible about myself at this point in life (or smog my car in CA).  I thought they had a less expensive OE-spec rebuilt M42, but it is not listed on their site, and I have not received a response to my inquiry.

Let this thread perhaps be a place for a listing of all the items to be replaced for a thorough refreshing of the motor, and machine work needed to do it "right."

GO!

[haledj]

Wow you seem to be having a rough year so far

[Cobra Jet]

To really stop these bolts from coming loose on M42's, could the problem bolts just be tack welded after reinstalling them?  I'm referring to a very small tack weld - or maybe even use a little dab of JB Weld?  A tack weld or even a small JB Weld spot can easily be "snapped" if needing to turn the bolt free for a future repair event...

Just throwing an idea out there, as it seems these bolts are coming loose due to engine vibrations and even after some have used Loc Tite on them, they still seem to back out over time.

[sheepdog]

BTW, who has some sharp info on doing a really nice OEM rebuild for the M42?  As much as I want a Metric Mechanic motor, I don't think I can buy a Sport M42 from them and still feel responsible about myself at this point in life (or smog my car in CA).  I thought they had a less expensive OE-spec rebuilt M42, but it is not listed on their site, and I have not received a response to my inquiry.

Let this thread perhaps be a place for a listing of all the items to be replaced for a thorough refreshing of the motor, and machine work needed to do it "right."

GO!

I keep wanting to pull mine, but I am scared to. Reading this makes me even more scared to.

There is a company doing "performance rebuilds", higher compression and bored a bit I guess. They started about $3900 if I remember right. I don't have a name or anything though.

I do know Metric can do a bored out setup for a lot less, and if you do not want the cams or intake or custom chip (I would still get the head work) you could probably come in just over $4 (just a guess). This would probably be good for a 20-30hp gain without making you fail smog.

[bmwman91]

To really stop these bolts from coming loose on M42's, could the problem bolts just be tack welded after reinstalling them?  I'm referring to a very small tack weld - or maybe even use a little dab of JB Weld?  A tack weld or even a small JB Weld spot can easily be "snapped" if needing to turn the bolt free for a future repair event...

Just throwing an idea out there, as it seems these bolts are coming loose due to engine vibrations and even after some have used Loc Tite on them, they still seem to back out over time.

It would not really work, unfortunately.  The problem is not so much them coming out and being in the pan, but moreso that they come out, allowing the gasket to shift & fill your oiling system with air.  Tacking them to the upper pan would keep them out of the lower pan, but the threads can still be torn from the timing case, rendering the bolts useless anyway.  Clamping force is only exerted if the threads are still attached!

[sheepdog]

It would not really work, unfortunately.  The problem is not so much them coming out and being in the pan, but moreso that they come out, allowing the gasket to shift & fill your oiling system with air.  Tacking them to the upper pan would keep them out of the lower pan, but the threads can still be torn from the timing case, rendering the bolts useless anyway.  Clamping force is only exerted if the threads are still attached!

Sounds like safety wire may be a good option once it is sorted.

I have some spare bolts, maybe I will get them drilled for it before I go back in.

[tjts1]

Why does it seem like most of bolts holding the M42 together were undersized about about 2-3mm? I hope the fix holds out.
Good luck

[D. Clay]

The problem is oil pickup and sucking air into the lower front cover. May be impractical but I've thought about attaching the oil pick directly to the front cover and TIG welding it in place and cutting away the oil pan.  BMW solved the problem on the M44 with a different type of gasket. There is a groove machined into the block and a rubber gasket similar to the one used on the valve cover. The original setup is a good example of over engineering.

[bmwman91]

Sounds like safety wire may be a good option once it is sorted.

I have some spare bolts, maybe I will get them drilled for it before I go back in.

It would be tough!  The one is up in that cavity behind the dipstick, and I don't think you could get a safety wire out to another bolt head.  Still, the wire wouldn't prevent the threads in the timing case from being torn out from thermal cycling, which gets my vote as the cause for them being torn out so frequently (closely followed by all of us being pessimists & over-tightening them).

Still though, we should do like a group buy on bolts with the safety holes in them.  I sure can't do them on my father's mill...holes of that diameter take some crazy spindle speeds!

The problem is oil pickup and sucking air into the lower front cover. May be impractical but I've thought about attaching the oil pick directly to the front cover and TIG welding it in place and cutting away the oil pan.  BMW solved the problem on the M44 with a different type of gasket. There is a groove machined into the block and a rubber gasket similar to the one used on the valve cover. The original setup is a good example of over engineering.

If only I was good enough at TIGing Aluminum, got a TIG unit sitting in the garage at my parents' house......

[sheepdog]

It would be tough!  The one is up in that cavity behind the dipstick, and I don't think you could get a safety wire out to another bolt head.  Still, the wire wouldn't prevent the threads in the timing case from being torn out from thermal cycling, which gets my vote as the cause for them being torn out so frequently (closely followed by all of us being pessimists & over-tightening them).

I used to work on aircraft, that's nothing.

No it would not prevent the treads from stripping, but it would keep them from loosening up. They could be run a little on the light end of the recommended torque spec and not worry about them falling out at all. They can strip no matter what though.

Hmm, maybe oversize and then safety them.
Not sure, I would need to get up in there to look at what could be done.


By the way, the dipstick slides out easily enough.

[Cobra Jet]

Could the original threaded holes that are a problem for these bolts be oversized and a larger M? bolt be used?  I guess this could work providing there was enough "meat" there to oversize the hole(s).

Isn't there a better Loctite other than the common "red" as found in parts stores?  What about using a stronger product that still secures the bolts, but would not be an issue when removing them at a later date?

Also, how often should these bolts be checked on AFTER already putting them back in & torquing them after a rebuild?

[sheepdog]

Also, how often should these bolts be checked on AFTER already putting them back in & torquing them after a rebuild?

I think that is something that will need to be explored.

[bmwman91]

I used to work on aircraft, that's nothing.

I stand corrected lol.  I guess I need to look at some aircraft up close sometime!

[D. Clay]

Could the original threaded holes that are a problem for these bolts be oversized and a larger M? bolt be used?  I guess this could work providing there was enough "meat" there to oversize the hole(s).

Could be "the hot tip".

[sheepdog]

I stand corrected lol.  I guess I need to look at some aircraft up close sometime!

F-16's have some small spots to deal with, the whole jet is like working on an old Ford Festiva, never more than 3inches of clearance anywhere, but you could usually see what you were doing and it was never more than a few inches inside. F-111's on the other hand, you often had more room (not always), but a lot of the time you were doing it blind and deep inside a panel.

The engine mounts on the F-111 were particularly grueling, 2 bolts one on top of the other about a foot up inside a 3 1/2in access port, you had to do this over your head, crouched (unless you were short), and blind. We used to give that to the new guys , after a few tries they usually got it.