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Leaky Lower Balance Shaft cover - M8 bolts not holding torque

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Old 03-23-2018, 08:28 PM
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Lemikson
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Default Leaky Lower Balance Shaft cover - M8 bolts not holding torque

Finally found what the cause for my small, but annoying, oil leak from the Lower Balance Shaft cover area – jest behind the Power Steering Pump Bracket.

The bigger M8 bolts that go at the cover front end cannot hold torque as specified (11 ft-lb and than 14 ft-lb). Three out of four can barely make 7-8 ft-lb. PO, or somebody before him, who worked on this car must had tried to get rid of the leak by simply applying more and more torque to these bolts, while all of them soaked in oil, and the thread simply started to give in. I guess I am just lucky it is not busted completely and oil is not just raining out : ). Red arrows are pointing to three M8 bolts that don’t hold torque. Red scribble line around the bolts shown on the LBS cover is the area where oil sips out/collects before starts dripping down.

I tried to seal all of it the way some members did it before to avoid removal of the Lower Cover. Applied Hylomar Blue to try to seal mating surfaces between the cover, washer and bolt heads. And then run bead of it all around the bolts along the leak path. Before sealing, cleaned everything with lots of oil cleaner, than brake cleaner, and than chased all the threads on bolts and in the holes, and then chased again, in order to remove as much oil as I could so I could get a bit more of the remaining toqrue from the threads…. Front end of the Balance Shaft is completely re-sealed with all new seals including Metal Collar!

Bottom line, it is again leaking. Not much, but I am lucky enough that the rest of my engine is completely dry, not even sweat marks from oil anywhere…. And, I can’t stand oil marks ☹

Anyone having any idea for remedy that is other then:

1. re-tap holes to M9 bolts (not sure if this is even possible with cover in place)

2. or, M9/M10 helicoil for which I would need to get the cover off.

I am trying to see if I can avoid removing the cover to fix this leak. And, no, engine is not going out anytime soon, fingers crossed.


Old 03-23-2018, 10:52 PM
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PaulD_944S2
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Will a longer bolt reach in with out bottoming out?

Otherwise, might hold or make a mess, but buy some 9mm bolts. Cut or grind a slot in them from the tip to about 1/3 of the way up. See if they will thread in, if not, drill into the old thread with using a drill bit about that size, but only 5-6 mm. Try threading the bolts in and see if they will self thread and meet torque specs.

Idea is to cut a clearance slot in the bolt and use it to cut new threads into the block using the existing stripped out hole. The other option is to use a tap run in and out several times to gently thread the hole.

If not, LBS cover will have to come off. There just aren't very many options.
Old 03-24-2018, 03:39 AM
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Humboldtgrin
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Sounds like you should actually reseal the balance shaft cover using the proper 574 loctite. And helicoil the holes back to an M8 not just tap them to a bigger bolt. Also it's not that difficult to reseal that balance shaft cover. Just train your neighborhood squirrel (or mouse) how to turn a wrench and have it take off that balance shaft cover then put it back on.
Old 03-25-2018, 11:05 AM
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V2Rocket
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Something I've done on questionable threads with success is clean the hole out (blow out with brake cleaner and q tip), put jb weld in the hole and thread the bolt in and snug it good. The epoxy will form new threads around the bolt.

alternatively you could try epoxying or loctite on a stud for those holes and nut the cover down.
Old 03-25-2018, 02:25 PM
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Tom M'Guinn

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Originally Posted by Humboldtgrin
Sounds like you should actually reseal the balance shaft cover using the proper 574 loctite. And helicoil the holes back to an M8 not just tap them to a bigger bolt. Also it's not that difficult to reseal that balance shaft cover. Just train your neighborhood squirrel (or mouse) how to turn a wrench and have it take off that balance shaft cover then put it back on.
Totally agree. No need to make the threads bigger. I doubt an M10 would fit through the b/s cover holes (?), and M9's are super rare, but even so you'd be doing the car a disservice doing that. That's exactly what helicoils do -- they restore stripped threads like this to the original size and are easy as pie to use. Pull the cover off, clean the mating surfaces, helicoil those hole, and seal it with Loctite 574. If a longer bolt catches deeper threads, then that is the only other thing I'd try, but even then you're at high risk of stripping the remaining thread (if not enough to hold 15 ft pounds) and the seal may be compromised such that the leak persists anyway.
Old 03-25-2018, 03:55 PM
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gruhsy
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Helicoil, Time cert and others hold more torque than aluminium threads
Old 03-26-2018, 04:13 AM
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ealoken
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Buy some studs in M8 and use loctite.
Old 03-28-2018, 12:45 PM
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kev951
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Dont forget about the lovely black o-ring for the balance shaft end cap in the power steering console (if you haven't changed it already) its right near your lower arrow



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