Threadlock and Crankcase Bolts

[146C]

When assembling the crankcase, inlet manifold and reed bock three days ago I used threadlock(blue) on the bolts on a mates advice then torqued them.
There were no problems not even a hint of stripping.

Yesterday I realized I left a fitting off the inlet manifold so removed three top bolts replaced the fitting and started torqing the bolts.
First bolt didn’t even get firm before the thread stripped in the crankcase.
Second done up a little tighter as did the third before the threads stripped.

Would it be from using the threadlock or just coincidence?

I will be taking it somewhere for repair, will the reed block and inlet manifold need to be removed for them to fit helicoils etc?
Am now worried it might happen to the other 14 or so bolts which could be expensive.

Dave

[tunaticer]

Go to a bolt place and buy the helicoil set in the threads you need. Very basic to install and not difficult at all. You will need to remove everything to get access for tapping and fitting the helicoils. Sure is a helluva lot cheaper to do ten yourself rather than paying someone $20 / coil.

[Tickleish]

Man i hate locktight but i love neversieze. If a bolt is torque'd correctly their should be no need for locktight.

I do feel for ya, good luck with the repairs.

[oldboot]

Hmmmm

I am a great lover of thread locker.... but I have serious questions about it when used in alloy.

I have undone a few threads that have been steel or brass fittings in alloy that have had some sort of thread locker used....& I haven't been impressed with the result.

I don't have the experience or evidence to support my thaughts but it occurs to me that the thread locker may actually be stronger than the alloy, so when you undo instead of the thread locker braking at the glue line it takes some of the alloy with it......I don't think this is an issue steel on steel, or even brass on brass or steel.

Remember alloy is quite soft..and more pourous than many people think

I also have questions about thread locker and corrosion..I suspect it may promote corrosion.....remember steel bot in an alloy case, there will be a dissimilarity and possible electrolisis.


SO
it occurs to me that

sometimes thread locker or sealer is unavoidable, like in fuel tank fittings......But I have concluded, reworking that joint may be a once or twice thing, if at all.

It may be wiser to use some sort of softer thread locker or sealer if possible.

and
Often the thread locking isn;t the issue we think it is....perhaps the sealer ( gasket sealer) used on the joint may be sufficient for the joint and the thread locking.
Hell I've pulled sumps off cars that would have stayed there for ever with all the bolts removed because of the good sealer job.

AND
perhaps corrosion is an even bigger issue, and perhaps we should be using something like duralac on those bolts.

and now another issue that just occured to me.....it is well documented and recomended not use antifoul with copper in it on aluminium hull boats.......so do we have an issue with using antiseze with metals like copper in them ....all the major brands of antiseze have heaps of copper in them

It occurs to me that good practice in motorvehicles may not translate to marine situstions.

In the manuals I have they seem very specific about the types of sealer and lubricants used in outboard service.......there may be more to this than some of us think.

now think about those helicoils.......are they going to introduce another dis-similar metal into the situation..and what do you do about that...duralac perhaps.

or is it better to do something else......like tap out the fastener to the next size bolt or have it welded and redrilled and tapped, or even just fit a longer bolt a fit a nut on the other side.

more questions than answeres I am affraid..... but that is the way I see it.

cheers

[146C]

Go to a bolt place and buy the helicoil set in the threads you need. Very basic to install and not difficult at all. You will need to remove everything to get access for tapping and fitting the helicoils. Sure is a helluva lot cheaper to do ten yourself rather than paying someone $20 / coil.

Any idea how much the kits are?

Hmmmm

I am a great lover of thread locker.... but I have serious questions about it when used in alloy.

I have undone a few threads that have been steel or brass fittings in alloy that have had some sort of thread locker used....& I haven't been impressed with the result.

I don't have the experience or evidence to support my thaughts but it occurs to me that the thread locker may actually be stronger than the alloy, so when you undo instead of the thread locker braking at the glue line it takes some of the alloy with it......I don't think this is an issue steel on steel, or even brass on brass or steel.

Remember alloy is quite soft..and more pourous than many people think

I also have questions about thread locker and corrosion..I suspect it may promote corrosion.....remember steel bot in an alloy case, there will be a dissimilarity and possible electrolisis.


SO
it occurs to me that

sometimes thread locker or sealer is unavoidable, like in fuel tank fittings......But I have concluded, reworking that joint may be a once or twice thing, if at all.

It may be wiser to use some sort of softer thread locker or sealer if possible.

and
Often the thread locking isn;t the issue we think it is....perhaps the sealer ( gasket sealer) used on the joint may be sufficient for the joint and the thread locking.
Hell I've pulled sumps off cars that would have stayed there for ever with all the bolts removed because of the good sealer job.

AND
perhaps corrosion is an even bigger issue, and perhaps we should be using something like duralac on those bolts.

and now another issue that just occured to me.....it is well documented and recomended not use antifoul with copper in it on aluminium hull boats.......so do we have an issue with using antiseze with metals like copper in them ....all the major brands of antiseze have heaps of copper in them

It occurs to me that good practice in motorvehicles may not translate to marine situstions.

In the manuals I have they seem very specific about the types of sealer and lubricants used in outboard service.......there may be more to this than some of us think.

now think about those helicoils.......are they going to introduce another dis-similar metal into the situation..and what do you do about that...duralac perhaps.

or is it better to do something else......like tap out the fastener to the next size bolt or have it welded and redrilled and tapped, or even just fit a longer bolt a fit a nut on the other side.

more questions than answeres I am affraid..... but that is the way I see it.

cheers

I kinda thought this may be the case too...

Should of just applied a little engine oil to the bolts like I was originally going to do.

Dave

[FNQCairns]

If you do pull another bolt instead of doing up then torque up, with a small spanner work the bolt in and out going in just a little further each time. All the dry plastic like junk in the hole is expanding it as you torque to spec.

Nothing wrong with cleaning the bolt thread 35 times as you work through the process above.

I like using nothing more than grease for this purpose and even then because it's aluminium it effectively locks it's self.

You sure the bolts are steel? quite a few bolts are actually high grade aluminium.

[Spaniard_King]

If you do pull another bolt instead of doing up then torque up, with a small spanner work the bolt in and out going in just a little further each time. All the dry plastic like junk in the hole is expanding it as you torque to spec.

Nothing wrong with cleaning the bolt thread 35 times as you work through the process above.

I like using nothing more than grease for this purpose and even then because it's aluminium it effectively locks it's self.

You sure the bolts are steel? quite a few bolts are actually high grade aluminium.

FNQ are you having a go at this guy???

High grade aluminium bolts... exacly where and who uses these in engine assembly

[FNQCairns]

Yeah Gary pretty sure, used as engine bolts on bikes too (not as head bolts) i am pretty sure my yam 90 has a few also. dunno what engine the OP has.

They are a type of aluminium alloy I probably wouldn't get to see otherwise.

[Spaniard_King]

Yeah Gary pretty sure, used as engine bolts on bikes too (not as head bolts) i am pretty sure my yam 90 has a few also. dunno what engine the OP has.

They are a type of aluminium alloy I probably wouldn't get to see otherwise.

Sorry Scott, no aluminium bolts on any outboard that I know of.. definitely your 90 yam does not have any.

Manufacturers use a coating these days for there steel bolts and 50% of the time it dosnt work either.. they do look a bit like ally bolts.

[FNQCairns]

You could be right Gary, i know the bikes use them largely for the pretty anodising on the flash bike engines they have today but they still do a steel bolts job, it's been like 4 or 5 years since i redid this Yamaha engine, sure i remember taking note of the lightness of a bolt and marvelling at the technology at some stage, extra light too but still it was a while ago now.

Planing to do some maintenance in this area in the next month or two so will pay particular attention if only for my own curiosity.

[tunaticer]

Two years ago I purchased an M10 helicoil set with 10 extra coils for about $75 from memory, so it works out a lot cheaper than paying $20 per coil from someone else to do exactly what the instructions tell you to do. Basically you drill out the remaining thread with the pilot size for the helicoil tap, tap the new thread into the block, then insert the helicoil into the tapped block and break the tang off eith the tool provided. Done. Took me a couple of minutes per hole and no hassles and that was tapping brass, not alloy.

[146C]

Thanks for the advice so far especially Jack.

I have decided to have a go at doing it myself and have located a kit but the helicoils are only about 10mm long, i have read in another post that the helicoils should be around the same length as the bolt. The bolts are M8 X 30 & 35mm, would the 10mm helicoil suffice or should I try find a matching size?

Also do I torque to original specs? around 23nm from memory.

Dave

[tunaticer]

When I bought the helicoils they were available in two lengths, 1x diameter and 1.5x diameter, I took the 1.5x which was 15mm of thread. Helicoils are actually stronger than the base alloy due to much greater surface bonding area.
I have seen M12 x 4.6 grade bolts separate and not damage the helicoils using a 1/2" rattle gun on them.
I do not know your torque rating needed sorry.

[mitch92]

What are these helicoils? anyone got a link?

[finga]

http://www.emhart.com/products/helicoil.asp

Just google helicoil and the world's your oyster