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Handling Conflicting Instructions

cdeerinck

Well Known Member
I am curious about how people here deal with conflicting instructions. Not necessarily a specific situation, but just in general.

Here is one that I ran into today while installing a throttle body adapter onto a cold sump.

Instruction #1 from the adapter Mfr.:
Attach the sump adapter to engine sump using 5/16"-24 x 1 1/4" socket head screws. Use Ultra Black Silicone Gasket Maker between the engine sump and the adapter. Use blue Loctite on the 5/16" socket head screws and torque to approx 180 in. lbs.

Instruction #2 from the Ultra Black instructions:
Apply continuous 1/8" to 1/4" bead on the surface to be sealed. Finger tighten until it starts to squeeze hour. Wait one hour, then torque to specifications.

Instruction #3 from the LockTite Blue bottle:
Apply 1-2 drops on threads, and immediately tighten. Full strength will be reached in 24 hours.

The best I could reason was to follow the Ultra Black instructions to get a good seal, ignore the LockTite "immediately tighten", and assume that the torque after an hour of the LockTite curing would be negligible, so just stick with the 180 in. lbs. as instructed. Does that sound about right?

I would be interested to hear of other similar situations, and how you reasoned past the conflicting instructions.
 
1) If you're married then you get used to managing conflicting instructions.

2) If you're single then ask a married friend.

3) If you're married and still confused do whatever makes the plane happy because a happy plane is a happy owner.
 
I generally try to ask "why". In this case it has to do with set times.

In you specific example i would allow the rtv to set for 1 hour as the rtv instruction specifies, then after 1 hour I would apply the loctite and torque to 180 inch pounds. That seems to make all three instructions happy.
 
I believe I'd install per the Ultra Black instructions to get a good seal, including the torque but not the blue Loctite. Once it was fully cured, however long that might be, I'd remove one fastener at a time and reinstall it with its blue Loctite.

Dave
 
In you specific example i would allow the rtv to set for 1 hour as the rtv instruction specifies, then after 1 hour I would apply the loctite and torque to 180 inch pounds. That seems to make all three instructions happy.

Ok, great idea, and now I feel like a fool. That is one of the reasons I was curious to post this here.
 
Bingo. As the rtv slowly oozes out over an hour, the torque on the fasteners is going to loosen. That said, a 5/16 bolts with blue thread locker is not going to back or or cause the joint to leak even if you lost half your clamping pressure. In all practicality, I doubt you will go wrong with either method, but Dave's method as outlined below would be the best of all worlds (giving the sealant time to squeese out and recomended torque.)

I believe I'd install per the Ultra Black instructions to get a good seal, including the torque but not the blue Loctite. Once it was fully cured, however long that might be, I'd remove one fastener at a time and reinstall it with its blue Loctite.

Dave
 
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Follow the instructions from the adapter manufacturer, which was apply sealant, install, and fully torque.

The conflicting information is the instructions on the sealant tube, which requested a large quantity of sealant (1/8 to 1/4 inch bead), followed by only enough clamping to begin squeeze out. It's an automotive practice with roots in old stamped steel oil pans and valve covers, which rarely have flat flanges. The idea was to form a "gasket" in place, with actual thickness separating the parts after cure. That's generally undesirable in mechanical assemblies. We typically want clamped close contact between parts, with only a very thin (~0.001") film of sealant. To do it, apply a smear of sealant (or perhaps a 1/8" bead max), and apply full clamp torque on the fasteners while the sealant is wet.
 
A caution about RTV as a gasket sealer. If too much is applied subsequently squeezed out it may make big blobs on the inside of the joint. If that blob happens to get into the oil pump the incompressible blob has broken oil pump parts.

For a sump, the oil suction screen should stop any excess from entering the lube system.
 
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