coupler installation

[scoflaw]

Can't find info on what to put on the coupler bolts before torking

 

[Alpheus]

Re: coupler installation

I dont understand your question.

I can hook you up with a manual if you tell me what model engine you got...

 

[fossill]

Re: coupler installation

I think he asking if you put locktite on the bolts maybe.

 

[Bluestream]

Re: coupler installation

Can't find info on what to put on the coupler bolts before torking

I think you mean torquing? Nothing goes on them.

 

[Howard Sterndrive]

Re: coupler installation

clean and dry

 

[dakine]

Re: coupler installation

clean and dry

This is really bad advice!

Every fastener should be clean and coated with something before torque.
The coating depends on the application and torque specs depend on the coating.

Loctite, appropriate anti sieze and lube oil or grease are all used.

Rod and head bolts are designed to be torqued with oil on them.
Anti sieze is so slippery that proper bolt stretch is often reached at lower torque values than normal.
Loctite is good if vibration or accessibility is an issue.

So, at the least, I'd put 30 weight oil on them and torque to spec.
Me, I'm paranoid, and put loctite on flywheel/clutch or coupler bolts.
Since you hope to not touch them for 10 years or so, it's good insurance.

There are many types of anti sieze and you need to know your metallurgy to know what type to use.
Silicon dialectric grease is also used for steel into aluminum to reduce electrolysis.

 

[Bondo]

Re: coupler installation

clean and dry

Ayuh,.... That's what I do....

 

[StorminNormin]

Re: coupler installation

So, at the least, I'd put 30 weight oil on them and torque to spec.

If you put oil on the threads you need to drop the torque 20% to compensate. Manufacturers torque specs are designed to be dry, unless otherwise stated.

 

[Howard Sterndrive]

Re: coupler installation

20%?
doesn't it depend on the oil? and fine thread vs. coarse?
And steel fasteners vs. stainless?
Nuts and studs vs. cap screws?
Used bolts or new?
Hardened Washer vs. Lock Washer vs. no washer?
Grade of fastener?

and if one oils the threads, why not the underside of the bolt head? that's where all the friction is....

bottom line:
too many variables for a spec with oil, so Mercruiser specs. coupler bolt torque for clean, dry threads only.

I know of some fasteners where the manuf. recommends HALF TORQUE with anti-seize vs. dry

Unless otherwise specified, all torque values given in the manual are for clean, dry threads.

Anyone thinks they are smarter than Mercruiser engineers can put any fluid they like on there.... but that's not what the OP asked, and adjusting the torque to compensate is a science beyond most DIYers.....

Do you go higher torque or lower torque when you add unnecessary loctite?
Because it's a lubricant until it dries.....then it causes more friction
but how fast it dries, whether you used quick-cure primer and how fast you get it torqued up are going to change with each fastener....

 

[dakine]

Re: coupler installation

Put them in dry and you can expect corrosion.
By dry do you mean totally degreased or simply as supplied by the manufacturer with residual oil?

ARP rercommends pulling up all its fasteners with oil on the threads, especially critical ones like main and rod bearings.
The oil recommendation is because it gives a uniform coefficient of friction wheras dry assembly bolt stretch depends largely on bolt surface condition.

Mercruiser does things its own way but that doesn't mean it is the only right way.
My stuff doesn't break or come apart so after using appropriate coatings on fasteners for over 40 years, I'm not about to change.

Most stainless fasteners require anti seize to torque correctly due to galling of stainless.
I just bought $1000 worth of stainless bolts from Totally Stainless for an old Vette I'm restoring and they came with instructions and a bottle of nickel anti sieze.
They are not warranted if you don't use the anti sieze and their torque recommendations.

Virtually every bolt installed in a refinery or chemical plant gets anti sieze.

The only way to truly correctly torque a critical bolt is with a stretch gauge as I do with rod bearings in my racing engines.
Or, for big stuff, a hydraulic bolt stretcher is used to guarantee correct bolt strain.

Put em in totally degreased if you want.
Good luck getting them out.
Especially with steel or stainless fasteners into aluminum.

 

[6meter]

Re: coupler installation

Just tighten it up a quarter turn before snapping the bolt.

 

[sasto]

Re: coupler installation

Just tighten it up a quarter turn before snapping the bolt.

I usually tighten them till they break....then back them off a quarter turn.

 

[Howard Sterndrive]

Re: coupler installation

Good luck getting them out.

I've never heard of anyone struggling to remove coupler bolts or nuts that were installed dry by Mercruiser.

 

[mkast]

Re: coupler installation

Mercruiser does things its own way but that doesn't mean it is the only right way.

In this case, yes it does.
You didn't mention which field your engineering degree is in.

 

[Howard Sterndrive]

Re: coupler installation

Mercruiser does things its own way but that doesn't mean it is the only right way.

Ok, so he lubes them.... Now, what torque value do you advise he use??
The standard torque provided by Mercruiser for clean and dry?

Are you just going to pull a number out of a hat? Spend hours computing a torque vs. stretch analysis of this application?

lubricant might provide for a more uniform stretch across the multiple fasteners and provide consistency. And, it might prevent some corrosion.

But:
you don't have a spec for a lubed fastener in this application

The only spec. available is from Mercruiser.
And their spec is for a clean, dry fastener.

This thread started out with a question specific to a Mercruiser coupler.

 

[Bluestream]

Re: coupler installation

I recently removed my coupler and after 22 years the bolts came out looking like new. If compound or sealant was needed they would have put it on at the factory.

 

[Bondo]

Re: coupler installation

Ok, so he lubes them.... Now, what torque value do you advise he use??
The standard torque provided by Mercruiser for clean and dry?

Ayuh,... When I pull 'em outa the Bolt Bucket for reassembley, whether Dry or Oily,....
I run 'em up to the standard 3/8" coupler torque value of 35/ 40ft.lbs. of torque,...

Of course using my Calibrated Elbow for the final settin's....

 

[Alpheus]

Re: coupler installation

Put them in dry and you can expect corrosion.
By dry do you mean totally degreased or simply as supplied by the manufacturer with residual oil?

ARP rercommends pulling up all its fasteners with oil on the threads, especially critical ones like main and rod bearings.
The oil recommendation is because it gives a uniform coefficient of friction wheras dry assembly bolt stretch depends largely on bolt surface condition.

Mercruiser does things its own way but that doesn't mean it is the only right way.
My stuff doesn't break or come apart so after using appropriate coatings on fasteners for over 40 years, I'm not about to change.

Most stainless fasteners require anti seize to torque correctly due to galling of stainless.
I just bought $1000 worth of stainless bolts from Totally Stainless for an old Vette I'm restoring and they came with instructions and a bottle of nickel anti sieze.
They are not warranted if you don't use the anti sieze and their torque recommendations.

Virtually every bolt installed in a refinery or chemical plant gets anti sieze.

The only way to truly correctly torque a critical bolt is with a stretch gauge as I do with rod bearings in my racing engines.
Or, for big stuff, a hydraulic bolt stretcher is used to guarantee correct bolt strain.

Put em in totally degreased if you want.
Good luck getting them out.
Especially with steel or stainless fasteners into aluminum.

Gotta love when the auto mechanics come on here and start throwin out advise, like us boat owners are a bunch mindless morons who have not a clue as to what we are doing when it comes to turning a wrench.

Last time I checked there were no stainless bolts used in aluminum on the coupler...