insuring against stuck bolts? torquing head bolts with marine grease?

[pcrussell50]

the longer i'm into this hobby, [just under two years now], the more horror stories i keep hearing about frozen bolts that snap off and get stuck in the block and such.

since i live by the ocean, i do my fishing and utility boating in salt water, with my boston whaler. i also do most of my own work, since i'm at the stage in the automotive hobby where i build my own engines and such, so outboard maintenance has been pretty easy for me so far.

anyhow, i REALLY do not want to end up with say, a snapped off head bolt, especially on my nice, yamaha 40 that's on the whaler. i've already re-done all the powerhead mounting bolts and lower unit bolts with grease, [they were DRY from the factory]. but now, i'm wondering if i ought to do the head bolts, too?

- can i remove and re-tighten them one-at-a-time?
- or is it best to just take the whole head off and do a new, fresh gasket and all?
- and what about using marine grease when torquing?

in the car world, when doing heads and all shortblock assembly, i use ARP bolts and "moly", [molybdenum-disulfide] assemebly lube, and they specify a different torque using this super slippery stuff than when not. is it the same with outboards? or can i use marine grease on the head bolts and just torque to factory specs?

thanks as always,
peter

[rock]

I have always used light oil on my head bolts.
Rock

[sschefer]

I have always used light oil on my head bolts.
Rock

That's what the book calls for. There's an old racers trick where you blend 30w non detergent oil with White Lithium grease and come up with a light weight assembly lube. You can't use if for bearings because it has Parafin in it and is a pain to digest but it works well on other assemblys that require lubrication. The problem is finding 30w non-detergent oil today.

What you can do is figure out what part of the bolt is in the threads and give the rest a light coat of the dreaded zinc based anti-sieze compound. It will break down and turn to dust but it won't fuse weld on you.

[pcrussell50]

sooo... should i pull the head now while i can, an re-do it with some lube on the bolts?

-peter

[Bies]

Anti seize

[rock]

That would be up to you. Pulling them now might keep you from having to deal with them frozen down the road but now you have torqued the aluminum threads an extra time maybe unecessarilly. I don't know that I would cuz I have seen aluminum threads let loose more than once. That motor may never need the head removed during it's tenure. I do, however , understand not wanting to deal with them frozen but I don't know if oil would help. The anti-sieze might but I don't know how well it would torque.
Rock

[blackvector]

Its a good idea to change head gaskets every so often so I would pull them and change them.

[JR IN JAX]

On all of my below the water line [in the salt] hardware I use plenty of Locktite to seal the threads and keep the salt from eating the aluminum threads away from the stainless bolts. So far it has worked pretty good for me.

[Action Dave]

I coated just about every bolt with gasket sealing compound and I've never needed a torch.

[bill van steenwyk]

When you "torque" a bolt, you are basically stretching it to a certain percentage of its yield strength. Different materials/thread sizes/diameters of bolts require different torques to stretch them to that percentage of predetermined yield to attain the "clamping force" that the manufacturer has determined will keep whatever assembly together that is being assembled.

All that being said, if you use ANY type lubricant on the threads or under the head of the fastener, and you use the torque setting that the manufacturer has determined is correct, and that manufacturer has not used the same type lubricant as you are, you run the risk of WAY over torquing the bolt, possibly past it's yield point and making it worthless as a fastener for the assembly being bolted together.

I have 20+ years with bolted flanges and fasteners in the power generation, refinery, etc., industries, with torque values and the equipment required to go to 80,000+ ft. lbs of torque so I have some experience in the matter. There are bolt charts available, probably on the internet, that give you correct torque ratings for various fasteners based on material, thread size diameter, lubricated or not, etc., etc.

Short and sweet, if you follow manufacturers specs you are far better off than you might be if you make up some concoction of "never seize", lube oil, or whatever, so as to try to eliminate a rust or corrosion problem.

Surely the manufacturers knowing how the product is used and the environment it is used in would have some suggestions??

The absolute best way to correctly tension a threaded fastener is by a product called a "bolt tensioner" which is nothing more than a hydraulic cylinder with a threaded end on it which is threaded on to the stud after the nut has been run down to the flange and then the cylinder is pressurized so as to achieve a straight line pull on the stud to a certain pre-determined hydraulic pressure which has been converted into tension. When this is achieved, the nut is turned on down snug with the flange and the pressure released. This type "tensioning" is used on any type "critical" bolting such as the top of a nuclear reactor in which the bolts may be 8-10 inches thread size diameter to the head, rod, and main bearing bolts on locomotive and ship engines, and even some NASCAR engines for the last 20 years or so after they found how important it was. Ultrasonic bolt measuring gauges are used to measure the stretch of the bolt before and after.

[flabum1017]

When you "torque" a bolt, you are basically stretching it to a certain percentage of its yield strength. Different materials/thread sizes/diameters of bolts require different torques to stretch them to that percentage of predetermined yield to attain the "clamping force" that the manufacturer has determined will keep whatever assembly together that is being assembled.

All that being said, if you use ANY type lubricant on the threads or under the head of the fastener, and you use the torque setting that the manufacturer has determined is correct, and that manufacturer has not used the same type lubricant as you are, you run the risk of WAY over torquing the bolt, possibly past it's yield point and making it worthless as a fastener for the assembly being bolted together.

I have 20+ years with bolted flanges and fasteners in the power generation, refinery, etc., industries, with torque values and the equipment required to go to 80,000+ ft. lbs of torque so I have some experience in the matter. There are bolt charts available, probably on the internet, that give you correct torque ratings for various fasteners based on material, thread size diameter, lubricated or not, etc., etc.

Short and sweet, if you follow manufacturers specs you are far better off than you might be if you make up some concoction of "never seize", lube oil, or whatever, so as to try to eliminate a rust or corrosion problem.

Surely the manufacturers knowing how the product is used and the environment it is used in would have some suggestions??

The absolute best way to correctly tension a threaded fastener is by a product called a "bolt tensioner" which is nothing more than a hydraulic cylinder with a threaded end on it which is threaded on to the stud after the nut has been run down to the flange and then the cylinder is pressurized so as to achieve a straight line pull on the stud to a certain pre-determined hydraulic pressure which has been converted into tension. When this is achieved, the nut is turned on down snug with the flange and the pressure released. This type "tensioning" is used on any type "critical" bolting such as the top of a nuclear reactor in which the bolts may be 8-10 inches thread size diameter to the head, rod, and main bearing bolts on locomotive and ship engines, and even some NASCAR engines for the last 20 years or so after they found how important it was. Ultrasonic bolt measuring gauges are used to measure the stretch of the bolt before and after.

This is all fine and dandy in steel or Iron castings, but the bolts on an outboard screw into an aluminum casting. The casting threads will shear long before the yeild strength of the bolt is acheived.



I'm with ActionDave.... gasket sealing compund.... good stuff

[pcrussell50]

At my relatively mild level of auto engine building and power output, 400-500 horsepower out of 408-427 cubic inch ford windsors, i've been served well by using ARP hardware and following their guidelines for torque. they provide torque recommendations for molybdenum disulfide, and for ordinary 30wt mo-oil. presumably, they have done their engineering dilligence with stretch gauges, such that a certain torque with a known lubricant and proper cleanliness, will get _most_ shade tree builders close enough, as long as you are not building a motor out to the razor's edge of rpm... like they do in nascar and formula1.

also, as long as we're getting theoretical and all, a lot of auto manufacturers these days, use "torque-to-yield" bolts, with sophisticated torque wrenches that can detect the yield point as a _very_ subtle drop torque required to continue. naturally, these are one-time-use-only bolts.

back to outboards:

-does anyone know if the OEM outboard manufacturers have switched to TTY bolts?

-also, does ARP make hardware for well known outboards, such as merc promaxes and omc crossflows?

-peter

[johnboy 88 vegas]

gasket sealer for saltwater

[Charger200]

#1 step i recomend is chasing the threads of the block and the stud with taps and die's. Then blow the threads of the block out to make sure you get all the loose material out. Then use anything to keep the lube. Better yet buy a head stud kit from Brendan power and throw all your worries in the water. I havent made the investment but if this is a real problem for you then its wise to do. He's a member on the boards and has a website too, if ya need his # pm ill grab it for ya.

I pulled the threads outta my block on 2 studs last summer and i credit it to no cleaning all threads.

Jay

[pcrussell50]

flabum, you're right. under the circumstances, it would be hard to believe that torquing to yield would be right.

charger, even better than running a tap through, you can get specifically made, "thread chasers" that are for doing what you are talking about. I have a set that i use on my auto engine buildups. taps are ok, better than nothing, but they really are more for actually cutting metal.

-peter