crankcase sealant 89 115hp merc

[reynold460]

hi guys i am currently rebuilding a 1989 115 hp 4 cylinder mercury outboard serial number oc106992 and am wondering about what sealant to use between the two crankcase halves my seloc manual says to use loctite master gasket sealant kit c-92-12564-1 which includes loctite 518 sealant and loctite 7649 primer is it possible to just use the 518 sealant without the primer as i cant see being able to spray the primer on the matting surfaces without getting it into places it shouldnt be what have you guys used in the past thanks.... also my manual says to use loctite "a" around the outer diameter of the seal in the lower end cap is this just a thred locker thanks for any advice you could give in advance

 

[emckelvy]

Re: crankcase sealant 89 115hp merc

I wouldn't worry about a bit of 'overspray' on the primer, you can wipe off any excess and whatever residue is left will just wash out of the crankcase anyway.

The primer does help get the surfaces real clean and promotes a faster cure time, but I've used just a tube of Loctite/Permatex 518 by itself and it seals just fine.

You do have to be sure to get the sealing surfaces of the block and intake very clean, any residual oil will hinder curing.

On the crankshaft seal O.D., I've used Permatex No. 3 Aviation-Type gasket dressing and haven't had any seals fall out yet!

If you wish to stick with the manual's recommendations, I'd expect Loctite "Grade A" would give you a stout seal; same caveat as the crankcase, gots to be real clean.

Grade A is High-Strength and most auto parts stores sell a Red High-Strength Loctite which I assume would be generally equivalent to Grade A.

There are a ton of different types of Loctite for all applications but the generic auto parts store Red High-Strength should do the job nicely.

It's what I've always used on rod bolt threads and haven't had one blow up yet!

HTH & G'luck with your rebuild.......ed

HTH..........ed

 

[reynold460]

Re: crankcase sealant 89 115hp merc

thanks for the help, should i use thread locker on the rod blots then

 

[emckelvy]

Re: crankcase sealant 89 115hp merc

The old-stye rod bolts had a body-fit thru-bolt with nut. I've used Loctite on these with good results.

Newer motors like yours use a different style of rod, which is threaded to accept a stretch-type rod bolt.

You may not be aware that the stretch-type rod bolts are only meant to be used once. That didn't come to mind before or I would have mentioned it.

P/N for the rod bolt "screw" is 94320 and list price is 5.10.

Boats .net has them for $3.57 and I found them here for even less:

CRANKSHAFT, PISTONS AND CONNECTING RODS - Mercury Marine Parts - Mercury Performance - 94320 - SCREW, CONNECTING ROD (3/8-24 THREAD)

Note that these bolts aren't just tightened to a specific torque value. You have to tighten them to the recommended value then turn the wrench another 90 degrees (or as specified) for the final stretching. I found a recommended initial torque of 30 ft-lbs but you should verify via a good manual the actual value.

Rod Bolt L3, L4, 3.0L V6, 3 cyl 75-115 HP - RB9000 - Offshore Marine Parts - Quality Aftermarket and OEM Boat Engine Parts and Accessories

In order to achieve the correct torquing and bolt-stretching, you do need to use the proper lubricants/compounds (as specified) on both the bolt head where it contacts the rod cap, and the bolt threads. You should consult the manual for recommendations for your motor.

There's a bit of controversy amongst the racer dudes, most like to use Loctite but many also use a higher-performance aftermarket non-stretch bolt. Probably best to stay with mfr's OEM-spec parts & recommendations unless you plan on racing (this motor isn't really built for that anyway!).

Here's a very interesting discussion on the Scream 'n Fly racing forum, if you're so inclined:

SPS Rod Bolts

HTH........ed

 

[reynold460]

Re: crankcase sealant 89 115hp merc

thanks for the info, i have a seloc manual it says to torque the rod bolts to 30 ft-lbs but doesnt mention turning another 90 dregrees would this be correct ? i have to wonder if this manual is very thorough