OMC 3.8L Block Freeze Plugs

[michaelclyde]

I have what i'm pretty sure is a 1984 OMC Chevy 229 3.8L V6 sterndrive (attached to a 18ft Mercedes boat bowrider) . . .

and, on passenger side lower block forward, there's a Freeze Plug that appears to have popped out! It's directly inside the engine mount which consists of a "unit" that has hydraulic lines leading back to the rear mounted electric trim motor and my QUESTION IS ->

If i support the engine via a small jack and unbolt the unit from the block (2 screws) will it easily lift up and out of the way or do i indeed have more engine mount removal to do (ie: is it simply resting (via pins) on top of the floor mounted assembly)? ?

i've already removed the fuel pump to better get at it and Are Such Freeze Plugs Still Readily Available?

Great Forum, thanks! Much help already!

 

[Howard Sterndrive]

Re: OMC 3.8L Block Freeze Plugs

If i support the engine via a small jack and unbolt the unit from the block (2 screws) will it easily lift up and out of the way

Yes, you can trim the front of the engine up, then build a little crib out of pieces of 2X4 or other lumber (I used old textbooks once)and trim it back down onto the crib
just be careful no to power down and push the cribbing through the boat

Are Such Freeze Plugs Still Readily Available?

yes, every auto parts store has them.
I think you want 1 5/8" -and brass

you might have to buy a kit with enough to do a whole chev 350, but the whole brass kit is usually around $15

keep in mind if ice pushed it out, the engine is scrap iron.. the 3.8 is not one of those engines where you can get lucky on a frozen engine and have it survive.
If it just fell out after thousands of heat cool cycles as they rarely do, but can, you'll be ok

 

[Silvertip]

Re: OMC 3.8L Block Freeze Plugs

Just to pick at this a little -- that is a "core plug" not a "freeze plug". The holes are in the block to flush out the sand from the casting process. They are not intended as protection agains block freeze-ups.

 

[michaelclyde]

Re: OMC 3.8L Block Freeze Plugs

I think you want 1 5/8" -and brass

If it just fell out after thousands of heat cool cycles as they rarely do, but can, you'll be ok

Mount wasn't that bad, just took time; three bolts from the floor stringer and three on the block using the free standing screw jack from my 94 Explorer as temp support.

that is a "core plug" not a "freeze plug"

Phew! Looks like I got lucky as the engine otherwise appears to be running just fine stored in AZ for years and now Atlanta. Having just replaced a bad starter WILL DEFINITELY BE WINTERIZING NEXT YEAR regardless!

Thanks for all info, off to store to buy replacement(s); to install should I look for a certain sealer as well?

 

[Howard Sterndrive]

Re: OMC 3.8L Block Freeze Plugs

the engine otherwise appears to be running just fine

that really means nothing.

An engine with a cracked block runs fine. Especially with a core plug out preventing any water pressure.

This 3.8 ran fine:

 

[michaelclyde]

Re: OMC 3.8L Block Freeze Plugs

that really means nothing.

An engine with a cracked block runs fine. Especially with a core plug out preventing any water pressure.

Howard aye, you are right (n i m sad!) 'cause upon change oil about an extra 2 gals of milk was sucked out after wet running on and off for about 10-15 min total! So much for "mild" GA winters! The oil had looked fine, uber clean (as if just changed) just prior to replacing starter & core plugs so next logical step (having already cried) is . . .

Very few engines with cracked blocks leak on muffs running in the driveway.

Rerun with exhaust manifolds/risers bypassed and, if needs be, proceed to heads, gaskets and beyond?

What Are "Muffs"? lol

(found this reading plus here thx!)

 

[[OBC]Patch]

Re: OMC 3.8L Block Freeze Plugs

Muffs are a earmuff looking setup with a garden hose connection. Place them over your raw water p/u, turn the hose on and supply the engine with water in the backyard.

 

[Howard Sterndrive]

Re: OMC 3.8L Block Freeze Plugs

Rerun with exhaust manifolds/risers bypassed and, if needs be, proceed to heads, gaskets and beyond?

plug hoses at red X's with bolts and clamps, introduce air at green arrow to 15 psi max.

listen for hissing.

probably all cracked in the lifter area like the 3.8 block I pictured, need a new engine

 

[michaelclyde]

Re: OMC 3.8L Block Freeze Plugs

plug hoses at red X's with bolts and clamps, introduce air at green arrow to 15 psi max.

listen for hissing.

probably all cracked in the lifter area like the 3.8 block I pictured, need a new engine

Roger on the "earmuffs" (of course!) The green arrow hose, the one that leads back to the intermediate housing, is that the only way raw water intakes from outdrive pump (engine block and pump otherwise being a closed loop in middle) with red X manifolds again being the only way out? Sorry 4dumbq, book's not too clear

Thanks! Flushed/replaced the choc oil out today sooo . . . will do compression & your pressure check as directed and, upon taking intake manifold off, would I still be able to perform another pressure check if valve area appears ok(?) or indeed, if as you say IS the case . . .

Any chance / I've heard of some temp cast success in using a sealing epoxy such as J.B.Weld?

Great Forum! I'll post a pic of my former 1963 '43 Pacemaker Sportfish with twin '68 427 Thermo-Electron Crusaders,

I wish I had u around then, Thanks Again!