Repair a cracked engine block?

[BK911]

Pulled the engine out of the old sea ray to freshen it up, and found this:



That's one heck of a freeze plug. Maybe its welded in!
So now what?
Replacement engine?
It is a mercruiser 165hp inline 6.
I see them online, but is there a better replacement engine?

[1990C4S]

If the block is no longer available or super-expensive you could gouge the cracks out and nickel weld them with a stick welder. That's what I would do.

Or JB Weld it and cross your fingers.

If you can get a new block then you should go that route, assuming you want longevity.

[Arizona_928]

Drill the end of the crack as well...

[LWJ]

I am not a welder but a million years ago, I sold welding supplies.

My recollection with the nickel weld rod is that before and after welding, you need to heat soak it. Meaning, run it up super hot, weld, heat again, leave in a thermal blanket of some kind.

Don't take my word. Do the research. This type of welding has is super prone to failure.

Me? I would junk it.

[Yorkie]

Look into metal stitching. Back when I was a wee lad in the UK working as an apprentice in a heavy engineering shop we would stitch across cracked castings. Seemed to work back then and I have heard its quite common practice when a replacement block is tough to source.

[peppy]

I had the same issue with a volvo penta. I drilled each end of the crack (not all the way through) and then gouged the crack. I used a product called Marine Tex. It's been on there for years and never leaks.
My logic was I was never gonna run it out of water and as long as it didn't fill the bilge and sink me I would be fine.

[asphaltgambler]

Originally Posted by LWJ

I am not a welder but a million years ago, I sold welding supplies.

My recollection with the nickel weld rod is that before and after welding, you need to heat soak it. Meaning, run it up super hot, weld, heat again, leave in a thermal blanket of some kind.

Don't take my word. Do the research. This type of welding has is super prone to failure.

Me? I would junk it.

This method if you're patient is the most permanent best structurally.

[1990C4S]

Also, knock the plug out and see how they look from the side.

[908/930]

Yes it can be welded, as already mentioned carve groove and need to preheat the crap out of it and keep it hot. There is a possibility you could also braze that, also requires lots of preheat. Possibly need to gently stress relieve the weld after.

Did you have water freeze in the block?

When much younger I welded up a cracked cast iron punch press with Nickel rod, held up with much higher loads than your block will see.

[Tim Hancock]

I have successfully and unsuccessfully brazed cracked castings before. If it was mine and had been running that way without leaking, I might just pretend I never saw it.

If attempting to weld, if you can't preheat and then slow cool, you have a good chance of hearing a loud crack some minutes after welding.... BTDT

[BK911]

I am guessing at some point in its 50 year life, somebody didnt properly winterize it.
If its cracked there, it may have other cracks too.
The oil was always a little milky, I just changed it frequently.
The chevy 250 inline six is apparently the same engine but not marine grade.
Rebuilt for around $1500, then swap over some parts to make it marine grade.

Thanks for the input.

[908/930]

Is it freshwater cooled or raw water? The oil is possibly just condensation from a low temp thermostat, or stat stuck open.

Pressure test the cooling system in the block, should be able to tell if it's cracked internally.

[Eric Coffey]

Originally Posted by BK911

It is a mercruiser 165hp inline 6.
I see them online, but is there a better replacement engine?

LS swap...duh.

[GH85Carrera]

I know almost as much about boats as I do about spacecraft orbital math or the mating habits of bigfoot.

It would seem like a great excuse and a good time to upgrade to a newer engine. Maybe time for some Tim Taylor "more power!" grunting.

[rfuerst911sc]

Maybe a Mercruiser 4.3 V6 swap ? You would be getting some more power , there are tons of them out there and it wouldn't over power your outdrive .

[sammyg2]

First question: is it leaking or was it leaking when in service?
Second question: is it a fresh water cooling system or closed loop (pressurized) cooling system?


Thoughts: if it's fresh water and not closed loop, it is not a pressurized system. That plug will likely never see 1 psi and doesn't really need freeze plugs anywho.
If it's a non-pressurized system and not leaking now, it probably never will.
IOW is it really a problem?

If it's a closed loop pressurized cooling system or shows signs of measurable leaking in the past, then yes it probably should be fixed.
Brazing or welding with niresist rod (nickel) requires significant pre and post-weld heating. It would also be a good idea to bake the block to clean the pores to get good adhesion.
Note that welding with nickel niresist is a mechanical bond like brazing, and NOT a molecular bond. it would not be as strong as new.
Point is, you might need to line bore and hone the block after welding if it warps or moves, and that makes it not worth it unless it's really rare of expensive or special.
At very least you are looking at complete dissasembly to do it right.

metal stitching is pure friggin magic, if you can find a true metal-stitch artist you will be blown away. Incredible what they can do but it's a dying art. Not cheep for good ones either.
About $200/hr is what I've paid in the past.

If it's not leaking and not going to leak, consider it problem fixed.
If it's leaked before or will leak enough to be a problem, then personally I'd look at replacement.

https://www.boatpartsdepot2019.info/w-pick/165-hp.html
165 hp Mercruiser 6 cyl GM 250 CI good used engine block: $285.99
I'd make em an offer for $200 and see if they bite.
They also have a complete engine for sale (used) for $1750
Seems high to me but what do I know?

If if you're rich: $2,399.00 plus shipping for complete remanufactured engine with warranty
https://www.michiganmotorz.com/inline-base-marine-engine-1963-p-546.html

Prolly lots more and better deals out there, I only looked for a couple minutes.

[sammyg2]

More info for the block above, it;s on e-bay:
https://www.ebay.com/itm/165-HP-Mercruiser-6cyl-GM-250ci-4-1L-Good-Used-Engine-Block/124159346369?hash=item1ce87946c1%3Ag%3AkZcAAOSwt9B ect6E&LH_BIN=1#viTabs_0

This item was removed from a 165 HP Mercruiser 6cyl GM 250ci 4.1L. SN: 4610794. This engine is from a freshwater environment.

This is a: Good Used Engine Block - This will need a light hone before final use.

Item Location: Ohio

I will strap this to a pallet for $40 and you can arrange your own freight shipping. If you want padding, crating, etc, you will need to hire an outside vendor for that.

[sammyg2]

165 HP mercruiser engine and outdrive for sale in Asheville, North Carolina
$900


I have a very excellent running 165 hp inline 6 cyl mercruiser chevy engine and mercruiser outdrive for sale. I got a job boat to return and I'm converting it to outboard drive, so I have no requirement for the engine or outdrive.
The engine is set up so that it can be started and heard running, the outdrive would not enter into froward gear and I discovered that the sort shaft was frozen up and stuck. Are parts are consisted of, consisting of a new inside exhaust bellows. Will certainly require shift cable television and outdoors exhaust bellows. Controls consisted of.
I was informed that the engine just has 300 hours on it, however can not confirm. It does start and run fine, and I can do a compression check if you care to examine it out.
Cost is negotiable, and I 'd be interested in trades such products as ... Ham radio equipment.
Little Electric start "kicker" long shaft outboard (8-15hp).
Kayaks.
Guns.
Pop-up camper.
Upper end backpacking and camping devices.
Trailer for 12'-14' jon boat.
36"+ wood lathe.
Large table saw and/or telescoping miter saw.

https://asheville.americanlisted.com/boats-yachts-parts/165-hp-mercruiser-engine-and-outdrive-900_28073733.html

[BK911]

Dang Sammy, only things left for you to do is pick up the engine on your way here to install it!

[sammyg2]

mercruiser foot n motor - $400 (oakley)

posting for a friend of mine he has a mercruiser out drive and engine not sure of the size also an extra prop enging and outdrive comes complete reason for selling the transom is cracked big time across the bottom and up the left side email for number price 400 for all must take boat and trailer he needs it gone thanks
do NOT contact me with unsolicited services or offers
post id: 7138511876 posted: about a month ago

https://asheville.craigslist.org/bpo/d/asheville-mercruiser-foot-motor/7138511876.html

I'd offer him $100 to haul it away.