cracked block? what am i looking at here?

[kirayotaka]

hi. long time lurker first time posting
ok so ive got a mercruiser, the serial on the rear is b472268

the starboard exhaust manifold is cracked, missing a core plug and leaking water...
im thinking cracked block so i check the lifter valley and here is what i got





i dont know much about boats, but ive always wanted to so about 2 years ago i bought one. the guy says "we just had the motor rebuilt and had a baby. no time to take it out, so im selling it" i figure "yeah right" but the price was right and i liked the model so i bought it. its been sitting so i change the oil and convince my father in law (who has had a boat for years) to take me out on it to check it over. about half way thru the trip he notices its overheating at idle and only cooling down at near full throttle. i figure it being November and the river being so cold was helping things out a bit (but what do i know lol).

i park it back at the house, drain the manifolds and it waits till spring (till spring in this case being about two years) when i finally get around to trying to get it out i notice the starboard side manifold is cracked and rusted (i have no idea if it was this way when i bought it and the rust just made it noticeable or if it cracked since i bought it.)

i smell the gas, put some muffs on it and fire her up. no water from the crack... uh oh me thinks. i do some research and check the impeller. its toast, the metal cup is even melted up into the plastic housing.. more research and i shove to garden hose into the pipe in the upper outdrive and yep... theres water pouring out of the the manifold, and a smaller crack on the block near the dipstick tube (both of which look repairable) . after reading up a bit on what to check (this forum is great btw) i lift the intake and am confronted with what indeed appears to be a very low mileage/hour motor with no cracks that i can see (perhaps i don't know what im looking for?)

the only thing stopping me from bolting this back together and going out is the amount of rust in the rear coolant ports and a tick coming from around the rear port side of the engine. is that much rust normal for a boat? think the tick is anything terrible? where do i go from here? any damage you can see i missed? thanks for reading and any help you can offer

ps can you tell me what size/part number is the core plug on the exhaust manifold (the smaller one just a hair over an inch across)?
i lost mine somewhere

 

[kirayotaka]

Re: cracked block? what am i looking at here?

i double checked and it seems the the serial number is b580070 as stated on the valve cover.
(i tried to edit my original post but its not letting me for some reason)

 

[jasonbrodsky]

Re: cracked block? what am i looking at here?

What size your motor? I am going through the same thing. However, so far I have only had a rusted out manifold. I have water in my oil, boat did sit in my driveway also for a year. Previous owner had no idea what they were doing. I am planning on pulling intake to help clean out oily water.

Let's do it together.

If you have a small crack near dipstick, you might beable to weld. Your manifold probably should by new one. There is a guy on ebay that has brand new ones for half the cost.

You can email me direct if you want.

 

[Scott Danforth]

Re: cracked block? what am i looking at here?

take a picture of the cracks. from the pictures, i see a clean lifter valley and crud in the water passages. Manifolds will need to be replaced.

 

[mxcobra]

Re: cracked block? what am i looking at here?

first thing we wil learn here is you can not let boats sit with out proper precations.....
take a wire brush and clean out the rust best you can... vacum it all up.
replace manifolds here is what i did.
http://forums.iboats.com/showthread.php?t=532819
if their is no water in the oil you may be able to salvage the block for while...
that wil probly get you started but be prepaired for more problems machines do not like to sit for years......

 

[kirayotaka]

Re: cracked block? what am i looking at here?

i'll get some pictures today. the manifold has already been cold welded but youll get the idea.

id like to get one season out of the manis and risers and two to three out of the block
im not upset about repairing stuff that comes up, i knew the boat had been sitting for a while when i bought it
and thought that would be better to learn on than going out and getting a newer boat and blowing it up because i didnt know to do this or that.

the good news is that im in kentucky so no salt water for me, and if i get stranded on a small lake its not as large a concern as being swept out to sea. i always run up river so the current will bring me back to the ramp if things go awry.

 

[kirayotaka]

Re: cracked block? what am i looking at here?

ok here are the pics



i plan on drilling at the two ends, cleaning/grinding down, and using some sort of metal epoxy to seal the crack.
ive got to clean off all the old gasket material. but the elbows and manifold look like they've still got some life left in them to me. agree/disagree?

 

[Scott Danforth]

Re: cracked block? what am i looking at here?

based on the first pic, your block is toast, that crack is from lack of winterizing. in addition to the crack, you can see the core plugs have been pushed out a bit. I would start looking for a new block and heads..

 

[kirayotaka]

Re: cracked block? what am i looking at here?

what do i lose if i try to patch and run it? if i got a block now would i just swap over the cam and crank pistons valves etc? or would all that have to be new/re-machined anyway? id like to fix this right but at the same time im low on cash (like everyone right now)
thanks for the input btw even if it is bad news

 

[Pete104]

Re: cracked block? what am i looking at here?

Nothin, unless your getting water in the oil!

 

[HopinImFloatin]

Re: cracked block? what am i looking at here?

i ran my 4.3l last season with a similar crack, it must have rusted itself shut because it doesnt leak that ive seen. Im fully aware its not good and there is a good chance its also cracked internally somewhere and may expose itself at any time, BUT, i also intend to run it until it makes the horrible screech just before the bearings lock up. I figure, what do i have to lose at this point, the engine is already junk but running, no water in the oil ...yet. Wouldnt advise running it anywhere you wouldnt want to be floating without power for a bit though.

 

[Scott Danforth]

Re: cracked block? what am i looking at here?

what do i lose if i try to patch and run it? if i got a block now would i just swap over the cam and crank pistons valves etc? or would all that have to be new/re-machined anyway? id like to fix this right but at the same time im low on cash (like everyone right now)
thanks for the input btw even if it is bad news

Find a low mileage truck engine from 1996-2000 and swap over your cam, change the head gaskets to marine and use brass core plugs and your off and running, or look into a reman

 

[Struc]

Re: cracked block? what am i looking at here?

I've had a very similar expirence - I ran my 4.3l with a crack several times last summer, but didn't even know about it until I was pulling it to do a refresh. Check out my thread - it should help some:

http://forums.iboats.com/showthread.php?t=520824

Also, if you want to see what happens to boats that you run with cracked exhaust manifolds, be sure to check out the threads in my signature.

 

[kirayotaka]

Re: cracked block? what am i looking at here?

so its 2 in favor of running it the way it is, and 2 in favor of re-powering right now, do i have that right?
lol i guess i should have made this a poll

 

[joewithaboat]

Re: cracked block? what am i looking at here?

It wont hurt anything to run your current freeze damaged parts. All you will be out really is your time, some money for epoxy and gaskets. If it doesn't work.

Your pictures show tell tale freeze damage and you more than likely have cracked internal places you cant see.


I completely disassembled a badly cracked V6 Buick powered boat. Meticulously cleaned, drilled, tapped, plugged and epoxied the block in multiple places. The boat ran for two long Texas summers before epoxy gave out and filled the crank case with water. I was much younger than and that stuff used to actually be fun to me. I have ground, welded, epoxied patched manifolds with some success. Today i would save my time, spend some money and use parts that have a greater chance at working long term.
As long as working on it is fun to you... have fun! Id rather be out on the water!!!
Just my .02

 

[kirayotaka]

Re: cracked block? what am i looking at here?

yeah i dont mind messing with it and i have an old 88 4x4 k1500 with a the 5.7 l. it needs a valve job but the blocks good. im thinking ill run this with epoxy till she blows up. then maybe pull the 5.7 and do the swap. if im doing a motor job id like to end up with a better motor. anyone know what parts will bolt over to the 5.7? will i need a new bell housing? (starter, alt, etc)

 

[joewithaboat]

Re: cracked block? what am i looking at here?

Just to be clear, coming from someone who has done what your thinking of doing. Its a waste of time and money. Unless you have nothing better to do and are entertained by working on a boat. Success rate of getting cracked cast iron to not leak is very low.

 

[joewithaboat]

Re: cracked block? what am i looking at here?

If you are really determined and no rust damage prevents you from reusing your cracked parts...

There are two professional ways to repair cracks in cast iron..

heating and welding.. I'm guessing you don't have a furnace so that's out

and pinning, check link

http://www.locknstitch.com/

You have one of the cheapest easiest to replace engines, that's where the smart money should be spent.

 

[Struc]

Re: cracked block? what am i looking at here?

Your block cracked pretty much in the exact same spot mine did. After finding it, and looking at the costs involved, it made a LOT more sense to just replace the block.

I paid $200 for the truck engine, and got more than that back when I sold off the TBI & Intake manifold, and the clutch that came with it. So essentially, I got the engine for free.

I think I paid $55 for a FelPro engine gasket set, which includes everything I need.

Check Craigslist for people parting out 1500 series trucks or S10's in your area. I find them quite often. I actually have another full engine sitting in storage that is a 96 with the Vortec heads that I'll rebuild into a boat engine one of these days.

Swap your marine parts over to the truck block, and be done with it.

 

[kirayotaka]

Re: cracked block? what am i looking at here?

man... im right at that age where youthful excitement is starting to tip toward age and wisdom. im teetering back and forth on this subject 3 times a day..... so the really right thing to do would be to just find a running 4.3 out of a truck and then all i have to swap over is the cam? (not counting all the explosion safety stuff starter, carb, dist, etc) wont i have to get new lifters and all that nonsense?