Cracked block.....now what?

[temperedtim]

Boat runs great....stays nice and cool. Havent noticed any water in the oil...changed the oil once since owning and it just looked like used motor oil, no signs of water. Motor runs well. Found water dripping down the side of the block from under the manifold, of course its going to be a cracked block. Can I keep using the boat? Will this crack spread, cause more damage? JB weld? any good storyies of the stuff holding up?

 

[Bondo]

Re: Cracked block.....now what?

Ayuh,.... What Motor,..??

 

[ENSIGN]

Re: Cracked block.....now what?

There's no place on a boat for JB weld...

 

[Kainon]

Re: Cracked block.....now what?

I've seen Inline 4's and Inline 6's run for many many years with the blocks' JB Welded. Theres little water pressure in the block , while I dont really reccommend it, I would have to say it depends a little on where and how big the crack/hole is, if close to the head ( say 2" or less) you may be risking a blown head gasket at some point.

I've seen some really good welding/Pinning Repairs too, i had a hole in my #1 Spark Plug hole, and it was leaking water, it was "pinned" and you cant even tell where the hole in the head was, and doesn't leak.

 

[temperedtim]

Re: Cracked block.....now what?

Sorry its a 3.0, gonna have to take the manifold off to see how bad the crack is.

 

[dls322]

Re: Cracked block.....now what?

JB Weld, let it cure, then try it. That would be my approach, especialy since everything else is working great.

 

[dls322]

Re: Cracked block.....now what?

http://www.amazon.com/J-B-Weld-8277..._4?s=automotive&ie=UTF8&qid=1277911500&sr=1-4

I would try this.....

Anyone suggest this over the normal jb weld??

 

[temperedtim]

Re: Cracked block.....now what?

Well I will be pulling the manifold off tomorrow, manual says its "moderate" which is usually pretty easy. Any keys to success here so I dont makes things worse rather than better? I got my face up under the manifold and can see it leaking from a section about a 1/8 of an inch or so...maybe the cracks longer but it only coming through a small section.

I have every intention of pulling the manifold but some people must just leave it like that.... never even notice until its too late...? Well off comes the manifold tomorrow, Ill take some pictures and post them.

 

[TrybalRage]

Re: Cracked block.....now what?

Definitely interested in seeing some pictures of your work, keep us posted

 

[jagilbert]

Re: Cracked block.....now what?

I've got the same motor and the same problem: a drip/trickle from under the manifold. I plan to pretend not to notice it, run the bilge pump from time to time and hope for the best.

I'm very interested to see how your project goes.

 

[temperedtim]

Re: Cracked block.....now what?

The more I investigate the more I think its an actual head gasket... the leak os so high, def very close to the head. Not good being that close from what I hear. No water in my oil and the level doesnt seem to be getting any higher so Im pretty sure its an external only crack or leak. At this point I think Id rather have a crack then a head gasket leak. Could it be the headgasket without any other signs? no water in oil, no spitting or sputtering and maintaining a 150F temp?? Do people look the other way on this repair....? Should I?

 

[HotKetchup]

Re: Cracked block.....now what?

Of course not...Why would you prefer in not to be a head gasket. Theyre way cheaper than a new block. Ignore it and it will eventually lead to a new block anyway.

 

[temperedtim]

Re: Cracked block.....now what?

Headgasket replacement seems a bit "out of my league" or so I feel. Ive had the engine out twice but thats just a few bolts and a tractor bucket.

Why is it that if the block is cracked...but close to the head its a done deal? Wouldnt it still be worth a shot? and if so... (block cracked and a done deal) shouldnt I bolt the manifold back on and still hope for the best? I mean....the motor runs perfectly well (right now) why wouldn't I keep running it the way it is (if its not fixable of course)...? Its up so high its either a headgasket or really close to the head...thats how hard it is to tell, its all a wet rusty mess.

 

[SSSuper83]

Re: Cracked block.....now what?

There's no place on a boat for JB weld...

I know this has been hashed out a million times..but on a 2.5 or 3.0 block..there are PLENTY of places for JB weld. When I was young and dumb to boats, I boat an 18' Glassport, 3.0 Merc, nice boat but the block had a painted over SLAB of RTV on the cooling port side. I removed all the RTV, and coated the entire deal with JB. It never leaked again and I had the boat for three more years. I wouldnt slap it on the side of a blown out 350, but the block is cracked anyway..get a season out of it!! Esp. with a Merc iron 4 cyl...

Just my .02... BTW get the manifold off that engine and find out where the crack ends. If it goes into the head area..well..you are on borrowed time anyway...

 

[temperedtim]

Re: Cracked block.....now what?

Well now Im torn.

here are my newest thought.

1. Is it worth taking of the manifold with the crack that close to the head?
2. Any possibility I could cause more good then damage?
3. Can I JB weld without drilling?
4. Not trying to prdictthe future but how long can a crack like this hold up?

It seems that most agree that if the crack is close to the head, and I believe mine is within an inch from the head, that there is really nothing I can do. So, that leads me to believe maybe Id do more bad then good by getting in there and trying to fix this thing. The thought of having a crack in my block makes me wanna at least try but If there is a good chance I am going to fail with this repair (because its so close to the head) then I dont want to be drilling holes to only have the JB weld flop off 2 weeks from now and then I have created 2 holes which will leak more than it does now and my summer will be ruined as far as boating is concern. Also, how hard is it to make this manifold off? I know there are only a few bolts etc....but would torquing it back down mess with the head gasket since it may or may not already be weak with the crack right below it? I guess part of me is thinking that if its doomed anyway then why go in there and mess around. I know if I ignore it it WILL either leak more or blow a gasket...eventually, but I may make it till winter when the thought of replacing the block sounds much more intriguing. Can I JB weld without drilling? meaning that if the JB does flop off it wont be leaking anymore than now? Do I keep poking at this thing with it that close to the head or do I continue to run the boat...keep an eye on my oil and temps and hope for the best while I shop for a new block...? As of today the boat runs very well...maintains temps, doesnt sputter at any throttle and doesnt show any signs of water in the oil...that is of course at this moment, Id hate to make it worse or put the nail in the coffin trying a repair that most seem to think it hopeless anyway.

 

[boattech]

Re: Cracked block.....now what?

Its not at all uncommon to see the mercruiser 4 cylinders come through my shop regularly with a crack running 1 inch bellow the head. the crack is usually 6 inches or more long and 9 times out of 10 has either JB weld or Permatex silicone all over it. In my experience JB weld will work for alittle while if done POORLY! The key to fixing one of these properly is a tedious process. I start by taking a wire wheel on a drill and cleaning the crack thoroughly and clean several inches of fresh metal around the crack. If it is a narrow crack (you cant see through the crack) I then take LOCTITE Primer and prime the crack. Then get a bottle of loctite 271 and fill the crack with it ( it will run, its thin) then take a small ball ping hammer (similiar size to a regualy nail hammer) and litely hammer the crack back together. dont take big swings! just repedative taps all up and down the crack about 1 inch outside the crack. It doesnt seem to move alot and takes along time but it will close up. The whole time you are pinging keep adding more loctite to try and keep it worked into the crack. Once you get the crack closed up let it sit overnight to let the loctite cure properly. At this point the crack usually will not leak a drop, But I then take a grinder and clean a larger area around the crack and cover the area with Marine Tex two part epoxy (similiar to JB weld) I then let that cure 24 hours. That is alot of info Im sure, but it is pretty simple once youve done it 100 times! HEHE! Ive never had one come back leaking though. I also have a patch for 5.0 and 5.7 chevy blocks that works even better.

Taking the manifold off is simple, just take your time in unhooking everything and watching where stuff went and you will be fine. You wont mess up the head by doing anything with the manifold. On a side note it isnt hurting anything really to leak it just gets water in the boat, and in the long run rust will make the crack bigger.

 

[antsmands]

Re: Cracked block.....now what?

Boat runs great....stays nice and cool. Havent noticed any water in the oil...changed the oil once since owning and it just looked like used motor oil, no signs of water. Motor runs well. Found water dripping down the side of the block from under the manifold, of course its going to be a cracked block. Can I keep using the boat? Will this crack spread, cause more damage? JB weld? any good storyies of the stuff holding up?

I used JB weld 2 part epoxy and putty on mime. Works well! Prep is key. Plenty of info on this repair on this forum.

Good Luck!

 

[DINK136]

Re: Cracked block.....now what?

I got a block crack repaired this spring. My crack was about 3 inches long and went right up to the head. As in my situation, if you are thinking of just repairing instead of replacing then I would not bother taking the head off. I grinded out as much of the crack as possible and filled it with MARINE TEX. As for the area against the head, I just put the MARINE TEX over the seam and slightly over the gasket area. Everything is running great.

 

[temperedtim]

Re: Cracked block.....now what?

I don't want to drill... In fear of the JB failing and creating larger holes for the water to leak from. SO clean it up...grind out all rust.. And prep a few inches larger than the crack...and JB weld it without drilling stop holes? I like the tappping it back together idea too...dependin on how large the crack is although I know the water is only getting through about 1/8 of an inch section from what I can see under the manifold but the rust (again what I can see) makes me think the crack is about 3 inches.

 

[marlboro180]

Re: Cracked block.....now what?

I don't want to drill... In fear of the JB failing and crrating larger holes for the water to leak from. Can I clean up the crack really well but not drill?

Tim,

Boattech has given some pretty good advise on how to seal that thing up.

I had/ have a crack in my 3L as well. I did pretty much the same as he suggested, and all is well for now. BTW- When I got my boat, I had several problems that the PO did not know were even there. One of which was a couple cracks in the block, behind the manifold, 1 right under the head deck , 2 near the core plugs. , smothered in marine tex. He had been running it that way for years. ( I later found out it was a 1995/6 repair, and I had to re- do the repair in 2009) Hows that for borrowed time?

I ground em out in a vee with an air grinder, cleaned with acetone and JB welded it up. No more leaks in the block.... No, I did not drill, neither did the previous guy.