Cracked manifolds due to freezing

[lakelivin]

There seems to be a lot of questions about cracked manifolds lately. Brought back to mind a thought I had when one of my manifolds (’89 4.3L Cobra) cracked due to freezing years ago. Thought I’d bring it up for comment <br /><br />When one of mine cracked I thought about jb weld on the outside, and was wondering if there was anything similar but in a liquid form so you could pour in it and 'coat' the manifold from the inside as well. I actually called JB Weld. Not positive about the details, but recall them speculating about the possibility of 'thinning out' JB Weld with something (forget exactly what) to the point of reaching a liquid consistency and giving that a try. Obviously off recommended product use, and I didn't want to risk it so put on a new manifold.<br /><br />But I wonder if the idea has any potential? Anyone know if there is another product you could use to do this, and if there was a way to test it before actually trying it on a manifold you were going to put on your boat? I know, better safe than sorry (that's why I just bought a new one), but with some OMC manifolds not available and other manifolds out of this world as far as price, thought I'd throw the idea out for comment. I realize the manifold would have to be in relatively good shape besides cracks due to freezing, i.e., not just generally rusted out.<br /><br />I was trying to think creatively at the time and recognize that I know next to squat about boats & mechanics in general, so no need to worry about offending me with your response .

 

[Don S]

Re: Cracked manifolds due to freezing

First of all, it would be a hit & miss type repair at best, but all you have to loose is an engine.<br />Second. Cracks in cast iron get worse due to expansion and contraction as the manifold (inside sections) get hot from the exhaust passing through. Epoxy is not going to weld the crack together and it's going to have a different rate of expansion.<br />While the epoxy may work on the external parts of the manifold, that part does not see the heat the inside sections see. That's why some external repairs will hold for a while.<br />Someone may want to give it a try, like I said, all you have to loose is the engine not just the manifold.<br />DO YOU FEEL LUCKY????

 

[Bob_VT]

Re: Cracked manifolds due to freezing

I would also hate to see loose pieces of epoxy that break away be circulated through the cooling system.<br /><br />Bob

 

[trog100]

Re: Cracked manifolds due to freezing

what about the old fashioned stitching method.. too labour intensive to pay someone to do it and the tools and stuff needed might not be avalable.. but i would imagine it would work.. i have seen old frost damaged engine blocks fixed this way..<br /><br />trog100

 

[Don S]

Re: Cracked manifolds due to freezing

Just how do you propose you get the equipement used to "Stitch" the crack inside passages you can't even see, let alone touch? Is there some magic machine that is that small and can see the crack and fix it?<br />The inside webs of the manifolds between the exhaust and water is usually thinner than the outer parts of the manifold anyway.

 

[crazy charlie]

Re: Cracked manifolds due to freezing

I cant remember what it was that needed repair it was so long ago, but I needed to do exactly what you described.I used marine tex for the repair.I let it get warm on the dash board of my car on a sunny day in the summer before I mixed it together.I applied the marine tex and hit it with a heat gun and it softened and thinned to the point where it seeped into the crack.As a matter of fact I had to top it off with more marine tex the following day to bring the repair back to being flush.I did not need to compromise the marine tex to get it to "flow".Charlie

 

[Don S]

Re: Cracked manifolds due to freezing

Ok crazy charlie, I asked trog the same question, how do you get this stuff to a place you can't see touch or even know if there is a crack in. What do you do, coat everything with an impervious coating of epoxy, over a dirty, rusty, scaley, worn out surface by some unknown process? And it holds ???? ......... yea right, if that was possible it would already be a common process, but it's not. Every instruction I have ever seen for epoxy says apply to clean dry surface. <br /><br />It's nice that you guys are into hypothetical thought processes, but it has nothing to do with anything in the realm of reality to the original question about there actually being a product to do all this.

 

[f_inscreenname]

Re: Cracked manifolds due to freezing

You all talking about coating with this and that made me think of a question. You would think by now they would have come up with a coating (like ceramic) for the inside passages so they would not corrode like they do. Maybe it is just not cost effective. As for fixing a manifold with anything is a shot in the dark at best with very high stakes (your motor). Like I said in another post “hydro lock is very expensive”.

 

[Don S]

Re: Cracked manifolds due to freezing

Good point F_ but one question. Who is "THEY" really, because "THEY" really are getting backed up with things "THEY" should be doing.

 

[whywhyzed]

Re: Cracked manifolds due to freezing

I don't endorse this for the general boating public. However, I got one season out of mine so far - 3.8 OMC manifolds were freeze cracked externally.<br />I tried JB weld by itself and it failed pressure testing miserably. I cleaned it all off and mixed a new batch with fiberglass matting mixed in. I am quite satisfied with the results. My situation is unique in that these manifolds are worth more than the engine. Worth more than the whole boat actually...

 

[rabidfish]

Re: Cracked manifolds due to freezing

Let's set the record straight... <br /><br />JB weld,Marine tex, or any other epoxy, is not a repair, it's a patch. If you're out to sea and need to get home, it's ok. If you need a real repair, that is lasting and has no adverse affects, then you need a new manifold. <br /><br />Even welding is a patch. The material expands and contracts at different rates and causes the cracking to continue. <br /><br />The only thing worse than making a mistake and "freezing" an engine/manifold, is being in denial and not fixing it properly.

 

[yoced]

Re: Cracked manifolds due to freezing

In all deference to Don (I have only been examining cracked manifolds for 10 years now, not near his experience level) I have never actually seen a manifold crack on the inside from ice damage (heard tell of, but never seen). Even manifolds which have had their walls blown out have shown no signs of interior damage... so far.<br /><br />Still, I won't warrant any parts which get fixed by the customer (or his mechanic) by any method once the ice damage has occurred.<br /><br />F_, the coatings have been tried, it is just that they (like you guessed) are very expensive. On top of that they don't last very long in that environment. The heavier coatings (like ceramic) tend to flake off in crusty chunks - then you get bare metal in a small spot which is attacked by the rust at a far faster rate than you have when the whole manifold is being exposed. You also now have chunks of insoluble material floating in your exhaust system. The end result was a more expensive piece of equipment which could not be warranted for any longer than the traditional iron.

 

[lakelivin]

Re: Cracked manifolds due to freezing

I've still got my old manifold that had hairline external cracks due to freezing sitting in my basement. Wish I had the equipment to cut it apart to see what the insides look like, just out of curiosity....

 

[lakelivin]

Re: Cracked manifolds due to freezing

Seems like this topic is almost approaching the FAQ stage. Don't see having time in the near future, but if that changes, would it be worth trying to cobble together some of the common questions, answers, explainations, etc. for review for placement in the FAQ section? Seems like the topic has been pretty thoroughly covered in several posts over the past couple of weeks...<br /><br />Thoughts?

 

[f_inscreenname]

Re: Cracked manifolds due to freezing

Don: They = Anyone I have to buy exhaust manifolds from when mine are done. It doesn't seem like that exhaust manifolds technology has advanced much in the last 20 / 30 years. Why should it. They keep making them that way and we keep buying.