More 87 Mercruiser 3.0l problems. help........

[toneybrown]

There is an issue, and the freeze plug as something in it, might be an attempt to seal up instead of replacing

I'm not quite understanding. The black circle I assume is the freeze plug, does it not look right?

 

[alldodge]

I'm not quite understanding. The black circle I assume is the freeze plug, does it not look right?

Correct, most look similar to this, but do think your manifold may have a crack somewhere

 

[toneybrown]

Hmm, yeah that is completely different.....

I'm going to see if I can get a picture of water or video of water actually leaking......

Thanks for your help

 

[toneybrown]

More to add. I took some pictures and video with the motor running. The leak does not go past the plug. I can't see if it starts at the plug or not, but it seems like it isn't coming JUST from the plug area. I could be wrong, but it doesn't seem like I can tell for sure without taking the manifold off.

 

[alldodge]

If its just the plug, that would be great news. Cheap to replace and not hard. Could even use on of the expandable ones if needed.

 

[toneybrown]

Ok, few things.

First. I don't think I have an overheating issue anymore. I'm pretty sure the impeller is working and I'm getting flow. I ran the boat for a good 10 min at about 1k rpm and then some at idle. At no point did the temp gauge even reach 145 degrees. Now, this is without the old T-stat I removed last night. I assume it wold have gone up at least to 145 or so with a T-stat.

Next thing, I took more pictures of the bottom side of the manifold and there is a brass? plug like you posted earlier on the rear section of the block. The black one is on the forward end of the block. Which has me puzzled as the expanded engine block diagram shows the brass plug to go on the forward end of the block. Attached is a pic of the plug on the rear section.

So, I'm answering some questions and gaining more also!

 

[toneybrown]

If its just the plug, that would be great news. Cheap to replace and not hard. Could even use on of the expandable ones if needed.


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I wish. But the water is coming from above the black plug, not from it

 

[alldodge]

I think your manifold is cracked

As for the freeze plug, it shows 2 and both illustrate on the port side
http://www.mercruiserparts.com/bam/subassembly/30912/963/290

 

[toneybrown]

I think your manifold is cracked

As for the freeze plug, it shows 2 and both illustrate on the port side
http://www.mercruiserparts.com/bam/subassembly/30912/963/290

So, I'm assuming the next step is to pull the manifold off? How do you test it after that?

 

[alldodge]

If your not able to just see the crack. Probably the easiest is pour a little acetone in the water jacket and see where it comes out. Tilt it around a bit to see if it will show any cracks. Otherwise remove the riser and seal opening with sheet rubber and plywood, bolted down. Then pressurize to 15-20 psi

 

[toneybrown]

If your not able to just see the crack. Probably the easiest is pour a little acetone in the water jacket and see where it comes out. Tilt it around a bit to see if it will show any cracks. Otherwise remove the riser and seal opening with sheet rubber and plywood, bolted down. Then pressurize to 15-20 psi

Ok, I'm going to attempt to pull off the manifold. At that point I should know if it is the manifold, the gasket or the block...

Wish me luck!

 

[toneybrown]

Well, pulled the manifold off, pretty easy process.

Cracked block......

Looks like someone had put something in the motor to try and seal it in the past as a hard substance looks like it had oozed out of the crack at some point in the past.

Now, repair options.

I have read some other stuff online that this kind of crack, that does not cause water in the oil can be repaired with welding, or even JB weld. I only have $2000 ish in this boat so replacing the block is a last resort option.

I am also going to call the guy that sold it to me and give him a piece of my mind about selling a boat with obviously known issues as "Lake Ready". I swear, when I sold my old boat I tried to outline every last detail and quirk the boat had so the new owner wouldn't be blindsided by anything.

 

[Grub54891]

I'm afraid to say it, but I think it's the block. Common area on that one for them to crack, freeze damage. On that note, I have one that was cracked there, Dremeled it out a d sealed it with jb weld. Not saying it will hold up long term, but mine is still working 4 years later. We will see how season 5 goes pretty soon.

 

[alldodge]

Bummer, but there are folks like that all over and we just never know when we will run into the next one.

As Grub mentioned, JB weld can work if there is enough room to put a good layer on the block. There is very little pressure so many cases it will hold, but may be rolling the dice.

Is there room for a good layer of JB?

 

[Grub54891]

I removed the manifold for the repair, got it cleaned up really well and then put the jb on.

 

[toneybrown]

There is room for JB Weld, but looks like that was how they fixed it last time. I'm a teacher and our school has an Ag department with a welder. Would actually welding the crack be a better solution?

BTW, looking through the registration it seems the guy I bought it from bought it in 2013. I guess it is possible he didn't know about the crack, and it was the first guy who did the repair.

 

[toneybrown]

Also, what flavor of JB weld should I use if I go that direction?

 

[alldodge]

You cannot weld cast iron. If the crack is cleaned up real good, and as Grub mentioned grind out a Vee in the crack, it should hold. Use regular JB in slow 2 part epoxy. the key is how clean it is, and use acetone to clean then dry before JB

 

[toneybrown]

Cleaned it up with a grinding wheel and wire brush. Used some degreaser cleaner then followed that up with Acetone. First coat of JB Weld is on, will put another layer on tomorrow. Hopefully Monday I can crank it and be leak free....../crosses fingers

 

[Grub54891]

When you put the final layer of jb on, wet your fingers and smooth it out. Then I took a cotton rag, and lightly pressed/dabbed it to the Jb, making it look like cast. A little good black rattle can paint and it looks pretty good.