Block sealant...in a raw water system

[Reserector_]

Lately, I have been trying to "block seal" the small leaks in the outer water jacket of my 3.0L.
It was the engine that came with my restoration project, and had typical cracks from lack of winterizing by the person who gave me the boat.
I found the main cracks during the overhaul, and I brazed them. It wasn't until I had it in the boat that I discovered another small crack or two up higher, behind the manifold. I tried JB Weld, but it did not hold.
My braze repair has held. It is the upper crack that showed up later that I am fighting. It is a minor leak. I can run the boat for a couple hours before it gets high enough to pump anything out. I can keep running it like that until the engine market gets back to normal and I can afford a new one.



My understanding is that most sealers need warmth and pressure to push their sealing materials into the leak, where it will hopefully remain.
Understanding that my boat is not like a car in that it cannot continue to circulate the sealant after the thermostat opens, my hope is that it will be able to work BEFORE the thermostat opens so that I can either shut it down and repeat the circulation, or let it dump out onto the lawn.
A raw water system will not build pressure from heat, like a car. It builds BACKpressure between the impeller pump and the restrictor plate at the end of the exhaust where the water exits. If there were no pressure, there would be no leak.
I've also noted that the higher the RPMs, the greater the backpressure, because that is when it leaks the most.

I tried K-Seal Ultimate, and it worked, and then it didn't. Let me explain; I drained a good amount of water from the engine and then closed the drain. Then I poured the contents of the bottle into the large U-hose, which leads into the bottom of the block via the recirculating pump.
I started the engine and almost immediately ran it up to 2,300prm on muffs. I saw thin white streams dribbling down from the crack,,,then they sealed up. In seconds! I let it run like that until the thermostat was about to open, and shut the engine off.

After a complete cool-down, I started the engine and ran it up again. I saw the same amount of white streams again. Mind you, I can't see the crack because it is up behind the manifold. I assume the leaks were from the same places.
But again, they quickly stopped. I ran it up to around 3,200 and it was holding. I shut it down again and did the same routine one more time that evening. Same results.
The next evening, I got the same thing, so I just let it run after it sealed and let it stay at 175° for several minutes. But after a cool down and restart, the leaks were back, just plain water this time.

My next attempt will be the same plan, but with CRC's K&W Block Sealant. I'll let you know how it goes.
In the meantime, here is a picture of my pretty engine, my pretty self looking at said engine, and a photo of my restored '93 Caravelle 1750.

 

[alldodge]

90% of all is prep. It must be really, really, really clean for stuff to hold.

Suggest remove the stuff, grind it, the wire wheel it real clean. Wipe done with acetone, then mix up JB Weld and put a thin coat on just around the crack. Let it dry and ruff it up some with sand paper.

Wipe back down with acetone and apply a larger layer of JB Weld to first and go out a bit farther

 

[Bondo]

It is the upper crack that showed up later that I am fighting. It is a minor leak. I can run the boat for a couple hours before it gets high enough to pump anything out. I can keep running it like that until the engine market gets back to normal and I can afford a new one.

Ayuh,...... You could try AD's idea,.....

I'd probably just let the rust seal it up, 'n replace it when ya can,.....

I doubt any block sealer will work,..... maybe,....

 

[Scott Danforth]

enecon has a few products. however as AD mentioned, the surface must be clean

 

[Reserector_]

I did grind and acetone before the JB weld. Even put some fiberglass window screen it it for good measure. I did it in one pass, though. Not layered like he mentioned.



I'll try this K&W. See if it seals from the inside. It says I only need half a bottle of that snake oil for the system volume I have. Probably less, but I'll dump half the bottle and holler "Seven come eleven! Baby needs new shoes!"

 

[Grub54891]

I dremeled out the crack a bit, cleaned it well and put the jb in, smoothed it with my wet fingers, then dabbed a shop rag to make it look like cast. A little paint and you cant see where the repair is. Two motors of mine that havent leaked in 5 years.

 

[salvageyard saviour]

Did a 120 hp that had smaller crack up high like that, but not through that thick middle part.
I also did layers, and yes, paint it to keep rust from creeping under it.
When I use that weld product, I never let it set up before applying. The runnier the better. Pull the runs up with a wet finger or putty knife if you have to.

 

[Reserector_]

I tried CRC (K&W) Cooling System sealant this weekend. It did nothing at first, but then suddenly stopped the leak. But then it started again. And then it stopped.
It started back to leaking as the thermostat opened up and I shut it down.
I only needed half a bottle of that, so I still have a half a bottle to store on the shelf.
I have one more to try: Bars Leaks Liquid Aluminum.
I also ordered another manifold gasket so I can make another attempt at the JB Weld on that upper crack. I'll try the stop leak, just for fun, but the Liquid Aluminum will be the last one I try.

 

[GA_Boater]

None of your leak-fixers in a can will work. All of them need a pressurized cooling system to force the magic goop into the crack.

 

[Grub54891]

See post number 6.

 

[Reserector_]

None of your leak-fixers in a can will work. All of them need a pressurized cooling system to force the magic goop into the crack.

But it actually IS pressurized. Hear me out:
1. There is a restrictor plate at the outlet end of the exhaust manifold that holds the raw water back a bit. I assume that is done to keep water in full contact with the inside of the manifold.
2. The pump impeller speed increases with rpm, and therefore increases flow as the engine speeds up.
3. With the exhaust plate holding the water back, and no relief valve to bypass the excess flow, the system builds pressure.

What I DON'T have is time. These sealers need time to build up in the leaky spots and get their particles and fibers all organized. 15 minutes is a common requirement. Unfortunately, the thermostat opens in less than a couple of minutes and wahes away the sealer.

I have tried to circumvent this by shutting the engine down before the t-stat opens. However, that doesn't give the sealer much time to work.

But, hey! Nothing ventured, nothing gained. I'm learning things and passing that along. No harm in that. Who's to say I won't stumble across one that works in this application? That would be a good thing, right?

 

[Scott06]

But it actually IS pressurized. Hear me out:
1. There is a restrictor plate at the outlet end of the exhaust manifold that holds the raw water back a bit. I assume that is done to keep water in full contact with the inside of the manifold.
2. The pump impeller speed increases with rpm, and therefore increases flow as the engine speeds up.
3. With the exhaust plate holding the water back, and no relief valve to bypass the excess flow, the system builds pressure.

What I DON'T have is time. These sealers need time to build up in the leaky spots and get their particles and fibers all organized. 15 minutes is a common requirement. Unfortunately, the thermostat opens in less than a couple of minutes and wahes away the sealer.

I have tried to circumvent this by shutting the engine down before the t-stat opens. However, that doesn't give the sealer much time to work.

But, hey! Nothing ventured, nothing gained. I'm learning things and passing that along. No harm in that. Who's to say I won't stumble across one that works in this application? That would be a good thing, right?

I think you will have best luck with JB weld, which over time probably will break off eventually.

Hey if it leaks a little but doesn't get water in oil, who cares. Center State Engine was selling reconditioned bare blocks on ebay or be patient you can probably find a good running tear out.

 

[Grub54891]

But it actually IS pressurized. Hear me out:
1. There is a restrictor plate at the outlet end of the exhaust manifold that holds the raw water back a bit. I assume that is done to keep water in full contact with the inside of the manifold.
2. The pump impeller speed increases with rpm, and therefore increases flow as the engine speeds up.
3. With the exhaust plate holding the water back, and no relief valve to bypass the excess flow, the system builds pressure.

What I DON'T have is time. These sealers need time to build up in the leaky spots and get their particles and fibers all organized. 15 minutes is a common requirement. Unfortunately, the thermostat opens in less than a couple of minutes and wahes away the sealer.

I have tried to circumvent this by shutting the engine down before the t-stat opens. However, that doesn't give the sealer much time to work.

But, hey! Nothing ventured, nothing gained. I'm learning things and passing that along. No harm in that. Who's to say I won't stumble across one that works in this application? That would be a good thing, right?

 

[racerone]

Replace the block !

 

[Reserector_]

I'm also looking into "stitching" with the Lock-N-Stitch system. I may be able to fix it that way for a few hundred bucks and not have to remove it, let alone tear it down.

 

[Bondo]

I'm also looking into "stitching" with the Lock-N-Stitch system. I may be able to fix it that way for a few hundred bucks and not have to remove it, let alone tear it down.

Ayuh,..... Not the best choice, as yer crack is so close to the head,....

Stitching utilizes tension to hold 'em in place, 'n being at the top of the block, the head bolts are already tryin' to pull that area up,....
Addin' stitches will increase the upward pressure, probably causin' an unflat deck, 'n head gasket leaks,....

Braze it, 'n/or epoxy it, 'n start lookin' for another motor,....

 

[Reserector_]

Ayuh,..... Not the best choice, as yer crack is so close to the head,....

Stitching utilizes tension to hold 'em in place, 'n being at the top of the block, the head bolts are already tryin' to pull that area up,....
Addin' stitches will increase the upward pressure, probably causin' an unflat deck, 'n head gasket leaks,....

Braze it, 'n/or epoxy it, 'n start lookin' for another motor,....

Hmmm. That would sick to spend over $300 stitching that only to have a head gasket fail and need the block decked. It's a slippery slope.
But just to be clear, the Lock-n-Stitch pins draw the metal toward the pin, not wedge it away. Video HERE

I haven't winterized it yet, and hope to take it for for one more spin, so maybe I WILL try the Liquid Aluminum just to know what it does or doesn't do. I anticipate disappointment.
But, I already have it and would never use it in a car, so why not have some cheap fun?

 

[racerone]

Have you checked this block for internal cracks ???----I am not sure how that block behaves when frozen.------But you have to investigate.

 

[Reserector_]

Have you checked this block for internal cracks ???----I am not sure how that block behaves when frozen.------But you have to investigate.

Only visually when I had it open to reseal it and check clearances. No water in the oil at all.

 

[Grub54891]

I'll say it again. dremmel out the crack, Clean well, jb the crack and smooth it with wet fingers. Dab a rag on the surface to give it the cast look, and paint. I've done this repair, and it does work.