Hairline cracks in engine block...

[aeffertz]

Hello everyone at AF,
I'm in desperate need of some help. I have searched for this, but couldn't seem to find the right info for my case. Anyway, to the point.
I just purchased a 1991 Saturn SL1, and noticed that it leaks anti-freeze above the thermostat/below the exhaust manifold. Very little, but still leaks. It only seems to have the anti-freeze to seep out when it is revved up. I can see 2 very small, hairline cracks. And possibly a very, very small pinhole right below them.
So, my question is this. How could I fix this? Is it possible to use some sort of epoxy on them to seal them up? Or is it possible to maybe weld them? Any help would be greatly appreciated.
Thanks in advance,
Alex Effertz

EDIT:
I should also add in that this is an aluminum block, not cast iron.

[MagicRat]

Ideally, you would want to replace the leaking part, since that sounds like its a pretty bad leak. If its a small item, like a thermostat housing, then this may be the best way.
A cheaper, quicker solution may be this:
Head off to your local GM dealership or AC/Delco parts store and get some cooling system sealer tablets. They usually come in 6 per package.

Drain the coolant and put at least 4 of them in the lower radiator hose. Refill and run the engine for at least 1/2 hour and the leak should stop.

However, this solution should be considered to be temporary. If the cracks get worse, you may get another leak. However, often, these tablets can plug a leak for months or years. You just have to keep an eye on it, and carry a jug of anti-freeze with you.

[bobss396]

I used to use Solder Seal's Block Saver. It might do the same job as the tablets, but I've seen it work well at least on cast iron blocks. Cracks are worse to deal with in aluminum components since the coefficient of thermal expansion (CTE) is much higher than cast iron. You should explore longer term fixes if you plan on keeping the car.

Bob

[partsmgn]

I had a blown head gasket on a 2.8l engine..... it would only leak when revd up to mid throttle.... anyway I used a product made by Car-go it's called Seal Up it work great...... you drain the antifreeze out of your car flush it all out, re-fill your block with clear water, add sealant and then run for 15 mins..... then leave sit for 12hrs and drain and replace with new antifreeze

[curtis73]

Hairline cracks eventually become bigger cracks. There is no way to fix it permanently except getting a new block/engine. You can't weld cast aluminum reliably.

One thought is to maybe solder/braze it. That would fill the cracks and temporarily stop the leak, but like I said, small cracks get bigger and it will eventually fail again. At that point, I would consider pushing it off a cliff and buying a Honda

Just kidding. But not really.

[Moppie]

Just a small note, these products are also really good at destroying an engine.

They have a limited life, and any leaks they seal up, will start leaking again.
They also stick to more than just the leak, and can gum up, and restrict water flow through out the rest of the engine.
Usually it is impossible to clean the stuff out again, and you have to start again with a new engine.


I have seen these products block up water passages in cylinder heads, inlet manifolds and turbos.
They can also stop heater valves from working, and even seal up sections of a radiator reducing its efficiency.


As a possible quick fix to get out going in an emergency, they might work.
Just be aware of the potential for greater damage else where in the engine.

[bobss396]

Originally Posted by Moppie

Just a small note, these products are also really good at destroying an engine.

They have a limited life, and any leaks they seal up, will start leaking again.
They also stick to more than just the leak, and can gum up, and restrict water flow through out the rest of the engine.
Usually it is impossible to clean the stuff out again, and you have to start again with a new engine.


I have seen these products block up water passages in cylinder heads, inlet manifolds and turbos.
They can also stop heater valves from working, and even seal up sections of a radiator reducing its efficiency.


As a possible quick fix to get out going in an emergency, they might work.
Just be aware of the potential for greater damage else where in the engine.

That's a fact Jack! I've seen heater cores, radiator cores clogged up, mainly from "cures in a can" like Barrs Stop Leak. The pelletized or powder remedies are less likely to do that.

Bob

[markjs]

If you can get the area absolutely clean, and have time to let it sit a good 12 hours minimum, then you might try JB Weld. Don't use the quick kind, but the regular stuff is amazing. I once fixed a cracked crankcase cover on a motorcycle with it. The place where the crack was had oil pressure behind it, but you just get the area completely, immaculately clean, and it should work (was an air cooled bike too!).