anyone ever tried coolant sealers for cracked heads...

You could give it a shot, I would very much doubt that it will work. Obviously the best solution is to replace.

dont waste the time or money and stop up your cooling system with gunk. in 20+ years of mechanic work ive seen block sealer work twice. Ive seen way more stopped up radiators from people trying the stuff.
Fix the head before it wipes out your bearings and oil pressure starts dropping.

i wouldn't do that. most of that stuff coats EVERYTHING in the cooling system. you may be very unhappy when you try to go and remove a head, water pump, etc in the future. i know this may sound odd, but a guy i know and used to work with-a service writer at a jeep dealership-bought a '00 xj with the 0331 cracked head about two years ago. he pulled the valve cover, cleaned the holy hell out of the cracked area on top of the head, and used some kind of high temp epoxy something(it may have been jb weld, can't recall now-reg stuff, not quick-weld) to seal up the crack and buy himself some time. he drove it that way for at least 4-5 months that i know of, before finally replacing the head with a new aftermarket casting. not a drop of water in the oil. apparently, according to him, this was second time he had done this with a cracked 0331 head. the first one went 6 months before it started to leak again, by that time he had a new head and swapped it out. it'd be worth a try. i believe the key is to get the crack/head absolutely as clean and dry as you can, use a GOOD high temp two part epoxy, and let it cure 100% before putting it back together. i believe he let it sit all weekend before putting it back together. had i not witnessed that myself, i don't think i would have believed it could work.

I used some on my comanche. plan on flushing the hellout of it before and after. I had OK results, enough so that I will not pull the head. Keep in mind that I am planning an engine swap later this year anyway, so if it toasts the motor after 10k miles, then I don't care.

The engine isn't dreaded, just that wretched head.

I believe the thread on head interchanges was also yours - but I answered that part there.

Since it's the upper surface, and therefore not subject to direct compression or corrosion, it should be relatively easy to fix (now that I chew on it.) I've never like the "cooling system sealers" that are on the market - how do you know they're going to deposit in the right place? How do you know they're not going to deposit in the wrong place?

Repair? Yeah. Start with fully disassembling, cleaning, &c, &c...

1) Identify and fully delineate the extent of the crack. You're going to want to make sure you get the whole thing - dye-check, or Magnaflux and have it all marked out.

2) Centre-punch both ends of the/each crack (there may be more than one. You want the punch mark centred on the very end of the crack as much as possible.)

3) Stop-drill the crack. Use a 1/8" drill bit, set it in the punch, and drill through (until you get into the cooling jacket. Stop there - you only need to punch through one layer of metal!)

4) Use a grinding burr, and "bevel out" the crack. You should end up with a nice little 90* Vee shape, and you do not need to go all the way through!

5) Typically, cracks are on the underside of the head. Therefore, typically, they are welded. However, this is a top-surface crack that is only subject to oil rundown (on top) and coolant pressure (from below - not more than 16psig.) So, you don't need as much strength. Therefore, as I see it, there's no reason you couldn't braze the crack closed! The stop-drilling should still halt the spread of the crack, and the Vee-grinding will still help the brazing filler metal penetrate (it's just an adhesion process, rather than a fusion process. But that's fine - you shouldn't need anywhere near as much strength! I wouldn't bother with solder tho - not strong enough for something like this.) You won't need to "dress" the surface of the repair, since it doesn't seal against anything. All you need to do is make sure that you get actual and relatively full penetration of the brazing fill metal into the crack - you should see it wick into the crack just a bit before you can build up a surface bead.

A proper job of brazing isn't anywhere near as strong as a proper job of welding - but welding cast iron is a pain, and you shouldn't need that sort of strength for this repair anyhow. So, brazing could save you a good deal of trouble in fixing it.

I haven't yet been able to obtain an 0331 head, so this repair remains theoretical. I'd like to get at least two - both cracked. I want to section one to see why they crack (and maybe get a warped TUPY head to see what's different there...) and another to attempt the repair I just outlined and have pressure-tested to see how well it worked...

Well thats what I meant by dreaded motor was the year of it. I would agree these are great motors just not this year. So it sounds like I will stay away from the fix in a bottle route. Too good to be true. As for repairing the head or swapping it I wish I had the time for all that. I wont get into why I am too busy to want to mess with this, but I recently replaced the pan gasket and looked at the bearings and they are still fine. I may just drive it until I can fix it or just let it die and buy something else.

Oh and I was under the impression that the crack occurred on the compression side. Weird that I never saw any signs of a leak when I had the valve cover off, doesn't surprise me. Guess I could pressurize the system and pull the valve cover to see the leak. As far as brazing goes the head would have to be fully dissassembled wouldnt it?

Put a couple of egg whites in the radiator.

hey, I have seen that work before. Swear to god.


Granted we didn't leave it that way. Once he got home I helped him fix and flush.

JJacobs said:

Put a couple of egg whites in the radiator.

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I had a friend who peed and put pepper in the rad once to try and fix a head gasket. That was interesting.

I have actually fixed leaks with that 'method' before. It was after a rollover, the fan punched the radiator on my old CJ. Crimped off the adjacent tubes in the radiator but it was still spewing. We put cracker crumbs, Cheezits, tobacco, everything we could think of in there until somebody grabbed a couple eggs out of the RV's fridge. That stopped the leak. You could actually watch the egg white bubble out of the leak then it stopped.

Recommended in an XJ motor, no, emergency fix, sure.

Rmart30 said:

dont waste the time or money and stop up your cooling system with gunk. in 20+ years of mechanic work ive seen block sealer work twice. Ive seen way more stopped up radiators from people trying the stuff.
Fix the head before it wipes out your bearings and oil pressure starts dropping.

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When I was 18 (13 friggin years ago? damn I'm getting old) my buddies and I headed from Burlington Vermont up to Limestone Maine for the big Phish show :greensmok:greensmok:greensmok. We piled in his already old Toyota van (remember those?) The water pump leaked so bad we had to stop to fill the radiator every hour or so. We got as far as St Johnsbury when I found Bars stop leak at a gas station. We didn't have to fill the radiator again the whole trip.

Granted that story is completely irrelevant since it was a water pump, not a head, and the van was on it's last legs anyway.

I hate to be the Devil's advocate, but I have fixed MANY cars with Sodium Silicate. (Liquid Glass).

I just go to the pharmacy and pick up a jar... (Most sealants use Sodium silicate and some sort of other chemicals, usually metal based).

You simply flush out the coolant, replace it with water and the jar of sodium silicate and let it run for at least an hour.. If you have a TON of pressure in your cooling system, best to pull the spark plug where the crack/bhg resides.

Let the car sit overnight, and you have what they SAY is a permanent repair.

My best case was a 94 Explorer with a cracked head. Had a bit of pressure in the cooling system, overflow tank was bubbling. I sealed it 6 years ago, and it's STILL driving around, has been on several long road trips as well.

I'm not guaranteeing results, but if you do it RIGHT, it may work and save you quite a bit of labor.

4-6 ounces of Schillings finely ground pepper.

n1ywb said:

When I was 18 (13 friggin years ago? damn I'm getting old) my buddies and I headed from Burlington Vermont up to Limestone Maine for the big Phish show :greensmok:greensmok:greensmok.

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ugh...I did that trip from the northwest corner of CT to Limestone for IT back in 2003 in my brand new Dodge Ram 2500 Quad cab with 4 other people and a bed mounted tool box full of 30 packs. Drove 12 hrs straight and sat in traffic for 12 hrs... I'm still not the same...


I digress...just replace the head and you won't have to keep questioning the integrity of your engine.

DrCheeto said:

I hate to be the Devil's advocate, but I have fixed MANY cars with Sodium Silicate. (Liquid Glass).

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I didn't know BHO was a contributor here!

Isn't this the same Magic Elixir that 'fixed' a lot of vehicles last summer? Although, it was added to the crankcase....

water glass (mentioned above as liquid glass)

heyhar said:

I didn't know BHO was a contributor here!

Isn't this the same Magic Elixir that 'fixed' a lot of vehicles last summer? Although, it was added to the crankcase....

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Yea.. Same stuff they poured into crankcases. It's some pretty interesting stuff.

n1ywb said:

When I was 18 (13 friggin years ago? damn I'm getting old)

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Heh, heh, heh. When I was 18 gas was 28 cents a gallon.

Boatwrench said:

4-6 ounces of Schillings finely ground pepper.

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...Do you think McCormack pepper would work??

JJacobs said:

Put a couple of egg whites in the radiator.

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For a young whippersnapper that is decidedly old school. I prefer the powdered aluminum.