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Best Block Sealer???

I have a 94 exploder v6. i've done major work on the engine, cylinder heads, all gaskets, 2 injectors. current situation - car starts fine and runs perfect until it gets hot then starts taking coolant into the #6 cylinder. will a block sealer resolve this problem for me? i've read that some of the available products actually form a molecular bond between both sides of the crack. Is this true? Anyone have experiences, good or bad, with any of these products?

thanks for your responses
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Comments

  • edited February 2008
    It sounds like someone missed something in that major engine work. You could try Bars Leak, but it won't help a big leak. Are you just trying to buy time before replacing the truck or engine?
  • edited February 2008
    Never tried high tect Block-sealers, but seen them about. If you rebuilt both heads (valves, springs, etc.)consider starting over with a good short block and your good Top End (and maybe Crank, as reqd.) If ya just paid someone to swap gastets (no machine work-valve job-seals, etc.) and ya want to get a year or so out of it, I sugest ya try the sealers. I think ya must follow label EXACTly (pull T-stat) temp of engine, etc. May work, I just hate to fill good, clean Heads (or a sound block) with Sealer- cant be good for long term cooling or repair!! Were pistons clean and bores free from scratches when Heads last off? You (or GOOD mechanic who did work ) should know condition od heads,pistons, rings, etc.- that opionion should guied in putting more $ in- If repairs to date first rate-consider proper rebuild, if repairs to date "stop Gap" (regardless of cost), try sealer! Your Car, my 2 Cense- been there, et cetera!! Rock on!
  • edited February 2008
    I'm not a fan of blocker sealers and seldom buy into the cracked head/block diagnosis very much.
    Was the cylinder head block mating surface inspected and surfaced if necessary? Was the block surface inspected for flatness? What about the intake manifold flanges? Were the intake manifold surfaces on the heads inspected for flatness?
  • edited February 2008
    A block sealer is a last resort. That said, I had good luck with K & W seal on my 1947 Pontiac. Coolant was getting into the oil. I removed the cylinder head and the block was cracked around a couple of the valves (this was a flathead 6 cylinder engine with the valves in the block). I put the engine back together and used the K & W seal as directed. I ran the car another year until I could afford something better. I saw the car on the street a couple of years later. At least while I owned the car, the K & W seal kept the coolant out of the oil.
  • edited February 2008
    Yeah. What ok4450 said. You can attempt to re-torque the heads. Perhaps the original torque settings were done out of order or one or two of the head bolts have loosened. Re-torque both heads. Make sure that you torque the bolts in proper order. Make sure that the torque wrench is accurate. Use the 1/2, 3/4 then full torque method. Do one head at a time but do both heads. If that doesn't work, then you'll need to pull the defective head and have the surface checked for flatness and cracks, especially near the water jackets. Magnaflux is one way to check for cracks. If any show up, get an auto recycling center (junk yard) to pull an exact replacement head and rebuild that head. Your auto machine shop (rebuild shop) should be able to help you with this. You might luck out to where the machine shop has one that's already been magnafluxed and checked for flatness. You should be able to re-use your valves and springs, et., but if the shop has not yet installed new valve guides and seals, then they'll need to do that, also. Besides, they'll need to fit the valve guides and valve stems to each other. The thing with a pour-in block sealer that a lot of folks tend to overlook is what does that stuff do to the inside of your radiator and water pump? Those sealers are temporary, at best. Then it's right back to where you are now. Don't forget new head gaskets. I.M.H.O., I still believe that the crushable steel or brass or copper head gaskets are still the best. You might luck out again and find that the head gasket is one of those 1 in 1,000 that are defective. Then all you need to do is remove the old gasket, clean all surfaces to "eat off of it" clean, replace the gasket, etc. I would still check the torque on the other head.
  • edited February 2008

    I've rebuilt a few engines in my day...and the only time I've ever seen this was when there was a flaw in the surface of the head. Pulled the head and had it milled smooth and then reinstalled a new head gasket. I don't think any sealer is going to fix this.
  • edited November 2008
    Bar?s now makes a new product called ?Headgasket Fix.? It?s very different from the older ?Headgasket Repair.? It comes in a tall cylindrical bottle. It doesn?t require draining the radiator like most products. It?s simple ? pour it in and go.
    I used ?fix? on my 1998 BMW 5 series when it began running rough, steaming out the tailpipe and losing coolant. Oftentimes the leaking cylinder piston would stick causing the starter gear to grind and make a horrible noise as if I had a thrown rod. To loosen the stuck piston I put the car in drive and pushed it a few feet. After that I added the Bar?s and drove it around for a while. My car began running better and better the more I drove. After about 100 miles it ran perfectly and was no longer losing coolant. This stuff works great. ? BTW, yes, you just disconnect the upper radiator hose and pour it in.
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