Does this look like a cracked head?
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Thread: Does this look like a cracked head?

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    Default Does this look like a cracked head?

    Take a look at these pic's and tell me if this looks like a crack in the head. I cleaned off the engine and noticed a rusty area between the first and second piston. The area looks discolored from the exhaust heat but if you look closely it seems like there is a small crack on the head.











    If this is a crack can it be repaired or am I looking at a new head?

    I also noticed oil seeping around the exhaust gasket on the number two piston which is also seeping where the exhaust manifold connects to the turbo.





    Could this also be signs of a bad head?

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    Default yes

    Yes, it could be a crack. Are you loosing coolant? Are you loosing oil? Does the engine run good? Does it seem to be running efficiently or does it smoke a lot? The oil stain on the exhaust maybe unburnt fuel, oil that is leaking from the valve guides and not burning whilst in the combustion chamber (I'm just guessing) but if the other cylinders don't have that issue something is up. Clean up all the areas and see if it comes back. On the intake manifold oil might be from a leaky turbo seal but the exhaust shouldn't look like that.
    I talked to a machinist who specializes in head repair and he stated that the cummins didn't have enough coolant circulation in the head, especially around the injectors and valves and they tend to crack. A Cummins technician told me he nevers sees cracks.

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    Default crack

    yup, that looks like a crack, if there`s no coolant coming out and the engine runs good, don`t worry about it. I don`t think there`s any coolant in that part of the head. the oil/exhaust leak can be fixed with a new set of exhaust gaskets.
    71 vega w/ sd22 nissan diesel turbo, 5speed, 50 mpg. 70 chev suburban 4x4,60/14bolt ff,divorced 205,pto lu-4 winch,3.73 detroit locker rear, power loc front, 35s on 16.5"x12" weld wheels, 2400 allison 5speed,triple disc billet torque converter, tcm by Brayden Fleece, 8.2 Detroit fuel pincher turbo v8, 18 mpg. `94 suburban 1/2 ton 4x4, 3.42,`92 6bt, 47rh, Hx35/12cm, 4" exhaust,3200 spring.16/17mpg city, 22mpg freeway

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    Quote Originally Posted by Elbonk View Post
    Yes, it could be a crack. Are you loosing coolant? Are you loosing oil? Does the engine run good? Does it seem to be running efficiently or does it smoke a lot? The oil stain on the exhaust maybe unburnt fuel, oil that is leaking from the valve guides and not burning whilst in the combustion chamber (I'm just guessing) but if the other cylinders don't have that issue something is up. Clean up all the areas and see if it comes back. On the intake manifold oil might be from a leaky turbo seal but the exhaust shouldn't look like that.
    I talked to a machinist who specializes in head repair and he stated that the cummins didn't have enough coolant circulation in the head, especially around the injectors and valves and they tend to crack. A Cummins technician told me he nevers sees cracks.

    My motor runs good but does have a bit of white/blue smoke during the initial warm up. I assumed this was the unburnt oil or fuel that was in the number two exhaust port burning off. After warm up this smoke dissipates.
    I don't notice any coolant leaking but there is more rust discoloration on this exhaust port than the others so I figure water must be coming from somewhere near here.

    I have cleaned the area and found the staining coming right back after it's run.


    Can a crack like this be repaired or should I find a new head?


    And since I might have the head off should I just bite the bullet and do a full rebuild on my 1988 4bt?

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    Quote Originally Posted by jtamulonis View Post
    yup, that looks like a crack, if there`s no coolant coming out and the engine runs good, don`t worry about it. I don`t think there`s any coolant in that part of the head. the oil/exhaust leak can be fixed with a new set of exhaust gaskets.



    Fix it with a new exhaust gasket?

    What your really saying is.............don't worry about it right?


    Where do you think the leak is coming from? Valve? Head gasket?

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    I can't see any coolant coming out of the crack area but.......there is enough rust staining to that cylinder "and none to the others" that I figure coolant must be coming out somewhere near.

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    The crack is most likely superficial. I wouldn't worry about it. I agree with the exhaust leak - fix it and don't worry. Actually, you probably dont even need new gaskets. Just remove the stock bolts which have relaxed from all the heat-cool cycles and replace them with stainless bolts. Use anti-sieze on the threads when you install them. I would bet good money that alone will fix the exhaust leak. The black oily residue is probably partially burnt diesel fuel which weeps it's way through when the engine is cold. Once it warms up and the metal expands the leak goes away.

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    The crack looks like a sand casting crack .

    1. If it was a crack you'll be seeing oil or coolant .
    2. It's not a turbo seal because you have a low rear mount turbo ,it could do that if it was high mount turbo and would leak down the manifold when it seal cooled down .
    3. The white,Blue smoke is oil from a blown head gasket oil port and or valve seal so the the engine get hot the seal expands .
    4. A compression test need to be done , because it's only going to get worse .

    Use a stock exhaust bolt or stud , SS isn't that great for the heat that these manifolds see .

    Scott

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    Quote Originally Posted by CrewCab59 View Post
    The crack looks like a sand casting crack .

    1. If it was a crack you'll be seeing oil or coolant .
    2. It's not a turbo seal because you have a low rear mount turbo ,it could do that if it was high mount turbo and would leak down the manifold when it seal cooled down .
    3. The white,Blue smoke is oil from a blown head gasket oil port and or valve seal so the the engine get hot the seal expands .
    4. A compression test need to be done , because it's only going to get worse .

    Use a stock exhaust bolt or stud , SS isn't that great for the heat that these manifolds see .

    Scott



    Thanks for the information guys.
    I will change out the exhaust gasket and bolts and not worry about the crack.

    Scott, I will be calling you in the near future for a few parts. Just putting my list together and trying to save some cash up.

    Thanks again for the education.

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    Quote Originally Posted by CrewCab59 View Post
    Use a stock exhaust bolt or stud , SS isn't that great for the heat that these manifolds see .

    Scott
    The heat is the precise reason stainless hardware is better. The stock bolts become tempered to essentially mild steel strength and lose their stretch when heated to these temps. The loss of stretch is why you end up with leaks. The loss in strength is also why they break so easily when you try to remove a siezed bolt. Not to mention the stock steelies rust badly when exposed to such heat, making them more likely to sieze in the head. Austenic stainless maintains much of its strength at the temps where exhaust manifolds operate (meaning they maintain their preload), they don't rust, and particularly if you use anti-sieze they will be easier to remove later if the need arises.

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    Default slobber

    Be careful not to confuse diesel slobber with a fuel or oil leak. Slobber is a cold run condition in which water and carbon run down from the exhaust ports. The solution for slobber is to put the engine to work. This is usually not a problem for on road turbo diesels unless excessive idling is involved.
    1973 F-250 with 4BTA and GM NV4500, 3.73 Ratio Dana 44 Front and Dana 60 rear. 31.5" tires. HY35W Holset Turbo with Denny T Stage II fuel pin and 4" Exhaust. Enjoying driving every day. Work in progress. God is good all the time!

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    Quote Originally Posted by jlk5269 View Post
    Be careful not to confuse diesel slobber with a fuel or oil leak. Slobber is a cold run condition in which water and carbon run down from the exhaust ports. The solution for slobber is to put the engine to work. This is usually not a problem for on road turbo diesels unless excessive idling is involved.
    Precisely

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    Slobber could be a possibility. Right now my motor is run on a stand and not in my truck. Would make sense.

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    Quote Originally Posted by MaxPF View Post
    The heat is the precise reason stainless hardware is better. The stock bolts become tempered to essentially mild steel strength and lose their stretch when heated to these temps. The loss of stretch is why you end up with leaks. The loss in strength is also why they break so easily when you try to remove a siezed bolt. Not to mention the stock steelies rust badly when exposed to such heat, making them more likely to sieze in the head. Austenic stainless maintains much of its strength at the temps where exhaust manifolds operate (meaning they maintain their preload), they don't rust, and particularly if you use anti-sieze they will be easier to remove later if the need arises.

    The only reason the stock exhaust bolt snap is because nobody cleaned the threads,they reuse the old bolts and they over tighen them .


    Scott

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    Quote Originally Posted by CrewCab59 View Post
    Use a stock exhaust bolt or stud , SS isn't that great for the heat that these manifolds see .

    Scott

    Quote Originally Posted by MaxPF View Post
    The heat is the precise reason stainless hardware is better. The stock bolts become tempered to essentially mild steel strength and lose their stretch when heated to these temps. The loss of stretch is why you end up with leaks. The loss in strength is also why they break so easily when you try to remove a siezed bolt. Not to mention the stock steelies rust badly when exposed to such heat, making them more likely to sieze in the head. Austenic stainless maintains much of its strength at the temps where exhaust manifolds operate (meaning they maintain their preload), they don't rust, and particularly if you use anti-sieze they will be easier to remove later if the need arises.

    Quote Originally Posted by CrewCab59 View Post
    The only reason the stock exhaust bolt snap is because nobody cleaned the threads,they reuse the old bolts and they over tighen them .

    Scott

    I work for a major oil company in one of their large chemical manufacturing facilities. Adherence to metallurgy specs is not just a matter of reliability it is potentially a matter of life or death. In applications where heat cycling / heat stress is an issue, stainless steel B8 studs are used in place of B7 carbon steel studs. While B8 studs are not as strong as B7 studs, they will endure the stress of heat cycling much better than B7. I personally have snapped heat cycled 5/8" B7 studs with a combination wrench and I only weigh 145 lbs.
    .

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