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304 Valve Job.

Discussion in 'Early CJ5 and CJ6 Tech' started by Ol Fogie, Dec 1, 2024.

  1. Dec 1, 2024
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    Question for you engine building folks. As part of my 304 engine overhaul I took my cylinder heads to the machine shop to have new valves and hardened exhaust seats installed. Look really nice when I picked them up. They had been tank cleaned, all new valves, seats, new spring rotor caps and seals. they were really clean, looked like new cast iron and had been resurfaced. When I got home I was looking closely and I realized the heads had been painted with a cast color paint after they were cleaned. Painted all over except the block surface. the paint would scratch off of the sealing surface where the manifold gaskets will need to seal very easily with a few rubs with a scotch brite, OK, no problem I will just clean the gasket surfaces before assembly. Then I realize that the interior area around the valve springs and all the area under the valve covers were painted too! my question is, can this paint come loose or be dissolved by my the motor oil and clog my oil filter? and oil passages? :shrug:. Anyone seen this before? Maybe I am over thinking this? IMG_6490.JPG IMG_6488.JPG IMG_6453 - Copy.JPG In the center photo it can be seen where I sanded a bit of the paint off where the gasket will be. The paint is a really thin coating. I called the machine shop and they said it was a coating to prevent it from rusting that it would not hurt anything.:shrug: Opinions please.
     

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  2. Dec 3, 2024
    73 cj5

    73 cj5 Not ready for the junkyard yet

    Clinton, Mississippi
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    Most likely is cast blast paint and it generally adheres very well if the part is clean and dry but I personally wouldn't leave it on the cylinder head top side because it could flake off and end up on the pickup tube screen.
     
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  3. Dec 3, 2024
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Have tried some solvent on it? Might wash off with brake cleaner or lacquer thinner or such.
     
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  4. Dec 3, 2024
    Ohiowrangler

    Ohiowrangler Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    I never leave paints, coatings or oils on any sealing surfaces, always clean and dry. I'd also clean the areas under the vale covers. Good luck, Ron
     
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  5. Dec 3, 2024
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    Thanks for the replies and suggestions. I was just looking at the situation this evening. I agree the stuff needs removed for sure, It doesn't appear to be stuck very well, you can almost scratch it off with your thumb nail. I will try some lacquer thinner and see if it will dissolve. I thought of trying paint stripper, but I am almost afraid I might get it on the new valve seals and damage them. Break clean, will it harm the valve seals? The only other option would be to remove the new valves and seals and bead blast it. lots of trouble. If anyone has any more thoughts please let me know. Thanks again. Jim
     
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  6. Dec 3, 2024
    Ohiowrangler

    Ohiowrangler Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    I'd go with brake cleaner or lacquer thinner. Ron
     
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  7. Dec 3, 2024
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    Thank you, I have both in the shop. I will give them a try tomorrow and report back how it goes.
     
  8. Dec 4, 2024
    Ohiowrangler

    Ohiowrangler Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    If you would, check with the machine shop and ask what the coating is. Ron
     
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  9. Dec 4, 2024
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    Good idea! I willl do that.
     
  10. Dec 4, 2024
    Stakebed

    Stakebed Member

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    And ask why the Hell did they paint sealing surfaces and under the valve cover. Heck, ask why they painted at all?
     
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  11. Dec 4, 2024
    Ohiowrangler

    Ohiowrangler Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    Corrosion inhibitor?
     
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  12. Dec 4, 2024
    sterlclan

    sterlclan Member 2025 Sponsor 2024 Sponsor 2022 Sponsor

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    common practice as i recall, makes them look clean and stops flash rust. cast blast for the win
     
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  13. Dec 4, 2024
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    Well the machine shop guy said it was a corrosion inhibitor, Thought it was cast blast. They use it on all their cyl heads as soon as they remove them from the cleaning tank. Never had anyone that had a problem with it, as it is a high temp coating. So I did some testing today, tried brake clean and lacquer thinner and a wire brush. Both worked about the same, had to let it sit on there for several minutes and it would soften up just a little but not remove it without still hard and repeated brushing. but it would come off. I don't think it would be good if I got Brake clean on my valve stem seals, probably impossible to clean all around the valve springs without getting some on them. Just not sure if the cast blast is ok to leave under the valve covers even if it is considered high temp resistant paint, it still might not be oil resistant. :shrug:. With the heads being not installed yet I could just remove the valves, and seals, use some soda or glass bead media in my blast cabinet to remove it. Might not hurt to leave it in there but I would just feel better if it were removed .Probably the easiest and fastest way to solve the problem. Thanks again for all your help. Any further thoughts and comments please post them. Jim.
     
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  14. Dec 4, 2024
    45es

    45es Active Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    I understand you are not comfortable with an internal engine surface being painted. That in itself doesn't mean it is a problem. A paint that is commonly used is Glyptal Paint. Look up Glyptal 1201q enamel paint. There are OEM's that have done this such as Jaguar and Deere. Last, I don't think an engine machine would be doing this if there was a chance it would compromise their work and lead to a lot of warranty repairs.
     
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  15. Dec 4, 2024
    Stakebed

    Stakebed Member

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    Nooooooooo, don't blast any surface that is internal to your engine and that gets exposed to engine oil.
    Try as you might, you will not remove every grain of blasting media.
     
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  16. Dec 5, 2024
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    I know what you are saying. I first thought of that, Then I realized there are no oil passages in the cyl head except the drain back holes in the bottom of the valve chamber. My thought was to remove the valves and seals, cap the valve guides and tape the only two water jacket holes and bast the area under the valve cover. Like this there is no place for media to hide Then pressure wash it. maybe use walnut hull media instead of soda, glass bead or aluminum oxide. Not quite the same as blasting an engine block with oil passages drilled all inside. What you think? Still too risky?
    I suppose I could take them back to the machine shop and have them retank/ clean them.
     
    Last edited: Dec 5, 2024
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  17. Dec 5, 2024
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    Interesting, now that you mention this I can remember seeing paint on the inside of some older military engine blocks. If I do decide to just leave the paint in there, I still will need to remove it from the countersunk bores where the cyl head bolts go. I did put a head bolt into one of the bolt holes and spin it a bit to see if the paint came off under the bolt head and sure enough the paint fleak bits came out from under the bolt head, so they would then be in my oil.:(. lots to think about. :confused:.
     
  18. Dec 5, 2024
    73 cj5

    73 cj5 Not ready for the junkyard yet

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    Nothing wrong with blasting engine parts as long as you thoroughly clean the parts. It'd be no different than the shot blasting process.

    Personally, I'd take a strong pressure washer and maybe something like oven cleaner or coil cleaner and strip it down to a bare surface and repaint it how you'd like.
     
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  19. Dec 5, 2024
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    IME shops often apply cheap spray bomb to heads and blocks to stop rust. This comes off with lacquer thinner.
    If it does not come off, that says to me that it will be stable to engine oil.

    You can buy stronger solvents like "Goof Off" that are meant for adhesive and graffiti and such.
    Small can, not cheap - maybe contains methylene chloride.

    If the shop says it's ok, I'd leave it alone and reassemble. "Perfection is the enemy of the good."
     
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  20. Dec 5, 2024
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    I know your probably right, if the lacquer thinner doesn't cut it motor oil surely would not bother it either. Plus many of my attempts at perfection in the past have jumped up to bite me, when I should of left well enough alone! Good advice, Thanks. Jim.
     
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