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F134 Exhaust Tappet Sticking

Discussion in 'Early CJ5 and CJ6 Tech' started by Scott Sherraden, Sep 30, 2020.

  1. Sep 30, 2020
    Scott Sherraden

    Scott Sherraden Member

    Kansas
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    Hi all, trying to diagnose why my F134 just wasn't getting much power. I found that exhaust valve #3 was stuck open so I was only working on 3 cylinders. After looking it over, what I see is that the exhaust tappet is sticky. It isn't seized, it just doesn't move freely like the others.

    I poured in the Marvel Mystery oil, and ran it for about 30 miles on various trips, but it hasn't improved. So I'm undecided if I should just give it a bit more time, or pull the motor and remove/replace that tappet. Seems like a lot of work but I'm not sure what else to try.

    At times the tappet WILL free up, I'll be going along the highway stuck at 45-50mph, and it will suddenly surge like a turbo kicked in and I'll be doing 55-60mph just fine. Then the next time I drive, it will be stuck again.

    I know the spring is OK, the valve itself is fine and moving freely in the guide, it is definitely the tappet being stuck.

    So 2 questions:

    1. Opinions, is it a lost cause, should I pull the motor? Or give it more time or try something besides Marvel Mystery Oil?

    2. Does anyone really know how the tappets are fed with oil? In the FSM I don't see a picture of any oil feeding the tappets. Is it just fed from splashing oil?
     
  2. Sep 30, 2020
    PeteL

    PeteL Member 2020 Sponsor 2019 Sponsor

    Hills of NH
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    Where did you pour it?
     
  3. Sep 30, 2020
    Scott Sherraden

    Scott Sherraden Member

    Kansas
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    Lol in the crankcase
     
  4. Sep 30, 2020
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    What is the overall condition of the engine? What do you think caused the tappet to stick?
     
  5. Sep 30, 2020
    Scott Sherraden

    Scott Sherraden Member

    Kansas
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    Glenn, overall quite good condition. As you recall my other thread, I had to replace the cam and cam bearing. That all went well and while I had the motor out, I checked everything over. The engine has probably been rebuilt based on the good condition of main bearings and also the fact that I have good oil pressure and compression.

    When I replaced the cam, I did not remove the tappets, but I did lube them with some assembly grease. So I'm sure that I just got some dirt or contamination on that tappet. Or it's even possible that the particular #3 has always been sticky. I have only owned this since July, so I don't have a good comparison or baseline on how it drove prior.
     
  6. Sep 30, 2020
    Scott Sherraden

    Scott Sherraden Member

    Kansas
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    If anyone knows, this would help.
     
  7. Sep 30, 2020
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Yep, I do remember that thread. You must have verified that they freely moved up and down if you were able to lube them. Have you verified the spring is good after having the tappet problem? Maybe it's weak? Maybe it's busted and you didn't notice it?
     
    dozerjim likes this.
  8. Sep 30, 2020
    Scott Sherraden

    Scott Sherraden Member

    Kansas
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    Hi Glenn yes, when I put it all back together and lubed the tappets they did move OK. However it is just a nagging thought that maybe the one wasn't moving like the others, if so I just didn't notice or catch it. With assembly lube they all move a bit sluggish, but once the motor has been running and they are oiled they all move really freely. You can almost spin them like a top. That isn't the case when they have heavier assembly lube. So unfortunately I can't say with certainty whether this problem was introduced by some contaminants at that point or later.

    I have a theory that the contamination happened after, but it would help if I understood better how these tappet journals are oiled. Maybe some contamination like a piece of RTV got in the galley if there is a galley feeding it. Or if it is just splash oiled from above the journal, I can't really understood how something got in there.

    Yes I did check the spring out, it isn't broken, and seems to have the same force as the others. That is subjective however, I don't really have a way to measure it. If I do end up taking the motor out to replace the tappet I will go ahead and replace all 4 valve springs just because they are not terribly expensive.
     
  9. Sep 30, 2020
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    How about adjustment? Are you sure the clearance is enough? If that exhaust valve was sticking open the engine should run pretty crappy and I would imagine some bad noise would be accompanying it.
     
  10. Sep 30, 2020
    Scott Sherraden

    Scott Sherraden Member

    Kansas
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    Yes clearances are to spec .018 on all 4.
     
  11. Sep 30, 2020
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    As far as oiling I honestly don't remember that part.
     
  12. Sep 30, 2020
    Scott Sherraden

    Scott Sherraden Member

    Kansas
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    It runs on 3 cylinders, surprisingly well without a lot of noise, it just doesn't have a lot of power.
     
  13. Sep 30, 2020
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    This lack of noise doesn't seem logical. At some point the cam lobe and the tappet would have to be hammering away. Are you sure it's just not the plug or ignition?
     
  14. Sep 30, 2020
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Bad plug wire? Heat related? After a certain bit of time starts breaking down?
     
  15. Sep 30, 2020
    Scott Sherraden

    Scott Sherraden Member

    Kansas
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    If the tappet is sticking up, which it is, the cam lobe isn't making contact. Therefore no hammering, it isn't even making contact or making a tapping noise. And I have on new plugs and wires. I don't think it is heat related. When I start the car and start driving I know it is sticking, it doesn't make a lot of noise but you can just tell it isn't running great. And like I said sometimes going down the highway it will start working - you can immediately feel a surge, it sounds different and has more power, so it seems like the tappet frees up.
     
  16. Sep 30, 2020
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    It would have to be making minimal contact when the cam rotated to the exhaust stroke. Maybe you wouldn't hear it but it would have to be right there unless the cam somehow pushed it further? When it frees up does it do it at the perfect time so it is normal contact when the lobe rotates? I guess it could happen if luck is on your side. :)
     
  17. Sep 30, 2020
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    I take it you rotated the engine and watched it open but not necessarily close as it should or didn't close smoothly?
     
  18. Sep 30, 2020
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    The flathead 230 in my ambulance has sticky tappets or valves, not sure which or maybe it's both and it's pretty noisy. This is why I am mystified about your F-head not having any related noise. I took someone's word that the engine was good and didn't do anything to it when I bought it.
     
  19. Sep 30, 2020
    Scott Sherraden

    Scott Sherraden Member

    Kansas
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    Yes indeed that is why the sticky valve is frustrating. When I put the engine back together and rotated it, I didn't see or notice any problem with any of the exhaust valves. I really think it must have developed after running.

    As far as the noise, there definitely isn't a ticking or noisy valve issue, which I agree is strange. The best I can describe is that it just doesn't run as smooth as it should. And obviously under load, going down the road it runs fine but noticeably underpowered.
     
  20. Sep 30, 2020
    baldjosh

    baldjosh Member 2020 Sponsor

    pacific north west
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    just thinking outside the box...could it be working fine while running, but in addition you have a no spark to a cylinder that will kick in to give the boost of power?
    turning the engine over by hand wouldn't produce the violence that goes on in a cylinder...maybe its a little sticky but...???
     
    PeteL and Glenn like this.

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