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  1. #1

    Default 1994 PCM 5.8L Pro Boss Lifter Tick

    Second problem on this engine has been happening for past 6 years. The engine sounds like it has a sticking lifter but after replacing the lifters, the noise is still there. Thinking the noise may be coming from somewhere lower in the engine but it has been running fine (other than starting problems) for the past 6 years. Seems like there are just not a whole lot of mechanics that know how to deal with this beast. If i stay boating, i think my future is with Mercruiser.

    Anyone have any suggestions?

  2. #2
    Join Date
    Sep 2008
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    Maryland - USA
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    Default Re: 1994 PCM 5.8L Pro Boss Lifter Tick

    If its in the valve train, you'll have to find the worn part(s) & replace them....checking the cam would be a prudent first step.

    If its not in the valve train, you'll have to find the source.

    Another option is just enjoy it 'til it quits...

  3. #3

    Default Re: 1994 PCM 5.8L Pro Boss Lifter Tick

    Engine has under 400 hours so I couldn't believe anything really major. The mechanic that replaced the lifters also was suspicious of the cam. Would that be a gouged cam lobe that might cause the tick? How difficult (read expensive) might it be to check out the cam?

  4. #4
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    Default Re: 1994 PCM 5.8L Pro Boss Lifter Tick

    I'm thinking worn vs goughed....

    shouldn't be much - valve cover gasket set and some labor....maybe an hour if the engine has easy access.

  5. #5
    Join Date
    Mar 2009
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    Portland, Oregon,
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    Default Re: 1994 PCM 5.8L Pro Boss Lifter Tick

    .......................
    Quote Originally Posted by fishga0130 View Post
    Second problem on this engine has been happening for past 6 years. The engine sounds like it has a sticking lifter but after replacing the lifters, the noise is still there. Thinking the noise may be coming from somewhere lower in the engine but it has been running fine (other than starting problems) for the past 6 years. Seems like there are just not a whole lot of mechanics that know how to deal with this beast.

    If i stay boating, i think my future is with Mercruiser.
    If you purchase a fresh 5.8L Ford engine, they are all pretty much the same engine.

    Anyone have any suggestions?
    If you are still using the mechanical fuel pump, perhaps the actuator arm is causing the noise.
    This arm is actuated via an eccentric unit at the front of the camshaft.
    Suggestion:
    Remove mechanical fuel pump and block-off the fuel pump area within the front cover.
    Start engine and see if the noise is still there.
    Click image for larger version. 

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    Quote Originally Posted by fishga0130 View Post
    Engine has under 400 hours so I couldn't believe anything really major. The mechanic that replaced the lifters also was suspicious of the cam. Would that be a gouged cam lobe that might cause the tick?
    Not necessarily..... but a worn cam lobe may cause the cam follower (what some call a lifter) out of it's adjustable range (for those engines with non-adjustable rocker arms).
    If (key word "IF") you have adjustable rocker arms, try once again setting the hydraulic cam follower plunger depth.

    FYI...... we are not actually adjusting valves (valves are not adjustable).
    We are actually adjusting the rocker arm stud nut as to set the push rod into the cam follower as to set the depth of the
    hydraulic plunger.

    The hydraulic cam follower plungers will have an approx .100" to .125" of travel.
    This adjustment is done once ZERO rocker-arm-to-valve-stem lash has been established.
    Once zero lash is achieved, we use the OEM adjustment as to set the plunger at approx 1/2 of it's travel.
    This creates the hydraulically adjustable function.

    How difficult (read expensive) might it be to check out the cam?
    You would first need the cam profile specs.
    You would then use a dial indicator to check the lift.
    The lift specs may be given as direct cam lobe lift, or a lift dimension X's the rocker arm ratio.
    The specs will clearly give this info!
    Last edited by RicardoMarine; 05-14-2019 at 10:53 AM.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  6. #6

    Default Re: 1994 PCM 5.8L Pro Boss Lifter Tick

    Thanks for all of this info. The 5.8L Pro Boss has throttle body injection and has two fuel pumps - one low and one high and both have been replaced. I know the high pressure pump is electric and I think the low pressure is as well but in any event, it was replaced.

    I would have thought that the mechanic that replaced the lifters would have done the check on the rocker arm and that the mechanic that just checked it out (he pulled the valve covers and observed that all valves were working and there was no sticking) would have done the same thing.

    I have been told that there was no adjustment on the rocker arm as the lifters are hydraulic. I guess this just goes to show there are mechanics out there that really don't know everything.

    As far as a fresh engine, my wife has pretty much put the kibosh on that. We've spent thousands already on trying to get this boat to run properly (new fuel pumps, new relays, new lifters, new sensors) and it has fought us every step of the way. It's very frustrating because the interior and exterior of the boat are in perfect condition - unusual for a 25 year old boat. Unless I can find a relatively inexpensive fix, this boat is history.

  7. #7
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    Default Re: 1994 PCM 5.8L Pro Boss Lifter Tick

    ...........................
    Quote Originally Posted by fishga0130 View Post
    Thanks for all of this info. The 5.8L Pro Boss has throttle body injection and has two fuel pumps - one low and one high and both have been replaced. I know the high pressure pump is electric and I think the low pressure is as well but in any event, it was replaced.
    OK.... then that eliminates a mechanical fuel pump as being the source of the noise!

    I would have thought that the mechanic that replaced the lifters would have done the check on the rocker arm and that the mechanic that just checked it out (he pulled the valve covers and observed that all valves were working and there was no sticking) would have done the same thing. I have been told that there was no adjustment on the rocker arm as the lifters are hydraulic.
    OK.... some of the 335 series Ford engines offered adjustable rocker arms..... apparently yours does not!
    Yours is the style that allows you to fully tighten the stud nut.
    In theory, this properly sets the hydraulic cam follower's plunger depth.
    In reality, it may not compensate for worn cam lobes.... if the amount of wear causes the plunger to become out of it's pre-designed range!
    (this is rather hard to explain without going into great detail)

    Look at the GIF file.
    Note how the rocker arm adjustment controls the push rod depth which in turn sets the plunger depth to within it's proper travel range.






    I guess this just goes to show there are mechanics out there that really don't know everything.


    As far as a fresh engine, my wife has pretty much put the kibosh on that. We've spent thousands already on trying to get this boat to run properly (new fuel pumps, new relays, new lifters, new sensors) and it has fought us every step of the way. It's very frustrating because the interior and exterior of the boat are in perfect condition - unusual for a 25 year old boat.
    In terms of expenses, I've always thought that with a clean and nice boat with good interior, good transom and stringers, etc......, engine troubles are the least of your worries.

    Unless I can find a relatively inexpensive fix, this boat is history.

    Questions (assuming that this a valve train related issue):
    Is this by chance a roller cam engine?
    Why did the mechanic change the cam followers?
    If Flat Tappet, when the old cam followers were removed, what did the "cam lobe face" look like?
    If the convex profile was gone, why did the mechanic NOT consider checking the cam specs?


    If by chance what you are hearing is lifter noise (cam follower), it will be due to the plunger "topping out" within it's travel range, of which in turn creates excessive rocker-arm-tip-to-valve-stem lash.... hence a clicking or clattering sound.
    The non-adjustable rocker arms prevent you from further adjusting and setting the push rod further into the plunger's cup.



    .
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by RicardoMarine; 05-15-2019 at 08:55 AM.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  8. #8

    Default Re: 1994 PCM 5.8L Pro Boss Lifter Tick

    To your questions:

    Why did the mechanic replace the cam follower/lifter - because it sounded just like a stuck lifter and at least two other mechanics suggested that. We tried thicker oil and adding transmission fluid in an attempt to unstick things.

    Why did he not check out the cam, cam specs and check out the cam lobe face. All good questions. All he did was complain how hard it was to come up with replacement lifters and after he changed them out, suggested the sound was slightly softer. I couldn't hear any difference.

    Is the engine a roller cam? I don't know. Getting information about a 25 year old marine engine is difficult and getting parts just as difficult. Vince at Discount Marine is a good source of information and parts but he can only do so much. As an example, once the coil packs go, there is no repair or replacement for the ignition/efi. You have to completely switch over to electronic distributor and carburetor.

    The latest mechanic (we dumped the last one after he returned the boat in a somewhat damaged condition after waiting for a fix the entire season) just observed all of the valves after pulling the valve covers and volunteered the information that the noise wasn't coming from the lifters but somewhere inside of the engine. He thought it might be a broken wrist pin. He didn't seem to want to go into the engine much further to check out the cam either.

    One thing I have always thought was that there was a plugged oil passage. The GIF you included showed to me how that might be possible. Just replacing the lifters wouldn't do anything to clear that passage. And would explain why the original mechanic thought the noise was slightly better. The lifter had oil in it from being soaked in oil before being installed. Once that charge left, the noise went back to how it was before.

    Again, thanks for all of your information. I wish you were closer than Oregon.

  9. #9
    Join Date
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    Default Re: 1994 PCM 5.8L Pro Boss Lifter Tick

    ...........
    Quote Originally Posted by fishga0130 View Post
    ................................

    He thought it might be a broken wrist pin. He didn't seem to want to go into the engine much further to check out the cam either.
    Wrist pins do not break without giving catastrophic signs.
    It would be more likely if a piston wrist pin area was to crack!

    With the engine warm, you may be able to determine which cylinder may have a wrist pin issue by removing one spark plug cable (from the distributor cap) at a time.
    By removing combustion from the equation.........., it may (key word "may") cause a difference in the sound.
    If so, you will have identified which cylinder is causing the issue.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

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