401 rebuild with tapping noise...

Discussion in ''Da Nailhead' started by 1966buickgs, Aug 22, 2016.

  1. 1966buickgs

    1966buickgs 1966buickgs

    Just got done with the break in an all of a sudden a tapping noise is coming from what sounds like the right side valve cover. Went to the builder an he says to change the break in oil to 10-30 weight an add a zinc additive so I did,went with valvoline an hyper plus additive . Ok so still tapping in idle more noticeable in idle than in drive but still there. He's saying to take off valve covers an check each rocker to see if there is any squeesh feeling to them. I have not done this yet, I wanted to here what else I could check an what could it be and am I hurting this new rebuild by still driving it right now. The noise sounds like a sewing machine ticking,open the hood an it is tapping,damn! Any ideas,thank you
     
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Could be several things. You need to take off that valve cover and look for the obvious things first. Bent/damaged push rod or rocker arm. See if you can isolate the noise to the valve that is affected.
     
  3. philbquick

    philbquick Founders Club Member

    You could have an air locked lifter. Yes take the valve cover off and look for the simple stuff. I doubt that you are hurting your engine. I would look at the break-in oil by straining it through a paper towel to see if there's any metal. If there is significant metal, stop running it and take the engine back to your builder.
     
  4. GSBuick65

    GSBuick65 Well-Known Member

    Mines been tapping for years, mine comes & goes

    Sent from my LG-H740 using Tapatalk
     
  5. John Codman

    John Codman Platinum Level Contributor

    Pull the valve cover, then run the engine. Put a finger on each rocker arm at the pushrod end; when the rocker arm moves to open the valve, the action should be smooth. If it is not and it feels as if the arm is being hammered open, you have located the problem. There is an issue with either the pushrod or the lifter. The good news is that on the Nailhead, it is very easy to access either, and removing the intake manifold does not involve draining the cooling system.
     
  6. ttotired

    ttotired Well-Known Member

    I think the important points to be taken here are "I went to the builder" and "its making a tapping noise" and "I just finished running the engine in".

    New engine, built by someone (commercial?), take it back and get them to fix it, if it was commercially built, there should be a warranty involved, which can also mean, if you open the engine, warranty no longer counts

    I personally would NOT be driving it around until its fixed, hydraulic lifter engines do not "tap"

    This could be something as simple as a faulty lifter right up to a "wiped" cam lobe or blocked oil gallery.
     
  7. 1966buickgs

    1966buickgs 1966buickgs

    Ok found one of the rocker arms was loose unlike the rest of them on the passenger side. I am assuming push rod may be bent or lifter stuck.Ok so didn't have time today but tommorow I am pulling the rocker arm assembly and I am going to pull the push rod out, im hoping the lifter is not stuck or worse. I made a video couldn't get to upload off of phone of how much play between rocker arm an push rod. I was told by the builder that I may be able to spin the push rod while it is still in the motor underneath rocker assembly to see if it wobbles so I want have to take the assembly off, if anyone has done this I would appreciate the help,thank you.
     
  8. telriv

    telriv Founders Club Member

    Do yourself a HUGE favor & get a shop manual.
     
  9. philbquick

    philbquick Founders Club Member

    You should be able to rotate the push rod with the rocker on as long as that valve isn't open. If you remove any push rods DO NOT pull them straight up, push them to the side to break the suction between the rod and lifter then pull up otherwise you could pull a lifter out of the block (which isn't a big deal on a nailhead, as mentioned, but it could make unnecessary work).
     
  10. 66electrafied

    66electrafied Just tossing in my nickel's worth

    Depending on the type of lifters used, you might find that there is a mismatched lifter in there. I had that happen, and unfortunately it almost destroyed my brand new engine. Go back to the shop that built it and asked if they lined up the lifters before they put them in, or if they just took them straight from the box into the block. That was the shortcut I took. Dumb, dumb, triple dumb, never again! It didn't help that the set of lifters was a bargain set from China. Found a SBC and a Caddie lifter on the driver's side bank; in the meantime it busted the rocker shaft into 3 pieces and destroyed 2 rockers completely. Didn't wreck any pushrods though, and didn't take out the cam. I managed to drive the car 150 miles on 5 cylinders at 65 mph to get it home. (No kidding, it was dark, raining and there were bears out there, no way I was going to stop, and I thought the engine was already done for anyway.)

    Bottom line there has to be a logical explanation, how I found I had a short lifter was by sticking a screw driver into the offending rocker when it was running; - quieted right down.
     
  11. 1966buickgs

    1966buickgs 1966buickgs

    I pulled the rocker arm assembly off this mourning an took out 3 pushrods,1 that was seated an tight against therocker arm,the other 2 pushrods I pulled were loose an I turned them before I pulled the assembly off an they looked to have a wobble. So I compared them an sure enough those two wobled when I rolled them. But they did not visually look bent enough to cause the gap between the rod an rocker arm so I'm thinking lifter next. How do I pull the lifter the best an safe way, thank you for the help.
     
  12. ttotired

    ttotired Well-Known Member

    Simple, intake manifold off, then the tin plate under that and there they are

    Make sure any that you pull and not replace go back into the holes they came from, same as the pushrods ect, they wear into each other and if changed around, means a re break in and unnecessary extra wear
     
  13. Aussie V8

    Aussie V8 Well-Known Member

    I hope you find something. We have a similar problem. There was a significant rattle from the lifters on our engine, so we replaced them all. Now there is just one rather loud tapping / knocking coming from inside the engine. Currently have oil pan off checking oil pump ( good ) and pulling con rod bearings to check.
     
  14. 1966buickgs

    1966buickgs 1966buickgs

    I got Mellings lifters an push rods today just two of each but I'm thinking replace all of the lifters an rods while I'm in there too. Does this mean putting break in oil back in it? Also does anyone know the torque spec for the rocker arm assembly to put it back correctly? Thank you
     
  15. Aussie V8

    Aussie V8 Well-Known Member

    Rocker arm shaft bracket > cylinder head 25-35 ft/lbs
     
  16. 8ad-f85

    8ad-f85 Well-Known Member

    I'm hoping you don't mean that you saved the original break in oil for re-use, there's metal fragments in there now.
    You can successfully use just cam lube and decent oil without much worries.
     
  17. 66electrafied

    66electrafied Just tossing in my nickel's worth

    I'd soak the new lifters in clean oil (don't pump them up though) and then place them in with some cam break-in oil, which is a lot like ZDDP. Pop the coil wire off, crank it up to get some oil pressure happening, then put the coil wire back on and fire up. Run it at idle or a little faster to build up pressure and get the rattling to stop, but I don't think you have to run it to 2000 rpm like an initial break-in. The cam and that is already tempered. The way I look at it it's a fine balance to get some oil pressure in there quickly, but not run it fast enough to rattle it all apart.

    But like always, I'm probably wrong and an expert will tell me I'm all wet. But this has worked for me plenty of times in the past and I've never shotgunned a cam or collapsed a lifter or bent something.
     
  18. 1966buickgs

    1966buickgs 1966buickgs

    I looked at the drivers side rocker arm assembly today an it has a piece of metal like a oil splash guard bolted to the assembly. Is there supose to be one on the passenger side too? Oh also there are french locks holding the manifold now but at first I had a leak an I had them resurfaced to mate better. My question could I messed up an exhaust valve an that cause the tapping or if I overtighten the bolts before putting those french locks on holding them where they want back out anymore?
     
  19. doc

    doc Well-Known Member

    determine which rocker arms are clacking,,, then mark them and go from there,,,, first off , I would not run any thinner than 20 wt. oil in a nailhead engine... plus ZDDP.... but ,, before going any further,, try subbing 1 qt of atf for 1 qt of engine oil... a lot of times it will make a lifter pick up... or take a small soft headed hammer and tap the back side of the lifter as the engine idles.... had a lot of them pick up that way.... next look for defective rocker arms/push rods/ valves that dont come all the way back up.... then if that has not resolved the problem,, pull the intake off and the valley cover and look at the bottom of the lifter/s and check the cam lobes involved.... if that builder did not coat the cam with moly grease when he installed it , it could have wiped a lobe or lobes.... but really he built it , he should stand behind it....:Brow:
     
  20. 1966buickgs

    1966buickgs 1966buickgs

    What is the best specific oil an weight type an zinc additive to use?The builder did say to sub that quart of ATF, but something about transmission fluid in a newly rebuilt motor sounded kind of off. I will try it now that bout a quart of 10w30 valvoline spilled out while we had the valve cover off training to locate the exact location of the tapping before pulling the intake an valley cover an replacing a lifter or two. I already replaced a couple push rods that wobbled when I rolled them. How precise do the tips on those push rods have to be? I pulled three an two wobbled for sure but looking at them they didn't look bent till you rolled them.
     

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