Tappet repair ???

[rbonnett]

I have a loud tappet sound coming from 6 or 7 (I think , using my cone of paper stethoscope). I re-adjusted the push rods, drove around for a while and then re-checked. That seems OK. So I'm going to pull the head and replace at least the bad tappet. This is a job I haven't tacked before. Questions I have:

- Short of pulling the camshaft, will it seem obvious that the roller, slide or guide are bad as opposed to a bad lobe on the cam itself?
- Since I'll have the head off, its tempting to just do them all, $$$ aside. Is there a downside to that, other than having 8 X as many chances to screw up?
- Any tips or gotchas that aren't in the GB or Haynes?
- How long a job should this be, given its my first time. The weather is iffy here right now, so I can wait til I have a whole weekend of no rain to start this.

Thanks

[thixon]

To make sure I'm clear, when you say you adjusted the pushrods, I'm assuming you mean you adjusted the valve tappet clearance. Is that right?

If so, were you able to adjust said clearance to factory spec (.010)? Also, did you adjust in the proper sequence?

I just want to clear this up before I try to diagnose.

Also, don't pull the head just yet.

[Tim Smith]

Don't pull the head unless you have another reason to.

Just to be sure, I'll let you know that I've found pushrods riding outside their normal position after a head pull. Lots of noise and weird running until I figured it out. Not saying this is your case but do take care and make sure you have everything in position before diagnosing bad gear.

Even if the rods are bad, it's not the cam shaft you are pulling. Just the rocker cam bar (on top of the head). This is simple and all you have to remember is to keep the springs and cams in place.

Then once it's out, you should be able to shine a flashlight down to the cam rollers and identify a problem down there.

Just do your due diligence in checking the motor before you find yourself in a lot more hours of work than is needed is all. You're certainly not going to break anything by going at it like a bull. :D

[rbonnett]

Yes - everything adjusted to 0.010. I did adjust them warm, then rechecked them after. Checked them again cold - still seemed fine.
I'll definitely try just removing the rocker assembly and having a look at the push rods and down the holes to see if anything jumps out at me.

[Terrys]

If you adjusted them all to .010", then are you sure your noise isn't from the fuel pump, that runs between 6 and 7 I believe.

[slorocco]

You can check for a bad cam without pulling the head. Go to the local autoparts store and borrow a dial gage. You should be able to use that to measure cam lift at the rocker arm without pulling anything off.

[rbonnett]

The fuel pump was replaced with an electric some time back. If the noise had started then, I would have said it was something trying to push the fuel pump that isn't there any more.

[rbonnett]

You can check for a bad cam without pulling the head. Go to the local autoparts store and borrow a dial gage. You should be able to use that to measure cam lift at the rocker arm without pulling anything off.

Where would be the best place to measure this? I'm thinking at the head of the push rods? neither Haynes nor the GB has any suggestion for this that I can find.

Also, is it the cam lift (0.257 int and exh) or the valve lift (0.403 int, 0.388 exh) that I should be measuring for?

Thanks for all the ideas. If I can at least Dx this without taking things apart I'll be a happy man

[rbonnett]

Finally had enough sun time to tackle this. I didn't try the dial gauge; I never used one before and wasn't sure I'd know what it was telling me if I did. I did pull the rocker assembly (twice really - the first time I somehow skipped one of the push rods :o).

Once I had the rods out, I looked them over - all nice and straight - no signs of dings, scratches or other obvious issues. Peering down with my light, I could see that all the cups on the slides looked bright and identical to each other.

Reassembled everything, did the clearance cold. It was already quieter. Then drove around for a bit - re-checked the clearances. Once it was warmed up the noise was louder - but still seems better than it was.

Here's the one bad thing: the bolts holding the rocker assembly in place were WAY over-torqued by someone, except for one. These are the smaller ones down the center of the brackets. Once removed, the rear-most bolt has flatted threads on about the bottom third. This is the one that was not overly tight. Re-assembling, I did torque these to the manual value - that last one will snug down, but then breaks loose and turns again when I tried to torque it - no way to tell how much; my wrench only goes down to 15 lbs.

The larger bolts for the brackets didn't seem too tight - at least when I had them torqued to 65 lbs it didn't seem to take different effort to re-loosen them.

I don't know if the general over tightening or maybe that one bad bolt was causing noise from the rocker assembly somehow. I'll order a new bolt tomorrow; keeping my fingers crossed that the threads in the head aren't stripped too :(

Thanks for all the advice.

[thixon]

Don't worry, if the threads are gone you can install a heli-coil.