Tappet problem

[Dave_EH]

I drove my car to the mechanic today for a road worthy - on the way I had to stop twice to tighten a tappet - its a 179 Motor.

The second time I didnt have anywhere to pull over and by the time I could it was starting to miss etc.

A guy was walking past and stopped and said he used to be an engine reconditioner.

At first he thought I had stripped the cam timing gear by the noise, but when I explained I had already tightened a tappet he seemed to think these could be the problems

1) that the nut rataining the tappet was old and worn and simply not keeping tight

2) because I had adjusted them with the motor off, I had no oil pressue and was experiencing lilfter pump up

3) the double valve springs were playing a part

4) the stud was being pulled out (he didnt think so)

5) some of the other valves were tightened too much

I think it is mostly a case of no. (1)  - can I use some teflon tape or locktight, or try another nut?

I hadn't had a chance to adjust them with the motor running as I only got an exhaust yesterday and couldnt hear anything before then.

any tips appreciated.

Cheers
Dave

[craiga]

Dave,

You don't say exactly but from the fact its a 179 I would guess it has adjustable tappets, not the later self adjusting units.

You can adjust the tappets in two ways, engine off, or engine running. Engine off is slower and probably a little more of a challenge if you aren't experienced, and HEAPS cleaner than the engine on method!!

Here's how you do it with the motor running -

1. With the tappet cover off, start the engine and have it running at a normal idle, say 700-800 RPM
2. Starting with No1, slowly back off the tappet adjustment nut a 1/4 of a turn at a time until the tappet starts to rattle, or become noisy
3. Now wait a few seconds for the lifter to settle.
4. Start doing the adjustment back up, again just a 1/4 of a turn at a time until the noise just goes away.
5. Once its just gone, tighten the nut up 1/4 or 1/2 turn at a time until you are 1 1/2 turns from the point where it went quiet.
6. Let the engine speed settle and continue through all tappets, using the exact same method.

You could also have a'sticky' lifter, and this would explain the noise being intermittant. It may be that the nut is moving, to prove this you could mark its position relative to the rocker stud and see if it does move. I don't remember this ever happening, and we used to rev these red motors over 7000rpm. I have however heard of and experienced cracked tappets, and studs being pulled from the head itself.

Good Luck, let us all know what you find.

Cheers,

Craig.

[Dave_EH]

Thanks Craig,

Thats the way I intended to adjust them - I just didn't get a chance between exhaust fitting and getting it to the mechanic.

It seems like just a nut that won't hold its position at the moment - a job for the virtual dyno i guess!

When I adjust them I'll try a different nut and maybe a little teflon tape around the thread and go from there.

fingers crossed its something simple

Cheers
Dave

[craiga]

Dave,

Don't use the teflon tape, you would be better off sourcing new nuts or using some thread locking compound like Loctitie.

Hope to catch up one day and have a run on the virtual dyno.

Cheers,

Craig.

[ACE]

Dave,
If your running a modified cylinder head the rocker studs are usually pinned or modified to screw in studs. Originally they would have been pressed in.
An easy way to check if the studs are pulling out of the head is run a straightedge along the top.
If the problem is one of the nuts coming loose you could fit locknuts
Regards ACE  

[Dave_EH]

Thanks Ace and Craig,

I'll try and sort it out tomorrow night.  So it is not imperative that you use identical looking (and shaped) retaining nuts on the threaded studs?

Do you think the nylon type locknuts would be suitable for this application (will they take the heat)?

It is a Yella Terra Cylinder head - should the studs be identical legnth?  I would have thought so, yet one retaining nut has about twice as much thread above it than the other 11 studs - this would indicate a longer stud or being "pulled out" - I had the cylinder head fully overhauled befoerf fitting and no problems were found, although whether this would have been checked is unknown.

Dave

[Jockster]

Dave
All of the studs should sit at the same height, the amount of thread showing will depend upon valve overall length and lifter variations. If you have a lot of thread showing it is possible that either a lifter has collapsed or.....you didn't lubricate the camshaft lobes properly and bed the cam in at 2000 rpm for 10 minutes on initial start. If you didn't bed the cam in properly then you may have worn the bottom of a lifter off or worn the camshaft lobe off. I have seen a lobe go from new to totally worn off in less than five minutes when the cam bedding in process has not been done right.
Cheers
Jock

[Dave_EH]

Jockster,

The cam is a stock item and has not been touched.

So to diagnose the problem

1) If I put a straight edge across and all are flat - I have a lifter problem

2) If one stud is higher - could possibly be a replacement and is naturally higher, or is pulling out - in which case mark its position, test run and go from there?

I have a new set of lifters - can a single lifter be installed with the old lifters still in place?

Regards
Dave

[nicko]

sure can ,are you replaceing one new lifter with another?or do you have a new set?if a new set not installed then maybe you should put whole new set in making sure to prime all lifters first by covering new lifter/s with fresh engine oil and pumping up lifter while keeping covered in oil using a push rod then its right to install (never install unprimed lifters)now your ready=with rocker cover and side plate removed undo offending rocker take out pushrod and remove the lifter from its bore then just reverse procedure with new lifter in place,having said that you would be in right place to check that you are getting full cam lobe lift while side plates are off, just to be safe

[Dave_EH]

Thanks nicko

I have a complete new set.  The old ones have done about 16 000 miles but sat idle for several years.

The motor runs and accelerates well - could that be possible with a colapsed lifter?

I should also make it clear that the tappet that is coming loose IS NOT on the stud that has more thread above the retaining nut than the other studs.  I have had no problems with this particular tappet.

I don't pick up my car until tomorrow, so I'll put a straight edge across the studs, adjust them with the motor running and test drive and go from there.

Nicko - when priming the new lifter (is that basically filling it with oil?) where do I sit the lifter while i cover it in oil and pump it with the push rod?  Can this be done in the bore?

Cheers all - this seems to be my final teething problem before I enjoy some weekend cruising and my first drive of a Holden

I'll also try to take her into the cylinder head shop and get them to run their eyes over it.

Dave

[nicko]

yes you can do it in bore just keep squirting a bit of oil into top of lifter then putting rod back on and pumping it until it goes hard and slowly keep pressing down until it it takes no more oil,i use an old coffee tin or ice cream container outside of engine bay on bench as its easier on my back,(getting old lol)also it is unlikely that a collapsed lifter would let a motor rev smoothly as it would basically be running on 5 cylinders.