Edumacate Me About Hydraulic Lifters, Please....

[rs899]

I confess, I don't know much about them.

My Jetta is exhibiting some very suspicious cam wear and coloration:

http://www.vwdiesel.net/forum/index.php?topic=26699.0

I haven't really done anything about it yet, as I have been playing with a rebuilt IP (almost done, seems OK).

I did notice that the cam is not touching the lifters when the engine is cold- there's perhaps .015 or so clearance , much as in a mechnical cam/lifters setup.

I think I am reading that the lifters should always be preloaded (not sure about VW, but general theory ) Is this correct?  Are my lifters "collapsed"?  Is the cam whacking against the lifters causing this wear when it should always be in contact?   

[doonboggle]

We would ... if we knew what 'Edumacate' means ? ? ? ?

I confess, I don't know much about them.

My Jetta is exhibiting some very suspicious cam wear and coloration:

http://www.vwdiesel.net/forum/index.php?topic=26699.0

I haven't really done anything about it yet, as I have been playing with a rebuilt IP (almost done, seems OK).

I did notice that the cam is not touching the lifters when the engine is cold- there's perhaps .015 or so clearance , much as in a mechnical cam/lifters setup.

I think I am reading that the lifters should always be preloaded (not sure about VW, but general theory ) Is this correct?  Are my lifters "collapsed"?  Is the cam whacking against the lifters causing this wear when it should always be in contact?   

[rs899]

It's just a folksy way of saying "educate".

I performed the test for the cam followers as described in the Bentley, that being to remove the valve cover when hot, and try to depress the lifters with a piece of wood.  The spec is less that .004".  It was difficult to measure, but I don't think mine moved that much.

Oh, and I misspoke above.  The cam does contact and preload the lifters when the valves are shut.

So now, I am stumped again.  What to do?  Buy new lifters for $65?  Use a different cam? Rip it all off and run a different head? 

Watchful waiting?

[rs899]

I think it's about 45-50 psi hot at speed, 15-20 at hot idle per my gauge.  Should be enough, no?

[Vincent Waldon]

I think it's about 45-50 psi hot at speed, 15-20 at hot idle per my gauge.  Should be enough, no?

Yup... you're fine from an oil pressure perspective, imho.

The factory lifter test is:

1) run the engine up to operating temp and then shut it off
2) quickly remove the valve cover
3) using a wooden or plastic stick (to prevent scratches) attempt to depress each lifter in turn.. they should not noticeably give.
4) if any of them do, replace 'em all

In general I've never personally have lifters wear out.. but at 8 bucks each I tend to replace 'em pretty liberally whenever I do a tear-down etc... so maybe have just never accumulated enough miles.   

[rs899]

Vince- yes I did that last night and got no measurable "give" (<1mm) from any of them.

So, now that I have some of the major "heads" thinking about this, what's your opinion?

See the pictures in the earlier thread.  There's a noticeable discoloration, at least on all leading and trailing edge surfaces of the cam. The cam and lifters I got from Tyler and I am sure they looked fine when I put them in about 5K miles ago.  They were a matched set, but they didn't go back in the order they originally played ( in the head that Tyler scrapped).

If it was your ride would you...

Replace lifters? (~$65)
Replace Cam? ( don't have a good hydraulic one, lots of mechanicals)
Replace head?  ( again, no hydraulics, but have a couple of mechanicals I could swap, would have to plug the block)
Do nothing?

Understand that this head was rebuilt by a machine shop when someone screwed up the timing.  I don't know what springs they used under the lifters.

Just looking for wisdom...

Is it possible that all this "wear" happened the first time I cranked the engine with the lifters perhaps not pumped up?  I did pressurize the system by spinning the oil pump before I re-ran the rebuilt engine.

[R.O.R-2.0]

is it ticking? if its not ticking like theres no tomorrow, i would just run it..

[rs899]

Nope, not ticking at all.  I just thought the nice part about having hydraulic heads was being able to forget about it... 

It's going to be hard with this one....

[Vincent Waldon]

Well, then, it boils down to your nature.   

If you can really pull off "watchful waiting" I'd say go for it... if there is a lifter or so amiss it's not going to grenade your engine all of a sudden... just start to make noise... or more noise.

If you will always wonder if "today's the day"... well, a new cam and 8 lifters is pretty affordable against lost sleep??!!

Me... and this is just me... if I didn't already have it changed over I might schedule a cam/lifter refresh with the next timing belt when it's all apart anyways... and then keep my eye on it every oil change or so.

[Smokey Eddy]

I just changed all my lifters the day before yesterday. They have an interesting black coating on the tops of them that my old lifters did not.
reason for change - horrendous ticking.

I never noticed a gap on mine. im surprised no one has said anything about the gap...

[rs899]

sorry, no there wasn't a gap- I couldn't shove any feeler gauge under the cam.

So, I really can't find anything wrong with the lifters, but I got these stress marks on the cam.

I am inclined to just let it ride-perhaps it was an initial startup anomaly (aka screw-up).  It might even sort of wear itself away (not sure if that would be good, though)