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collapsed lifter?
Posted by: zac ()
Date: March 31, 2007 04:46AM

OK, I did a search and found some info, but I'm still looking to bounce some ideas around.

I was driving my car the other day; engine warmed up, oil temps good, shifting into 3rd at about 5500rpms when things started to go south. First a bit of clatter, then worse-but still not _too_ bad, definately down on power. Nursed it home to look things over...

Comp test showed 180-190psi in all cyl except #2 which reads at "O". Won't even move the gauge. Ok, I pull the valve cover and the rocker is waaay loose, tighten it up (hot, running adj) and everything is right in the world again. Motor sounds good, revs freely again, let the engine run for awhile to make extra,extra sure I'm done before buttoning it all back together, patting self on back for a job well done. You can see where this is going...once the valve cover is back on, I decide to fire it up and go for a spin to enjoy my newly fixed car. Right back to where I started; sounds like crap, is missing on one cylinder (gee, I wonder which one?), kicking self in ass... Comp. test a day later shows "0" on #2.

Some background: this is the engine that I'm running over 9:1 CR on hence the high cranking psi #'s. I have approx 1000 miles on it since I've done the heads. Valve springs were checked and shimmed to 80-85lbs @ installed height, guides were in great shape, new seals on intakes, etc, etc-all done when I was freshening up the heads. Since I've owned the car (~2 yrs), if I let it sit for more than a few days SOMETIMES I would get a bit of valve clatter until the lifter(s) pumped back up. Nothing major, went away in a few miles, but it was still there. Engine runs great other than this new development. When I pulled it apart the other day: pushrods, rockers and balls, valve springs and retainers all looked good.

So, I'm thinking that I had a weak lifter that finally went bad. I really don't like the idea of putting new lifters on an old cam, but I do have a bunch of old lifters and I was thinking of pulling the spring and guts out of one and transfering it to my old lifter, assuming this is really the problem. That way I still have the old lifter body that's matched to that cam journal, but with better internals. Is there any reason why this shouldn't work? I've never tried to butch together a lifter before, but since changing the cam in the Corvair is such a major ordeal I can't just throw a new cam and lifters in and be done with it. I'm going to check out the rocker nut carefully tommmorow to see if it's lost its tension, but I'm not real hopeful- it seeemed to snug up just fine the other day. And I'll carefully look over the valvetrain to make sure the valve is opening/closing like it should.

Now, I don't know if this was the lifter that was clacking in the past but I'm guessing it was and it finally just broke the spring. I still don't even know if a lifter IS the problem

Ever hear of a collapsed lifter "righting" itself temporarily and then dying again 30 min later? Any other suggestions?

Zac

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Re: collapsed lifter?
Posted by: freeulster ()
Date: March 31, 2007 04:51AM

don't see why you couldn't change out the guts of that lifter. I'm sure matt or kevin et. al. will chime in soon.

Kent Donnelly
Living in sunny Brigantine Beach NJ
64 Vert
Philadelphia Corvair Assoc and CORSA
"EM's are faster than LM's because we don't have all those extra lug nuts weighting us down"

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Re: collapsed lifter?
Posted by: MattNall ()
Date: March 31, 2007 06:30AM

Collapsed lifter wouldn't cause "0" sorry...must valve seat! GRR

Hope I'm wrong....

Check valve stem height ...

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Re: collapsed lifter?
Posted by: Brett Wall ()
Date: March 31, 2007 11:48AM

sad smiley I'm sorry, Zac... Matt's right.

____________
00 [__] 00
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Brett Wall
Nashville TN

"Ensure that the path of least resistance is not you..."

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Re: collapsed lifter?
Posted by: richard1 ()
Date: March 31, 2007 12:03PM

I've never had one apart, but frequently find lifters that are noisy and not holding pressure. So far I have been successful at fixing all of them on older engines with a treatment like AutoRx. The noises go away within the first few days, although we leave the treatment in for 1200 miles to get the full efect of cleaning the seals and carbon.
There is one shop that uses it in his engine rebuilds instead of replaceing the lifters.
On newer engines, I fix the lifter noise with thinner oil.

Obviously more things can go wrong than sludge and carbon, but often the cause is simpler than it seems.

Restoration in Bolivia
Richard's Mini Pickup
Richard's Corvair
Richard's Renault Dauphine

Selection of the Right Motor Oil for the Corvair
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How to polish and restore stainless and aluminum trim

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Re: collapsed lifter?
Posted by: ScottS ()
Date: March 31, 2007 12:10PM

which rocker - intake or exhaust ? If the intake stays shut , you will get 0 compression because the cylinder is empty.

Maybe the pushrod is bending , when you readjusted the rocker it took up the slack until it bent some more . I had a pushrod that bent so far it broke.
I have not had any coffee yet so I take no responsability for anything I say.

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Re: collapsed lifter?
Posted by: TheL36Driver ()
Date: March 31, 2007 03:22PM

You can get 0 psi if the intake is staying closed. Besides a bent push rod, dropped seat or collapsed lifter its also possible the cylinder stud is pulling out of the block. On an intake it will cause the same pressure reading.

I've owned three too many Corvairs.

Carl in St. Joseph, Mo.
'62 Monza coupe W/110 hp. Replaced the turd 140.
My other car is a '67 Corvette.
[forums.corvetteforum.com]

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Re: collapsed lifter?
Posted by: Bob Helt ()
Date: March 31, 2007 04:51PM


I vote for the head stud pulling out of the crankcase.

Also internal parts of a lifter are matched to the body, so swapping parts may get you into trouble. That's without even considering that there are so many different lifter designs in use that can't have the internal swapped among them.

I really doubt that the problem is a lifter, but if it is, just install a brand new lifter in its place.

Regards,
Bob Helt

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Re: collapsed lifter?
Posted by: zac ()
Date: March 31, 2007 05:03PM

I guess I should have explained my theory a little better. I realize a collapsed lifter will cause the valve to not open, so you wouldn't see "0" comp. My thought was that the lifter collapsed causing the rocker to be loose. Then I come along and see it loose, so I crank it down until I'm at zero lash- 1/4 turn. Then the lifter starts to pump up again (?), now causing the valve to be held open, thus no pressure. Again I'm not 100% sure it's a lifter right now, not until I dig in to the motor in a little bit here.

When I checked it over the other day: both pushrods were straight and flat (checked on a piece of glass), both rockers and balls showed no signs of fatigue (kept them matched together as well), springs, retainers and guides looked good, didn't check head studs but since the other cylinders are showed great compression I wouldn't suspect that as the problem, and finally when I adjusted the rocker all the symptoms went away (don't remember if it was the intake or exhaust off the top of my head). I wouldn't think a dropped seat would show an improvement by tightening the valve lash.

Today I plan on checking it further and trying to put some air into the cylinder to see if I can determine where the "leak" is coming from. Think leak-down test without the ability to hold pressure. Also want to check valve stem movement & height, plus check pushrods again to make sure I didn't bend one after the last adj. And check comp without the rocker arms to see if the problem is "further down" in the engine.

Right now I'm leaning towards (hoping) either a loose rocker nut or a lifter that's dying a slow death. When I drove it the other day and got it up over 2200-2500rpms or so, it _seemed_ to run MUCH better, like the lifter was pumping up (??), but that could just have been the other cylinders masking the power loss once the rpms, and power, were up a bit. I'll report back any findings for future research for others (people still use the search function before they post,don't they...) My pain is your gain smiling smiley

Zac

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Re: collapsed lifter?
Posted by: MattNall ()
Date: March 31, 2007 05:33PM

Zac, seats fall out.....manytime pop back in..then fall out, etc....

Usually in the end if run long enough..dis-integrate and cause big damage

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Re: collapsed lifter?
Posted by: Lon wall ()
Date: March 31, 2007 07:11PM

Zac - It's a valve seat. If it were something other than a Corvair we might be more inclined to assume other things - first.

Like Matt, I hope I'm wrong, but my experience has taught me that there's about a 95% chance it's a valve seat.

Heads just recently done? Doesn't mean a thing. I know of numerous cases where engines with less than 1000 miles on them will drop a seat - NOW, as with all Corvair seat failures, it can be traced back to something preventable. (I want to stress that so we don't get a raft of people who start wailing "what are we going to dooooo....Corvairs drop valve seats!!!They're no longer reliable")

Good luck - hope we're wrong. Lon

www.corvairunderground.com

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Re: collapsed lifter?
Posted by: zac ()
Date: March 31, 2007 08:27PM

OK, just got back from the garage. I pulled the valvetrain apart and both lifters on #2 look good. Took them apart and springs, etc all in good shape. Bummer. Cam lobes show no signs no damage (used a mirror to look at them through lifter bore). Pushrods still roll straight, valve stem heights and movement all look as intended, rocker nuts still tight. So, valvetrain all functions per spec. Even checked piston movement by inserting a piece of coat hanger through spark plug hole (fine). And when I first went back to check the lifters, the intake lifter felt "spongy" when I pushed on the pushrod, so I thought I had found my problem right there. Also checked the oil for telltale signs of destruction and nothing shows on the dipstick.

But alas, still no comp pressure. And when I put ~125lbs of pressure into the cylinder, I'm not getting any air blowing past ANYTHING. It holds the pressure just fine. None past the rings into the crankcase (checked @ oil fill cap), none past the exhaust valves (ck'ed @ exhaust tube), none past intake valve (ck'ed @ carb), plus you can not hear any air movement at all. So, while I can't ADD any pressure to the cylinder by cranking, I can HOLD pressure once it's in there. Weird. Could the valve seat be moving to prevent building pressure, but once there is pressure coming from the "other side" it's pushing the seat into place and holding pressure??? I sure wasn't expecting that kind of result. There has to be something wrong with my test procedure for holding air- I'm going to try a slightly different method because there _should_ be air movement somewhere. Plus, I can't believe that the seat could move around like that on a cold engine and not be able to hear it, or have it run pretty well (all things considered) once the RPMs are up a bit. More news as it happens.

Zac

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Re: collapsed lifter?
Posted by: Darren ()
Date: March 31, 2007 09:24PM

zac I would try lowering the air pressure. Try 20 psi

Darren
66 Monza SS Convertible
140HP 4 Speed
Colorado Springs, CO
[www.flickr.com]



Edited 1 time(s). Last edit at 03/31/2007 09:24PM by Darren.

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Re: collapsed lifter?
Posted by: Bob Helt ()
Date: March 31, 2007 10:00PM

ZAC,
Are the ends of the rocker studs all even? How about the # of exposed threads above the rocker nuts?
Regards,
Bob Helt

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Re: collapsed lifter?
Posted by: richard1 ()
Date: April 01, 2007 01:10AM

You could also look for something that is on-and-off. My Grand Cherokee used to drive me crazy, ran great then stopped had to tow it, a little later started fine and ran for days, then repeating. Turned out to be a combination of weak valve springs and keepers that did not seat all the time. Changed out the springs and keepers and never again had a problem.

Restoration in Bolivia
Richard's Mini Pickup
Richard's Corvair
Richard's Renault Dauphine

Selection of the Right Motor Oil for the Corvair
Selection of the right transmission oil for the corvair
How to polish and restore stainless and aluminum trim

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Re: collapsed lifter?
Posted by: zac ()
Date: April 01, 2007 06:01PM

Nope, I went back and redid my air pressure procedure and, yes, the problem was me! Once I corrected my testing error, I found out that the air is indeed leaking past the intake valve. So, ding-ding, we have a winna! Intake valve seat. Damn. And this folks, is why I always say to replace valve seats when you have the heads done. You can pay now or you can pay more later. If only I took my own advice! In my defense, the machine shop told me it would be 3-4 weeks to have my seats done (to my specs-NOT GM's wrong specs) and I really couldn't wait that long to get the car back together. So I didn't do the seats, and now I get to do the heads all over again. Hopefully it hasn't chewed up all my nice porting, chamber work, milling, et al. Oh well, I wanted to weld and mill more on the quench pads anyways, and do the exhaust tubes and weld flanges on for a tri-port...

Zac-in the garage, getting ready to swap motors.

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Re: collapsed lifter?
Posted by: Brett Wall ()
Date: April 01, 2007 06:04PM

Glad you didn't just keep driving... as most do. That kept damage to a minimum.

____________
00 [__] 00
-o====o-

Brett Wall
Nashville TN

"Ensure that the path of least resistance is not you..."

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Re: collapsed lifter? Now intake valve seat
Posted by: zac ()
Date: April 01, 2007 11:36PM

Ok, final analysis for anyone keeping track. The intake seat did come loose, but it only moved about an 1/8" or less. Just enough to keep from making compression, and not enough to visually notice while watching the vavletrain. Valve tracked straight and threads showing all were even-give or take a thread or two. The seat was/is still firmly attached to the head, at least at ambient temps, so I dodged a bullet on that one. Going to the machine shop on Mon to see how long for deep seats and such.

So, for anyone that comes across the same symptoms, check REAL carefully the valve stem heights and change the seats no matter how good they _look_.

Zac

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Re: collapsed lifter? Now intake valve seat
Posted by: WalterElias ()
Date: April 02, 2007 12:10AM

Hi Zac,

Sorry to hear about your bad luck with the heads. I myself got sick of taking chances a few years ago with the valve seats. BTDT, FT !! Thing is, if they've never been replaced, they most likely have seen plenty of heat cycles and abuse over the years. If they've been replaced, question is, were they done right? Ended up becoming to much of a chance for me especially when I added up the cost of all the other parts. Also, I depend on my Corvair's to hold up on vacation. I take mine camping and on other much anticipated trips. Trips that I want to enjoy taking the Corvair on but also trips I don't want fouled up by a mere $400 worth of seat work. I can tell you from experience that $400 seems real cheap in hind sight. I myself go ahead and replace the seats on any heads I don't know the history of. Once done by a reputable shop, you shouldn't have to do them again and it gives you peace of mind.

Dan Kling
1961 Greenbrier Deluxe, 110 HP, 4spd, 3.89 stump puller
1963 Spyder Coupe, restored, converted to 4spd Saginaw
1967 UltraVan #299, The migration has begun, we're on the road again......Save the Whales!

Photos of our Greenbrier, UltraVan and work-in-progress @

[www.flickr.com]

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Re: collapsed lifter?
Posted by: ultravan201 ()
Date: April 02, 2007 12:42AM

I once had the same problem on a 65- 110. The problem was the valve seat had came out,then went back in place for a short time,then came out for good. You most likely will need a good valve job and a new valve seat installed. it could be worse it could have injested the seat and done a lot of dammage,or even worse you could be driving a jap car.Good luck and happy corvaring.

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