Question re: lifters - need a quick answer

[Syndrome Zed]

So the thread below I mentioned having to replace the head on my 91 base Metro, G10 engine. Sure enough, the exhaust valve in #3 cylinder had a crescent shaped chunk missing, and #1's not a whole lot better. So off with the old, on with the new....

But here's the thing: I tried to test my lifters since they seemed a bit noisy before (already checked the pistons for cracked skirts, etc.) by pushing down on them with a screwdriver as described elsewhere. The lifters in my old engine were all very difficult to push, but all of them were able to be pushed down about the same amount. The lifters in the "new" head are all much easier to push down on. In fact I can push the center "pin" (or contact point, or whatever it's called) by hand when I have the lifter out and submerged in 10W-30, but I can't do that with my old lifters.

So the question - should I swap my lifters for the "new" ones? How easy should it be to move the contact point on the lifters - are mine worn, or are the potential replacements, or is it just totally irrelevant?

I'm putting the engine back together tomorrow so I need to decide before I reinstall the camshaft. If it matters, I'm going to use my camshaft, it seems to be in better shape.

Oh, and I managed to take pictures this time, so I'll post the "Two Day Head Job" in my other thread when I'm done.

[91Caprice9c1]

You should not be able to depress the lifters with your bare hands. When I reassemble engines (be it a metro, an expedition, cherokee - whatever) I have to drain them with a vice or a hydraulic press before installing them. Lifters are spring loaded, and what you are checking for, is that they "bounce back" after being depressed, if they stay compressed after draining them, and a solid smack on a work bench doesn't bring them back, it's a dead lifter. If they give little or no resistance to being compressed, it's a dead lifter and should be replaced.

-MechanicMatt

[Syndrome Zed]

Great! That's what I guessed too, but I knew I'd better make sure. I have a feeling they were sitting oilless for a while in the junkyard, which couldn't be good for them. Thanks for the quick response, now I can finish installing the camshaft and try cranking the lil' bugger up.

Originally Posted by 91Caprice9c1

You should not be able to depress the lifters with your bare hands. When I reassemble engines (be it a metro, an expedition, cherokee - whatever) I have to drain them with a vice or a hydraulic press before installing them. Lifters are spring loaded, and what you are checking for, is that they "bounce back" after being depressed, if they stay compressed after draining them, and a solid smack on a work bench doesn't bring them back, it's a dead lifter. If they give little or no resistance to being compressed, it's a dead lifter and should be replaced.

-MechanicMatt

[91Caprice9c1]

Goodluck zed!

-MechanicMatt

[Syndrome Zed]

Muchas gracias! I didn't get to finish, had to take someone to work (or rather, have him take me this time ). Got the camshaft in, but still need to finish the timing belt and all the other goodies - cover, crank pulley, etc. Sunday's the big day, thanks for the wish!

[Syndrome Zed]

Well, I've had nothing but bad luck. To make a long story short, I've put the new head on three times now, twice with one head gasket and once with a second one, and every time I get oil in my coolant water and billows of white smoke.

So what can mimic a blown head gasket?

Can a head be warped enough to cause sealing problems, but not so warped that putting a straight edge against the gasket face wouldn't show any bend?

Can a block or head be cracked in a way that there'd be no noticeable cracks or leaks on inspection, but enough of a crack that would allow the oil and water to mix?

What else could cause the oil to get into the coolant? The oil itself looks fine, no water at all, but the water turns milky-white with oil.

I've rebuilt the thing three times now and just ran head gasket "repair" stuff through the system. I use orange RTV on the manifold gaskets but not on the head gasket. There are no visible leaks or anything, just white smoke, carbon fouling on the plugs and in the combustion chambers/exhaust ports, and water that turns greyish-white with oil droplets emulsified into it.

HELP!!! WTF is going on here? I know I may just need to run up to LA and pick up a JDM engine, but I want to make sure I'm not forgetting something stupid along the way or if I've missed something that I can fix. TIA all!

[91Caprice9c1]

Things that can cause these symptoms:

Cracked head; Cracked block; Warped head; Warped block.

I do assume you used a feeler gauge in conjunction with the straight edge. When used properly, you WILL detect any significant warpage. COMBINED warp between the mating surfaces of the head and the block should not exceed 0.003".

Did you check the head gasket mating surface of the block as you did the head? It is very common with these motors for the cylinders to fall beneath the surrounding deck. This will not allow the head gasket to seal. Another thing to look for are any indentations around the cylinder sealing surfaces where the head gasket seals compression gasses between the head and the block. If the head or the block have impressions left in them from the ring in the head gasket, the aluminum has gone soft and has been heat-cycled to the end of it's serviceable life, meaning the head and block are garbage and you must start with a new core.

If there are no impressions, and you are absolutely sure that the head and block are straight using a straight edge and a feeler gauge, then either your block, or your head is cracked. Of the 6 G10's I've rebuilt, I haven't come across any cracks in the head/block. I have had tweaked blocks and tweaked heads, and cores I could not use because the aluminum had gone soft, but no cracks yet. So first be sure that the head and the block are STRAIGHT, and that the mating surfaces on both the head and the block are without impressions from the metal ring in the head gasket which seals compression gasses.

-MechanicMatt

[Syndrome Zed]

Originally Posted by 91Caprice9c1

Things that can cause these symptoms:

Cracked head; Cracked block; Warped head; Warped block.

I do assume you used a feeler gauge in conjunction with the straight edge. When used properly, you WILL detect any significant warpage. COMBINED warp between the mating surfaces of the head and the block should not exceed 0.003".

Did you check the head gasket mating surface of the block as you did the head? It is very common with these motors for the cylinders to fall beneath the surrounding deck. This will not allow the head gasket to seal. Another thing to look for are any indentations around the cylinder sealing surfaces where the head gasket seals compression gasses between the head and the block. If the head or the block have impressions left in them from the ring in the head gasket, the aluminum has gone soft and has been heat-cycled to the end of it's serviceable life, meaning the head and block are garbage and you must start with a new core.

If there are no impressions, and you are absolutely sure that the head and block are straight using a straight edge and a feeler gauge, then either your block, or your head is cracked. Of the 6 G10's I've rebuilt, I haven't come across any cracks in the head/block. I have had tweaked blocks and tweaked heads, and cores I could not use because the aluminum had gone soft, but no cracks yet. So first be sure that the head and the block are STRAIGHT, and that the mating surfaces on both the head and the block are without impressions from the metal ring in the head gasket which seals compression gasses.

-MechanicMatt

I'm thinking it must have been a hairline crack - the feelers only showed .003 warpage, but maybe it was just enough of a "flex" to need a little extra sealing. Crack or warp, the gasket "repair" sealant seems to have done the trick, as far as the coolant/oil mixing. I still may be burning a little oil - slightly carbony smoke comes out of the tailpipe, mostly when the engine's cool - and at idle and low throttle it's still misfiring sometimes. Oh, and my gas mileage is a pathetic 32 highway. But this weekend I'm going to replace the throttle body gasket, check the TPS, replace the PCV valve, and check the oxy sensor for carbon fouling. So if there's a vac leak or the TPS is off thanks to all the monkeying around I've been doing, I'm going to find it and kill it. Oh, and I'm going to check the cat for plugging. I know the EGR system is clear, I did that while I did the head last week. Admittedly, I ported the intake and exhaust to try and boost the performance a bit, and it seems to have helped as I can climb the local hills in overdrive without increasing the throttle very much (I used to have to downshift). But even the extra airflow shouldn't cause me to lose THAT much mpg - I would expect 2-3 mpg, 4 at the outside, but not 8-10. So SOMETHING else is going on.

Once I'm sure everything's copacetic I've got some decent pics to post of my amateur porting and one-hour head teardown. Don't want to post pics of something that's not going to work, you know?

[91Caprice9c1]

Keep up the good work, and keep us posted on your condition. I would be very interested in seeing this port work and some explaining of what you did. Best of luck to ya buddy.

-MechanicMatt

[Syndrome Zed]

Originally Posted by 91Caprice9c1

Keep up the good work, and keep us posted on your condition. I would be very interested in seeing this port work and some explaining of what you did. Best of luck to ya buddy.

-MechanicMatt

Heh, thanks

So I didn't do the oxy sensor or check the cat yet - time is my worst enemy right now. But the good news is, I found the vac leak that was causing the idle and low throttle unsteadiness. I tested several of the sensors - TPS, MAP, a couple others - and they were all fine. I blew out the MAP gas filter, replaced the tubing even though it seemed fine, and I suspect the problem was with that "silencer" unit under the air cleaner. The tubes were on tightly, but the ends were a bit cracked, so I replaced both tubes. The silencer had become a little clogged too, so I sprayed brake cleaner in it, dried it out, then blew air through it. It had a little oily residue upon cleaning - probably from oil that blew into the air cleaner from the valve cover previously. Anyway, one of those tubes was the vac leak, so I didn't even have to yank off the throttle body to fix that gasket.

Oh, and of course the PCV valve was gunked up, so I tossed that one and replaced it. Also replaced the rotor cap and distro cap with ones in better condition, though I don't know if they really needed it.

So the engine was running much better, and it looks like my mpg are back up at least some of the way.

But...there's always a but....

I still have some smoke coming from the tailpipe. A little carbon soot when the engine's cold, but that goes away after warming up. I can't tell anymore if the smoke is oil or water-based, but I see no oil buildup in the coolant, and no leaks of either kind are visible. From what I found after pulling the plugs today (next paragraph), I suspect it's oil.

From what I can tell, there's only one thing left to deal with, and it's a tossup right now between two possibilities: The thing to deal with is the loud clacking sound which no longer goes away after the car's been running and the fact that the #2 cylinder is still getting oil-fouled. I was on the way to work and during a climb, the car started to ping and had a nasty misfire. I pulled it over and adjusted the timing, but it did it again. I pulled it over again and this time yanked the plugs before I re-adjusted the timing (this is "by hand", so I have no idea until I get home what my timing is currently). #1/#3 were both very nice - the carbon that had been on them had been burned off/cleaned off by the Seafoam and driving. #2 though, must have been the problem child making all that racket, because the #2 plug was still gunky with oil fouling. I cleaned it off with my trusty can of brake cleaner, let it dry, wiped the leads a bit, and replaced it. The car was fine the rest of the way up to work - another 60 or so miles.

So, the way I see it, I've got one of two things going on: A bad lifter/valve stem seals on #2, or a broken piston again (last year was #3). I'm not burning a lot of oil, but it's more than it should be using - about a quart, now maybe less than that, every 400 miles or so. I fixed a small leak around the valve cover that was probably contributing. I lean towards piston because of the compression test on the previous head - a 40 psi jump from dry to wet on the #2 cylinder, whose valves were both ok in that head (it was the 1 and 3 exhausts which had burnt) - and because the noise doesn't get quieter after the car's been running. I lean towards the valve stem seals because it's a small amount of oil, and last time I had a broken piston skirt it tore up the oil ring and left me with billowing plumes of smoke all the time. I see most of the smoke right now when I'm first accelerating or if I rev the engine while in neutral, and IIRC those are signs of oil leaking down from around the valves. Can a gamey lifter contribute to wearing a valve stem seal prematurely?

I'm almost hoping it's the piston - I've already got a piston ready to be attached to a connecting rod, the rod bearings and other rings have barely 50K miles on them, and I've reached the point where I can tear down the head in about an hour. On the other hand, I'd probably need a new head gasket and definitely need new head bolts, which I just bought two weeks ago. But if it's the valve stem seals, it's either a LOT more work or a trip to a "real" shop and some . I can get the valve mechanisms apart pretty easily thanks to a bit of poking around at Teamswift's forum - any tips on getting them back together more easily? You know what they say, it's always easier to destroy than to create...

Anyway, things are nearly back to normal, so hopefully towards the end of the week I'll be able to upload and then post the pics.

EDIT: Add two things - as of last night, my gas mileage was back up to around 38 with A/C, much closer to normal. Two - I tried to do a compression test on #2 to see if I could narrow down the choice of ring vs. valve problem. I couldn't thread the damned tube - it looks as though the #2 spark plug socket has been rethreaded. Ever since I retightened that #2 plug, though, the misfiring has stopped. Clearly, all my problems are now related to cylinder #2.

[91Caprice9c1]

Definitely get that compression test goin, and I think it would be worth your while to pull the pan - just to make sure it's not a piston. Doing valve seals on these cars with the head off is very easy so long as you take your time the first time around. The trickiest thing about it is finding a valve spring compressor with the proper adapter. Congrats on solving the other problems. Sooner or later, you metro's gotta get tired of throwing crap at you and stay fixed... right?

-MechanicMatt

[Syndrome Zed]

Originally Posted by 91Caprice9c1

Definitely get that compression test goin, and I think it would be worth your while to pull the pan - just to make sure it's not a piston. Doing valve seals on these cars with the head off is very easy so long as you take your time the first time around. The trickiest thing about it is finding a valve spring compressor with the proper adapter. Congrats on solving the other problems. Sooner or later, you metro's gotta get tired of throwing crap at you and stay fixed... right?

-MechanicMatt

Well, I must have done something wrong in the comp test - left something unplugged, perhaps - because I got zeroes on both cylinders 2 and 3 (didn't bother testing #1, I was going to go and find out what I had left unplugged first). But it wound up not mattering, because I found the problem. Incidentally, I did have to rethread the #2 plug socket - the previous rethread job was not very good and was preventing me from doing the comp test.

You know that sinking feeling you get when you reach into your oil pan and feel shards of your piston? I know it, too well now.

Frankly, I'm amazed this engine continued to run at all - at one time, for about a week, it had a cracked #2 piston skirt/rings, burnt exhaust valves on #1 and #3 cylinders, and a vacuum leak. .

I nicknamed the car Napoleon - because it's kind of small, but it just keeps soldiering on in spite of everything. Anyway, I'd have replaced the engine as a unit if I'd realized it had several different problems instead of what I thought was one problem causing all the symptoms. That's my amateuritude showing through, I guess.

So after verifying that both 1 and 3 are ok still, and only 2 is crapped out, I went and dug up a piston from "my personal parts car" - a '92 Metro LSi at Ecology Auto in Rialto, CA, whose head I already got and whose pistons I just pulled this morning. If someone else hadn't already taken the fuel injector off the throttle body, I could have taken the TB and manifolds and just installed his entire engine (even though I don't know exactly what killed it).

Now all I have to do is get rings, head bolts and a couple gaskets (again!) and borrow a cylinder hone/ring compressor from Autozone. And maybe a ridge reamer, we'll see. At least I've gotten good enough to do the work faster, for what that's worth.

And then when I have again, do a preemptive strike and replace the #1 piston.

BTW, anyone have any idea why these piston skirts seem to crack fairly frequently? Or even why they have the skirts in the first place? I'm tempted to take a piston to a machine shop and have them remove the skirts - get it done evenly and professionally - and see how the piston runs. Maybe you'd get less cracking w/o skirts.

Right now, though, I did manage 42 mpg with the broken piston and the A/C on. Can't wait 'til it works completely!

[Crvett69]

skirt keeps the piston from rocking in the bore, you don't want to remove it. if you look at crack closely it will probably start in the oil ring groove on the piston, have to make sure you clean all the buildup out of the slot before you install new rings or it will do it again. this is why i just install JDM engines with a warrenty. leaving something unplugged will not cause a low compression reading, it may make it run bad but won't affect compression. if you have 2 cyl next to eachother its usually a blown head gasket but it could be 2 burned exhaust valves. when you pull it back apart check the head gasket and see how it looks.

[91Caprice9c1]

+1 Crvett - Yes, skirts are nessecary. Skirts usually break after a prolonged condition known as piston slap which occurs as a result of excessive piston (skirt) to cylinder wall clearance. I think it would be very worth your time to invest in accurately measureing your cylinder bore and comparing to spec. Having snapped two pistons in this block it's safe to say that either you have timing that is too far advanced, an inoperative EGR, carbon build-up worn out cylinders.

Broken pistons also happen via pre-ignition as a result of improper tuning clogged EGR and/or carbon build-up however, in these instances it is more common for the head of the piston to get broken through and not the skirts, though it certainly would be possible to snap the skirt from the massive pressure spikes that occur with pre-ignition seeings how it is the weak link in these pistons. Having mentioned the burned valves, it is very worth your while to investigate the flowability (for lack of a better word) of your EGR system as well as measure the cylinder bore, to determine which condition keeps breaking the pistons.

Something else to think about - If your vacuum leak was large enough to exceed the ECM's ability to compensate for, it could have been causing a lean condition mean enough to cause pre-ignition.

-MechanicMatt

[Syndrome Zed]

Originally Posted by 91Caprice9c1

+1 Crvett - Yes, skirts are nessecary. Skirts usually break after a prolonged condition known as piston slap which occurs as a result of excessive piston (skirt) to cylinder wall clearance. I think it would be very worth your time to invest in accurately measureing your cylinder bore and comparing to spec. Having snapped two pistons in this block it's safe to say that either you have timing that is too far advanced, an inoperative EGR, carbon build-up worn out cylinders.

Broken pistons also happen via pre-ignition as a result of improper tuning clogged EGR and/or carbon build-up however, in these instances it is more common for the head of the piston to get broken through and not the skirts, though it certainly would be possible to snap the skirt from the massive pressure spikes that occur with pre-ignition seeings how it is the weak link in these pistons. Having mentioned the burned valves, it is very worth your while to investigate the flowability (for lack of a better word) of your EGR system as well as measure the cylinder bore, to determine which condition keeps breaking the pistons.

Something else to think about - If your vacuum leak was large enough to exceed the ECM's ability to compensate for, it could have been causing a lean condition mean enough to cause pre-ignition.

-MechanicMatt

Hmmm.....definitely worth considering. Thanks both of you for explaining these piston skirts. I yanked the piston over the weekend - thank you Autozone for loaning all those tools - and boy, was it fragged. I'll be posting pics of this whole experience soon, maybe by the weekend, and I'll include the broken piston. Anyway, vette was right, the crack looks like it started at or in that open slot within the piston oil ring. Hard to tell though, everything from the oil ring down on that side was just gone.

I'm wondering if that vac leak caused ALL the problems? OK, granted, I'm a biologist by trade and my instinct is to try and find a single "disorder" that caused all the symptoms. But if the vac leak did cause the engine to run lean, that could explain both the cracked piston (although the head of the piston was ok above the oil ring) and the burnt exhaust valves.

So yesterday I tried to drive it and the head gasket had leaked badly. I limped home from going around the block (yes, that badly) and disassembled everything. Cleaned out the white oil (lots of emulsified coolant in there) with new oil, cranked the engine a couple times, then changed the oil again (and oil filter, natch). My compression tester is, in lay terms, wonky. I got a nice reading of 197 on cylinder 3, but then got nothing but zeroes. I tried to do the wet test on 3 and got a zero again. Pulled the gauge itself, left the tube in place, and had my stepson crank the engine. Definitely had some compression. I have no idea what's up with that gauge, it's rather annoying. Maybe the bleed valve sticks or something. Anyway, after I reassembled everything it was overheating still, but there were no leaks this time and the exhaust didn't have any unusual smoke output (oil or coolant). It was only overheating after being driven too, and the temp would rise and fall very quickly. Being paranoid, I ran some of that gasket seal through the engine once again. Then, realizing I was being paranoid, I pulled the thermostat. Engine stayed cool after that pretty much.

Only here's the (hopefully) last issue. I drove it to work today, using water wetter and plain water for coolant (just for this trip, I'm going to put in regular antifreeze/water later today). The car heated up while I drove, finally getting close enough to overheating after driving for close to an hour between 55 and 75 mph (with some slower speeds thrown in earlier on as I tried to seat the new rings). After letting the car cool down, I finished my trip. It stayed very warm but didn't reach overheat (about 2/3rds of the way up the temp range, 3/4ths of the way if I ran the A/C or drove faster). At the end of the trip, I noticed at high revs (at the top of the revs just before upshifting mostly) it started to make a loud clicking/clattering-type noise. Not as bad as the broken piston, more like a noisy lifter or something. And after hard braking when the engine ran down the oil pressure would drop low enough to cause the light to flicker once or twice. It didn't seem low when I checked the dipstick. No sign of bad oil or contaminants either. The lifters had pools of oil next to them as usual, nothing appeared to have gotten dry. Still no sign of burning the oil either, or of leaks, as far as I've seen.

So what can do this? Am I going to have to replace the oil pump now too? Or can a stuck ring do this? How good is Seafoam, or is there another recommendation, for unsticking rings - or do I just have to yet again pull the head off this sumbitch and re-do the rings?

Oh, almost forgot - the ring end gap with the pistons in is right on target (.013 IIRC). Would it be bigger if the cylinder bore is enlarged enough to cause piston slap? Would getting slightly oversize rings help at all (not even sure they'd fit, though, at this point)?