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Old 04-16-2010, 04:39 PM
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lifter or lobe?

Hi again, i just adjusted the valves the other day and my car started running pretty good again. Now one of the valves (#8 exhaust) started ticking again. I though maybe the adjusting nut backed off a bit, so checked that and all was tight. I ran the engine with the covers off and noticed #8 exhaust is def ticking again and it dosent go up as far as any of the other valves. Its not a major difference, just a slight bit, but its not going up as far as the intake valve.

I think maybe its a stuck lifter or a came lobe is going south because of the flutter in the vacuum gauge. Also when when the car is off and i get #8 to tdc, the exhaust valve sits lower than the intake valve. Its about a centimeter lower. While at WOT the car will stumble. When cruising the car will jerk under 2k rpms. But if im in 4th gear while doing maybe 40 and floor it, the car will accerlerate pretty smoothly until the rpms rise, then it will stumble and miss.

Sorry for all the threads lately, but you guys are by far the most helpful compared to thirdgen.org.

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Old 04-16-2010, 04:57 PM
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Quote:
Originally Posted by stroker444
Hi again, i just adjusted the valves the other day and my car started running pretty good again. Now one of the valves (#8 exhaust) started ticking again. I though maybe the adjusting nut backed off a bit, so checked that and all was tight. I ran the engine with the covers off and noticed #8 exhaust is def ticking again and it dosent go up as far as any of the other valves. Its not a major difference, just a slight bit, but its not going up as far as the intake valve.

I think maybe its a stuck lifter or a came lobe is going south because of the flutter in the vacuum gauge. Also when when the car is off and i get #8 to tdc, the exhaust valve sits lower than the intake valve. Its about a centimeter lower. While at WOT the car will stumble. When cruising the car will jerk under 2k rpms. But if im in 4th gear while doing maybe 40 and floor it, the car will accerlerate pretty smoothly until the rpms rise, then it will stumble and miss.

Sorry for all the threads lately, but you guys are by far the most helpful compared to thirdgen.org.
There are a few things that can cause this.
1. The lobe is getting wiped out
2. The lifter is leaking down
3. The rocker stud is coming out or nut is loosening
4. The lifter is sticking

But, you already know these can be the problems. I would remove the intake and the #8 lifter and look at the bottom of it. If it's rough or concave, you have a lobe & lifter problem. Check to make sure the lifters will rotate in the bores, they have to rotate in the bores or you'll wipe them out. While you're at it, take a look at the lifter lobe.
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Old 04-16-2010, 06:47 PM
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Yeah it could be one of those things^^^. Hopefully it is because those are easy to correct.

At one time, I had a #7 exhaust valve that needed constant adjusting. Come to find out the pushrod was slightly out of alignment and would make the rocker arm "swipe" across the valve-tip. Over time, the pushrod started to bend and the rocker arm (stamped steel) would cut into the rocker stud. I checked all the way across the head and none of the other pushrods/rockers had this problem, so I figured maybe the lifter-bore, or the pushrod guide-hole (in the head) wasn't centered when machined at the factory. All I could do was change the pushrod and rocker arm. I didn't keep that truck long enough to see what would happen over time. But if it was the lifter bore being out of alignment, that's an engine-block defect that can't be corrected. If it was the pushrod guide-hole drilled out of position, a head swap (or some careful grinding and adding a guide-plate) would have done the trick.

Hopefully yours has an easy solution.

P.S. Just thought of something. Depending on the year of the head, could it be the hardened valve-seat might be coming loose, making the valve "hang" open (since the valve doesn't come-up as high as the rest)? Just a thought...
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Old 04-16-2010, 08:19 PM
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Hey im back. I removed both #8 lifters. I noticed on the intake lifter, the thing in the middle is as far to the top as it will go. The exhaust lifter, the thing in the middle is only 3/4 of the way up. What else should i check for?
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Old 04-16-2010, 08:56 PM
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Quote:
Originally Posted by stroker444
Hey im back. I removed both #8 lifters. I noticed on the intake lifter, the thing in the middle is as far to the top as it will go. The exhaust lifter, the thing in the middle is only 3/4 of the way up. What else should i check for?
You can try jazzing around w/penetrating oil and a p-rod to see if you can free the lifter up, but it may just stick all over again unless you take it apart and clean it.

You can remove the lifter and clean it out and free it back up. Replacing a lifter on a broken in cam is an invitation to wiping out a lobe. Even the battering the lobe and lifter will take while having the lifter plunger (aka piston) stuck in its bore like it is, can damage the cam and lifter.

If, when you get it out, it looks to be undamaged, you can disassemble the lifter by popping the circlip out of it's groove and tapping the lifter upside down on a cloth covered block of wood to dislodge it. If that doesn't work, you can put the lifter into a pan of water and heat it over the stove. The heat will expand the air/oil trapped under the plunger and will pop the plunger out. I've had to actually heat the lifter w/the circlip and lifter seat removed w/a flame to get it to pop out. You do not need to heat it to anywhere near red hot- it'll come out before then- but it can shoot out w/a LOT of force, so you have to wrap a rag over the open end, or "aim" it in a safe direction!

There will be a top p-rod seat, a small disc, then the plunger, the plunger will have a cup presses onto its bottom- remove this and inside is a small spring and check ball.

Do it over a large towel so as to not lose anything, remove the cup carefully w/a pick, and clean everything, checking for burrs, spots that look to be rubbing, etc.

Then reassemble the lifter as it came apart lube it w/motor oil, lube the bottom of the lifter w/moly cam lube and the lifter outer body w/motor oil and reassemble the engine.
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Old 04-16-2010, 11:29 PM
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How much damage could be done? its a hyrdraulic roller lifter
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