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Bad Lifter?

livid4dirt

livid4dirt

1/2 ton status
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Hi guys, my 84 Jimmy developed a sudden dead cylinder #7 it's a 350. Sportsman 2 heads, hardened pushrods,guide plates, aluminum roller tip rockers. Running perfect up to this time:
1. All ignition components check out fine.
2. Timing is spot on.
3. Good compression in all holes.
4. Took rocker cover off, all valvetrain oiling well and moving.
5. Drained oil, filtered it through a clean cloth no metal. No metal on magnetic pan bolt.
6. Cut oil filter in half.......no metal.
7. So i would say cam is fine?
8. Screw in studs and they are were the should be.
9. Springs and retainers all check out good.
It's hard to tell just how far all rockers are moving in relation to one another while it's running.
Could a lifter go bad and still have good oiling through the pushrod?
The header tube on #7 is luke warm to the touch, so we are not getting enough fuel through the intake valve.
Any ideas on getting an accurate measurement on the rocker arm movement?
Or any other thoughts/input?
Thanks...Roger
 
no fire on #7 :dunno:
put the timing light on the #7 wire and see if its gettin juice.
or take the plug out and hold it against metal.
im a n00b so what do i know...
 
I wana say you have a weak valve spring and if its not popping up through the carb id bet u exhaust valve spring is weak. check the height then take it and have a machine shop check its pressure at height. or weak spark on one cyl, its possible :crazy: im assuming you allready tried new plug and its not fouled or cracked.
 
livid4dirt said:
Hi guys, my 84 Jimmy developed a sudden dead cylinder #7 it's a 350. Sportsman 2 heads, hardened pushrods,guide plates, aluminum roller tip rockers. Running perfect up to this time:
1. All ignition components check out fine.
2. Timing is spot on.
3. Good compression in all holes.
4. Took rocker cover off, all valvetrain oiling well and moving.
5. Drained oil, filtered it through a clean cloth no metal. No metal on magnetic pan bolt.
6. Cut oil filter in half.......no metal.
7. So i would say cam is fine?
8. Screw in studs and they are were the should be.
9. Springs and retainers all check out good.
It's hard to tell just how far all rockers are moving in relation to one another while it's running.
Could a lifter go bad and still have good oiling through the pushrod?
The header tube on #7 is luke warm to the touch, so we are not getting enough fuel through the intake valve.
Any ideas on getting an accurate measurement on the rocker arm movement?
Or any other thoughts/input?
Thanks...Roger
Click to expand...

These two items don't add up. :deal:
 
Plugs are good, ignition is fine (had the beejesus shocked out of me) so we got spark. The weak valve spring theory, wouldn't that cause the valve not to seat all the way? I have good comp. Just not enough fuel entering comb. chamber, so something is not allowing the valve to open enough. That is why i was leaning towards bad lifter.

Thanx for the input........Roger
 
Thanx for the reply 4x4high, i was hoping you would chime in. Yes there is compression thats what has me messed up. Could the lifter be weak?
 
If you have compression but you mean that the cylinder is weak in power then you need to be checking plug and wire for that cylinder. Remember that electricity will take the path of least resistance. A bad plug boot could be allowing spark to arc through the boot and ground out on the head rather than across the spark plug gap. Also just because the wires are new doesn't mean there isn't a bad wire. Check the ohms resistance from one end to the other and see if it is within spec for the length of wire. I suggest moving a couple plugs and wires around to see if the problem moves to another cylinder (the one in which you switched the plug and wire with).
 
pull the valve cover on the # 7 side.....fire the engine....take a BIG screwdriver and push down against the top of the rocker against the cam side of the #7 cylinder...

You should get a feel for how much push you get out of the cam/lifter...
Move to the next cylinder and repeat...you should feel the same amount of lift and pressure...

if you don't....

if it a collapsed lifter, you should be able to feel a difference in the lift ...
if it's a bad cam lobe....the lift will not be as high and there may be some play in the rocker ( chatter )

also look to see that the valve stems are all straight...I once had a valve guide fail and the valve would rock front to back....( once I pulled the head and could actually see it.)

I'm with 4X4HIGH and would work on eliminating all the electrical/fuel gremlins first..Is this carbbed or injected?
 
I'm with the spark bunch.
The fact that you got shocked, just means that the spark is escaping the wire, not that it is getting where it should be going, unless you were touching the electrode.

Sometimes the old things still work.
Do you hear blow-back or popping through the intake? If not, then most likely the intake valve is not failing to close.

Place your hand gently over the end of the exhaust pipe while it is running, or, if its too hot, use a piece of paper.
Does it suck back every so often, if not, then the exhaust valve is closing all the way.
If it runs quietly, with no clatter, then its unlikely to be a collapsed lifter.

I hope you log in tonight, because you need to do this next test at night.

Crank up the truck with the hood open, turn out all the lights. Look for sparks.
Especially around the bad cylinder.
If you don't see any, grab a spray bottle of water. Old Windex bottles do great.
Give all the wires a good spritzing. See any sparks now?
Did the skip get worse? Time for new wires.

Your good compression pretty much eliminates a bad spring, and most of the time a bad lifter or cam lobe will cause some clatter.

J.
 
Carbed, truck avenger. I'm pretty confident that i have the electrical gremlins taken care of. I will try your screw driver method tomorrow and see if i can tell a difference in movement.
Thanx guys
 
Fordum, there is clatter when running. Won't be able to do the night time fire up tonight, but i will keep that in mind.
Thanx
 
You can pull all the plugs to make the engine easy to turn...have a buddy roll the engine over with a breaker bar and watch the lift on the # 7 cylinder closely....heck measure it with a Popsicle stick if you have to....what you are looking for is the same amount of lift from one cylinder to the next... on both the intake and exhaust...

if it's not popping back thru the carb or the exhaust...I wouldn't suspect valves....as confirmed with the compression test...

also did you pull all the plugs when you did the comp test and block the carb wide open ? if not,,, re-do the test.

also,,pull the dist cap and make sure there are no carbon tracks....
 
Thanx Wasted, I will redo the comp. test today just to make sure. Carb was wide open last time i did the test. Yeah i'll figure out some kind of a measuring device to determine movement.
Hey i have never seen the end results of a wiped cam lobe right after it happened, there would be obvious metal in filter, and oil correct? I've seen the damage done to old cam and lifters but that was after the po tried to cover things up with an oil and filter change, only leaving the rounded cam lobes and fubard lifters after i yanked the cam out.
 
No carbon tracks anywhere, in fact i had a new cap and rotor on hand and tried that even. So i feel good about the ignition.
 
livid4dirt said:
Thanx Wasted, I will redo the comp. test today just to make sure. Carb was wide open last time i did the test. Yeah i'll figure out some kind of a measuring device to determine movement.
Hey i have never seen the end results of a wiped cam lobe right after it happened, there would be obvious metal in filter, and oil correct? I've seen the damage done to old cam and lifters but that was after the po tried to cover things up with an oil and filter change, only leaving the rounded cam lobes and fubard lifters after i yanked the cam out.
Click to expand...

I lost a couple lobes last year, there was what looked like a graphite material in the oil, and it was built up in spots in the lifter valley. I did not cut the filter open, but I'm sure it would have been obvious.
 
Yeah thanx i hear ya, there was no metal anywhere. No grit just plain old 2,500 mile oil. I'll get it figured out, this isnt no dd just my wheelin rig anyway since i just picked up a clean 83 k-5 last month. So i'm not in a fix to get her going, i'll just keep plugging away. I'll will measure the rocker arm movement today and that should let me know for sure what direction i'm headed.
Again Thanx......Roger
 
A rare but possible ignition failure in one cylinder can be caused by a defective pick up coil or reluctor,I found a reluctor with a missing "tooth" and it evidently had hit and chipped off the die cast point on the pick up coil,and the cylinder it triggered wasn't firing properly..

A bad cam lobe might still allow it to have good compression,but I'd think you'd notice it popping back at high rpm's ..any other valve or cylinder woes should show up with lower compression than the other jugs..
 
Yeah Diesel been down the dizzy route and the pick up coil thought. I have one brand new dizzy plus a donor from pull and save. Chances of both of them being defective seem pretty slim. I tried both of them and ended up with the same symptoms. The more i study and cipher it looks like new Cam & Lifters to me.
Thanx......Roger
 
OK, if its clattering, that points more to valve train.

With no metal in the oil, unless it all happened just before your last change, and it got flushed out without your noticing it, I would tentatively absolve the cam lobe right now.

One quick and easy thing, look close at the rollers on the tips of that cylinder's lifters.
Depending on the model, I have seen the bearings inside the roller, if it has any, fail and let the roller shift upward.
Same on the shaft bearings if it has any.
A close examination while stopped will show that up. Its obvious when you look.
It has been so long since I had to do any of this kind of work, I don't even know what is out there anymore.
I know that there used to be roller rockers that had roller bearings inside the rollers and inside where they rode on the rocker tube.
Don't know if they make them anymore or not.

If it turns out to be a lifter, I can tell you what I did once and got away with it.
A guys stock engine had a lifter collapse with about 50K on the clock.
We were able to get it out without pulling the heads, but the insides were toast.
A new lifter was not a problem, but we were worried about wear patterns.
The old lifter and cam lobe had seated to each other, and putting a new lifter on the old lobe would seem to invite trouble.
I was able to disassemble the two lifters and put the new guts in the old housing.
I know it gave no problems for at least a year and a half until I graduated and moved away.

J.
 
Got my measurements done today on the valve movement. I took the demesions off the top of valve spring retainer @ max. valve lift to a common point on head and #7 intake does not open enough. Demension was about 3/8" difference, so it's pull the intake, take a look see and order some parts........might luck out and just be the lifter afterall, if not a new cam & lifters will be in the works.
Thanx for the input guys........Roger
 
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