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Pushrod Damage, please take a look

16K views 22 replies 8 participants last post by  Overdriv 
#1 · (Edited)
Hey gang, a friend of mine has this engine in his musicle car and has been having trouble with the valve train beginning to rattle after very few miles. It is a show car and spends 99% of it's time just driving in and out of the trailer. The damage you are about to see has happened in less than 100 miles and dyno time by vender.

Please take a look at the attached pictures and tell me what you think is happening. I don't want to give any parts names or venders names so as not to spoil the thought.

The engine's exhaust push rods are longer than the intake. Only the exhaust pushrods show damage to the bottom. Only one intake push rod shows damage to the top. Check out the wear patterns.

ETA, pics and to note that the lifter on the right is an intake, the lifter on the left is an exhaust.

This engine has 10.5 compression, aluminum heads. Hydraulic lifters. 1.60/1.55 rocker ratios.
What is going on in this valve train?




 

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#7 ·
I guess I should add the reason for looking into the engine, is it started making top end clicking noises and it only got worse and finally it started rattling. The push rod that shows distress on the top was making a lot of noise. The depth of that push rod tip is .95" deeper than a push rod with no damage. If you look closely you can see where it has been egged out a bit.
 
#10 ·
My take is either pushrods radius doesn't match the radius of the lifter pocket, which could be lifter or pushrod at fault; or cheap pushrods; or pushrods with a bad heat treat.

How well does a good pushrod end fit the lifter cup?? If good on that, then the pushrods are the problem, and I'm leaning to poor quality or the heat treat(too soft) more than the lifter myself from those pic's,... unless the lifter cup is deformed in a way that doesn't show well in the pic's..
 
#13 ·
ericnova72 said:
Whoops, I just relooked at the pic's, the lifter has no oil feed hole in the cup to the pushrod, they are incorrect for a pushrod oiled valvetrain. There's your problem 100% :pain:

Mopar?? Lifters for a shaft fed system used with a stud rocker set up??
Yes it is a shaft oiled system and it is getting adequate top end oiling. Good call EricNova72.

Even the good lifter/pushrods do not fit the cup well in my opinion. If you look closely, you can see where the pushrod is seated about a 1/16" down in the cup. Neither intake or exhaust push rods fit down in the cup further. I thought the pushrod should bottom in the lifter cup??

Suppose to be a big name brand quality lifter and pushrod.

Could detonation cause this? It seems odd to me only the exhaust pushrods show so much damage on the bottoms. The one pushrod with damage to the top cup, it is an intake. This is not the first time this engine has had pushrod lifter problems.

I appreciate the comments guys. I need to figure a permanent cure for this thing as he is trying to sell the car.
 
#15 ·
Overdriv said:
I agree. Shouldn't the push rod fit all the way into the cup?
It should fit fully into the cup.

Problem is, the damage would be on the OD of the ball if the pushrod didn't fit down into the cup, Damage looks more like a 5/16" pushrod run in a lifter with a 3/8 cup, in order to get mangled on the point of the ball.... Or is the damage around the oil hole in the p-rod coming from everything getting loose and the pushrod getting out of the cup and getting beat up?? so hard to tell from the pics.

Are these 1-piece pushrods?? I ask because it almost looks like they have insert tips?? or is that the "rim contact" wear pattern and degradation that almost makes it look like an insert tip, and the others(ok looking ones, as far as the oil hole) haven't worn that far yet and gotten so loose that they get beat to hell?? Maybe we are seeing both initial problem and consequential problems both...the mashed balls around the oi hole are a result of the rim contact wear and things getting loose??

Are the exhaust pushrods the shorter set?? If so they would get beat up sooner, as soon as the wear got to be bigger than lifter preload, as they would start out with less preload due to the shaft set up if it isn't an individually adjustable rocker set.

Another tangent, probably going nowhere...valvetrain been checked for coil bind, both inner and out spring if multiple coils?? retainer to top of guide clearance check??

As a check, blue up(Dykem) or black marker a good pushrod tip, and using valve lapping compound to get a pattern, spin a pushod in a lifter cup with a drill, to see the actual contact pattern easily...might reveal a lot.

Just throwing things out there as they pop to mind now...
 
#16 ·
Problem is, the damage would be on the OD of the ball if the pushrod didn't fit down into the cup, Damage looks more like a 5/16" pushrod run in a lifter with a 3/8 cup, in order to get mangled on the point of the ball.... Or is the damage around the oil hole in the p-rod coming from everything getting loose and the pushrod getting out of the cup and getting beat up?? so hard to tell from the pics.

I think because the pushrod not going into the cup fully, it comes out of the cup a bit and then bangs down on the edge of the cup.

Are these 1-piece pushrods?? I ask because it almost looks like they have insert tips?? or is that the "rim contact" wear pattern and degradation that almost makes it look like an insert tip, and the others(ok looking ones, as far as the oil hole) haven't worn that far yet and gotten so loose that they get beat to hell?? Maybe we are seeing both initial problem and consequential problems both...the mashed balls around the oi hole are a result of the rim contact wear and things getting loose??

The pushrods are two piece. But the insert is the cup at the pushrod/adjuster interface. The lifter end of the pushrod looks like a 3/8" straight pushrod for a BBC, ETC.

Are the exhaust pushrods the shorter set?? If so they would get beat up sooner, as soon as the wear got to be bigger than lifter preload, as they would start out with less preload due to the shaft set up if it isn't an individually adjustable rocker set.

The longer pushrods are the exhaust.

BTW, we are talking about a 477CID Hemi.


Another tangent, probably going nowhere...valvetrain been checked for coil bind, both inner and out spring if multiple coils?? retainer to top of guide clearance check??

No. We have not checked anything as this engine came from a big name builder of Hemis. It's been apart with valve train problems four times now and back to them three times and on the dyno each time. But we're thinking it's about time we took it apart and build it right.

As a check, blue up(Dykem) or black marker a good pushrod tip, and using valve lapping compound to get a pattern, spin a pushod in a lifter cup with a drill, to see the actual contact pattern easily...might reveal a lot.

If you look close at the intake lifter you can see a thin ring wear pattern about 1/16" down from the top of the lifter cup. Then look at the intake pushrods and you can see that the very bottom most 1/3 of the taper has not been touching anything as they appear to me to be actually riding on the edge of the cup rather than in the cup. Agreed hard to see in the pictures, best I could do.

Just throwing things out there as they pop to mind now...

And I do appreciate every comment. I think we ae thinking on the same track here.
 
#17 ·
More thoughts...

Ok, Hemi...HEAVY valvetrain, maybe valvespring is also too light(becuase of Hydro lifter needs spec) and things are going into valve float and getting beat up?? I kind of don't think so, the lifter to pushrod fit seems like the real problem.

I thought the 2 pushrods looked flattened, now I know it is a cup(Whoops!), pics had me fooled in 2D. Dang flat images :boxing: !! Knowing this now, I'd say cup damage is a result of other end problems.

I see now the ball tip damage knowing it is a one piece formed end on that end... thats a big amount of wear, the pushrod is being "swedged" into the cup on every rotation of the cam, clearly a fit problem there - is it a 3/8" pushrod trying to fit into a 5/16" lifter cup?? Sure is starting to look that way, do you have a 5/16" tip pushrod(don't matter what it is out of) to check this out against the lifter cup??

spitballing again - could be lifter was assembled with a small block cup?? or a small block lifter?? (I can't remember small block pushrod size, seems like it was 5/16", but I know all Chrysler lifters are the same OD - .904", so a mix-up might be possible).

Longer pushrod is exhaust, blows my preload amount theory(I was thinking Wedge head single shaft for all rockers). Knowing now it is hemi...that long exhaust rocker is higher ratio than intake. correct?? (I don't have a ton of specific Hemi knowledge, maybe I'm wrong here). If so, the higher ratio magnifies force on the pushrod, so they see wear sooner??

I know I would be extremely BENT if it had been back to a "noted Race shop, with Hemi experience" THREE times for a valvetrain issue. With hydro lifters, it isn't like this is a valvetrain-straining 9500rpm Super Stock or Pro Stock engine, there shouldn't even be a problem. I would be all over them this time, like the Hammer of God, let them know I am ready to nuke them on every hot rod and race forum out there if they refuse to get it right and stand behind there work at no cost to the owner. Take tons of pics, of everything you check, measure, and verify fit of. Video if you can do it.
 
#19 ·
ericnova72 said:
More thoughts...

Ok, Hemi...HEAVY valvetrain, maybe valvespring is also too light(becuase of Hydro lifter needs spec) and things are going into valve float and getting beat up?? I kind of don't think so, the lifter to pushrod fit seems like the real problem.

I thought the 2 pushrods looked flattened, now I know it is a cup(Whoops!), pics had me fooled in 2D. Dang flat images :boxing: !! Knowing this now, I'd say cup damage is a result of other end problems.

I see now the ball tip damage knowing it is a one piece formed end on that end... thats a big amount of wear, the pushrod is being "swedged" into the cup on every rotation of the cam, clearly a fit problem there - is it a 3/8" pushrod trying to fit into a 5/16" lifter cup?? Sure is starting to look that way, do you have a 5/16" tip pushrod(don't matter what it is out of) to check this out against the lifter cup??

spitballing again - could be lifter was assembled with a small block cup?? or a small block lifter?? (I can't remember small block pushrod size, seems like it was 5/16", but I know all Chrysler lifters are the same OD - .904", so a mix-up might be possible).

Longer pushrod is exhaust, blows my preload amount theory(I was thinking Wedge head single shaft for all rockers). Knowing now it is hemi...that long exhaust rocker is higher ratio than intake. correct?? (I don't have a ton of specific Hemi knowledge, maybe I'm wrong here). If so, the higher ratio magnifies force on the pushrod, so they see wear sooner??

I know I would be extremely BENT if it had been back to a "noted Race shop, with Hemi experience" THREE times for a valvetrain issue. With hydro lifters, it isn't like this is a valvetrain-straining 9500rpm Super Stock or Pro Stock engine, there shouldn't even be a problem. I would be all over them this time, like the Hammer of God, let them know I am ready to nuke them on every hot rod and race forum out there if they refuse to get it right and stand behind there work at no cost to the owner. Take tons of pics, of everything you check, measure, and verify fit of. Video if you can do it.
That is what I think also, a bad mismatch of lifter/push rods. It is unbelieveable they could screw this up so many times.

Ericnova, as you suspected, the lifter cup seats a SBC 5/16" push rod a lot better, but not as well as a SBC lifter does.

The angle at which the exhaust push rod runs is quite a bit more than the intake. That, I believe is why the exhaust push rods exhibit more damage. They are bouncing around on the edge of the cup a lot more.

Vendor says 7000RPM redline. Owner has a 6500RPM chip in it.

When this is all resolved I will post the company involved. I just don't want to jeopardize any possible outcome in favor of the owner.
 
#20 ·
engineczar said:
Looks like the adjusting screw on the rocker arm is not extending below the rocker arm far enough and the cup end of the pushrod may be hitting the bottom of the rocker arm. On Mopars you generally want 2-3 threads showing below the bottom of the rocker.

Are the rocker shafts shimmed?
Engineczar, the rocker arms and adjusting screws all seem to have a good relationship to the push rods. The one intake push rod that has the top cup mashed down is the only one like that. The adjusting screw drove into the cup so far that the top edge of the cup was hitting the bottom of the adjusting screw threaded portion, of course that is what egged the cup.

It is my opinion that the incomplete seating of the push rod into the lifter cup allowed the push rods to bounce around causing all the damage.

Again, thanks for all your comments guys!
 
#21 ·
This is late model hemi (426 based). With high lift cams it's possible there is some interference along side the pushrods in the block and heads. We used to have to clearance grind and ream for this in the old days when we used stock blocks and heads in the top fuel motors. There are different styles pushrods, lifters and rocker adjusters for these. You usually get a complete cam kit unless you know what you are doing with the race stuff. The race cars today still eat up pushrods regularly. I've seen them blue-black after only a half pass.

You also should look at the tops of the valve guides. They may not have been cut down and the retainers bottomed out on them.

Also if the block or rocker shafts have oil restrictors you simply may not have had enough oil up there. It can take a while to get the shafts full of oil so we used to oil them up pretty well before starting the race motors.

There is more to a late hemi than just slapping a bunch of parts together. They are not rocket science but there are areas you need to be aware of. They are not real common today so a lot of hotrod shops don't have a lot of experience with them.
 
#22 ·
Also if the block or rocker shafts have oil restrictors you simply may not have had enough oil up there. It can take a while to get the shafts full of oil so we used to oil them up pretty well before starting the race motors.

[/QUOTE]


I agree with this statement 100% all of the HEMI stuff I have messed with gets the valve covers pulled before starting one cold for oiling the rockers. You can't run one long without burning up the top end.

It's kind of the nature of the beast with the mess of a valvetrain they have.

If this car only runs a few min each time it's in and out of the trailer I would bet it just starts oiling before it gets shut down.
 
#23 ·
Nothing I've seem indicates rocker arm interference with the spring retainers or stack bind at full lift.

The rocker shafts and rocker arms are oiling fine, nothing blued or burnt up.

This is a street engine in a 1967 GTX. Mostly show car, 1% on the street only on perfect days.
 
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