How do hydraulic flat tappet lifters fail?

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Righty Tighty

Righty Tighty

Blame it on the dog
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Help me understand this. I had a lifter fail about 600 miles after break in, and consequently flattened a cam lobe. I thought I followed all the proper break in procedures - soaked the lifters overnight in oil, lots of assembly lube, machine shop confirmed all my clearances to avoid coil bind, etc., started up and took the RPM up to 3000 for 20 minutes, proper break in oil, and performed a prompt oil change.

Here's the deal, though. The car ran great up until I did some minor servicing last week. I had the lower radiator hose off to address a minor leak and fitment adjustment, and when I topped off the coolant, added too much concentrate and threw off the ratio of antifreeze to water. After that the engine began running just a little warm - 210-230F after 25 minutes on the interstate. It was suggested that I had air in the system, so the plan was to burp it out. The next morning, I tried burping the air out with no recognizable success, but then I heard a ticking coming from the #1 cylinder area. I also pulled out a piece of RTV from the rad filler neck that had dislodged from the intake.

I drove it home from work, and the ticking remained, however the engine began missing a cylinder. By the time I made it home, the engine was running rough. I popped off the valve cover and found a limp rocker at #1 intake. Removed the intake, and the corresponding lobe on the cam was garbage.

Here's my question: I know it impossible for any of you to know for sure what exactly went wrong simply by reading this, but are there any clues here as to why the lifter (and ultimately cam) failed? Thanks for reading.
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It's hard to tell, but it looks like several lobes are going away. The one directly behind the flat lobe in your first picture looks like it is being flattened to me, plus the chunk missing out of the lifter is something I've never seen before. Normally they can fail due to debris entering them, improper break in/oil used, or due to internal failure such as a plunger spring breaking. I am interested to see how the rest of the lifters and camshaft looks when you pull it out.
 
I'll certainly be posting pictures as it comes apart. Obviously my heart sank when I saw the flattened lobe, but I got a bonus scare when I saw the chunk missing. Fingers crossed the chunk made it to the bottom of the oil pan without getting jammed in a bearing or sucked into the oil pump.
 
I don't think one had anything to do with the other. Often times the lifters don't spin in their bores. If they don't there will be damage like you see. The bad thing, all that metal has ran through your engine and probably has caused more damage elsewhere.
 
I thought it was bad practice to fill lifter before installation. It becomes like a solid lifter and maybe valve hit piston creating damage.
 
tonysrt said:
I thought it was bad practice to fill lifter before installation. It becomes like a solid lifter and maybe valve hit piston creating damage.
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When you prime the oil before starting the engine, the lifters fill, no?
 
toolmanmike said:
I don't think one had anything to do with the other. Often times the lifters don't spin in their bores. If they don't there will be damage like you see. The bad thing, all that metal has ran through your engine and probably has caused more damage elsewhere.
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Is there a way to ensure that they do spin, or is this just a thing that happens out of our control? And yes, I'm not looking forward to what I find when I pull it apart.

tonysrt said:
I thought it was bad practice to fill lifter before installation. It becomes like a solid lifter and maybe valve hit piston creating damage.
Click to expand...

I was wondering about that because I had found conflicting information before the install. The lifters are Comp Cam lifters, and the instructions said to soak them overnight.

**Edit** The lifters are Lunati that came with the cam/lifter kit, not Comp Cams lifters.
 
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Guides too tall for the lift, too log of push rod and/or adjustable rockers preloaded too much can cause this. Was there a push rod length check done and was there a retainer to guide clearance check done? Soft cam and or lifter could cause this as could a poorly ground lobe or lifter face. The other could be the lifter bore or body is out of spec. Maybe too much spring for the break in?

All your break in sounds fine. Did you use a break in oil and was assembly lube used on the lifter face and lobe?
 
Righty Tighty said:
Is there a way to ensure that they do spin, or is this just a thing that happens out of our control? And yes, I'm not looking forward to what I find when I pull it apart.
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They should be free moving when you install them and almost go in without a fight. If you had to force them in, that is a sign the lifter bores are out of whack.
 
Righty Tighty said:
Is there a way to ensure that they do spin, or is this just a thing that happens out of our control? And yes, I'm not looking forward to what I find when I pull it apart.



I was wondering about that because I had found conflicting information before the install. The lifters are Comp Cam lifters, and the instructions said to soak them overnight.
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Edited for correctness. I originally said concave... the correct term is convex.

The lifters spin because the bottoms of them are not flat, they are slightly convex. That's what causes them to rotate slightly every up and down.
 
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dano said:
Guides too tall for the lift, too log of push rod and/or adjustable rockers preloaded too much can cause this. Was there a push rod length check done and was there a retainer to guide clearance check done? Soft cam and or lifter could cause this as could a poorly ground lobe or lifter face. The other could be the lifter bore or body is out of spec. Maybe too much spring for the break in?

All your break in sounds fine. Did you use a break in oil and was assembly lube used on the lifter face and lobe?
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Retainer to guide clearance was checked by the machine shop, as well as the springs, and I used an adjustable pushrod to check the length. However, I didn't use softer springs for the break in, just the same springs as I have been running. Maybe that was it?

I did use lots of assembly lube on lifters and cam.

RammerJammer75 said:
They should be free moving when you install them and almost go in without a fight. If you had to force them in, that is a sign the lifter bores are out of whack.
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Every lifter dropped in easily but snug, and I did ensure that they spun in the bores. The machine shop also checked the bores when they had the heads.

Now I'm wondering about the springs. I did read that some folks use lighter springs for break in, but for a reason I can't recall, I opted not to use them.
 
I will normally check when I get the lifters dropped in to see how easily they move. If you can move them with little effort, you're good, but if they were a little stubborn that's unnecessary drag that could keep them from spinning.
 
Righty Tighty said:
Retainer to guide clearance was checked by the machine shop, as well as the springs, and I used an adjustable pushrod to check the length. However, I didn't use softer springs for the break in, just the same springs as I have been running. Maybe that was it?

I did use lots of assembly lube on lifters and cam.



Every lifter dropped in easily but snug, and I did ensure that they spun in the bores. The machine shop also checked the bores when they had the heads.

Now I'm wondering about the springs. I did read that some folks use lighter springs for break in, but for a reason I can't recall, I opted not to use them.
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Single springs with dampers or double springs? I never soak the lifters. I assembly lube the bases ad put a thin coat of assembly lube on the outsides. I have a oil can and pump a couple 3 pumps of oil into the lifter. Soaking them fills them up and they act like a solid lifter until some of the oil bleeds off.
 
If you pre lube the engine the lifter bores will bet plenty of oil. Cam lube in the bores may be too much.
 
I used single springs with dampers, I have the spring rate and all the specs that I got from the machine shop at home. Okay, this go 'round I won't soak the lifters. I only used cam lube on the cam, assembly lube on everything else.

A friend suggested that running it hot will decrease the oil's viscosity and considering how it was the #1 cylinder that failed first, maybe that had something to do with it. His reasoning was that the #1 cylinder is farthest from the oil pump.
 
Doubt the anti-freeze is related to the cam. What causes lobes to go flat is pretty easy to say. The cause of the cause will be determined by you.
Common Causes After Proper Break-in:
  • Lifter doesn't spin (rotate)
  • Collapsed lifter that won't pump up
  • Not enough zinc in the oil with high pressure springs
  1. Lifters shouldn't be tight in the lifter bores. When you pull them up an inch, they should slide right back down to the cam.
  2. Lifters need to rotate. Sometimes you can take a paint marker and put a line in your push rods up by the rockers. You can verify them rotating with the valve cover off.
  3. You need zinc around 1200 - 1700 ppm in your oil. VR1, ZDDP additive, and a thousand other ways to get what's needed
 
I used Lucas Hot Rod & Classic, which is advertised to have 2100 ppm. I will say that when I popped off the valve cover, first thing I did was press on the rockers to test the plungers in the lifters. #1 intake was easily depressed with one finger, that's how I found which one it was.
 
Righty Tighty said:
I used single springs with dampers, I have the spring rate and all the specs that I got from the machine shop at home. Okay, this go 'round I won't soak the lifters. I only used cam lube on the cam, assembly lube on everything else.

A friend suggested that running it hot will decrease the oil's viscosity and considering how it was the #1 cylinder that failed first, maybe that had something to do with it. His reasoning was that the #1 cylinder is farthest from the oil pump.
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You should be ok then.
 
The only other thing I've seen eat a flat tappet cam is fuel wash from a way over fueled carb that contaminated the oil badly
 
Righty Tighty said:
Help me understand this. I had a lifter fail about 600 miles after break in, and consequently flattened a cam lobe. I thought I followed all the proper break in procedures - soaked the lifters overnight in oil, lots of assembly lube, machine shop confirmed all my clearances to avoid coil bind, etc., started up and took the RPM up to 3000 for 20 minutes, proper break in oil, and performed a prompt oil change.

Here's the deal, though. The car ran great up until I did some minor servicing last week. I had the lower radiator hose off to address a minor leak and fitment adjustment, and when I topped off the coolant, added too much concentrate and threw off the ratio of antifreeze to water. After that the engine began running just a little warm - 210-230F after 25 minutes on the interstate. It was suggested that I had air in the system, so the plan was to burp it out. The next morning, I tried burping the air out with no recognizable success, but then I heard a ticking coming from the #1 cylinder area. I also pulled out a piece of RTV from the rad filler neck that had dislodged from the intake.

I drove it home from work, and the ticking remained, however the engine began missing a cylinder. By the time I made it home, the engine was running rough. I popped off the valve cover and found a limp rocker at #1 intake. Removed the intake, and the corresponding lobe on the cam was garbage.

Here's my question: I know it impossible for any of you to know for sure what exactly went wrong simply by reading this, but are there any clues here as to why the lifter (and ultimately cam) failed? Thanks for reading.
View attachment 1715613313 View attachment 1715613314
Click to expand...

Are you using a high zinc oil?
 
For it to have failed with that few miles on it, to the degree of wear that you’re seeing now, it basically had to start failing during break it.
It starts as a tiny spot where the lifter and cam exchange a little material before the two surfaces have created a work hardened wear pattern.
Once that little surface defect is created, it’s just a matter of time before you end up with what you have there.
This is why the very first minute or two of the break in process is so important........ to make sure that exchange of material between the cam and lifter never happens.

When you remove the cam, see if there is evidence that other lobes are starting to go away.

Did you run the Lucas oil the whole time, or just for break in?

Was that cam a fast rate .904 lifter profile?
Those less tolerant of lifter bore misalignment.

I’d check the lobe taper on the lobes that are still good to verify it’s correct (you want around .002” taper).

I’d say these days, the most common reasons for a flat tappet failure of that kind is going to be from lobe taper being incorrect, incorrect crown on the lifters, or incorrect oil being used.

A few years before the whole lifter debacle situation happened(early 2000’s), I had an opportunity to see first hand how the wrong oil could impact a flat tappet cam when stiff springs were being used.
I had built a 440-6 for a customer, Crane hyd cam, Hylift Johnson lifters, Isky dual springs, HS rockers.
Dynoed the motor, no problems with break in.
There was no “break in” oil then as cam failures weren’t very common(or at least less common that now).
Motor was run with VR-1 20w50 for a few years, no issues.
The car got driven quite a bit....... it probably had 15,000 miles on it.

The owner reads some stuff on line about oils....... decides synthetic would be better for it.
Puts mobil 1 10w30 in it.
Within a month the cam has several flat lobes.

Nothing against Mobil 1...... I use it in my DD vehicles....... but gas mileage formulated oils aren’t really a good choice for your old school muscle car with a flat tappet cam and big springs.

I’m just pointing out, that they can still fail long after they have been put into service.
 
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