How do hydraulic flat tappet lifters fail?

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Well sports fans, the moment you've all been waiting for. Here's the cam and failed lifter. The lifter is worn down so badly that it was beginning to grind into the oil reservoir where the plunger is. Seeing this, I'm guessing the flattening lobe cause the lifter to decompress. What do you guys think about the other lobes?

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No doubt about it that lifter definitely failed because it was not rotating in the bore.
Either the bore was too tight and/or the cam lobe had no taper.
 
How do I check the cam lobes for taper? Also are the correct bore specs in the FSM? Or is there a rule of thumb as to how much tolerance should be allowed relative to the lifter diameter?
 

Well I for one consider this a good sign. Only one lifter and lobe. That clearly means the lifter was not spinning in the bore, which was the cause of the failure. So at least you know what did it. I would bring that thing all the way back down and get it as clean as humanly possible. I always run a brake cylinder ball hone through the lifter bores to assure they are not too tight and to clean them up good. Good luck.
 
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How do I check the cam lobes for taper? Also are the correct bore specs in the FSM? Or is there a rule of thumb as to how much tolerance should be allowed relative to the lifter diameter?
Use a calipers across a cam lobe from one side of the lobe to the other side you should have a couple thousands taper.
When you are using non factory parts you cant use the factory spec's. Always measure to make sure.
 
Well, add an oil pump to the list of parts I need.
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No, no, no. You’re supposed to say, “Slap a new oil filter on it and burn some rubber!!” Now that’s what I want to hear.

Then keep on commenting. Maybe somebody else will say it. I'm not going to. lol
 
Haha. While it’s not the easy thing do to, I know it’s the right thing to do. I’m just stuck somewhere in the five stages of grief. The good news is that I’ve pulled an engine before! Pretty recently, in fact...
 
Several of the lifters look terrible.
Hard to tell from the angle the pics were taken from, but I’d say there was a crappy looking lobe to go with every one of them.
For only 600 miles..... none of them look “good”.

My suggestion for your next foray into it would be to not use a fast rate .904 lifter design cam, get genuine Hylift Johnson lifters, and use Driven BR break in oil for the initial break in, along with the black moly paste cam lube for the lobes, dist gear, and bottoms of the lifters.

Then be sure to check the lobe taper and lifter rotation prior to final assembly.

As bad as that one lifter/lobe is in only 600 miles...... it pretty much had to have started to fail on or right after start up.
 
If you wouldn’t mind pulling the guts out of one of the lifters........ I’d like to see if we could tell who made them.

They’re supposed to be either Hylift or Eaton....... which used to have different styles of metering to the top, which could be used to tell who made them.

I’d also get ahold of Lunati and see what they have to say.
They’ll want it back, but that’s worth it if they’ll do something for you.
 
If you wouldn’t mind pulling the guts out of one of the lifters........ I’d like to see if we could tell who made them.

They’re supposed to be either Hylift or Eaton....... which used to have different styles of metering to the top, which could be used to tell who made them.
I don’t know what I’m looking for here, but here’s a lifter taken apart.
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Was that a new pump? I don't know that wouldn't find a new block and just start completely over. Just for the fact that this is the 2nd failure in the block sounds like bad juju! Lol
Brand new pump. Yeah, maybe the block has some bad juju...but maybe I’m also not a great mechanic?? I’m careful with everything I do, but it’s hard not to get frustrated.
 
Thanks...... so that isn’t a Hylift Johnson lifter.

The metering disc is the Stanadyne “style”, although Stanadyne doesn’t make lifters anymore........ so those could be either Eaton’s that have a different metering disc than they used to have....... or possibly an import(other than Eaton).

As far as I know....... the current Eaton stuff is made in Mexico, since they bought out a manufacturer down there a number of years ago.

The current flat tappet lifter.......well, maybe any type of lifter it seems........ is rather precarious these days.
 
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Thanks...... so that isn’t a Hylift Johnson lifter.

The metering disc is the Stanadyne “style”, although Stanadyne doesn’t make lifters anymore........ so those could be either Eaton’s that have a different metering disc than they used to have....... or possibly an import(other than Eaton).

As far as I know....... the current Eaton stuff is made in Mexico, since they bought out a manufacturer down there a number of years ago.
Now there is a Man who knows his lifters.
I like it.
 
I was going to replace the rod and mains anyhow just for piece of mind, but doesn’t the engine have to come out for the cam bearings?
You are going to need to pull out and done to clean and brush all the oil passages X 2.
 
If you don’t mind some more surgery...... how about pulling the check valve assy off the bottom of the plunger and letting us see what’s in there.
 
Interesting.

I’m not sure who is making that lifter.

It’s got the top part like a Stanadyne, but those didn’t have a check ball in the bottom.......they had a disc.

Eaton’s did use a check ball in the bottom though.

My “total guess” is....... that’s what you get from Eaton these days.
 
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@PRH do you attribute any particular type of lifter with some or all of the common failures?
 
My suggestion for your next foray into it would be to not use a fast rate .904 lifter design cam
What is the reasoning behind that? I admittedly don't know much about cams beyond the very basics - LSA, lift, duration, etc.
 
My suggestion for your next foray into it would be to not use a fast rate .904 lifter design cam

What is the reasoning behind that? I admittedly don't know much about cams beyond the very basics - LSA, lift, duration, etc.

The short answer is...... a lobe profile that’s designed to use up the entire area of the lifter has less room for any kind of misalignment or misplacement of the lifter bore in the block.

Depending on the particular block, this can be a big problem.

Quite a few years ago a group of people from Moparts got together and fielded an entry into one of the Enginemasters competitions(2001-2002 maybe??).
The rules that year mandated flat tappet cams.
We used fast rate .904 solid lifter lobe designs........ two of which promptly failed in short order on the dyno.

The motor was diassembled and the block brought to a shop for lifter bore correction(bushings).
The guy who performed the operation said several of the bores were .030+ out of position.
Since the lobe profiles were designed to come within .015-ish of the edge of the lifter, that situation was never going to work.
After the lifter bores were corrected...... no more cam failures.

So, by using a lobe designed to work with a smaller diameter lifter, there is a bigger margin for error with regards to lifter bore placement before the edge of the lifter is digging into the flank of the cam lobe.

Yes, there is a potential to make more power with a lobe profile designed to utilize the full diameter of the lifter....... but it has to live first.

At this stage of the game....... would you trade say...... 10hp to have been able to avoid what you’re going through now?

I have no idea if that’s what caused your failure or not, but moving forward I’d try and stack the deck in your favor if I were you........ and not using a fast rate .904 is one more item that can be applied towards that end.
 
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