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Lifter failure

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Tonyfixit Avatar
Tonyfixit Tony M
Duncan, BC, Canada   CAN
Personally I belive that the vast majority of cam and flat lifter failiers blamed on motor oil and the reduction of some EP additives withing that oil, are actually failiers due to substandard lifter and cam processing.

Kai, what problems have you found with the HD tuftrided lifters?

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jwerner Avatar
jwerner Gold Member John Werner
Staten Island, NY, USA   USA
My guess would be improper break-in of the motor as a major factor. a wise engine builder told me 10-30 oil 2000-2500 rpm for a good 20 min, on initial start up
and get your lifters from Wishbone Classics only......



Edited 1 time(s). Last edit at 2018-01-15 03:33 AM by jwerner.


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Doc250 Avatar
Doc250 Chris Holliday
Honeoye Falls, NY, USA   USA
1968 Triumph TR250 "Little Red One"
1975 Triumph TR6 "Lbc II"
Just so I am clear and complete. Break-in was done by packing the oil pump with Vaseline and after filling the engine with 6 qts of Royal Purple break- in oil we turned the oil pump with a shaft through the distributor access. We got good 80 psi of pressure for 1-2 min. When we started the engine we ran it for 20 min at 2000-2500 RPM. Like I said, there are only a couple hours of time on the engine if that. Couple runs around the block to test the OD, carb adjustments and get it up to temperature.

I'd like to believe this was a parts failure but that seems really excessive to fail in that short a time. When I look at the cam shaft through the push rod access, all the cam lobes seem to be covered in oil except this no 1. Any way that lobe wasn't getting oil?

Thanks for all the input. It's really great to have resources and ideas.

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wbclassics Kai Radicke
Syracuse, NY, USA   USA
In reply to # 1507555 by Tonyfixit Personally I belive that the vast majority of cam and flat lifter failiers blamed on motor oil and the reduction of some EP additives withing that oil, are actually failiers due to substandard lifter and cam processing.

Kai, what problems have you found with the HD tuftrided lifters?

Exactly what I believe as well. 95% of Triumph lifter failures are due to interface issues between the cam and lifter. Blaming the oil and / or the break-in procedure is an incredibly convenient excuse for guilty parties that sell substandard parts or don't know anything about the parts or the cause of failure.

Triumph picked a riskier geometry that wasn't tolerant of error. Unlike MG and the virtually every domestic pushrod engine here in the USA that used an interface geometry that could accept a bit more variance in production tolerances. Tappet bore to camshaft perpendicularity has to be perfect for TRs, while the other style of interface allows for greater production tolerances in the bore perpendicularity. Triumph's reason for doing this was because the lifters were originally 0.687" in diameter, which is pretty small for a tappet, so there was very little contact area. You can get more contact area with the interface geometry that Triumph used, especially for a smaller lifter diameter.

No magic oil and no magic break-in method will keep parts that are manufactured incorrectly from failing. There are cam manufacturers producing cams with the lobe profiles that generate excessively high hertzian stresses in the cam and lifter (this is a profile design issue). There are cam and lifter manufacturers producing lifters with the incorrect face geometry, so that you end up with point contact between the two parts rather a wider line of contact.

Exceptionally rough surface finishes also play a part in the failure of the components as well. When you have a surface finish of 40Ra on your cam lobe you are just making it near impossible for any sort of oil film to develop even under light to moderate RPMs, similarly the anti-wear films that develop on the face from ZDDP will be left in the valleys between the peaks of the asperities, and you'll still have the asperties rubbing. Parkerizing is a common cover-up process for poorly surface finished parts. The OEMs gave up parkerizing a long time ago when they realized improved surface finishes were the superior route to take to immediately reducing friction, minimizing break-in time and break-in wear, and establishing early anti-wear films.

Tonyfixit, on the HD unit you referenced purchasing there are issues with the face geometry not meeting original specs, the face surface finish is 6-8x rougher than an OE Triumph lifter and the pushrod seat. That's as specific as I'll get, that supplier should do their own R&D if they want to know the specific problems.



Edited 2 time(s). Last edit at 2018-01-15 08:35 AM by wbclassics.

wbclassics Kai Radicke
Syracuse, NY, USA   USA
In reply to # 1507573 by Doc250 I'd like to believe this was a parts failure but that seems really excessive to fail in that short a time.

A soft lifter will fail very quickly, it would be like having a lifter made of peanut butter as far as the surface loads being generated are concerned about.

That said, I have never seen a lifter failure to the degree of severity you've had. And I've never even seen a lifter failure like another posted had, with a hole in the side of the block from the failure. These are catastrophic failures, and it is very UNLIKELY it was because of the oil.

I'm assuming you're going to use some other lifters when you rebuild this motor, because 1) you're now short at least one and 2) you don't trust what you have.

I'll offer to inspect (at no charge, just ship them to me), the remaining lifters and see if we can find any issues there. If you include the broken pieces of the failed lifter, I'll even try to hardness test those (may have to set it in epoxy to be able to adequately hold the piece in position for testing). On the remaining 11 lifters, the hardness test dimple will render the lifters unusable unless they get slightly resurfaced to remove the raised rim that surrounds the hardness test zone (the dimple doesn't need to get removed, we just have to remove the ever so slight raised material at the edge of the dimple that is created when the diamond penetrator pushes into the surface). But it probably isn't worth doing that, just scrap them after getting the inspection data.



Edited 1 time(s). Last edit at 2018-01-15 08:18 AM by wbclassics.

Alfaduetto Jack Place
Greeneville, USA   USA
Does the crack have dark and brighter areas on the fracture line? Probably a heat treat quench crack that finally completed the task. Chilled iron has a high failure rate especially with newer motor oils.

Tonyfixit Avatar
Tonyfixit Tony M
Duncan, BC, Canada   CAN
"I'd like to believe this was a parts failure but that seems really excessive to fail in that short a time. When I look at the cam shaft through the push rod access, all the cam lobes seem to be covered in oil except this no 1. Any way that lobe wasn't getting oil? "

Almost impossible if the other lifter for that cyl was getting splashed with oil, the failed lifter must have had oil also.

I would be VERY interested to hear Kai's findings when he tests (what is left of) that lifter.

Now the question is: Where do you go from here?

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Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, OR, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1507448 by Doc250 Krom;

Excellent observations. The rebuild was done by a very reputable shop that had done many engines for club members as well as local racers. I trust his work. All the lifters were new as well as the cam so no need to maintain same lifter same hole. All parts from BPNW. As you can see from my other latest post I am equally concerned about metal bits inside the engine. I really don't want to pull the engine if I can avoid it but may have to. sad smiley sad smiley . Is there any way to "flush" all the oil galleys with the engine installed? I will defiantly pull the oil pump and inspect and clean or just replace it.

I believe the cam shaft is splash lubricated so is there any way the cam wasn't getting oil? Also, as i understand it, oil drains from the head down through the push rod access holes to lubricate the lifters. The rocker shaft supplies the oil to the rocker arms and that oil drains down through the lifter access holes through the engine. In the process it oils the lifters and cam shaft. Correct?

Doc:

While it is certainly true that oil drains down to lubricate the lobes, at idle and especially after the first start up this is hardly robust enough to insure a trouble free break in. The vast majority of the oiling on the cam is by splash, hence the need to do the 2,000 RPM break in. There must be as much oil as possible on the cam during startup as the lifters bed in.

The breakage of the lifter looks like it was a brittle failure, and I am at a loss to explain it unless the material itself had too much carbon and other inclusions in it. Honestly it looks like the iron in the lifter was very impure and very prone to a brittle failure.

Even so, why that part of the lifter should fracture is not obvious. It has almost no load on it, as it is simply there to guide the lifter up and down, so it has a minimal side loading on it and no compressive or tensile stress. What does the face of the lifter look like?

I must ask, what are the specifications on your cam? To get any side load on the lifter would require a very aggressive lobe profile, such that the perimeter of the lifter face digs into the lobe as the valve is lifted. THAT would put a large side load on the lifter and if the material is brittle it would then fail in that manner.

The smaller the diameter of the lifter, the less aggressive the lobe can be, in order to avoid the lifter digging in to the lobe. The TR6 lifters are fairly small, limiting the ramp rate of the cam. Remember the engine is a 1950s design, and cams were pretty lazy (slow opening and closing) back then. The lifter digging in would also cause the destruction of the lobe - once the lifter digs in the face of the lobe is ruined and lifter/lobe failure is guaranteed, no matter how much oil is present.

Another possibility; incorrect valve springs. Flat tappet cams on the best of days will tolerate no more than 300 lbs of over the nose pressure, so if you had some super gnarly valve springs installed, OR a piece of debris got wedged in between the spring coils such that the spring binds, instant cam failure. But that would not explain the brittle failure of your lifter, only the destroyed cam lobe and lifter face. So the most likely explanation in my mind is something causing an extreme side load on the lifter.

Publish the specs on your cam. One would need both the advertised and the 0.050" lobe duration in order to see if the profile is aggressive. Also, who is the manufacturer?

Cheers,

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore



Edited 2 time(s). Last edit at 2018-01-15 11:19 AM by Darth V8R.

POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
Kai,
Are TR6 lifters perfectly flat? If so, when you talk of poor interface, do you actually mean the bottom is off from 90° to the wall? Still can't understand how that one lifter could snap so cleanly, almost looks like it would have to had been whacked on the side (by the cam lobe?). Lifters I've seen in my own years ago appeared to be slightly concave with use but not necessarily pitted. I never decided if this was wear I was witnessing or denting. This was in the '80's, before the internet and forums that now bring to light valuable information (along with some BS). By the way great posts from you about these lifters. - Pete

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Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, OR, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1507618 by POW Kai,
Are TR6 lifters perfectly flat? If so, when you talk of poor interface, do you actually mean the bottom is off from 90° to the wall? Still can't understand how that one lifter could snap so cleanly, almost looks like it would have to had been whacked on the side (by the cam lobe?). Lifters I've seen in my own years ago appeared to be slightly concave with use but not necessarily pitted. I never decided if this was wear I was witnessing or denting. This was in the '80's, before the internet and forums that now bring to light valuable information (along with some BS). By the way great posts from you about these lifters. - Pete

Lifters are ground with a convex face. The cam lobes are ground with a slight taper, so that the lifter rides on the cam lobe slightly off center. This causes the lifter to rotate in its bore, distributing wear evenly over the face. Of course eventually wear causes this rotation to stop or nearly stop, at which point wear accelerates. A heavily worn lifter will thus have a concave face, and the cam lobe will develop a crown. The wear pattern will move from the middle of the lobe to the edges and then wear accelerates even more. The cam and lifter have completely failed at that point.

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

wbclassics Kai Radicke
Syracuse, NY, USA   USA
In reply to # 1507616 by Darth V8R
In reply to # 1507448 by Doc250 Krom;

Excellent observations. The rebuild was done by a very reputable shop that had done many engines for club members as well as local racers. I trust his work. All the lifters were new as well as the cam so no need to maintain same lifter same hole. All parts from BPNW. As you can see from my other latest post I am equally concerned about metal bits inside the engine. I really don't want to pull the engine if I can avoid it but may have to. sad smiley sad smiley . Is there any way to "flush" all the oil galleys with the engine installed? I will defiantly pull the oil pump and inspect and clean or just replace it.

I believe the cam shaft is splash lubricated so is there any way the cam wasn't getting oil? Also, as i understand it, oil drains from the head down through the push rod access holes to lubricate the lifters. The rocker shaft supplies the oil to the rocker arms and that oil drains down through the lifter access holes through the engine. In the process it oils the lifters and cam shaft. Correct?

Doc:

While it is certainly true that oil drains down to lubricate the lobes, at idle and especially after the first start up this is hardly robust enough to insure a trouble free break in. The vast majority of the oiling on the cam is by splash, hence the need to do the 2,000 RPM break in. There must be as much oil as possible on the cam during startup as the lifters bed in.

The breakage of the lifter looks like it was a brittle failure, and I am at a loss to explain it unless the material itself had too much carbon and other inclusions in it. Honestly it looks like the iron in the lifter was very impure and very prone to a brittle failure.

Even so, why that part of the lifter should fracture is not obvious. It has almost no load on it, as it is simply there to guide the lifter up and down, so it has a minimal side loading on it and no compressive or tensile stress. What does the face of the lifter look like?

I must ask, what are the specifications on your cam? To get any side load on the lifter would require a very aggressive lobe profile, such that the perimeter of the lifter face digs into the lobe as the valve is lifted. THAT would put a large side load on the lifter and if the material is brittle it would then fail in that manner.

The smaller the diameter of the lifter, the less aggressive the lobe can be, in order to avoid the lifter digging in to the lobe. The TR6 lifters are fairly small, limiting the ramp rate of the cam. Remember the engine is a 1950s design, and cams were pretty lazy (slow opening and closing) back then. The lifter digging in would also cause the destruction of the lobe - once the lifter digs in the face of the lobe is ruined and lifter/lobe failure is guaranteed, no matter how much oil is present.

Publish the specs on your cam. One would need both the advertised and the 0.050" lobe duration in order to see if the profile is aggressive. Also, who is the manufacturer?

Cheers,

Vance

Vance may be onto something here, and it is one of the things that baffled me when I saw this failure. But you're not going to be able to determine the velocity of the cam profile from published specs. The velocity of the profile is what governs the minimum required tappet face diameter. So on our street cams, we design for a minimum face diameter of 0.750" even though the lifter is 0.800" in diameter. This keeps us 0.025" away from ever getting to the edge of the tappet, which is necessary as you don't want to load the edge of the lifter and because so many of the lifters have chamfers on them that you need to stay away from the edge of the chamfer. Chamfer width varies considerably across the industry, and in most cases you'll be OK with a stock cam, because the vast majority of the Triumph cam profiles were designed for the smaller 0.687" factory tappet, so it isn't ever a worry anyway. Other cam lobe design variables that influence cam lobe and lifter life are things like the jerk value of the profile... you'll never know that information as an enthusiast, and you can't figure it out from published specs, and no one will ever tell you (if they even know). Our WBC performance profiles appear more aggressive on paper then some of our competitors as I tend to favor higher lift values and shorter durations (yielding higher "intensity" as Crane likes to call it, because we get more area under the lift curve that way), but we actually have lower jerk values when we've analyzed competitors cams on a Cam Doctor.

But as soon as you get into performance cams, that extra margin of unused lifter face diameter that the factory cam profile's velocity doesn't take advantage of is one of the areas we're looking to exploit to get our performance gains from.

There are so many things that can wrong, inadequate surface hardness / inadequate chill depth. Inclusions, cracks, etc. A few more pictures I took this morning after digging through my vast tappet sample archive.

The first picture shows an AE lifter which is the softest lifter I have ever found to date. 35-38HRC, it also had a chamfer width that was too wide reducing the effective face diameter too much for use with some performance cams. Also note next to the AE lifter is that sectioned lifter that I showed a microscope picture of earlier, that sectioned lifter tested in the mid-50s HRC. You can see the difference in the hardness test site size. Testing on the Rockwell C scale uses a 120 degree diamond indenter that presses into the surface of the part with a 300kg load. The more the indenter pushes into the softer material, so the softer lifters always have the bigger test dimples. You can see that difference in the photo. The test sites on the AE lifter are 50-60% larger than those on the sectioned lifter.

Second photo, of a black phosphated lifter that is representative of the "HD" lifters sold elsewhere. It tested fine for hardness, but this particular sample came through with a failure at the edge. How a part like this makes it out of the grinding department is beyond me, because it then went on to phosphating and then someone had to box it. Typical of the "I don't care, I'll pass it along" quality control that is dominant in this industry. Had this HD lifter actually ended up in someone's engine, I can't see how it would ever survive.



Edited 2 time(s). Last edit at 2018-01-15 11:55 AM by wbclassics.


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wbclassics Kai Radicke
Syracuse, NY, USA   USA
In reply to # 1507621 by Darth V8R
In reply to # 1507618 by POW Kai,
Are TR6 lifters perfectly flat? If so, when you talk of poor interface, do you actually mean the bottom is off from 90° to the wall? Still can't understand how that one lifter could snap so cleanly, almost looks like it would have to had been whacked on the side (by the cam lobe?). Lifters I've seen in my own years ago appeared to be slightly concave with use but not necessarily pitted. I never decided if this was wear I was witnessing or denting. This was in the '80's, before the internet and forums that now bring to light valuable information (along with some BS). By the way great posts from you about these lifters. - Pete

Lifters are ground with a convex face. The cam lobes are ground with a slight taper, so that the lifter rides on the cam lobe slightly off center. This causes the lifter to rotate in its bore, distributing wear evenly over the face. Of course eventually wear causes this rotation to stop or nearly stop, at which point wear accelerates. A heavily worn lifter will thus have a concave face, and the cam lobe will develop a crown. The wear pattern will move from the middle of the lobe to the edges and then wear accelerates even more. The cam and lifter have completely failed at that point.

Vance

That is NOT the correct Triumph specification... if you had an MG or any domestic engine, you'd be correct.

Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, OR, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1507627 by wbclassics Second photo, of a black phosphated lifter that is representative of the "HD" lifters sold elsewhere. It tested fine for hardness, but this particular sample came through with a failure at the edge. How a part like this makes it out of the grinding department is beyond me, because it then went on to phosphating and then someone had to box it. Typical of the "I don't care, I'll pass it along" quality control that is dominant in this industry. Had this HD lifter actually ended up in someone's engine, I can't see how it would ever survive.

If you look carefully, the edge failure is rippled, with the ripples spreading from the edge of the lifter. It also has a slightly concave shape.

This failure mode is called "spalling" and in general is caused by a brittle impact. My bet is that the lifter was dropped prior to Parkerizing, and landed on its edge, which caused it to spall. The lifter was picked back up and tossed back into the assembly line where it was processed and shipped.

Most manufacturing operations only sample check/inspect their product, so it was not one of the ones to get checked before it went out the door. Heck, it might have even gotten dropped BECAUSE it was pulled from the line for inspection. Check it, drop it (oops!), put it back in the line, or something like that.

BTW, this is one way to destroy an enemy battle tank. You fire a high explosive round at the enemy that flattens itself on the enemy's armor before detonating. This causes the armor to spall on the inside of the tank, and fragments of armor to break off and bounce around at supersonic speeds. Needless to say, the life of a crew member becomes short, exciting and VERY messy at that point. There will be no hole on the outside of the tank, but in the inside there will be a shallow cone shaped crater in the armor. Clever, no?

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
In the very first photo, what exactly am I looking at? Obviously at the bottom of the bore is the beat up cam lobe but what is the crescent at the bottom? Perhaps that lifter was cracked and unnoticed from the get-go? Heat treating causing a fracture of a part made of sub-par material?

wbclassics Kai Radicke
Syracuse, NY, USA   USA
In reply to # 1507651 by Darth V8R If you look carefully, the edge failure is rippled, with the ripples spreading from the edge of the lifter. It also has a slightly concave shape.

This failure mode is called "spalling" and in general is caused by a brittle impact. My bet is that the lifter was dropped prior to Parkerizing, and landed on its edge, which caused it to spall. The lifter was picked back up and tossed back into the assembly line where it was processed and shipped.

Most manufacturing operations only sample check/inspect their product, so it was not one of the ones to get checked before it went out the door. Heck, it might have even gotten dropped BECAUSE it was pulled from the line for inspection. Check it, drop it (oops!), put it back in the line, or something like that.
Vance

No doubt it was an OOPS drop at some point I'm amazed it wasn't reground to eliminate the chip completely at the factory... the machine operator in India must have been so lazy he couldn't even be bothered to make it look good again!

And yes, the vast majority of these lifters are coming from a variety of sources in India. There is also a source out of Turkey. The AE packaged units say "GB" or "IN" on them interchangeably, and every sample looked exactly the same with no discernible difference... I'd put my money on all the AE units actually coming from India. There are many unscrupulous suppliers out there that will manipulate country of origin or feign ignorance on it ("well our supplier is in Germany so we thought it was made in Germany..." which is one of my favorites in the British car industry).

Anyway the point is, the vast majority of available lifters have some sort of issue that makes them less than ideal for use.



Edited 1 time(s). Last edit at 2018-01-15 03:48 PM by wbclassics.

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