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Hydraulic roller lifter failure 1

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Fmangas

Fmangas

Automotive
Mar 14, 2009
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I'm having what I believe are premature roller failures. I'm seeing failures at between 2000 hrs and 10,000 hrs. I realize this is between 120,000 miles and 600,000 miles. These are in ford big block engines used in stationary continous duty applications. They are ran at 1800 rpm with oil being changed every 500 hrs. It is a mineral oil.

It is a retrofit roller lifter and cam. The cam has about .300 lobe lift and 195degrees at .050 duration. The springs are 110# seat pressure with a rating of 231#.

After through disassembly of several failed lifters and cams. It appears the needle bearings are microwelding to the axle assembly.

I have submitted cams and lifters to the manufacturer and he has said they are just wearing out. My belief is the spring pressure is to light and the lifter is bouncing coming off the nose.

Any other thoughts would be greatly appreciated.
 
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in my small block chev continuous run applications i switched back to old school lifters and cams and had better longevity by alot. as long as proper lube and break in was done at start up. standard lifters and came out lasted almost 2 to 1
 
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Sounds like a lube failure, but why run such high springs pressure at 1800 rpm?

"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein
 
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The clue of micro welding suggests lack of lube. The axle of the roller relies on splash oiling thrown off the crankshaft. Some oil will migrate down from the clearance between lifter and bore, but there may not be enough that makes it to the axle. The aftermarket cam co. Iskedendrian has a roller lifter that replaces needle style with a bushing. Greater load capability but still would require continuous oil supply. Are the lifters that failed always in the same position or do all of them show signs of distress?-----Phil
 
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I agree re the lube. 1800rpm is not a lot to throw oil at the cam. I normally break in cam/follower combos at 3000rpm just to ensure lubrication.

Maybe some sort of oil squirter via a notch or hole in the big end of the rod.

Regards
Pat
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I'm not discounting lube. I am surprised there wouldn't be enough splash considering. In an on-highway application the normal operating RPM is 1800 to 2000 RPM.

The spring pressure was what the cam manufacturer specified with cam lift and duration.

It is currently built with the largest capacity pump available.

From the samples I've looked at it appears the center 2 cylinders consistantly have the greatest failure rate but, it is random between intake and exhaust lifters.

I'm considering angle drilling holes (.100) from the lifter valley to as close to the roller end as possible.

Thanks everyone for the input
 
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Have you done oil analysis? Have you considered a quality full synthetic? 500hrs seems like a lot of hours between changes for a mineral oil. It might even be too much for a synthetic.

I would also suspect the lifter itself. It seems there are a few models of lifters that are considered much more reliable if you hang around performance forums enough.

The spring pressure comments are probably correct too. It sounds like that's the recommended spring for the cam, which is likely capable of controlling the valves up to something like 5500rpm or 6000rpm.

You could try cutting holes in the valve covers and record the pushrod/rocker/valve moving with a high speed camera. That might show if you have some strange valvetrain harmonic happening.

 
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Roller followers tend to break more from valve train separation than from valve spring pressure, however 1800rpm and a cam designed to be efficient at that speed would require minimal valve spring pressure.

Certainly a worn cam lobe can lead to erratic follower motion and valve train separation, so maybe that was where the problem started.

I agree, without knowing a few pertinent details, that 500 hours seems like a long oil change interval.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
 
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got any pictures of the micro welding?
How about the condition of the rollers, axles and races of some 5000>10000 hr lifters that have not failed?

If you can provide the dimensions of the rollers and races it might be interesting to see if the operating temp oil satisfies the "kappa" requirements traditionally described as necessary to achieve elasto-hydrodynamic lubrication in rolling contact bearings.
 
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On the oil change interval. These engines are started and ran until it's time for preventive maintenance. So there is very little cold start time for acids to buildup in the crankcase. They also have a 5 gallon reserve that is constantly topping off the crankcase. So, in 500 hours it may receive as much as 10 quarts of replacement oil prior to the oil change.

Right now I'm wainting to hear back from a different cam company for there opinion of the failure mode. When I get an answer I'll post it.

Thanks for all of comments
 
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Oil? Brand, viscosity? Additives?
Old aircraft engines, diesel engines of the past all used roller cam an tappets, and seemed to live just fine, as do lots of modern automotive engines nowadays. Need to answer questions above and pictures of needles and contact surfaces. If water is the lubricant used then that is the problem. Too much info missing here.
 
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I just wanted to follow up. I still haven't received any info from the cam manufacturer. I did do considerably more research and I believe valve recession is having an impact. As the valves are receding it's increasing the valve spring installed height. I believe it's reducing valvetrain control allowing the lifter to slide and bounce on the lobe.
 
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They have hardened seats and inconel valves. I suspect the seat width is too narrow and not having enough cooling effect on the valve. From the info I can gather the seat width is between .040 and .060 on both intake and exhaust.
 
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What is the fuel? Do the valves have rotators? I'm second hand aware of some applications that developed seat recession when using positive valve rotation.
 
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