Hydraulic roller lifter failure 1

[Fmangas]

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.

 

[Metalguy]

>"I spoke with the tech guy at one famous company whose high torque grind required springs rated in their literature to 7500+ RPM
When asked if I could go lighter on the springs if I swore to limit RPM to say 4000?
The answer was, absolutely not!"<

Be real interesting to know the why of that statement.

"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

 

[Fmangas]

Thanks for all of the responses. I'll try to answer all of the questions.

FoMoCoMoFo
Oil pressure does stay 50psi+. We are working on a spray bar or something like that to spray the rollers. I was not involved in the cam selection process. What I have found interesting is the overall HP of the engine needs to be limited to stay in a certain EPA engine range. Yet, they shortened the duration and increased lift over stock.

Dicer
I'm unclear of exactly what the root cause is. One cam manufacturer said the engine needs more spring pressure to ensure the roller is rolling on the base circle. They believe the roller is skidding and flat spotting. Another manufacturer said there is too much spring pressure and its causing wear on the roller axle. I'm not sure on misalignment. These lifters are tied together with a tie bar. I would expect both lifters to have the same wear pattern if there was a misalignment. This hasn't been happening in the majority of the cases.

Pat
These are hydraulic lifters on a hydraulic cam.

BCS5274
I have seen the same thing as you in the past. Thats one of the reasons I'm looking hard at valve seat width. Are the engines you deal with Automotive Derivatives? What type of head life are you seeing?

 

[patprimmer]

Yes. I saw the heading after I posted.

The shorter duration with higher lift is normally done to make more power at lower rpm.

My next move would be wider seats and if possible, reduced valvetrain weight.

Also check alignment of lifter bores to cam and if cam walk is restrained sufficiently to keep the rollers in full contact across the full width of the roller.

The oil spray bar can't hurt. An oil formulation with good anti wear additive can't hurt. I presume the cams are steel and properly hardened.

Also I believe that Iskenderian now makes a roller follower with a plain bushing rather than needle rollers. These carry higher shock loads without damage but need more lube.

Regards
Pat
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[FoMoCoMoFo]

As to the why of that statement.

I'm guessing the cam maker would rather you wear things out from excess pressure than destroy them more catastrophically from too little..

This was 25+ years ago and I don't recall the details of the conversation. He correctly pointed out that his people were better equipped to study valve train dynamics than I was.
But, he also seemed to imply that the relationship between spring pressure requirements & RPM was not as simple, direct and linear as a simpleton such as myself might think it is.
Was he right?
I ramble on here only because it may relate to the OP.
Whoever DID select the cam may well have chosen the most suitable roller cam available.
And yet, It may be too "radical" for longevity.
And maybe the cam maker is, for whatever reason, hesitant to adjust the spring pressure requirement down in line with the low 1800 RPM
speed ?

I guess if the TPTB like the cam, they can deal with making it and everything else survive?

 

[Metalguy]

Some cam grinders strongly urge users to run light pressure springs for the breakin of flat tappet cams, then change them to allow high RPM operation.

"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

 

[bcs5274]

fmangas;
yes we are running 5.7l gm industrials and some 7.4l gm

in the 1500 to 1800 rpm range our engines run continous for 3 to 4 years depending on fuel, with clean natural gas and good service (change oil once a month) no issues

 

[Fmangas]

BCS
Without getting to far off topic. Are you getting new GM industrial engines or rebuilt? How many hours are getting on heads? Have you set any of the 8.0L or 10.3 gm engines yet? Sorry for the questions. I've spent the past 4 years selling new GM industrial engines and I'm curious.

Thanks

 

[bcs5274]

new gm 5.7l industrials, run about 20,000 hrs or more before being rebuilt, haven't tried the 8.1l motors, from what we were told on them they lean out the back cylinders to bad from the tuned intake design making it to far of a run from the carb

 

[Fmangas]

Thanks BCS I was curious, thats about what we saw with 5.7L we sold.

 

[dicer]

So what is the application for all these engines that run nonstop?

 

[MikeHalloran]

At 1800 rpm? Has to be a 60Hz AC generator.



Mike Halloran
Pembroke Pines, FL, USA

 

[Fmangas]

Natural gas compressors

 

[dicer]

Are you going to try a different manufacture of lifters now? I would suggest the OEM.

 

[patprimmer]

That is if the OEM makes a solid roller lifter for this engine.

One other thought. Some roller lifters deliberately reduce oil to the top end by restricting the size of the oil feed hole in the side of the lifter and some cam/lifter combos cause a misalignment of the oil hole with the oil gallery if the base circle is not campatible with the lifter hole height.

Regards
Pat
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[dicer]

There is no reason at all that the lifters have to be solid in this application. Solids are more for performance / race applications. And besides for a pumping engine you don't need or want the maintenance of solids, that is lash checks etc. OEM's have been doing the roller thing for years now and get good longevity from them.

 

[patprimmer]

In my experience solids tend to be more durable and lighter and if set up right very rarely need adjustment. They certainly don't pump up if for any reason there is some valve train separation and as such can tolerate lower spring pressures. As there is some evidence this problem may be linked to spring pressures and valve float, a solid lifter will help this just as much as it helps a race cam overcome valve float and requirement for high spring pressures.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[BigClive]

Does the engine run on the same natural gas it compresses?
I have heard that running on natural gas (and propane?) can cause binding of the valves in the valve guides - maybe this could lead to lifter problems?

 

[dicer]

Are these engines running WOT at 1800 rpms? Any idea of what HP output is? Are failures mostly on the ex side? What kind of exhaust system? The recession is mostly the valve itself? What is tear down stem to guide clearance? Ever done egt?

 

[Fmangas]

Guy's
I haven't been answering questions because I've been deep into a different project and this has taken a backseat. I will try to answer the questions you have.

Dicer
These are existing blocks so we have to use retro fit kits on the lifters there is no OEM lifter. It seems for a standard retrofit lifter there is only one primary manufacturer. These engines are close to WOT at 1800, The failures appear to be a mix of intake and exhaust and not localized to a cyl. The recession is primarily in the valve seat. I haven't been able to get a head to teardown to measure yet. I haven't found any data that suggests an EGT study has been done

Clive
Yes the engine runs on the gas it compresses.

Pat
We really haven't had any discussion about going to solids. But that may be a good direction to test.

Thanks everyone for your suggestions.

 

[Frederick]

Have you done a metallurgical workup of the failed parts? The general tone of the conversation here seems to be that there is a lubrication failure. You should also look toward something like a fatigue failure of the bearing parts. If you get micro welding, what you might be seeing is the breakdown of the bearing metal at the surface with the tiny pieces that break out of the surface then becoming debris between the mating surfaces. The forces on these tiny pieces would be enormous, and they could be pushed into the surface, especially if they have strain hardened. There probably is not enough lubricant flow to wash the particles out efficiently, so they would tend to stay there. This could lead to the local welding you are seeing.

If this is what is happening, the fix could be pretty simple.