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.

 

[ornerynorsk]

Oil filtration? I'd agree with the poster that suggested an oil analysis. 500 hours does seem like a lot of hours on a change, even considering there is minimal cold startup.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[patprimmer]

Are there engines run at high load continuously. On a road application, the throttle opening changes regularly so there is often periods of overrun against a closed throttle thereby pulling a vacuum in the manifold and ports which will likely pull some oil past the valve stem seals and the PCV. If it very rarely runs at high manifold vacuum, could you leave the valve stem seals off as a back door way to introduce a bit of oil to the seats.

I also agree the seats are narrow for an endurance engine.

I wonder how much worse if any the seat recession would be with springs hard enough to still retain full valve train control after the seats had receded? ie just install shims to reduce installed height by a bit more than the expected seat recession.

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

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

for site rules

 

[pontiacjack]

Valvetrain control problems at 1,800 RPM? Sounds crazy...

 

[patprimmer]

Are the seats eroding at the surface where they contact the valves or are they sinking into the castings or both. I have seen seats sink into castings on aluminium heads and I have seen the head deform over time if the area was thin between the port roof and the spring seat. These happened reasonably quickly, but they also had 400# on the seat. I doubt yours are over 150# on the seat and I think you probably have iron heads. Also the ones I saw where the port roof sank, the aluminium heads had been welded and we think that tempered and softened the material.

If you are running aluminium heads, have they ever been overheated or run hot enough long enough to anneal or soften the material.

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

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

for site rules

 

[dicer]

Its time to try a quality brand of synthetic oil. So what viscosity is the oil?

 

[Fmangas]

Pat
The recession only appears where the valve contact area is. There is no sinking into the head. These engines are always ran at high load/low manifold vacuum. I'm trying to gather enough data to suggest starting with a tighter installed height.

Dicer
There is a lot of superstition about oil not mixing with natural gas. It's a very big struggle to get TPTB to allow a change in viscosity or type. Currently, there using straight 30W.

Thanks

 

[Metalguy]

Have you calculated/measured how much seat pressure you lose from the valve recession? I'd be amazed if that's the reason, unless the valve train is very heavy.

"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

 

[dicer]

The next question is who's the manufacture of the lifters? And have you tried someone else for lifters? It looks like there is no mention of the type of lifter meaning is it solid or hydraulic?

 

[SMOKEY44211]

I've done a fair amount of engines dedicated to using propane and CNG fuel. Most of them use sodium filed exhaust valves. Also I've seen exhaust springs that lost most of their pressure due to overheating. Overheating was due to diminished splash oil supply to provide cooling. Those springs also had a lot of coking attached to them. Does the engine in question show any indication of those conditions?------Phil

 

[patprimmer]

Good points smokey.
A significantly wider exhaust valve seat should also help reduce exhaust valve temperature.

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

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

for site rules

 

[Fmangas]

Dicer
After speaking to a number of valve train manufacurers there are only one or two retrofit hydraulic lifter manufacturers in the country. I have sent samples to several valvetrain companies for their opinions. These are retrofit style hydraulic roller lifters.

Smokey
The field samples I've seen are very clean around the spring area. The only wear I've seen is the normal ash around the valves and very clear valve and seat wear marks. Also, of the data I've been looking at there is no clear prevelence of either intake or exhaust valve receding more then the other.

I did get a preliminary report from one of the cam guy's. "The loadings you are using do not coincide with the wear on nose of cam lobe." "Lubrication seems to be OK as there is no discoloration at roller wheel or cam lobe." He said he had some other things to evaluate

 

[FoMoCoMoFo]

"The loadings you are using do not coincide with the wear on nose of cam lobe."

A bit vague, no?
I will guess he's saying the cam wear exceeds what he'd expect at those spring loads & hours of operation?

May I ask what the part# on the heads is?

Did you switch to a roller cam to try and increase cam/lifter life? or?

Forgive me if you've answered this one already, but,
Have you tested & compared the springs @ the affected lifters vs the others?
Is the valve recession associated with the abnormal lifter wear or is that consistent?

 

[LionelHutz]

I find it hard to believe valve seats eroding would cause such a reduction in spring pressure that you'd have issues. Have you done any measurements? You can get an on-head spring pressure tester for around $250 from Summit or Jegs if you're in the US and verify what spring pressure you have as installed.

A long standing trick to get more oil to the cam/lifter interface area is to groove the lifter bores. I'm not sure that would help with oiling the roller bearings though.

What does the cam profile look like? I doubt you're running a cam with agressive ramp rates, but that is still something to investigate.

 

[Metalguy]

At 1800 RPM the cam ramps would have to resemble square waves! The OP can rule out high inertial effects and combustion pressure loading. That leaves excessive valve spring pressure, lube or material problems.

"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]

FoMoCoMoFo
We use D9 heads 50% we have cast ourself and the balance are reclaimed. Because of the removal of ZDDP from oil. We started to have what appeared to be a large failure rate of flat tappt cams(This was prior to my employment here) We are doing a trial with a couple of different brands of lifter but it's to early to tell whether they are working. Also I believe the lot sample is too small (2 units)for an effective test. From the data I've extracted there seem to be a correlation between valve recession and lobe failure.

Lionel
We have seen between .050 and .100 valve recession. With our spring rates .050 works out to be 15% spring pressure loss on the seat.

Lionel,Metalguy
I thing the rates are pretty aggressive because of the low RPM usage. I do have some concern about the backside of lobe being too aggressive. I have suggested smoothing out the slope a little TPTB were not very receptive to the idea of a cam change.

 

[FoMoCoMoFo]

Well, it's sounds to me like you've got a cam that sounds mild by the numbers, but is actually a bit too "radical" for the sort of longevity you want.
And It's just beating up the valves/seats & lifters.
Still..
If I were the lifter manufacturer I would probably work on some positive oiling method.
Knowing that engine pump combo, I bet they're surrounded by 50+ PSI oil..
It also sounds as though the cam is just borderline and could be made to work with just a little gentler ramps. especially on the closing side..

 

[patprimmer]

I can't remember reading it. Are the lifters solid or hydraulic. A solid lifter on a hydraulic cam will beat the valve train to death.

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

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

for site rules

 

[FoMoCoMoFo]

Some more questions & comments:

Did you see a substantial performance gain with this cam switch?
Is max performance/efficiency even an issue?

I had a similar problem years ago. I was seeking maximum reliability & durability in that same engine
and so was wanting to use a mechanical
(not hydraulic) cam. I could not find one with as short a duration as yours. And the ones that came close still required fairly outrageous spring pressures.
I think the cam makers figure if you're using a roller or solid lifter you want to take full advantage by using an aggressive profile with a rapid open close rate, and therefor require appropriate springs.

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!

I'm not a fan of synthetic oil and very long change intervals. but, if ever there was an application for these, yours is it!

 

[dicer]

Retrofit lifters? Wear on cam? Isn't the cam nose wear the result of the needle bearings locking up and the roller doing the same? Or is it a tracking problem, meaning the rollers are cocked and axis not parallel with cam axis.

 

[bcs5274]

for natural gas compression running continous in the 1800 rpm range using standard flat tappets with hardened valves and seats running 15w40 or straight 40w oil we are getting 3 to 4 yrs run time on heads,cams, etc.