no drooling

[Chemgrad]

How exactly is that supposed to work? Valve float as I explained earlier is when the valves fail to re-seat. Solid lifters don't cause valve float so how could a hydraulic lifter which can not grow cause valve float? Perhaps we are using the term valve float to mean two different things or perhaps something else is occurring and you are attributing it to valve float. I'm not trying to be a ******* just really confused because my truck will get close to 100 psi of oil pressure when cold and I've never had an issue. It's a Cummins not a International but I'm having a hard time understanding how high oil pressure could cause the valves to not seat unless the valves springs are very weak then maybe instead of the lifter affecting the valves the pushrod flowing enough oil to create a situation in which the valve is being held open. I suppose that might be possible although those springs would have to be very very weak.

 

[nelstomlinson]

Read this, to find out about pump-up. Yes, apparently high-enough oil pressure can be a problem when trying to start.

 

[Chemgrad]

Read this, to find out about pump-up. Yes, apparently high-enough oil pressure can be a problem when trying to start.

I'm reading it and so far everything it says agrees with what I have been saying. The only way something like this could even possibly occur is if the valve springs are very very weak. Now I'm not trying to pretend to be an expert in valve train mechanics nor in fluid dynamics I'm just have difficulty accepting that the problem that was seen was related to the hydraulic lifter pumping up to the point that it prevented the engine building compression and that pump up was created by 90 psi or oil pressure. Now if we were talking 250 psi of oil pressure I may be more inclined to believe that was culprit. Like I said before not trying to be a jerk just not seeing that being the culprit in this situation. Perhaps it was related to the high oil pressure or perhaps it just fixed itself while the oil pressure issue was being fixed. I know my Dad one time had a dump truck that would start and idle great but when you go in it to drive it would go a little while and die. He figured dirt in the carb. Took it apart cleaned it same thing. Okay dirt in the gas tank. Took it apart and cleaned it. Same thing. Well maybe a little dirt from the tank got into the carb so he cleaned it again. Same thing. After fighting with it it turned out to be a small piece of rubber line by one of the inlets, been too long for me to remember exactly where. It would sit there just fine until you started getting on it then it would plug the line causing the engine to die. That would knock it back out and there you go weeks or months worth of irritation in something that is easily overlooked. My dad is a damn good diagnostician as well so it happens to the best of us. It seems like it is A so you follow A and solve for A and maybe it works for now and later you find out it was B but by then B has caused damage that could have been fixed or leaves you stranded and it's 30 below. Sorry for being so long winded. I'm going to bed for tonight folks.


(“While that part of their hypothesis was correct, the mechanism was initiated by valve bounce, and then the lifter auto-adjusting, and not any ‘pumping-up’ of the hydraulic lifter,” explains Godbold. “Engine builder [and multi-time Engine Masters Challenge Champion] Jon Kaase told me a story once about his experience with hydraulic lifter pump-up. Neither he nor I can fully explain it…”

“They had an internal check valve that got stuck in an oil pump, and the oil pressure went ballistic at higher RPM. This hydraulic lifter engine acted exactly like textbook ‘pump-up.’ The high-pressure piston has a little under half a square inch of surface area, so you would assume that nearly 400 psi of oil pressure would be required to overcome a 150 lb/in spring,” says Godbold. “That type of calculation does not even mention the crazy 1,500-plus-pound inertial forces from opening and closing the valves, but once Jon replaced that messed up oil pump, the engine ran just fine!”

While interesting, that is second-hand experience, which Godbold hasn’t been able to duplicate. “I have never seen anything similar on the Spintron, but we have never gone ballistic with oil pressure either. We could probably make a lifter [overpower the valvespring], but the math looks skewed against it being possible until you get well past 150 psi of oil pressure,” says Godbold. “At that point, you might effectively take away almost 50 lbs of seat load from the spring and thereby make your system unstable, resulting in the bounce up, and then holding open the intake valve 30-plus degrees like I described originally.”)

 

[nelstomlinson]

90psi doesn't seem like enough. Maybe those valve springs really are that weak? Maybe there was a problem with the lifters that was aggravated by the higher oil pressure? Without duplicating the problem, we'll never be sure.

I've had brake problems like your dad's dump truck problem: a little flap of the rubber inside the hose would act like a one-way valve, would let the brake apply, then make it drag after you released the pedal. That took a while to find, too.

 

[1mouse3]

so you would assume that nearly 400 psi of oil pressure would be required to overcome a 150 lb/in spring

Unsure the ratio of the idi rocker, so lets say there 1.5:1 and with a 150 lb/in spring that would be 100lb needed at the pushrod to over come the spring. With what I know working on sbc and bbc rockers, they need to be set at a given preload thats say .050in compression of the lifter. With the idi the rockers are fix and preload is set by length of the pushrod, so preload can be all over the place. It is debatable weather over 90psi is enought hydraulic pressure to overcome the 100lb needed to move the rocker, but is a plausible outcome that adds up to what occured tho. Here is two threads I found searching over this blown out o-ring, one saw over 100psi on a guage and several saying 90psi is the given failure point.


Anyone fix a stuck oil regulator valve or am i stuck with pulling my oil cooler?

Oil Filter O-ring blew! Twice! Why?

 

[Chemgrad]

Unsure the ratio of the idi rocker, so lets say there 1.5:1 and with a 150 lb/in spring that would be 100lb needed at the pushrod to over come the spring.

so you would assume that nearly 400 psi of oil pressure would be required to overcome a 150 lb/in spring

What? You are directly contradicting what you quoted. At this point it feels as if you have decided that you are absolutely right and nothing will change your mind. Maybe you are and maybe you are not, I do not know. If it were my vehicle I would not be satisfied with that explanation but it isn't mine. I really have nothing else to add to this conversation at this point so I wish you the best of luck with your truck.

Merry Christmas and Happy New Year everyone.

 

[1mouse3]

so you would assume that nearly 400 psi of oil pressure would be required to overcome a 150 lb/in spring

This is a incomplete statement that dose not factor in rocker ratio and unsure where this 400psi needed comes from in your statement.

Unsure the ratio of the idi rocker, so lets say there 1.5:1 and with a 150 lb/in spring that would be 100lb needed at the pushrod to over come the spring

This is giving the missing data to your statement, I gave a low ball ratio but could be higher.

It is debatable weather over 90psi is enought hydraulic pressure to overcome the 100lb needed to move the rocker, but is a plausible outcome that adds up to what occured tho

Since Im unsure how this 400psi equals the 100lb needed to move the rocker to compress the spring, I gave my thoughs on the situation. I would think it is a 1:1 and not 4:1 ratio for psi to lb/in force conversion, since fixing overpressure resolved the issue of odd sound after failed start. I am willing to chalk it as a fluke that there was a overpressure and odd sound occuring at the same time, but was just giving my theory based on what I see.

 

[1mouse3]

Read this, to find out about pump-up. Yes, apparently high-enough oil pressure can be a problem when trying to start.

Thanks for the link and sorry I missed it at first, lifter pump up would be the term I would be looking for.



http://web.archive.org/web/20180807.../2012/01/hydraulic-camshafts-and-lifters-101/

The very feature that allows hydraulic lifters to self-adjust and maintain zero lash can also work against the lifters at higher engine speeds. As engine rpm increases, the bleed down rate inside the lifters may be too great. There may not be enough time to refill with oil between each valve cycle, causing the lifter to collapse. Or, if the bleed down rate is too low and the lifters retain too much oil, they can pump up and overextend the valves. Either way, you can end up with valve float, misfiring and loss of power.

DId find another article saying something on this as well. That being high bleed down rate oil in a lifter is a collapsed one that in turn floats a lifter, where a low bleed down oil from a lifter is a pumped up one that in turn floats a valve

(“While that part of their hypothesis was correct, the mechanism was initiated by valve bounce, and then the lifter auto-adjusting, and not any ‘pumping-up’ of the hydraulic lifter,” explains Godbold. “Engine builder [and multi-time Engine Masters Challenge Champion] Jon Kaase told me a story once about his experience with hydraulic lifter pump-up. Neither he nor I can fully explain it…”

“They had an internal check valve that got stuck in an oil pump, and the oil pressure went ballistic at higher RPM. This hydraulic lifter engine acted exactly like textbook ‘pump-up.’ The high-pressure piston has a little under half a square inch of surface area, so you would assume that nearly 400 psi of oil pressure would be required to overcome a 150 lb/in spring,” says Godbold. “That type of calculation does not even mention the crazy 1,500-plus-pound inertial forces from opening and closing the valves, but once Jon replaced that messed up oil pump, the engine ran just fine!”

While interesting, that is second-hand experience, which Godbold hasn’t been able to duplicate. “I have never seen anything similar on the Spintron, but we have never gone ballistic with oil pressure either. We could probably make a lifter [overpower the valvespring], but the math looks skewed against it being possible until you get well past 150 psi of oil pressure,” says Godbold. “At that point, you might effectively take away almost 50 lbs of seat load from the spring and thereby make your system unstable, resulting in the bounce up, and then holding open the intake valve 30-plus degrees like I described originally.”)

Characteristic                         Value     Unit of Measure       Notes
Hydraulic Lifter Piston Diameter       .625       inch                 Typical for most hydraulic lifters
Piston Area                            .307       square inch          Area=Pi(R) squared
Oil Pressure                           100        psi                  pounds of force per square inch
Force on Pushrod                       30.7       pounds of force      F= pressure x area
Rocker Ratio                           1.7        :1                   The force to the tip is reduced by the rocker ratio
Total Force Acting Against             18.0       pounds of force      For typical seat street loads, these values could be 
the Spring Seat Load                                                   enough to offset more than 10% of the total spring seat load,
                                                                       but not nearly enough to overcome the total seat load.

This is the data missing from your quote of the article, that I was not seeing at first since missed the article. Did not see in the article how they used this data to calculate the value they came up with.

Here is a quick calculation table with real numbers of the force acting to open the valve. You would have to approach 1,000 psi of oil pressure to actually overcome the valve seat load, but even 100 PSI could offset ten-percent or more of the seat load.

The person that wrote that article came up with different numbers than godbold that the he quoted.

              Full unseat value      ~10% unseat value
godbold       1,500 psi              400 psi
scott         1,000 psi              100 psi

These are the 2 different values Im seeing in that article

 

[Chemgrad]

I don't know. Like I've said previously I'm not convinced that you were experiencing valve float. I'm not saying that you weren't seeing your valves sticking open but that doesn't necessarily have to be caused by lifter being over pumped. It could have been caused by the valves sticking in their guides.

 

[1mouse3]

It could have been caused by the valves sticking in their guides.

Will keep that in mind if find excessive rocker noise when running.