hydraulic tappets / hydraulic valves (or hydraulic lifters)

[ynardhowar1229]

This vid went viral on Moscow

[freddymathis820]

This video went viral on Vatican City

[seapeddler]

You do need to readjust an (OHV) hydraulic lash system especially after the valve seats into the seat, on a rebuilt engine. This seating-in exceeds the zero lash and puts stress on the lifter/cam, which prematurely bleeds the lifter overnight. Checking hot lash after 5000 km. is probably a good plan. You should only see a mirror smooth scrub pattern on the valve stem tip and rocker arm pad,even after 50 000 mi. But if you're rich don't worry.

[MrHeyDAWG]

hi thanks for posting that awsome video, it help me alote for my exam tomorow :)

[IYRONEJAMES]

using the hydraulic principle and physics , Explain how can a 10kg mass is capable of lifting a 100kf mass..

[golbis]

@IYRONEJAMES for ex, motorcycle front brake, squeezing the lever, pushes a small piston lets say 2cm diameter. it pushes liquid onto a larger piston 10cm which pushes the brake pads. the differences in piston size, is your power multiplier . in this case a 1kg force you apply on the lever, would mean brake pads are pushed with 5 kg force.

[RandallFlaggNY]

@IYRONEJAMES I use The Force.

[FORDGTFANATIC]

ok i get it now. glad my engine is hydraulic over the standard push rod

[nextgapdotcom]

@FORDGTFANATIC what engine have you got?

[FORDGTFANATIC]

@nextgapdotcom 351w

[nextgapdotcom]

@FORDGTFANATIC I think your ford gt engine does have push rods, but the valve lifters are hydraulic

[domyaska]

thanks a lot for the explanation!

[golbis]

Vincentantwerp has made a comment on hydraulic tappets (hydraulic lifters) i accidently clicked on REmove instead of REply :

Question:

So the hydraulic lifter will set itself to the right length.

If the hydraulic lifter over time needs to be longer to adjust, it will fill with more oil.

But what if f.e. the valve seat gets worn, the hydraulic lifter needs to be shorter: How does the oil get out to adjust itself???

Because the valve is a 1 way

Good video !

[golbis]

answer:

good question. well, the oil does not stay there forever, it constantly bleeds out. thats why the oil pump keeps sending oil to the system. and in any way, the tappet lifter oil pressure will never be stronger than the valve spring. it always adjust itself to the maximum tolerance possible, no more.

[golbis]

ok i think I know how you see it, and whats confusing you, but even if this tappet would fill with oil gradually as you say (which is sth it doesnt do and not supposed to do, but for the sake of theory ill continue with the idea), all you will get is LESS or MORE valve opening, without affecting the timing.

there is however a variable-timing-cam system, that works on the idea of an expanding chamber by oil pressure (not a tappet but sth else),it's the Kawasaki concours 1400 engine for ex

[QuantumCarl]

Yeah, VVT. Oil is routed into the cam gear where the timing can be advanced and retarded, usually the intake is advanced and the exhaust is retarded within' 5 degrees meaning that the intake is open quicker at high RPM so as to suck in more mixture, and the exhaust is open later to allow for a complete burn.

[QuantumCarl]

Also, the intake is retarded and the intake is advanced at lower RPM's to allow for much more torque and it makes things more fuel efficient.

There's also VVLT which controls valve lift, too.

[QuantumCarl]

OHHHH.

So it's like a sort of... old timey VVT?

[golbis]

mmm good comment :), but not really. the tappet is variable in length yes, but it doesn't change according to rpm, or change the valve timing. it just fills with oil as the engine works and expands only as much as clearance allows it, not more not less..

[QuantumCarl]

So what is it's point then, if not to allow a valve to open longer at high rpm and/or open shorter at low rpm?

It seems to me it causes a variance when it's empty from when it's full... :S

[FYI1337]

To maintain zero valve clearance. Rocker arms and push rods wear during use, and after a while you start to hear ticking with solid lifter because the things have shifted, but a hydraulic lifter takes up the slack and adjusts itself, and compensates for thermal expansion.

[QuantumCarl]

Ohhh! I get it.

So, since metal expands and contracts due to temperature, and an engine gets quite hot, this is a sort of... uhh... yeah, like... the rods expand in length just enough to cause an issue? And so the tappets act more so as a cushion...?

I just woke up so I'm struggling here... :x

[krispast8]

Thanks. I knew what they did but its nice to see it in motion. Just had one of mine fail completely and is rattling like mad in the head.

[golbis]

thanks for your comment. hope you get yours fixed soon..

[BarneyWobba]

Useful, thanks.