hydraulic tappets / hydraulic valves (or hydraulic lifters)

The internal work of the hydraulic valve lifters, commonly found on lots of cars and some motorcycles too. the idea behind this is that LIQUIDS CAN NOT BE COMPRESSED.

While some valve systems use screw-and-lock-nut OR shims (metal plates in different sizes) to adjust their valve clearances, engines with hydraulic valves do not need periodic valve adjusting.

This is how it works:
engine oil is pumped constantly by an oil pump, enters through the one-way entrance (where the green ball seats) into the chamber. The oil is then trapped in this chamber and acts as a solid (that can't be compressed remember?)- and by that eliminates any clearances in a chain of moving parts (between the cam lobe and the VALVE head).

Now in case of wear, there is a chance that when the engine is stalled, the oil pressure in this chamber will drop drastically, and that is why when you start such an engine once again, you will notice a ticking noise for a short while, maybe couple of seconds. Noise is clearances, and the noise stops as soon as the oil pump will push enough oil to fill the tappet chamber again.
In a good engine, pump keeps feeding the system oil, always equal the volume of oil leaking out of the system (of natural clearances between the parts, wear, etc)

The pros of this system is that it rarely needs maintenance and an engine that has such a system will need no periodic valve adjusting . In motorcycles most Harleys have hydraulic valves, and some KAWASAKI cruisers too.

The cons of the system is that a contamination (little metal part that the oil filter didn't catch, etc) can cause the hydraulic tappet to leak oil from the chamber , allowing it to be susceptible to squeezing = therefore not closing clearances = therefore causing valve system to make rattle/ticking noises. Repair then, is relatively complicated. This can happen in old engines where the wear is too much and the parts shown here (tappet lifter, plunger, body) cant hold enough oil, that leaks from the sides (where ever it can).

You can see a more clear flash version of this in:
http://www.motoetc.com/home/2010/03/hydraulic-valve-lifters/

Category:

Autos & Vehicles

Tags:

• hydraulic
• tappets
• lifters
• valves
• cam
• lube
• מרימי
• שסתומים
• הידראולים

[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.

[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]

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..

[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.

[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.

[arnoldt14]

@FYI1337 I noticed on some v8s that the cam lobes ride on shims over buckets on top of the valves, do you need to adjust these as much as engines with rocker arms or pushrods?

[RandallFlaggNY]

@IYRONEJAMES I use The Force.

[MrHeyDAWG]

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

[VertigoSqueal90]

Replace all of those parts, to completely fix the problem - which.. is apparently around 700 to 1000 bucks to do so. So, is there another trick to adjusting them? cause if not, I might as well shell out another 500 bucks and buy a completely rebuilt 3.9 V6 Magnum crate engine, for 1500. any suggestions or advice?

[VertigoSqueal90]

I have a question man, please help me out! - I have a 93 Dodge Dakota, 3.9 V6, and the engine runs strong.. but has a pretty good tick to it. I've taken the valve covers (tappet covers) off, and they are non-adjustable hydraulic valves, and from your video I'm guessing they adjust themselves - but why the tick? and I've been told now, to fix the ticking and shit, I'll have to replace the cams and all of the running parts.. (not the driving parts, but all in the engine).