Bad hydraulic lifters -- How can you tell?
 

I am in the process of replacing worn rocker arms and I am wondering about the lifters. According to the manual, you check them pushing with a hammer handle and making sure they do not "drop too fast". Mine do not move at all ... does that mean they are OK or just the opposite?. I also tried "Herr Fuchs finger test" but I cannot make sense of it. The rockers are out now, is there any other way I can check the lifters?
Your advice/opinion will be grately appreciated.

Also, does anybody have a lifter go-no-go test gage that you would like to sell/rent?
(I tried in the tool rental section with no luck)

Thanks.

Jl

they are technically adjusters not true lifters. and i think if they dont go down they are working as designed. the oil pressure supports them and brings them up under the ends of the rockers to keep just the right amount of pressure on the rocker so that it doesnt rattle.

tom w

What is it about the 'finger test' that you dont understand? It is used to get an estimate of the amount of compression in the ball stud when the tip of the cam lobe is pressing down on it, versus no pressure from the heel of the cam.

Tom,
Thanks for the explanation, I have a better picture of how it all works now except for the lifter/adjuster itself. I suppose it is pushed up by oil pressure when the engine is running and it holds pressure when the engine is off, and what we test is the ability to hold pressure.

Chuck,
I am not implying that it does not work. I guess I am not good at it. I just could not tell if there was any difference or not between lobe up and lobe down, probably because of the way I was doing it. Maybe I should have measured displacement with calipers or something. I misspoke, I should have said that I could not make sense of the results.

Jl

tough crowd!

yes, i think you have the idea now.

good luck

tom w

Well, that's the point. So it sounds like you did understand. If you could not feel a difference, then the ball studs are probably OK. And they also passed the hammer handle test.

Personally, I would put it back together - be sure you know that the oil tube fittings are OK - and see how it sounds with the new rockers.

Will do. Oil tube fittings are OK. I plan on turning the engine with the starter (coil disconnected) to make sure everything is in its proper place and that I get nice oil jets out of the lubrication tubes.

Jl

Be aware that this will cause a large mess, because the oil will quickly run down on to the exhaust manifolds (where it will smoke after you start the engine), and the floor.

Don't I know it! It makes a real big mess, but it is worth it to me. My rationale is that I should be able to discover any installation mistakes without causing heavy engine damage.

Jl

Cool :D

John Roncallo

Hydralic "elements"
 

Glad I found this thread.

I had a tapping sound from the engine. I located the #3 intake rocker because it could be wiggled by hand and none of the others could.

I replaced a hydralic adjuster only to find it was not the problem.

I measured with a fealer guage the gap beneath the cam (lobe up) and the rocker. I multiplied that by 1.3 (the cam contact point on the rocker is about 2/3 up the rocker so gap at valve is about 130% of gap at cam). I ordered the "S piece" (the adjustment shim) which was closest to this without being under. I figured the auto adjuster was to allow for the diffence between the available thicknesses.

Without the spacial tools did I do anything wrong?

If the hydraulic compensator is OK, you are down to three things: cam lobe, rocker and shim. One or more of those could be worn out from use. I assume you checked the rocker and it was OK. Assuming the cam lobe is OK too, you are down to the shim. The manual specifies substituting with the next thicker shim (standard is 5.1 mm). In your case I would measure its thickness and add to it the number you calculated. I would buy the shim with the closest higher thickness to the value you got. The reason is that, if I understand how it works, the hydraulic element can compensate for a higher thickness, but not for a smaller one.

Jl

that would make sense.

tom w