HLA, what are they, why do they tick, how to clean them, dissassemly/reassembly......

[Silver_Bullit]

Originally posted by Baja_Wes
So you agree there is air in there then

Here's some mathematics to think about. I have assumed the diameter of the high pressure chamber piston is 10mm cos I forgot to actually measure it.

2.5kg (5.5lbf) of force on the HLA will cause the internal pressure in the high pressure chamber to reach 45psi.

Similarly 45psi of oil pressure in the HLA will produce 2.5kg of force from the HLA.

I reckon it would take about 30kg (66lbf) of force to compress the valve spring, which relates to a HLA internal pressure of about 540psi.

At 45psi the air bubble will be 1/4 of it's free height. At 540psi the bubble will be 1/36 of it's free height.

The only time the internal pressure will see 540psi is when the valve is actually open. The instant the valve is closed the pressure will go back to the oil pressure, ie 45psi.

Similarly the air bubble height, and effective lifter height will also change.

Well, the valve springs (stock) are 175lbs/in.

see, what I don't understand is how if your car has been runing for a while the hla's aren't ticking and then you let it idle for 10 minutes or so and they start to tick. If the check ball was working like you mentioned it should be how does the internal pressure drop? It shouldn't drop untill after the car has been sitting for a long period of time. What makes it lose pressure so quickly that it no longer does it's required job of holding the internal pressure? Technically if the check ball was doing it's job the pressure chamber would never leak off the pressure. And you'd never lose the internal pressure to make it tick in the first place.

If the HLA's are clean, and the oil pump is within spec there won't be any tick, and the HLA's should hold their pressure for quite awhile.

I can say from experience that shimming the oil pump is one of the best things i have done. After about 2 hour of the car sitting, i can start it up and ther will be no HLA tick at all. Granted that is after driving for 15 min or more, and still warm, but i think that is a big improvement over starting it right after shutting it off when warm from driving for 15 min or more and having the HLA's tick as if the engine were still cold.

~Aaron

[DrPepper]

what will shimming it do? if you're just pulling it out a few mm's it doesnt sound like it'll do anything

[Silver_Bullit]

Originally posted by lowerdfool
He shimmed the oil pressure releif. Where is that on a 2.0l. I stripped my spare motor down to the block and found a spring in a chamber that I thought was the oil pressure relief but it was held in by a retaining clip on one end with a washer and there wasn't anything on the other end.

You found it and didn't even know it.

If you have a OEM tech manual, look at page 03-01A-77.

http://images.cardomain.com/member_i...71_70_full.jpg

~Aaron

[Silver_Bullit]

Originally posted by DrPepper
what will shimming it do? if you're just pulling it out a few mm's it doesnt sound like it'll do anything

Look at this thread for a description of what the shimming does, and why it is important.

http://www.probetalk.com/forums/show...did=1701022114

~Aaron

[Baja_Wes]

Originally posted by Silver_Bullit
Well, the valve springs (stock) are 175lbs/in.

175lbs/in, and they probably compress about 0.5inch, so that is 87.5lbf at full valve compression (ignoring the preload). So my guess of 66lbf was pretty good

OK, so you didn't shim the oil pump, you shimmed the pressure relief valve. That is completely different. It will increase the maximum oil supply pressure, but will not effect the oil pressure below what the previous maximum was anyway.

Maybe your car had crud stuck under the pressure relief piston and it was constantly bypassing a little. Otherwise it should not really have effected your idle oil pressure. I have seen the following probs in VW engine;
* crud under relief piston
* weak or broken relief spring
* stuck / seized relief piston

[Baja_Wes]

For all the people that have been confused by my strange new theories, here is the results of my testing.

I was changing my timing belt and valve cover gaskets, and thought I would look at my lifters. 2 of the 24 were spongy, and upon further inspection I found that they were spongy because they had air bubbles in them.

I bled the air bubbles out with a pin, so that the lifters were as hard as rocks again. I put the engine back in, and started it. Well it was quiet for a little bit, but the noisy lifter at idle started again fairly quickly.

So my next thing on the list was to change the oil. I was running a 20W/50 mineral oil (still there from last summer, from reading the Haynes manual it seemed like a suitable oil). I have read on these forums I should be running a synthetic. I also heard the valvoline filter I had wasn't so good. So I filled it up with Castrol Synthetic R 5W30, and used a RYCO filter (possibly australian). Started it up, still noisy, so left it idle. After about 10 mins of idling the HLA noise had magically gone. hurray!

2 hours more driving followed, and the HLA noise stayed away. So although we can't seem to agree whether the cause it entrapped air or crud, I know that the changed to synthetic oil fixed my noisy HLA problem.

But I still think air bubbles are a real problem, and nissan agrees with me. The following is from an S14 SR20DET manual.
http://www.offroadvw.net/bajawes/hla_bleed.gif

[Mr. MX6]

So basically all that Wes was to discover something we all knew all along.. lol..
Moble 1 is a god oil to use as well .basically any thin synthetic..
If you have been running crappy oil (not specifically you Wes) then if putting in synthetic doesn’t shut them up you would want to have a look @ doing the patented probe talk kerro engine flush..