Hydraulic Lifters

[BadWeather]

How do they work when there is no oil pressure. I fully understands what occurs when the engine is running however we all adjust these when the engine is not running. I know there is a spring inside and we compress the lifter when making the pushrod adjustment but why is it required to wait for the lifter to bleed down after adjusting. Where did the oil come from to bleed down, the motor is not running? Do new lifters come with oil charged into them? Crazy question I know and I've been adjusting lifters for a long time but I guess I really don't know.

[Mtclassic]

if brand new there is usually light oil if used there is residual oil left in them. I find it easiest to clean the lifter of all oil so they bleed down quicker.

[HDMD88]

The lifter has a reservoir of oil under the piston in the lifter body that it drinks from as the engine grows. When you relax the lifter by removing the push rod it takes a drink of oil as the spring forces the piston up and this locks the piston in place. As you adjust the push rod on a hyd. locked lifter the valve opens and its the valve spring that loads the lifter with enough pressure to bleed off the oil between the piston and lifter body wall. This bleed off time should take about 5 to 7 min, if the lifter is good, in this time the piston is being forced down into the lifter body and the valve is closing. Once the valve completely closes the oil is bled off in the lifter allowing the push rod to spin. If you rotate the engine while the valve is still open or before you can spin the push rod you will run the open valve into the piston or into the opposite valve.
The engine doesn't have to be running to maintain oil in the lifter body.
Doc

[BadWeather]

Thanks Doc I always try to understand the why besides the how. Is it possible to bleed all the oil from a lifter during adjustment and does it matter since you are really just pre-loading the spring. Also is there any preliminary steps that should be taken with a brand new lifter before install and adjustment.

[stair]

Originally Posted by HDMD88

The lifter has a reservoir of oil under the piston in the lifter body that it drinks from as the engine grows. When you relax the lifter by removing the push rod it takes a drink of oil as the spring forces the piston up and this locks the piston in place. As you adjust the push rod on a hyd. locked lifter the valve opens and its the valve spring that loads the lifter with enough pressure to bleed off the oil between the piston and lifter body wall. This bleed off time should take about 5 to 7 min, if the lifter is good, in this time the piston is being forced down into the lifter body and the valve is closing. Once the valve completely closes the oil is bled off in the lifter allowing the push rod to spin. If you rotate the engine while the valve is still open or before you can spin the push rod you will run the open valve into the piston or into the opposite valve.
The engine doesn't have to be running to maintain oil in the lifter body.
Doc

Clear,concise explanation that us laymen can understand,Well done Doc.

[HDMD88]

Originally Posted by BadWeather

Thanks Doc I always try to understand the why besides the how. Is it possible to bleed all the oil from a lifter during adjustment and does it matter since you are really just pre-loading the spring. Also is there any preliminary steps that should be taken with a brand new lifter before install and adjustment.

A proper adjusted push rod will set the piston into the lifter body about .100 to .120......this leaves about .060 to .080 of room before the piston bottoms out, this is the oil reservoir. You can only bleed all the oil off if you bottomed out the piston with an improper adjustment.
What to do with new lifters; There will be too many opinions on that so I won't touch that answer......
Doc

[BadWeather]

Come on Doc enlighten us with your wisdom. Or PM me!!!!

[rbabos]

The only thing you need to do is pump oil into the hole in the side until it comes out of the top with an oil can. Lube the roller end and throw them into the holes. Now they are ready to adjust. Place the cylinder you want to adjust to TDC on compression. Rotate the engine in the normal direction and watch the intake lifter raise and then lower. At this point the piston will be on the up stroke for compression. Set TDC with a screwdriver in the hole to find the high point. If using the OEM pushrods, install the correct colour into the correct lifter and button it up. Preload is determined with the pushrod length. If using the adjustable pushrods this is the time to adjust both intake and exhaust on that cylinder per directions regarding how many turns for preload. Repeat the same process for the next cylinder and you are done.
People tend to overcomplicate the whole process, mainly from bad info and techniques floating around on the internet.
TDC compression automatically places the lifters on the heel of the cam. Simple as that.
A good lifter will work anywhere form 1/4-3/4 piston compression and the 1/2 way point is what we normally shoot for. If it won't work anywhere in this range, it's basically junk with either a faulty check valve or internal clearances too great causing excessive leakage, or the actual term called leakdown.
At any given time there will be one or more valves being held open and this compresses the lifter to the bottom. As soon as it rotates back to the heel of the cam the piston in the lifter extends and will gulp oil from the galley to recharge it. The oil pump keeps this galley full all the time and the oil pressure force feeds the oil into the lifter to keep it extended to preset heel adjustment to create a zero lash in the system. Whenever a lifter cannot maintain it's charge within the timeframe of opening and closing the valve we have a condition where the leakdown becomes greater than the ability of the lifter to recharge noise occurs in the form of clacking. The actual noise is caused from air in the lifer. The piston rapidly compresses the air and then it makes sudden stop. The noise is actually the piston hitting the oil that remains under the air in the unit like a hammer. While not metal to metal as it sounds, it's almost as destructive as it transmits a shock load through the whole valve system it operates from the cam to the rocker. Didn't mean to get this long in the expanation, but though some would be interested.
Ron

[Coolmaker]

Originally Posted by rbabos

The only thing you need to do is pump oil into the hole in the side until it comes out of the top with an oil can. Lube the roller end and throw them into the holes. Now they are ready to adjust. Place the cylinder you want to adjust to TDC on compression. Rotate the engine in the normal direction and watch the intake lifter raise and then lower. At this point the piston will be on the up stroke for compression. Set TDC with a screwdriver in the hole to find the high point. If using the OEM pushrods, install the correct colour into the correct lifter and button it up. Preload is determined with the pushrod length. If using the adjustable pushrods this is the time to adjust both intake and exhaust on that cylinder per directions regarding how many turns for preload. Repeat the same process for the next cylinder and you are done.
People tend to overcomplicate the whole process, mainly from bad info and techniques floating around on the internet.
TDC compression automatically places the lifters on the heel of the cam. Simple as that.
A good lifter will work anywhere form 1/4-3/4 piston compression and the 1/2 way point is what we normally shoot for. If it won't work anywhere in this range, it's basically junk with either a faulty check valve or internal clearances too great causing excessive leakage, or the actual term called leakdown.
At any given time there will be one or more valves being held open and this compresses the lifter to the bottom. As soon as it rotates back to the heel of the cam the piston in the lifter extends and will gulp oil from the galley to recharge it. The oil pump keeps this galley full all the time and the oil pressure force feeds the oil into the lifter to keep it extended to preset heel adjustment to create a zero lash in the system. Whenever a lifter cannot maintain it's charge within the timeframe of opening and closing the valve we have a condition where the leakdown becomes greater than the ability of the lifter to recharge noise occurs in the form of clacking. The actual noise is caused from air in the lifer. The piston rapidly compresses the air and then it makes sudden stop. The noise is actually the piston hitting the oil that remains under the air in the unit like a hammer. While not metal to metal as it sounds, it's almost as destructive as it transmits a shock load through the whole valve system it operates from the cam to the rocker. Didn't mean to get this long in the explanation, but though some would be interested.
Ron

Good explanation. I will add one thing though, had an oil pump (SE plate and pump) that was pumping aerated oil not long ago and the lifters clacked when at idle. Cured the oil pump problem and the clacking went away. Clean oil without air and good pressure to the lifters is the key to them working properly as well.

[rbabos]

Originally Posted by Coolmaker

Good explanation. I will add one thing though, had an oil pump (SE plate and pump) that was pumping aerated oil not long ago and the lifters clacked when at idle. Cured the oil pump problem and the clacking went away. Clean oil without air and good pressure to the lifters is the key to them working properly as well.

Good call on the pump and aeration, when all four make noise. Chances of all four taking a dump at the same time would be slim to nil.
Ron

[HDMD88]

Originally Posted by rbabos

The only thing you need to do is pump oil into the hole in the side until it comes out of the top with an oil can. Lube the roller end and throw them into the holes. Now they are ready to adjust. Place the cylinder you want to adjust to TDC on compression. Rotate the engine in the normal direction and watch the intake lifter raise and then lower. At this point the piston will be on the up stroke for compression. Set TDC with a screwdriver in the hole to find the high point. If using the OEM pushrods, install the correct colour into the correct lifter and button it up. Preload is determined with the pushrod length. If using the adjustable pushrods this is the time to adjust both intake and exhaust on that cylinder per directions regarding how many turns for preload. Repeat the same process for the next cylinder and you are done.
People tend to overcomplicate the whole process, mainly from bad info and techniques floating around on the internet.
TDC compression automatically places the lifters on the heel of the cam. Simple as that.
A good lifter will work anywhere form 1/4-3/4 piston compression and the 1/2 way point is what we normally shoot for. If it won't work anywhere in this range, it's basically junk with either a faulty check valve or internal clearances too great causing excessive leakage, or the actual term called leakdown.
At any given time there will be one or more valves being held open and this compresses the lifter to the bottom. As soon as it rotates back to the heel of the cam the piston in the lifter extends and will gulp oil from the galley to recharge it. The oil pump keeps this galley full all the time and the oil pressure force feeds the oil into the lifter to keep it extended to preset heel adjustment to create a zero lash in the system. Whenever a lifter cannot maintain it's charge within the timeframe of opening and closing the valve we have a condition where the leakdown becomes greater than the ability of the lifter to recharge noise occurs in the form of clacking. The actual noise is caused from air in the lifer. The piston rapidly compresses the air and then it makes sudden stop. The noise is actually the piston hitting the oil that remains under the air in the unit like a hammer. While not metal to metal as it sounds, it's almost as destructive as it transmits a shock load through the whole valve system it operates from the cam to the rocker. Didn't mean to get this long in the expanation, but though some would be interested.
Ron

Ron
Your explanation of adjusting both lifters in a given cylinder when the Piston is at TDC on compression is fine for stock cams or even a very mild cam BUT..... when you get into performance cams that technique can get you into trouble. Longer duration cams with higher lifts and different LSA than stock cams can easily be on a ramp and not the heal of the cam when adjusting that way. Personally I set one push rod at a time ...... simply run the lifter to the bottom of the stroke (heal of the cam) and adjust it, it doesn't mater what stroke the engine is on as long as it is on the heal. Let the lifter bled off and rotate the engine to get the next lifter on the heal and adjust it. This method will assure you that your not on a ramp as you adjust. The push rods have to preload the lifter by .100~.110 simply because the engine can and will grow up to .090 to .100 on a hot day and you want the lifter to be able to handle this growth.
I'm not too sure the clatter from the valve train is from the lifter piston hitting the oil.....listen to the valve train with a stethoscope next time and I'm sure you'll hear the noise louder at the rocker arm than the lifter blocks.
I'm not saying your adjustment method is wrong because in reality that's just how the book would have you do it...but in the performance world things change and the LSA can put that cam in a different spot in relation to the piston position. Point is TDC on the compression stroke doesn't automatically put the lifters on the heal of the cam in the performance world......be safe and do one lifter at a time.
Doc

[Coolmaker]

Originally Posted by HDMD88

Point is TDC on the compression stroke doesn't automatically put the lifters on the heal of the cam in the performance world......be safe and do one lifter at a time.
Doc

Doc thanks, that is exactly how I do mine, and it has always worked for stock or aftermarket cams.

[HDMD88]

Originally Posted by BadWeather

Come on Doc enlighten us with your wisdom. Or PM me!!!!

I do as Ron does....squart oil into the lifter with a pump oil can, fill it up and install it.
Doc

[rob71458]

The last set of lifters I installed, I slid a clear piece of hose over the top of the lifter, lowered the lifter into a dixie cup of oil and hooked up a vacuum cleaner to the other end of the hose. This sucked the oil into the side hole and out of the top, removing all the air. The engine will fire up with no noise at all and no risk of damage to the lifter from lack of oil. Anal, I know, but works for me.

[rbabos]

Originally Posted by HDMD88

Ron
Your explanation of adjusting both lifters in a given cylinder when the Piston is at TDC on compression is fine for stock cams or even a very mild cam BUT..... when you get into performance cams that technique can get you into trouble. Longer duration cams with higher lifts and different LSA than stock cams can easily be on a ramp and not the heal of the cam when adjusting that way. Personally I set one push rod at a time ...... simply run the lifter to the bottom of the stroke (heal of the cam) and adjust it, it doesn't mater what stroke the engine is on as long as it is on the heal. Let the lifter bled off and rotate the engine to get the next lifter on the heal and adjust it. This method will assure you that your not on a ramp as you adjust. The push rods have to preload the lifter by .100~.110 simply because the engine can and will grow up to .090 to .100 on a hot day and you want the lifter to be able to handle this growth.
I'm not too sure the clatter from the valve train is from the lifter piston hitting the oil.....listen to the valve train with a stethoscope next time and I'm sure you'll hear the noise louder at the rocker arm than the lifter blocks.
I'm not saying your adjustment method is wrong because in reality that's just how the book would have you do it...but in the performance world things change and the LSA can put that cam in a different spot in relation to the piston position. Point is TDC on the compression stroke doesn't automatically put the lifters on the heal of the cam in the performance world......be safe and do one lifter at a time.
Doc

I agree, your method is fine as well, however just because the lifter is not 100% fully on the heel visually doesn't mean it's not on the same dimension as the heel prior to the ramp. The result is the same. I've never seen a lifter on a ramp moving a lifter when at exact TDC on compression.You would have no compression in that case. It's still in effect on base circle dia even when approaching the ramp.
As for growth when hot, you would have a serious freak of nature to grow 1/8" in the engine. Taking cyl growth of about .015 and valve seat and valve head expansion of about the same adding clearance to the valve train, throw in some fudge factor of about .010, it would still only be .040 tops for a normal engine. However , this is the reason hydraulics are used in the first place. Without their the ability to maintain zero lash the noise would drive you insane.
Ron