Solid versus hydraulic lifters (ahem...lash adjusters)

greiswig · **Posted:** Tue Sep 30, 2014 9:32 am

...or at least I think I am using those terms right.

I got my replacement cylinder head, and there is a stamping on the side of it that indicates it was cast in '08, I think.

My '05 engine that this is going on has solid lifters, in that there is no spring loaded assembly in the tappet. The bottom of the lifter is almost a square shoulder.

But I got some assemblies recently that are a very different design. Some have a strong taper to the bottom of the lifter, and they are hydraulic lifters: there is clearly a couple of mm of play between the socket joint and the main body of the lifter.

I'm being told that at some point VM Motori changed the design. Does anyone know when the design was changed, why it was changed, and whether they are interchangeable parts or not for this cylinder head? Is there a clear better design between these two?

flash7210 · **Posted:** Tue Sep 30, 2014 10:00 am

First...

Can we stop calling these things LIFTERS!
They are not lifters. They do not actually lift anything.
They are HYDRAULIC LASH ADJUSTERS.

There, I've said it and finally gotten it off my chest.

Second...
There should be no solid "lifters" in your CRD engine. They should be hydraulic.
Maybe your old ones are jammed up and wont compress.
If they really are solid, please post a picture so we all can see them.

The whole reason for hydraulic lifters and hydraulic lash adjutsers is so you dont have to set valve lash between rocker and valve stem.
Could you imagine trying to set valve lash on this engine???

greiswig · **Posted:** Tue Sep 30, 2014 11:23 am

Okay, here are pictures.

On the left is what I call "solid." The ball part of the joint between it and the rocker rotates, but does not go down into the plunger body. I have not tried putting in a press or anything, but the others move by hand pretty easily. Pressing it and tapping it pretty firmly with a piece of wood does not "free" it, and it seems like an odd environment for it to seize up in, given the constant wash in oil.

In the middle is one that looks almost exactly like the first one, but the ball part of the joint does recess into the plunger when you press it.

On the right is the design with the tapered bottom. This one also compresses.

I don't know how these things work, really. If the plunger "floats" inside the cavity that it fits in in the head, using oil pressure to keep it in place, why would it need a spring-loaded section at all? If that isn't how it works, how does it?

And again, is there one design here that is better, or one I should watch out for as being incompatible?

flash7210 · **Posted:** Tue Sep 30, 2014 12:12 pm

Usually what happens is some dirt gets inside which jams up the plunger or the check ball.
Sometimes you can soak them in diesel fuel or solvent to get them to free up.
The two on the left look like an older design with a retaining cap crimped onto the body.
The one on the right is a superior design with a retaining clip inside the body.

greiswig · **Posted:** Tue Sep 30, 2014 12:40 pm

flash7210 wrote:

Usually what happens is some dirt gets inside which jams up the plunger or the check ball.

I'll have to look through my stock lifters to see if any of them move. I think I only took a random sample of a few.

So if I ordered new ones from IDParts, which of these would I have gotten?

Hard to believe that any piece of dirt or metal large enough to jam this so firmly would have gotten past the filter. I may do a destructive deconstruction on one to see what's up.

papaindigo · **Posted:** Tue Sep 30, 2014 1:23 pm

If you ordered from idParts I suspect you would get the tapered base ones which is a newer design (the 06 parts manual lists a PN with an AA suffix while the idParts site has the same PN but with an AB suffix indicating and interchangeable but redesigned part).

I cannot find them, darn search function, but there have been posts discussing the compressibility or lack thereof for the lifters. Seems that soot in the oil can cause them to freeze up and IIRC correctly the early version of this part can be opened up and cleaned to restore compressibility.

greiswig · **Posted:** Tue Sep 30, 2014 1:30 pm

Thanks, Papaindigo.

Wikipedia (infallible font of all Knowledge) has the following quote concerning hydraulic lash adjusters:

Quote:

Tappets should be fitted while FULL of oil/diesel liquid: the original-equipment manufacturers specify that the installer should be unable to compress them BEFORE re-fitting, given that these components are intended to take up the slack in the valve train. The reason they tap when faulty is because they cannot keep the gap correctly.

Makes me wonder if somehow the ones I cannot compress are acting right? Is it even possible that they have a valve in them that retains oil so well that they could remain uncompressible for days/weeks?

RockyMountainYote · **Joined:** Sun Oct 20, 2013 8:32 pm **Posts:** 77

You should be able to stick a very small allen key or pin through the top hole of the lifter and that will open up the internal check ball allowing you to compress the lifter, and push the oil out. Not a good idea to stick them in a vice, and definitely not a good idea to stick used lash adjusters back in the head without collapsing them first! It is absolutely normal to be unable to collapse the Lash Adjuster just by simply squeezing it by hand unless you push a pin in it. BTW, That wiki article is garbage for telling you to fit them full of oil, that's how a valve gets stuck open and hits a piston! A little bit for lubrication is good, but you want to be able to squeeze it when you re-assemble

RockyMountainYote · **Joined:** Sun Oct 20, 2013 8:32 pm **Posts:** 77

Also, those are two different designs but work in the same bore, one having a stamped cap to keep the guts in, and the other uses a very fine internal snap ring. This was a failure point on my CRD when I bought it broken. Timing belt was still in time, but several lifters had fallen apart and caused the rockers to fall off. I had the internal snap ring style and this all happened at 98k miles. This is why I urge everyone to do rockers/lash adjusters at 100k. Several rollers were pretty much seized as well.

flash7210 · **Posted:** Tue Sep 30, 2014 2:11 pm

RockyMountainYote wrote:

and the other uses a very fine internal snap ring. This was a failure point on my CRD when I bought it broken. Timing belt was still in time, but several lifters had fallen apart and caused the rockers to fall off. I had the internal snap ring style and this all happened at 98k miles. This is why I urge everyone to do rockers/lash adjusters at 100k. Several rollers were pretty much seized as well.

Really?
I would think the snap ring would be better than a crimped on cap.
Or was it the siezed rollers that caused the lash adjusters to break?

IDK exactly which ones IDparts sells but the picture on their website shows the tapered bottom.

flash7210 · **Posted:** Tue Sep 30, 2014 2:29 pm

Here is a thread with some pics comparing old and new lash adjuster.
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=74904&hilit=rockers
Even shows one with a broken crimp cap.

GreenDieselEngineering · **Joined:** Sun Jun 07, 2009 5:10 pm **Posts:** 1111

Excessive soot in the oil is not good for the 'lash adjuster' and the support pin for the roller on the rocker arm is also worn by the soot. Marginal design at best.

gmctd · **Posted:** Tue Sep 30, 2014 4:39 pm

Instructions for installing new hydralic lifters are very specific: put them in a cup filled with engine oil, manually compress each lifter until unable to do so, then install - this 'pumps up' the lifter such that it can fulfill its function against valve spring tension - being full of oil , pumped up, will not cause the valves to hit the pistons

FYI: most shades, of which there are many on each and all forums, do not have the strength to compress a properly lubricated lifter, new or used, unless using a lifter test jig, designed for testing internal plunger and valve leak-by, where plunger-to-bore fit has exceeded design spec, or\and valve-to-seat fit is deteriorated past max spec

Crimps or snap-rings have finite life span, much as do the valves\seats, resulted by the constant "hammering" action - the internal ring does allow disassembly for inspection, but it is much easier to replace lifters, and cheaper in the long run by preventing future failure for a 'nuther 60-100kmi, or whatever your personal service schedule - early Diesel engines used solid tappets with specific valve adjustment intervals, usually involving removal of injector pipes to remove the valve cover(s), and manufacturers were reluctant to utilize hydraulic lifters due to precise valve-timing constraints, and sticking lifters due to sooty engine oil - sticking lifters will cause offset cylinder timing variation, which affects combustion temperature, which affects efficiency - valve timing is critical in Diesel engines - the ECU can now compensate for this, but was not available in those early times

Valve timing is also critical in gasoline engines, which is why solid-tappets are preferred, flat or roller, with adjustable rocker arms, for racing engines

GDE pointed out a specific concern: oil change and filter intervals are extremely more critical in a Diesel engine - they cannot be subjected to the same casual non-chalance as gasoline engines..............

senatorjohn · **Posted:** Wed Oct 01, 2014 12:23 am

Take notice of gmctd. When you assemble the engine, the lash adjusters should slowly compress to allow possibly all the valves to sit on their seats.( depending on cam lobe position - not 100% sure the collapse of the adjuster is sufficient to negate all of the valve lift ) Hopefully you will not have the engine on TDC or the valve will rest on the piston top as you fit the cams and cover - something could break as you tighten the can box down. Have not read the book on this but the design suggests this scenario. If the crank is at 90* after TDC as for doing the timing, the valves are clear of the pistons. As you fit the cam box, the adjusters will gradually collapse to allow the valves to sit on the seats. The collapse or leak down may take 5 to 10 minutes. I have not looked up the particular specifications, but am going on experience on 30 year old engines with hydraulic lash adjustors. When you start the engine, the oil pressure will quickly pump up any adjusters that have slack between them and the rest of the valve train. If you bleed any oil out of them, it will be replaced by air and on startup, you will have a noisy valve train until the air is replaced by oil - sometimes takes many minutes.
John

gmctd · **Posted:** Wed Oct 01, 2014 11:39 am

Correct - hydraulic lifter design specs clearance between plunger and barrel to allow some leakage -this cannot be overcome by hand pressure, but can be seen as valve train is assembled - the leakage serves to allow automatic adjustment to spec'ed valve clearance at normal engine oil-pressure operating levels

BTW, the internal spring is to ensure correct positioning of plunger and valve prior to oil fill

greiswig · **Posted:** Wed Oct 01, 2014 12:37 pm

gmctd wrote:

Correct - hydraulic lifter design specs clearance between plunger and barrel to allow some leakage -this cannot be overcome by hand pressure, but can be seen as valve train is assembled - the leakage serves to allow automatic adjustment to spec'ed valve clearance at normal engine oil-pressure operating levels

BTW, the internal spring is to ensure correct positioning of plunger and valve prior to oil fill

Interesting. So I verified that I can "free up" the lifters that I thought were solid by putting a thin rod down the socket hole and finding the valve near the bottom of the lifter. What amazes me is that these have now been out of the vehicle for several weeks. I guess they are working properly.

gmctd · **Posted:** Wed Oct 01, 2014 3:08 pm

Correct, and my bad - I used the term hydraulic lifter - hydraulic lifter design consists of a barrel-type 'tappet' with internal hydraulic valve lash adjuster.........................

Bearded1 · **Joined:** Wed Oct 01, 2014 4:53 pm **Posts:** 15

These are basically the same design lash adjusters as found in Mitsubishis (my other toy is a 3000gt). They have frequent tapping issues due to debris locking up the lash adjusters over time and air getting in the bodies. IMO, it's definitely a good idea to clean them in diesel/solvent if you have them out of the motor or have access to them, and oiling them before reinstalling.

gmctd · **Posted:** Sat Oct 04, 2014 6:56 am

Mitsu also used them in their o'head cam 2.6L pickup, passenger car, and STARION turbo engines

Bearded1 · **Joined:** Wed Oct 01, 2014 4:53 pm **Posts:** 15

gmctd wrote:

Mitsu also used them in their o'head cam 2.6L pickup, passenger car, and STARION turbo engines

'Most everything! Thats what I meant :mrgreen:

They've always been pretty good at overlapping designs. No need to reinvent the wheel for everything. Hopefully we'll get some overlapping parts from all these new v6 engines that VM will have running around the next few years.

Solid versus hydraulic lifters (ahem...lash adjusters)

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