Cams and clearances
 

Looking for Cam bearing and cam to lifter clearances etc., I'm not finding any information on this.

First I am getting some tapping not bad but none the less it was there and after Thstone incident this summer I don't want to let it go. I rebuilt the bottom end plus valves, valve springs, retainers etc. in the winter of 2012 to 2013. The top of the heads was pretty much just reassembled.

Is it OK to put new lifters into a used lifter cage. is there any clearance spec?

Is there a clearance to check between the head Journals and the cam bearings?

While checking lifters to cams is there any clearance minimum /maximum?

I noticed most of the lifters spring back to being pressed 2 don't. My guess would be these 2 are my tap. 4 other don't seem to depress as far, but still compress and then rebound.

Any thought or experience is welcome?

You can clean & test the lifters by submerging in new clean oil & heating to 250 degrees. Keep them in order so they can be returned to their mating cam lobe if good. Once up to temp compress the plunger & watch for dirty squirts coming out the side until it's cleaned out. If it won't pump up firm, replace it.



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That looks like a good trick Thank you.

Still if it come down to it are there any special trick, or measurement's that I have to maintain if I end up replacing a couple lifter or would it be best to replace them all and the cages. I already had a price it's about $1000 a head in parts.

For safety reasons, it's better if you do it when your wife is not at home… :p

Someone attended my M96 102 Engine Assembly School.

The clearances that you seek do not exist....

So for reasonable tolerance. If I use a digital inside inspection micrometer on two axis's say 12-6 and 3-9 on every hole in the tappet housing and there is less than .0002" to .0004" variation, the housing should be OK to reuse.

Then if I purchase a new OE Porsche lifter I should be able to install it with out a second thought.

How about measuring the housings and tappetts as above and then matching them up so the clearances are as even as you can?

Suggest you 'search' this issue.
1. The lifters were revised and an update part # given. Nobody knows what the change was.
2. The lifters that do not 'spring back' - are they jammed ? The tappet is in two mating pieces with a spring inside and a little circular retainer. So you mean the two halves of the tappet are jammed together?
I chased this issue hard recently .The tapping was not the full extent of the problem. A rod bearing was beginning to fail.A feint lifter (or so I thought) noise that over a few days got louder.BTW several of my lifters were jammed also.
Cut open you oil filter,drop the pan ,check your mag drain plug ,fit an LN Filter .
I am experimenting with BMW lifters because they were a fraction of the price.More if you search.

I have researched. You may try 99610504172.They supersede the others no real difference. This was mostly because the 2005 and 2006 987.1 engine they change all the number but many of the part are the same. Dealer show number superseded

I used an electronic stethoscope the noise was coming from the intake side of cylinder 4. Also where I found the tappets that do not pop back they are compress continuously at least while cold. I did notice that once the engine was hot the sound became less noticeable so I plan to steel my wife's electric fry pan and do the hot cleaning suggested. I may still replace them all anyway.

The sump was spotless and the filters have been clean since the first oil change after I rebuilt the engine and run in March 2013. The only things not replaced at that time was the cams, Lifter (tappets) and Tappet housings. I should have replace the tappets.

Just to clarify terminology: The Tappet is inside the Lifter.
Schaeffler Automotive Aftermarket Germany | Products | Hydraulic tappet
Most changes to the tappet would not be visible unless you dismantle the assembly and make almost microscopic comparisons between old and new.Both Porsche and INA changed their Part numbers.Porsche #.....72 is the latest. They are at least $40 each from the dealer.The alleged substitute is $9.At this price, I stopped playing with my tappets and replaced them all.
Once the tappet has jammed in the fully compressed position ,it is difficult to remove it without slight damage to the external surface of the tappet. When the tappet is jammed ,it will be noisy in operation.It won't unjam itself with use. If the tappet develops excessive clearances ,it will seem to function correctly but will be 'soft' when you test.It will also be noisy.When you test an unworn tappet,it is quite firm and compresses slowly-assuming it is completely full of oil..
My speculation is that once the tappet wears and goes 'soft' ,it will jam compressed when driven at high revs.When several jam, you'll get pronounced lifter clatter,not just tapping. Trying to differentiate between that clatter and early stages of crankshaft+connecting rod bearing noise is more than my ears+stethoscope could discern.
If your 'lifter' noise is on cylinder #5 (like mine was ) I would be concerned.I had both bearing wear and some tappet collapse issues simultaneously at 90k miles. The interesting question is -"Why?". The correct answer(s) to that question could save a lot of financial distress in the M96 community.
This is all just speculation -I am not an expert.

Most M96 lifters fail due to debris inside them. The 948 Cayenne engine used these same lifters and they do not fail. These are anti- drain tappets, as they only have one inlet in them and no outlet, makes them work great most of the time; but once debris gets in, it doesn't leave.

I have modified lifters in the past and found many benefits, some of my engines in the future will go to solid lifters as that development moves from the X side to the production side here.

solid lifter = higher redline?

able to tell the difference between lifters and piston slap with a stethoscope?

Not higher redline alone, much more radical cam grinds are possible. I tend to make power power under the curve, reducing the redline that necessary to make power. Most of my engines peak at 6,500 RPM. No need to ever take them to 7K.

Piston slap vs lifter noise
 

In theory you listen(with a 'scope) for lifter noise on the cam cover and piston slap on the lower part of the crankcase half. The problem would be if your bores are egg-shaped because of wear on the thrust side of the bore. You'll get some slap but there isn't much(inexpensive) you can do about it. The most appropriate engine oil may reduce the rate if such wear but .....
I like Jake's solid lifter because it eliminates (?) one source of problems.
It appears there was a design/tolerance/variation issue with the older lifters because some other cars that use the same INA/Schaeffler part had the same problem.
In my case all 24 tappets had honey colored oil in them. Despite that, some were jammed in the fully compressed position, some were 'soft',others were perfect. No debris in the oil ways, no abnormal wear on the lifter bores.Please note I said "jammed+fully compressed". New lifters are almost impossible to compress when they are correctly filled with oil. The new (BMW)lifters I purchased came in individual oil-filled containers. The funny thing is, they came airmail from Europe and I presume the pressure reduction during the long flight caused them to leak into the cardboard outer packaging. What a mess.

The lifters are always shipped in that thin oil that gets everywhere. When we order them I always ensure that they are double bagged. I've gotten nailed by my importer before.

We modify brand new lifters all the time.

Cayenne 948 lifters
 

Jake made a useful comment about the Cayenne 948 lifters.It would be useful to know the part# because the earlier Cayenne uses 996..... 72 just like the updated Boxster & 996 part#-according to Pelican.
For the Cayenne 2003-10 Pelican show:
Porsche Cayenne (2003-2010) - Cylinder Head & Valvetrain - Page 2
So I guess we need the lifter from a later 2011+ Cayenne ?

Part #s are deceptive. You can't judge a part from it's number these days.