tyro

Bill,

How did the re-torgue turn out?

Did you discover a discrepancy between your clicker and beam-style wrenches?

I've gone and ordered a Cometic gasket, as I'm expecting my wide fire is toast.

billindenver

No, my clicker turned out to be exactly the same torque as the new craftsman beam style I bought yesterday. It was worth checking though.

tyro

Back again..

Found what appears to be lift (?) on the exhaust side of the head - carbon trails to the water jacket. The fire rings were very much intact.

Installed my Cometic MLS and torqued the ARPs to 90ft-lb for fun.

No more lost coolant, but now a nice little oil leak close to the pressure port near #4.

Have a look at the photo, I wonder if the milling marks are not smooth enough to accommodate the MLS gasket?

No spray was used, Cometic only recommended RTV near the warm-up port near cylinder 1.

When does it ever end?

billindenver

Did you go with MLS? The pic shows a standard gasket.

tyro

I did go with MLS. Pictured is the WFHG that blew coolant - finish on head/block is the same.

billthe3

I was discussing head stud/bolt torques over the weekend with Andial951 and FRPorscheman with the stock studs. It is ok to torque the aftermarket studs up to 80ish, but what about the stock studs?

I'm thinking the reason for my bad compression may have been head lift, so with my planning on running higher boost than before, what kind of torque can I put on the stock studs?

m42racer

I gave up reading every post here. Here's my opinion.

The MLS Gasket compresses only the embossments, period. The Gasket DOES not compress, so the Torqure applied to the stud puts the head into tension. Heres what happens typically. The Head is never flat or the machining is too rough. There is a recommended RA finish for the Head when using the MLS. Most modern shops have machines that do this quality all day long. Nothing special here.

The Studs are never installed correctly. The Thread quality in the blocks are almost always compromised from over torquing and age. The stock stud will never stretch. The Gasket does not compress, so all of the torquing forces go into pulling or stretching the threads in the block. In most cases Thread locking fluid has been used. The heads studs should never be installed with Locktite or similar. They should go in with antiseize and never bottomed. When the stud is tightened, the stud should be able to turn until the thread engagement with the nut takes over. There is not friction or thread pulling when this occurs. The stock studs do not stretch either. Another bad no no. All of the tensile goes back into the threads in the block. Ever wondered why studs pull out of the block? Ever wondered why some Gaskets blow in ceratin places. Maybe the clamping loads are uneven across the head due to the anchoring of the studs in the block. Another bad fault is the similar threads at6 each end of the stud. They should be dissimilar so that each end torques up differently.

To ensure good clamping and even clamping, the condition of the threads in the block should be checked. The head should be checked for collasping around the stud holes as well. Reapir the threads in the block, install the proper designed studs without thread locking fluid, and torque with oil or antiseize paste under and on both sides of the head washer. Make sure the Head washers are flat. Bevelled washers will not give even friction on contact with the nut.

There is so much to this, but it is taken for granted by so many. Try it and see the difference.

tyro

While I agree with and have followed the bulk of your statements, there is one point that needs clarification:

When you say "The heads studs should never be installed with Locktite or similar", are you referring to the stud end which resides in the block?

I suspect that to be the case; so do you have any idea why the engineers/assemblers at Porsche put so much Loctite in there to begin with?

Perhaps you mean "leave well enough alone"?

billthe3

I was sort of wondering about the locktite on the studs myself a couple of weeks ago, as it seems that whenever you see an engine being built on one of the many car shows on tv they just thread the head studs in and torque them up.

tommo951

But as i recall ARP recommend using threadlock into the block/stud.
If nothing else it seals the thread against coolant ingress. What downsides does this have?

billindenver

It has none. I have to wonder where m42 developed his secret techniques, because many of us have built enough motors to number in the hundreds and every one of those had loctite on the head studs. If I were to count the ones at daimler/chrysler I guess I could probably count them in the thousands. Many of those were not Porsche motors though, so if Chris White agrees with m42, I guess I will revisit my techniques, as well as calling ARP to tell them they are wrong.

Also, a stock stud is a stretcher, that is how it holds its tension...it is supposed to stretch. Whether it stretches because the stud bottomed out or the threads are locked...it still stretches. I'm not sure I am properly following m42's logic.

evil 944t

Bill, if the stud is bottomed out you will compromise the threads. The studs are strong, the threads are not. You will damage the the threads way before you stretch the studs.

I never lock use lock tight on my factory studs and I have had no problems. I also don't use a cutting tap to clean the threads. I use a thread reforming tap on all the threads.

KuHL 951

I think the main reason ARP requires cured threadlocker is the the stud height is set prior to torquing the nut. If the stud was bottomed out or turned in the hole during torquing this would effect that height. I have always used Loctite on head studs, but never on head bolts obviously. The earlier statement that threadlocker 'should never be used' doesn't jive with anything I've ever seen or done before.

m42racer

One should always build an engine the way you feel is correct. There are many ways to do it for sure.
Who ever builds the engine has to stand behind what they did. If it works the way yopu did it, great.

But when you read all of the posts about failures and why, it is time to look at how the assembly was done and see where it could be changed for the better. I am not here to advocate that my way is the way at all. Just that when the smae issue keep coming back up, maybe its time to relok at the convential way.

The threads in the block are always stretched. If the stud stretched as it should, why do the threads in the block get compromised? Why does the head collaspe around the stud bores. Remember, Porsche built these engines with the old style Gasket for stock boost and for limited time against their warranty. Once out of warranty the repair is done by the book over and over again. You run more boost etc and the repair will be the done exactly the same way everytime. If the threads in the block are damaged, the block will be replaced. This is Porsche's line I'm sure. If you wish to use the engine in adifferent way to stock, more boost etc, then maybe the assembly ways have to change too.

To cahieve an even clamping load across the Head, everything needs to be looked at. The threads in the block need to of quality, the stud needs to under its yield length, installed in such a way that the torque or tensile is not affected by its installation, the head needs to be hard so it will not collaspe under the torque load and the nuts and washers be of quality so they do their job without adding friction etc.

From experience, studs are installed with locktite fior no other reason other than they (Porsche) wnat them to stay in the block upon disassembly. The Locktite adds nothing to the security of the stud once torqued. If the stud does stretch, the head does not collaspe and the threads in the block are good, how does the stud loose its tensile and come un done? It does come un done by other means. This is why the uneven clamping loads across the head often show up in failed Gaskets. You want the stud to turn under torquing, so that the thread engages in the block without bottoming. The clamping load from the upper nuts will take over and the stud will stop turning once the force overcomes the turning movement. This way most of the friction does not affect the torque load. The stud will turn and when the loads become greater than the turning movement, the torque will become effective. Bottom the stud in the block and this turning movement will pull the thread for sure. No amount of locktite will overcome the turning movement of the final torque. This is why often the stud seems to jump and chatter when torquing. All this is doing is compromising the final clamping loads.

This is nothing new here. Just good assembly practices and practiced by the top builders. Simple and correct assembly.

Again, the assembler should do it the way they think is correct. You have to be responsible for any failures. Porsche will not help you.

Cory9584

Does the block have to be resurfaced to use an mls, or is it usually enough to have the head done? also where does ebs get their studs from? another similar application? arp told me theres no such thing.