3.6 headstuds

safe · safe's Garage

Hi
I'm rebuilding a '90 3.6 engine. The headstuds are all steel (magnetic), no dilavar. Are there any issues with theese studs, good to keep?

/Magnus

Flat6pac · 10-20-2012, 05:16 PM

Sounds like someone has already been in there changing out the 24 dilivar that were there.
Bruce

safe · safe's Garage

This engine has the graphite head gaskets, so it might have been apart before. But based on the wear off the valve guides it must have been a loooong time ago....

On the other hand I'm not sure this engine ever had dilavar. I have checked a 92 RS engine and a 97 NA, both had 24 steel head studs.

But steel is OK on these engines??

Flat6pac · 10-21-2012, 02:55 AM

Yes steel is fine, otherwise you would have to replace 24 dilivars in and youre back into breakage possibilities
Bruce

Arrowhead · 10-22-2012, 03:43 AM

1990 came with steel head studs. The later 993 came with dilivar. It is my opinion that the later 3.6 dilivar head studs are the best way to go. These studs have recognition that is long overdo. Some rebuilder even reuse them, but I am not sure they will admit it to a customer. The problem is, they are expensive. If your on a budget oem steel satisfactiory.

safe · safe's Garage

Well, I was thinking of going with supertec studs, I have those in my 3.2 engine.
But I think I will stay with the steel.
Everybody is on a budget of some sort, rebuilding a Porsche engine is never cheap. If I can save money on the studs I can put it to good use for something else, lika a MAF-kit.

Henry Schmidt · Henry Schmidt's Garage

Supertec head studs are the best choice for all air cooled 911 engines.
For a plethora of reasons.
It might be helpful to post pictures of the sealing between the cylinders and heads if you have them.

safe · safe's Garage

Quote:

Originally Posted by Henry Schmidt

Supertec head studs are the best choice for all air cooled 911 engines.
For a plethora of reasons.
It might be helpful to post pictures of the sealing between the cylinders and heads if you have them.

Hi Henry
I think they are great too! I talked a friend into using them when he rebuilt his 993 engine, that had sealing issues on 2-3 cylinders.

I haven't looked at the sealing surface that closely on my 3.6 engine yet. I can take some pictures later this week.

safe · safe's Garage

Took a closer look at the sealing surface on one cylinder, the rest looks about the same.
I see that some parts of the surface is a little duller than others.

BTW, what is the easiest way to remove the head gasket and how would I prep the heads and cylinder surface before reassembly?

Arrowhead · 10-27-2012, 04:13 AM

Very good pictures. It looks to me like they were sealing very good.

safe · safe's Garage

Quote:

Originally Posted by Arrowhead

Very good pictures. It looks to me like they were sealing very good.

That was my thought too.
If I had to guess the duller parts of the sealing surface that is halfway between the studs may indicate that there has been some movement. But that would in my opinion be because the heads are to weak and flex and better studs wouldn't do anything to help with that.
But I'm just guessing, hopefully Henry, or someone else, will enlighten me with their wisdom!

Flat6pac · 10-29-2012, 09:34 AM

This engine has already been into because the head face is opened to the head gasket of the later engines and the cylinders have the gasket seal. Thats the reason for the steel studs.
Bruce

rollingjack · rollingjack's Garage

I used 993TT dilavar studs by rebuilding my 964 engine:

Flat6pac · 10-29-2012, 03:42 PM

Last time I used the 993 dilivars, they were a dollar more than the regular dilivars. Now about $40 each.
Br

Cupcar · Cupcar's Garage

Quote:

Originally Posted by safe

Took a closer look at the sealing surface on one cylinder, the rest looks about the same.
I see that some parts of the surface is a little duller than others.

Because Safe's engine is using steel cylinder studs the above photos of his engine are interesting since they look to me as though there is fretting of metal at the head to cylinder joint.

I think this fretting is because of the increased clamping force created by the relative lack of expansion of a steel stud and is exactly what one would expect during expansion and contraction of the engine when steel studs rather than Dilavar are used

Below is a photo of a 3.6 head I removed from an engine yesterday with stock Dilavar studs and 107,000 miles on it and it and the rest of the heads look very nice in comparison to Safe's with no fretting at all.