What is this, inside 78 911 3L

[Pat D]

Today I am disassembling my air cooled 3 liter to adjust vales and when I removed both exhaust valve covers I found these broken parts? What am I looking at and does this mean for damage and repairs

[TwoBluPorsches]

Yeah, not a big deal.

Drop the engine, rebuild it with new studs


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[Bill Douglas]

Sorry Pat.

That is the car speaking to you and saying you have to open your wallet.

[G450X]

Search Dilavar head studs and you will find one of the few downsides to air cooled 911SC/Carrera ownership…

[al lkosmal]

yep,
You have a couple broken head-studs. I've not rebuilt a 3.0 in the last few years that didn't have at least one. They typically used steel for the intake studs and Dilivar for the exhaust studs. The Dilivars break.

there are a few high-strength alternatives, but steel studs, intake and exhaust, work great.

regards,
al

[2.7RS]

Spanking machine. Welcome


You have to pay to play

[RSTarga]

Those represent your initiation fee to the air-cooled world.

[john walker's workshop]

At least they broke at the top end instead of at the case. Easier to remove then.

[Pat D]

What is the head stud discussion? Does this mean a motor rebuild or just replace all the head studs? I've got everything disconnected and ready to pull the motor out.

[Mark Salvetti]

Depends. How many miles? The cam carriers and the heads have to come off, and you need to pull off the cylinders. Most of us would replace all 12 exhaust studs at this point, the ones that haven't broken yet will likely break later.

Since the heads are off, it makes sense to have the valves and valves guides redone.

You don't need to split the case, but if you have very high mileage you probably should consider it.

Mark

[TwoBluPorsches]

Hi Pat,
My early comment that is isn't a big deal was flippant and I didn't recognize that you have only a few posts and are likely a newbie to 911 ownership.
I apologize for that disrespect.

You may or may not be looking at a full rebuild. Broken head studs often snowball into a full engine rebuild.

At a minimum you are looking at the disassembly of everything from the case outwards.

it is a big deal and fairly involved.

Getting the engine out and taking it to a shop is the first step.
Rebuilding a 911 engine is time consuming, expensive and has various pitfalls for those who don't put a lot of work into figuring out how to do it correctly. Not something you can learn from youtube.

Take a look through the engine rebuild forum and you'll get an idea about how much is involved.
I won't assume that you can't perform a 911 engine rebuild, but it is a big undertaking and most people won't attempt it once they see how much work it is.

normally a high mileage engine with broken studs would benefit from a full rebuild.

Take a look at this thread and see how he discovered that his engine needed cams, he had some issues with cam timing gears and while he was in there he had the heads rebuilt.
Another 911SC Engine Rebuild

As the engine comes partially apart to replace the head studs, you or your mechanic will be looking at the parts and determining what needs to be replaced and what needs refurbishment or can be reused after proper cleaning.

[rwest]

Originally Posted by Pat D

What is the head stud discussion? Does this mean a motor rebuild or just replace all the head studs? I've got everything disconnected and ready to pull the motor out.

This book is a great resource if you’re planning on rebuilding it yourself or if you are going to pay someone, so you at least know what to expect.

https://www.pelicanparts.com/catalog/shopcart/BOOK/POR_BOOK_BKPTEC_pg4.htm

[Mark Salvetti]

I just noticed that the photo of the valve cover shows what looks like a broken head stud without a barrel nut. What do you guys make of that? I suppose the nut could have safely found its way into the sump through an oil return tube?

Mark

[john walker's workshop]

No, the nuts are in dry areas.

[eastbay]

Originally Posted by Mark Salvetti

I just noticed that the photo of the valve cover shows what looks like a broken head stud without a barrel nut. What do you guys make of that? I suppose the nut could have safely found its way into the sump through an oil return tube?

Mark

Last motor I took apart was missing a nut and washer on one stud.

I take that as an indication that someone was there before me. As these motors approach the 50 year old mark finding an original and unmolested one becomes more rare.

[theiceman]

Just as a point of reference my 78Sc had this also. At the time i had 250k km .. i just dropped the engine , got Waynes rebuilding book and went at it. Decided not to split the case. The machine shop said the heads measured perfect and merely cleaned them up and replaced the seals.

It was a lot of work but by no means difficult. Learned a ton from the guys here and it was a great project.

Car has run fantastic ever since.
Thesed ays i Imagine that's about 8-10K worth of work these days to have just a top end done without splitting the case as costs have skyrocketed. But the guys with recent experience having it done will chime in for sure.

As noted above i just replaced all lowers with steel and it has been fine

[theiceman]

i think lots of guys have this pic so you are not alone.

[LIRS6]

What to expect to see when you get in there.

Jason

[Old H2S]

Here are some lessons learned the hard way
1. Neil says in a thread on the rebuild page " Everyone wants you to build their engine". There are 100 formulas for each type.
2. Is it leaking somewhere where the case needs to be split? where is it leaking really? some times hard to learn. It is hard to get what is better than what's in there now.
3.We are all Porsche fags here, what do you really need? How long will you keep it? If it comes out a dishpointment to you will you build it again? or sell it ?
4. I am being an AHOLE here, not to you but I just went through this experience and I got information for all. Do not split the case unless you have to, main reason is the parts you replace will be lower quality than what is in there and what you want or need can take time to find to build your creampuff engine. How fast do you want to go? How fast do you want it back together? This two are diametrically apposed. How much work can you do? How old are you? how old do you feel? Are you married? These seem silly until you read all the other threads here. If you do a shortcut and you do not know it was a shortcut it still will bite you in the butt. People think these are 6 lawn mower engines put together ... they have 130 places to leak and if it has a leak the resale price just took a dive, what else is messed up inside? When you see the pro's advice here it is a WARNING, pay attention grasshopper.
5. Parts.. are junk now, from Germany, from Porsche, counterfeit, China, Mexico. You will hate it when it takes time or money to get what you want. I do overkill, 20k in parts and machining is normal for 250 HP. labor not included. A lot engines here have been apart for a long time, we are all better in our dreams. Have you ever dropped an engine? It is no fun, but you will get good at it, speed comes experience, mission creep is real and striving for Porsche perfection is cheaper than a mistress, boat, plane, drugs, but it is going up daily and the prices for a 911 are starting to recied, a 30k engine price will not make your 60k 911 worth 90k. I'll stop here I'm starting to rave.