3 broken head studs, help me think

[kger]

I went to adjust the valves on my '81 SC yesterday morning and discovered 3 broken head studs on the exhuast side (2 in the passenger-side bank, 1 in the driver's). Needless to say, I'm feeling a rich mixture of sad, panicked, and lost today.

I'd love some help thinking through my options here, and how to navigate the decision tree from square 1 (3 studs in an oil pan, car still on jack stands).

I figure my options are:
1) Replace head studs only
2) Top end or full rebuild.
3) replacement engine (3.2 maybe?), sell my core and sacrifice matching numbers originality (car has a color change)
4) sell the car as-is and take a hit on the head stud issue. This option sucks.

Big Questions: What are the steps I need to go through to determine the extent of work needed? What is the right order of operations to diagnose this (i.e. should I button everything back up and do a leak down test or get the oil and filter analyzed to determine bottom end/ring health, or can/would that all be checked when the engine is torn down to get to the studs anyway)? What is the range of costs I should be expecting in 2018.

I might have space to do the work myself, though I am a fairly novice mechanic (5 years experience on a BMW airhead bike and an e30) and have never opened an engine. But, I'm in the SF Bay Area and have access to good mechanics and shops.

Some background on my car:
-177k+ miles (ODO broke a while back, but car was owned by elderly man and sat for a few years before I purchased it).
-Car ran well until now, no odd noises and pulled strong and smooth. I just drove it from LA to SF during a move last month.
-Has Carrera tensioners, turbo valve covers, MSD ignition.
-It has been burning/losing oil fast - about a quart every 400 miles. There is no noticeable smoke while running, just an occasional large puff right at startup, but there are some leaks (rear-end crankshaft seal, mainly) that could be dropping significant oil when running.
-Clutch is near the end of its life
-CIS has some air leaks but runs well after about 1 min at start.
-Otherwise the car is in good shape. 915 shifts well, new OK color-change paint job, interior is fine, I just rebuilt the entire brake system

I'd like to keep the car long term (at least another 10 years, but maybe /preferably for life).

Open to all thoughts! Thank you!

[walt]

At 177K I would think a top end rebuild including new exhaust studs and valve guides. If you do the work yourself the cost wouldn't be that great but can vary widely depending on what else you find. I might suggest getting Wayne's book on engine rebuilding to give yourself an idea of what lies ahead.

[pampadori]

At that mileage I'd split the case and do all bearings too. I think you can assume $15,000- $20,000 for a shop to rebuild it depending on the amount of work the CIS/airbox, needs to be replaced. Plan for being down for 4-6 months maybe.

Do it yourself and you can do the rebuild, buy the tools, and upgrade to EFI for about $7K- $10k.

Plan for being down for a year maybe.

[rxtrom]

You were about to tackle a valve job so I would say you have the aptitude to read up on engine rebuilding and try your hand at that.

These books are a start to your journey and a VERY good reference to take you all the way through the process.

https://www.pelicanparts.com/catalog/accessories/rebuilding-porsche-911-engines.htm

https://www.amazon.com/Porsche-911-Performance-Handbook-1963-1998/dp/0760331804

At 177k miles you might as well take it all the way a part and keep the original motor running.

Good luck.

[jhelgesen]

What he said.

Get the book, read the book, build the motor.

Ask lots of questions here.

Every job is a excellent excuse to buy more tools.

[Trackrash]

Your best bet is to do a complete rebuild. If you can do much of the wrenching you will be $ ahead. SCs are great cars, and in the long run you will get your money back.

A lot of guys will do the disassembly then send out their parts to be cleaned, inspected and re-worked as necessary. A good option, if you are good with a wrench.

HBTDT it is a TON of work, but so rewarding when you are done.

Which ever way you go take time to carefully DOCUMENT all the parts, labor, and work done. Too many times you hear stories about work done, with no documentation. No excuse for that IMO.

As mentioned, buy the two books mentioned and spend some time reading before you decide the direction you plan to go. There are also a number of build threads over in the 911 Engine Rebuilding Forum. Spending some time there could be worth while.

[RDM]

Good recommendation to read the books / read the threads (I'm particularly partial to this one; I was where you are now: Start with maintenance, end with disaster. Or opportunity) and figure out how comfortable you are with what you'll have to learn (with the help of the board, of course!)

An important question: What Pelicans / PCA members are near you who can drop by? It really helped my confidence to know there were other experienced people who could put their hands on my parts and tell me what to do when I was stuck.

I would split the case. My car had ~ 60,000 miles on it and the intermediate shaft bearing was showing some wear as was one other.

Budget: I think $7-10k is reasonable for doing it yourself, but wildly optimistic for including an EFI/ITB conversion.

[kger]

Thanks all for the quick replies and insights. Books are on the way for some light reading.

How about steps to diagnose the extent of work that will be needed. Should I do a leakdown/comp test now? Get the oil analyzed? Or is that just foolish and the full monty will be prudent regardless given the mileage (could be 300k) and lack of any record of a previous rebuild? I guess it's possible that there was rebuild, then the car sat and then the studs broke...

Any opinions on the value of matching numbers in a car like this 10+ years down the road? How about 5 years? I would consider swapping in a rebuilt 3.0 and selling my core - could save big money and time.

[jpnovak]

I would rebuild the original engine and keep it with the car. The market's do strange things and you don't want to separate unless you have to.

I would do a full rebuild at this mileage unless you have documentation that the bottom end was done. At this age the intermediate layshaft bearings will be all copper as well as the thrust bearing. Best to get in there and inspect and replace. Most likely you will find more wear on the rod bearings than mains.

[dwelle]

long term your best bet is to properly rebuild the motor you have. your car will be worth more, and any motor you buy for a swap will have some level of unknown that comes with it, unless you buy a fresh rebuild from a reputable shop, but that is likely to cost roughly what it would to rebuild your engine. it would have you on the road quicker.

also, being in CA, you can't swap a 3.2 in there and pass smog unless you get CARB to sign off on the swap. good luck there. also, you can't run a more modern EFI system as that won't pass smog either.

if the car is original, your best long term money is to rebuild the motor you have and maintain detailed documentation....

[Trackrash]

Your best bet is to rebuild the motor you have. You know it was running OK. No weird noises or abnormal smoking.

It wouldn't hurt to look around for another motor to swap. BUT unless you have an iron clad history on the new motor, you may not be ahead of the game. Lots of "rebuilt a while back by some German guy, but I don't have any receipts" stories, so be careful.

In this month's Panorama there is a horror story about a guy who sent his motor to some shop in LA only to get ripped off, so do some research on the places you send parts.

Here is something to consider. Use a mirror or jack up the car and look at the cylinders. Count the cooling fins on the cylinders. If they have 11 then you most likely have Mahles and there is a good chance they are re-useable. If they have 10 they are KS and will need to either be replaced or honed, plated and new pistons installed. Good news is, you can upgrade the cylinders to get 3,2L for about the same money as the stock 3,0, with KS cylinders being re-worked.

Good luck.

[Bob Kontak]

Originally Posted by jpnovak

I would rebuild the original engine and keep it with the car. The market's do strange things and you don't want to separate unless you have to.

I would do a full rebuild at this mileage unless you have documentation that the bottom end was done. At this age the intermediate layshaft bearings will be all copper as well as the thrust bearing. Best to get in there and inspect and replace. Most likely you will find more wear on the rod bearings than mains.

This is good info. My car (81) lost a stud at 75k. I did the top end rebuild with Raceware studs/nuts and shipped heads to Engine Builders Supply for a complete re-do including new valves. Ramps/chains. 1997.

Never even thought of the intermediate bearings because the rod bearings were tip-top looking and well inside tolerance with Plastigage. Ring gap, blah, blah, were all within operable service parameters.

There are two members in this thread stating intermediate bearings are an issue for concern even at 100k wear. I can't speak to this but these dudes have more experience than I do.

I suspect your mains are fine. Rod bearings are a little tired.

If you want to roll the dice you can check/change rod bearings without splitting the case assuming crank journals are fine. New rod stretch bolts or an ARP/Raceware/comparable set.

FWIW, Grady Clay (RIP) said just fix what is wrong. However, he was one of those guys that had the engine on a stand in 4 hours.

[Bob Kontak]

I know no one answered you question of how do I know.

Compression test primary. Leakdown secondary. This is from Bruce Anderson.

Then there is crank end play, off sets (I think that's for intermediate shaft), rocker arm ramp condition and rocker play on shaft.

Oh, and clutch pack. That's another long one even if you switch engines.

[Bob Kontak]

I will lend you my tools I bought in 97. Probably $500+ worth these days.

You will have to source a machinist with inside/outside micrometers for bore check like I did.

[3rd_gear_Ted]

Pull the motor and disassemble as needed.
Do a top end only repair.
Replace the clutch and rear seal
Bottom end S/B good to 300K, check oil pump for wear though
Source a 3.6 liter replacement for future and kick it up a notch.

[jjeffries]

My 82 SC was acquired with 181k miles and the engine already apart for a head stud job. That said, the car had a superb service history with frequent oil changes.

I'd done some engine repair before but never a complete overhaul. I really enjoy wrenching and even the cleaning, bead blasting and reconditioning required by this project. I was not/am not flush with cash and had to budget carefully.

A big early win was after fretting about my Alusil Kolbenschmidt cylinders...would I need to have them converted to Nikasil? It proved not: a local guru, Tom Butler (Tom1394Racing here) saw my post and offered to check my P&C's out, found they measured ok, did a special honing process on the cylinders, and soda blasted the pistons. They were fine, didn't even need new rings....great for my budget. I also bought used parts from Tom which sped things up, such as heat exchangers and a muffler.

I then obsessed about opening up/splitting the case. At some point someone here basically told me to man-up and just do it, which I did, and was glad that I did so. Despite my engine having had oil changes every 3k miles, it needed rod bearings, the intermediate shaft bearings were worse and both camshafts had galling. I replaced those those and other consumables, had the cams done by John Dougherty, had my heads and valve rockers done by Craig Garrett (CGARR here), then just took my time and was pretty meticulous. The main bearings amazingly showed no wear (great design). Wayne's book is seriously good to guide you through the process.

Net net the engine rebuild was one of the most satisfying things I've ever done. I've put around 8k miles on it and it runs sweet and leak free. Tom, John and Craig were superb to deal with, as was Len Cummings (did my fuel lines while engine was out) and others who chimed-in here on PP when I had questions. You join a special brotherhood when have your first rebuild under your belt. Best of luck, John.

[Marc Bixen]

We use to regularly do top end only on SC's up to 200,000, with rod bearings and rings. jjefries makes a great point about the rod bearings, but we replace these through the cylinder bores without splitting the case. Intermediate shaft bearings always show wear, but not a huge deal. What I would be most concerned with if you don't split the case is the #8 bearing o-ring leaking. You can only repair this by splitting the case, and that o-ring, if the motor hasn't been apart before, is almost 40 years old. Your call.
If you do split the case send your oil pump to Glen Yee Motorsports, GT1 products in San Demas, Ca. for rebuild and blue printing. Its only about $350, and well worth it.

[yelcab1]

You know, I am of the opinion that you fix what's broken and what is convenient to fix while you are in there, and what you have budget for.

At a minimum, replace all bottom head studs.
If you can afford it, do the valve job.
If you really have money to spare, address the bottom end.

Stop when you run out of money, especially if you have to pay for someone to do this.

[SalParadise]

Originally Posted by Trackrash

Here is something to consider. Use a mirror or jack up the car and look at the cylinders. Count the cooling fins on the cylinders. If they have 11 then you most likely have Mahles and there is a good chance they are re-useable. If they have 10 they are KS and will need to either be replaced or honed, plated and new pistons installed. Good news is, you can upgrade the cylinders to get 3,2L for about the same money as the stock 3,0, with KS cylinders being re-worked.

Good luck.

Get it out, look to see what pistons/cylinders you have, if they are KS Alusils do not touch them unless you really have to, get the studs out, put new ones in and put it back together. It may very well go another 50K - or more. I would go the least expensive route because once you go there it's $6K minimum, probably more, and then you'll be without a car. I would actually drive it until the Fall, pull the engine and do it this winter.

Keep what you have and be smart. Once you go into the Porsche 911 engine Circle Of Trust you're in deep - and only out of it when you've spent thousands and thousands.

[pmax]

At 1 qt/400 miles, I think at least a top end rebuild w/ a valve job is in order. The bottom end, it's up to you.

Mr Bixen's point on the IS bearing wear not being a huge deal is highly informative. Pay special attention to what pros like him say and recommend. I was wondering how much load that bearing gets during operation for a while given many tear downs reveal good crank/rod bearings but show IS wear.