Studs Snapped, Engine Rebuild Required!

keynsham1 · 05-04-2013, 10:45 AM

Just posted this on the general forun. I forgot there was a specific engine one!.....

I have just taken the offside (UK) lower cam cover off my engine to find four of the six studs broken. I suspect that they have been like this for a while as one of the nuts is missing so I think it was 'noticed' in the past with no action taken!

The engine runs perfectly and burns little if any oil. It certainly doesn't smoke. I want to get this rebuild right but don't want to do loads of work for the sake of it. I plan to replace every gasket I can get to so I eliminate my oil leaks, and obviously replace the studs. Is there anything else I should do whilst I am in there? I was wondering about piston rings? Also what studs should I use? I am no millionaire so some of the racing sets I have seen are out of the question. Are Porsche supplied ones OK these days?

E Sully · E Sully's Garage

What year and model, mileage, known history can you give us to work with.

keynsham1 · 05-04-2013, 01:09 PM

1978 911SC 3.0 targa. 74K miles, never raced ar been on a track as far as I know. Cam chain tensioners replaced recently with standard (not hydraulic) replacements. Completely standard engine with no known history of a rebuild. Was running fine. I just discovered the studs when I went to check the valve clearances.

E Sully · E Sully's Garage

The mileage is low enough to skip the bottom end as long as no sign of bearing material in the oil.
Top end I would just send to a competent shop to measure the valve stems and guides to see if in spec and replace as needed.
Cylinders, pistons and rings same deal, only thing being the cylinder type. If Alusil then it is recommended to reuse the original rings when possible. Nikasil I would install new rings if cylinders look good with the cross hatch still showing. Nikasil is slightly magnetic, Alusil is not.
On my '86 3.2 engine I replaced all the valve guides and exhaust valves due to known wear issues with their valve guides, and new rings in my Nikasil cylinders after having them cleaned up.
I also bought the slightly expensive o-rings for the rocker shafts to insure aginst oil leakage from that area.
Just make sure to mark and bag everthing carefully to reinstall in the same location.

Green993 · Green993's Garage

Call/email Henry at Supertec Performance (SoCal) to see if his head studs will fit your application. His head studs are arguably the best.

Supertec Porsche Engine Rebuilder

GeorgeRud · 05-07-2013, 03:29 PM

I'd second dealing with Henry at Supertec. He also has a idler arm bushing that gives a larger loading surface for the idler arms that is supposed to help with the chain tensioner problems. If you install the collars to prevent collapse of the original tensioners, you should be good to go.

timmy2 · timmy2's Garage

All good sound advice above, or... do what I did "on the cheap"... Replace the lower studs with the same steel ones used for the top row. Replace all the necessary gaskets. You will need the complete engine set to get everything you'll really need.
Re-use or replace the rings, measure everything without splitting the case to see if it is in spec, clean it all up and put another 100,000 on it.
I did mine with 81,000 on it, and 4500 miles later it runs great and hasn't used a quart of oil in the last 1600 miles since fixing a leak I missed/caused with the darn rocker shafts..... (torque is 20 not 12...!)

And I re-ringed it because I broke one, and I have the dreaded Alusil cylinders......

Add the tensioner guard or install the hydraulic ones (not cheap)...

Did a bunch of other "while you are in there" stuff but none necessary to the function of the engine.

Lapkritis · Lapkritis's Garage

Easy to get carried away and find yourself over spending if you go ahead buying what everyone tells you is the best. You can do just fine shopping with the host for basic bits to get your job done especially on a street duty car.

Dennis above gives sound advice if you're not in a hurry to part ways with a lot of cash.

johndaroza · johndaroza's Garage

Time for an engine reseal use your old barrings! and you can clean up every thing and change you'r rod bolts and recondition them too.

AlfonsoR · 05-07-2013, 10:18 PM

Quote:

Originally Posted by Green993

His head studs are arguably the best.

And by definition, also arguably not the best. But I would not mind calling Henry.

If you are sure no oil is getting by the rings, then I would not re-ring. When you pull your cylinders, pull the piston out with them so that they are not disturbed.

Since you have a 3.0, you can also inspect the rod bearings, and simply button it back up, if it passes inspection.

Good luck!

keynsham1 · 05-08-2013, 03:41 AM

Can I pull the barrel and piston out in one go by removing the gudgeon pin? I don't know if there is any room to do this. If so, I coudl then refit the small end, pin and fit new retaining clips.

timmy2 · timmy2's Garage

Quote:

Originally Posted by keynsham1

Can I pull the barrel and piston out in one go by removing the gudgeon pin? I don't know if there is any room to do this. If so, I coudl then refit the small end, pin and fit new retaining clips.

Pick up Wayne's engine rebuilding book. It tells you how to do it. I did mine like that, Had the pistons sitting in the cylinders for a few weeks while I waited for parts, replaced the studs and cleaned things up.
Then I broke one lower oil ring on re-assembly and said F...-it and ordered all new ring sets.

How to rebuild and modify Porsche 911 Engines is the title. With his 101 projects book and a Bently manual you can fix most everything on your car.

fred cook · fred cook's Garage

I just did this on my SC engine. With the engine on an engine stand, I started with cylinder #1 (left rear by the distributor). After getting the heads off, I set piston #1 at top dead center and pulled the cylinder back until the piston pin was just barely exposed. Then I used a small sharp flat bladed screwdriver to get under the locking ring and pried it out, catching it on a finger on the other hand. Then, and this is the neat part, I used a brake spoon (adjusting tool) that is sharply curved on one end and gently curved on the other to reach between cylinder #2 and #1 and used the sharply curved end of the brake spoon to press out the wrist pin part way and then reversed the brake spoon and used the other end to almost finish pushing out the pin. You will need to grasp the wrist pin with a set of padded pliers to work it out the last few millimeters to allow the rod to drop free. Repeat on cylinder #2 and then #3. Do the same process on the other side starting with piston #4. You should wind up with the pistons still in the cylinders, eliminating the need to compress rings and reinstall the pistons. Be certain to contain the piston pin locking ring as they try to "jump" when removed! Hope this helps.