1st time rebuild 3.0
 

Howdy, I'm new to Porsche. Got a sweet 1980 3.0 down to the cylinder base gaskets for seepage repair, and 1 Head bolt snapped. Every thing is great inside. I'm looking for advice on replacing the rings. Pistons and cylinders are round and undamaged. Replacement was the norm for my past experience with verticle engines. Should I reinstall the used rings? Thank you for your assistance. Mark

Check the end gaps when they are installed in their respective cylinders. Also, be sure to check the clearance on the upper ring lands. Anything more than 0.004 is too much.

How do the cylinders look in terms of hatching/wear? Typically you can hit these with some red scotchbrite pads and oil to "deglaze" them a bit. I did this on my recent 3.2SS build and the new rings on the old cylinder surfaces sealed up nicely.

Mileage on the engine? Take a magnet to the cylinder wall. If there is attraction? Pictures help.

Top end rebuild.......
 

Mark,

You did not mention the location of the broken head stud. I would guess it is the lower (exhaust) cylinder head stud. Was it made steel or not? Check for the presence of dilavar head studs on your engine. They are prone to breaking than steel studs. If they are dilavar, time to replace them.

Inspect the mating surfaces between the cylinder head and the cylinder for defect or imperfection that could cause leak. Depending on the mileage and condition of your valves, valve seats, valve guides, and springs, you could clean the heads and lap valve grind each one. Test for leak and sealing.

Tony

Thanks for the help.
Story time: This motor was transplanted with low miles
(40K), but it shows an overhaul with mismatched heads, Cam Chain Tensioner mod,etc. It sat for 15 years. My son brought it home. The fuel pump and alternator were dead. The oil had backfilled the case and flowed to the wrong side of the pistons. In The Great State of California I need to pass Smog with the EGR and Air Pump functional. So a clean and inspect was due.
#5 wouldn't hold pressure for a rotten exhaust valve seat. Looks like carbonic acid etching, and may be beyond grinding.

Tony, The broke stud is the aft exhaust on #4. There is less than an inch of shaft remaining at the case. Are visegrips the best tool? All the studs look the same; Only the exhaust were Dilivar, yes?

Mr. Sully, I don't know the milage, but the cylinders still show machining patterns.
The magnet does not respond.

KTl, The .004 checks good. The cylinders are not even dirty from previous tear down. I read that some folks did not recommend new rings in old jugs.

http://forums.pelicanparts.com/uploa...1348157203.jpg

Bad seat

http://forums.pelicanparts.com/uploa...1348159737.jpg

Broke stud

http://forums.pelicanparts.com/uploa...1348159798.jpg

Nice jug

http://forums.pelicanparts.com/uploa...1348159848.jpg

Looks like nikasil liners to me?

Non magnetic is Alusil.