sanchez

I own a 1981 911SC with 155,000 miles. Here's the bad news:

I have a broken head stud on the #6 cylinder. After the engines gets hot, I can hear a popping sound under load, coming from that cylinder. I understand that the engine must be torn apart to fix this problem, and every mechanic has suggested I do a full rebuild while it's opened up.

I really can't afford to rebuild, but the car is useless to me if I can't drive it. What can I expect to pay? (approximately?) Can I upgrade to larger cylinders/pistons and is this worth the extra cost? I'd like to keep the CIS system (hence, no 3.2 swap)

Any suggestions would be much appreciated!

TODD
1981 911SC

Bill Gregory

Todd,

If your leakdowns and compressions are sound and you don't have excessive play in your valve stems, just replace any studs that are broken or close to it (most likely all the lower exhaust-side studs). Yes, anytime your engine is out there is always stuff you can do or improvements you could make. However, remember the SC, barring head studs, has a very strong engine. Unless you have a reason to replace/upgrade, and money is a consideration, then don't do anything that might be optional now. I'd guess that replacing head studs (assuming you need to replace all the lower studs) you're in the $3000-$3500 ballpark.

On upgrading, read Bruce Anderson's "Porsche 911 Performance Handbook" where he discusses upgrading the pistons and cylinders with the Mahle "Max Moritz" (if I remember his name correctly) 3.2L upgrade.

I don't know what Florida requires for gas, however, if Florida goes to a gasoline requirement with ethanol as an additive, you might be glad to have that 3.2L engine with Motronic-based fuel injection, as opposed to CIS. CIS touches the gas more than any of the Motronics-based systems, and with ethanol holding water in suspension in the gas, this can lead to difficulties in the CIS fuel injection system. There have been several articles on this in Pano and reprinted in Up-Fixin'.

Tom F

You can drive these cars with broken head studs. I drove my '83 for over two years (an 20,000 miles) with two broken studs. When I pulled the engine apart, there was no damage to the cylinder or cylinder head mating surfaces, which is what you would worry about, I think. Also, the cost of a head and a cylinder is not so great that I would give up driving your car, or make yourself broke to do the repair. Save your money, and do the fix right in a year, in my humble opinion.

Porschephanatic

sanchez,If your cylinders are out of round, I think the 3.2L Max Moritz p/c conversion can be performed retaining the CIS, for $3500 more or less. Andial has compatible p/c sets as well, but Bill is right about the ethanol additive. Does Fla. mandate ethanol? My $.02.

sanchez

Thanks for the replies! I'd love to have the engine rebuilt RIGHT NOW, but this is not going to happen on my current budget. I'll have to look into the ethanol question.

If and when I decide to rebuild, can anyone recommend a mechanic in the SE Florida who I can trust to not rip me off once the engine is opened up?

TODD
911SC