broken valve spring
 

I could not figure out why my 911 sc was having the problems that it was having.
Driving along and all of a sudden it was running terrible. when I say terrible I mean really badly. I pulled the engine and went through everything trying to figure out how I would have a burning in the exhaust and issues on acceleration.. well I found it when going through the heads and saw a broken valve spring. it is just the one and I am curious if you guys think it is ok to just replace the one valve spring? I know that there is an inside and outside spring and consider that to be one.

here is a picture.. everyone loves a picturehttp://forums.pelicanparts.com/uploa...1413159246.jpg

Valve springs have become a really big deal. A company called PSI is doing the best valve springs right now. They use a super clean wire in manufacturing.

The standard for valve springs has been Japanese Kobe steel but there has been a real revolution in materials recently. VIMVARVAR (vacuum induction melted twice vacuum arc re-melted) valve spring steel produced in Pennsylvania is currently an alternative to the Kobe steel that’s produced in Japan.

Here's an article on wrote on valve trains last year.

Richard Newton

great article but if I switched over I would have to replace all 12 for continuity.


That was kind of the question...
thanks
Mike

911SC's, '78-'82, had a valve spring problem due to manufacturing QC so this is not uncommon. To this day, we still see broken ones that were not caught previously.

Today, each & every valve spring we buy/use gets tested to make sure its in spec and we only use factory ones in street cars. Race engines get something else, however thats another story altogether.

If your SC was built during that period and you have no documentation they were ever replaced, I'd strongly recommend replacing them with new factory ones. You do NOT need anything stiffer or different unless you are spending a lot of time at the track. :)

I had a '78 SC that had 5 intake valve springs replaces over the years before I owned it, the POs had great records on that car's history. I know not any help but just thought I'd share.

Steve, do you know dates of manufacture that are affected? My '83 was built in late '82 which creates some doubt here. Thanks!

This problem affected many '78-'82 SC's. Porsche didn't release a list VIN's, they simply dealt with any complaints on an individual basis.

Engines with a broken spring can "miss" a little bit at idle and a sharp person can note this. Unfortunately, other things can cause the same things so I recommend checking the springs at every valve adjustment.

Are we talking inners, outers, or both springs?

Mainly outers.

Mine was an outer spring... it had a top end rebuild at one point and I was sure the previous owner did the springs. I guess ultimately I will replace them all...

Thanks for the input.

Mike