Ok, so if we drop the "bulletproof" moniker, then how about "pick of the litter" with regard to other models of Porsche. Of course that could imply cats or dogs......and Jaguar has one of those already claimed.

I look at it like this, after owning a 911SC. There is a reason there are so many (relative to other autos) low mileage 911's in the world. The cost of a major repair can be exorbitant, so in fear of that they aren't driven that much. A higher mileage 911 that has been well cared for.....but probably has broken head studs and worn valve guides can be had for considerably less than a low mileage 911 that probably has broken head studs and worn valve guides as well, so in this instance "buy the best car you can afford" may not be wise. Got that?:D

It is quite common for some 3.2 to be running excessively rich resulting in poor low end performance and resulting in dangerously high cylinder head temperatures and premature valve guide wear.

Back when the late Bruce Andersen, PCA national tech chair when he was in business, he did observe a correlation between rich running Carreras with premature guide wear.


Joe

Just came across this thread. Jon Slocum's comments about being able to drive the car to the track , I've done that numerous times, (northeast Connecticut to Watkins Glen), flogged it mercilessly for 2 days, multiplied by having my brother use the car in another class, then drove it home with zero problems....I hoping to do that with the 82 SC coupe I bought (in pieces) last summer, but the car that's been there and done for me that is my trusty 74 Alfa GTV. The two cars are kindred spirits and the owners of one often seem attracted to the other (as per a number of guys on this forum). Not bad investments, either. John in CT.

Are you 100% certain it's just the valve guides? I've seen bad decel smoke from cracked rings as well. Did they do a compression test and leakdown also?

Did the white smoke suddenly appear or did this issue get worse over time?
Can you give us some more details?

Can anyone post some sort of explanation on what valve guides are, how they wear out, why you get white smoke on decel when they are worn, etc? I know what valves are, and I just looked up a photo of valve guides. I assume the valve goes through this tube? Does the tube get loose, allowing the valve to wobble and/or not seat properly?

Stuck a valve stem in a worn guide to show the space that sucks in oil. Seen way worse than this. The stem seal can't control the oil at this point. The seat pic shows how the grind stone is only contacting one side of the seat after replacing the guide. The valve had wobbled around and beat on the seat, wearing off material in the untouched area. Then exhaust gasses passing through the gap add to the erosion. Very typical side effect of worn guides, and a good reason to not put off the repair for many thousand more miles. The seat needs to be ground down until it cleans, then narrowed. Seat wear like this is generally where you get high leakdown readings.

http://forums.pelicanparts.com/uploa...1427754075.jpg
http://forums.pelicanparts.com/uploa...1427754093.jpg

Question - would worn valve guides cause more tapping? My 3.2 runs great, no smoke, no bad oil consumption but there's just more tapping which is noticeable from the cabin. It's not so bad but it's just noticeable. The other day it got worse but disappears at high rpm and what's weird is that the next few days it ran OK although the tapping is still there though not as loud. Sorry for the hijack but I feel the info may be useful in the future in this thread. Thanks again friends! Wil 84 Carrera

From my experience with my 3.2, YES

2.7s with their original copper guides would tap like crazy one minute and be quiet the next. Those guides wore so bad you could find 1/2" of slop at the valve head.

Not that I'm eager to do this but is there a difference between the $17-22 guides and OEM $165 ones from out host?

Very true,shame theres people out there buying low mileage cars for top $$$ and having early problems,have owned a huge amount of cars in my time ,never had problems with the well used ones ;)

The well used ones, if fairly well maintained, take care of quite a bit of maintenance for the guys who buy them later on in life!

I've used the canyon brand phosphorus/bronze ones for quite a while with no issues.

+1 on that - thanks Joe!

angela

Thanks for sharing the pics, John.

Can someone explain how oil passes through the worn valve guide hole?
This is my understanding on an engine.
The oil is down near area C, and doesn't go past the piston rings.
The valve guide is up near the cam in area E.
I can see how the valve gets loose and may not seat properly and start getting down down prematurely.

But how is oil getting UP to area E?
Wait, is this b/c the 911 has a flat 6?
Is oil passing through valve guides unique to 911's and their flat 6 configuration?

http://upload.wikimedia.org/wikipedi...ne_diagram.jpg

Sugarwood, the camshaft section is also lubricated with the same engine oil. This is where the oil that is lost through the worn valve guide come from. The pressure between the rocker and the cam lobe is one of the highest one in the whole engine, so have to be well lubricated.

http://forums.pelicanparts.com/uploa...1428440758.jpg

Explanation of Bird911's diagram:

1. Oil comes from bottom of external oil tank/reservoir, goes under oil cooler and enters engine case directly to oil pump pressure pump.

2. Oil pump delivers oil up into engine case.

3. Engine case distributes oil to oil galleries and on to crankshaft.

4. Near pulley end of crankshaft, in the case are passages that deliver the oil out of the case to the external cam housing oil feed lines

5. These oil feed lines connect onto the camshaft housings and deliver oil back into the engine again via the spray bars within the cam housing.

6. Oil from the spray bar is directed to the camshaft lobes via pin holes in the spray bar and also to the cam bearings via holes in the cam housing where the spray bar passes thru the housing.

7. Oil from the cams and spray bar is slung & sprayed all over the housing and therefore the rocker arm shafts, the valves and the valve springs are splash-oiled. So the guides see oil by coincidence of oil splashing all over the place around the rotating camshaft, rocker arm and valve springs

8. Oil from the cam housing and crankshaft gravity-drains to the bottom of the engine case and is sucked up by the scavenge section of the oil pump, to be sent back to the oil tank (filtered by the oil filter) and then start the process all over again.

Later 3.2's
 

I've got an 84 911. Am I to understand the valve guides were better for the earlier 3.2's? I hope so. 192,000 km and working well. Smoked alot when I first purchased the car but the PO had too much oil in it ;)