mnmasotto

I have a 1987 3.2 Carrera with 77K on the original motor. The oil has been changed every 3K since new. No short trips (car was not abused or a Garage Queen). I was using a quart of oil every 800 miles. I though this was too much although it is within factory specs. My mechanic showed 2-3% leak down on all cylinders and the compression was fantastic. The car ran GREAT and Never SMOKED! I decided to take the plunge and have the top end taken apart.

Thank God I did this! THE VALVE GUIDES WERE SO WORN OUT I COULD MOVE THE VALVES WITH MY FINGERS!!! The machine shop said this was very common in supposedly perfect 911's with >75K. The oil usage was soo bad that a few of the rings were sticking in the piston grooves - could of been an absolute disaster!

For what is worth - please pay attention to your oil usage! I got off easy. My P&C's were in great shaped and reused. By the way I re-ringed Alusil cylinders with great success!

r911

thx for posting this warning

were these the stock guides?

wwest

Huh...??!!

Compared to some of the engines I've torn down and overhauled over the years that one looks PRISTINE. Probably would have went another 100,000 miles without the tear down in my estimation.

mnmasotto

The photos in the above caption are before re-assembly(After machine work at Ollies, Santa Ana). The photos I took during the tear down were unfortunately too large to download onto this site. Sorry
The photos of the worn out original factory guides would have been great to post.
Mark

Mad_AL

try imageshack.com and link to it

pjc

Think you have been unlucky - these motors are pretty strong - I'm surprised you haven't been inundated with contrary comments.

My basic '76, 2.7 - not considered the best Porsche engine design, went over 100,000 miles before I got fed up with the oil leaks. All the tests, as with your engine, were factory spec but on tear down the tollerances were all used up hence new barrels, pistons (alusil not nikosil), cams, followers etc. Now shuffle pinned, decked, new bearings etc she should run for another 150,000 miles.

PJC

Gary R.

Did you notice that after sitting a while a giant cloud of blue smoke came out the back when you 1st started her up?

LaughaC

Isn't a puff of blue smoke normal after sitting 4+ days?

Gary R.

A "puff", i'm thinking more along the lines of a contained forest fire...

srf506

Sorry, just gotta ask, did you have valve adjustments made per the maintenance schedule? Sounds like you might have been running without properly adjusted valves for quite a while to have faithfully changed the oil every 3000k miles, only run cruising kind of trips and have that kind of wear after only 77k miles. That is a typical for those types of cars.

Steve Weiner-Rennsport Systems

Your situation mirrors exactly what we have seen for 25+ years.

Not only has Porsche used a very soft guide material that doesn't wear well, they REALLY vary in fitment from the factory. Some were simply fitted tighter than others and that effects how they last before needing replacement.

Last year, we did a 3K 993 (almost new) whose guides had .030 clearance and the valves wobbled freely in their bores. Needless to say, this car would have been a premature oil burner had the owner not proactively fixed it.

Worn guides do not reliably show in leakdown testing; one must pull the valve covers and measure the side-play in the valve spring assembly to assess wear and that takes a bit of experience to do that accurately.

Jay Gratton

Interesting, when I did my 911's top end at 150K it was perfect. I just had the engine out to do the clutch and did the heads anyway. Interesting warning however. Thanks for sharing this information.

UberXY

77k is about 100k short of a high mileage 911.

Steve
84 Carrera Targa

Peter Zimmermann

I have to agree with Steve, I don't think that the factory always operated within their own +/- tolerance range. We did 3.2 liter cars in the 40K mileage range, and have had 100K mile heads apart that were still OK. And it's true about leakdown tests, the guides cannot be evaluated because the valves are closed, and the guides are outside the combustion chamber. Using oil consumption as a guide (we usually let our customer cars get between 300-400/quart unless they chose to do the heads sooner), combined with engine sound (the sound of an engine with badly worn guides is very similar to an engine with loose valves), we never mis-diagnosed an engine. In all honesty I never learned the diagnostic method that Steve uses (measuring side play at the springs), but perhaps when some doubt exists it's never bad to have one more valid test.

One factor that I've always considered had a major impact on 3.2 liter valve guide wear was the quality of the 1,000 mile service. We took care of a number of cars that never had the covers off at 15K miles, and a few that had not had the covers off at 30K miles! Oster blender filled with marbles, anyone? Those cars needed guides before 75K miles, or were sold, but the cars that came in for the first major (15K) that had valves that were correctly adjusted early in the car's life fared much better.

Mark also mentioned something, in the many, many engines (with a history of faithful oil changes) that my shop had apart, we really never saw "stuck rings." I would be very interested to know more about the revs used for shift points, the type of oil used, if any oil additives had ever been used, etc. Almost 4K miles/year certainly qualifies for enough miles to avoid extended down time... this one really has me curious. We had an occasional customer ask us to ready their commuter car for a quick blast to Las Vegas, after the car hadn't been out of Santa Monica for three years. We always advised them to be sure to check their oil level after the first 100 miles, and put three extra quarts in the trunk for them. The reports were varied, some cars didn't use a drop the entire trip. some used two quarts in the first hundred miles, and nothing after that. Stuck rings? I don't think so, maybe rings that lost a little of their ability to seal because of extended low rpm city driving, but not stuck.

srf506

Peter, don't you need that extended mid-range-rev "cruise" every once in a while to keep the rings really pushed into the pistons in order to make a good seal? That's what we always did. On a brand new motor went a little easy until the motor "freed up" some and then ran it on up the rev band and held it there for a few laps. The old "urban myth" of long continuous RPM runs being not a good technique to break in a motor weren't really what the rings needed. I know the lugging at low RPM was a bad thing on the lower end, but the rings really needed that pressure to effectively get them sealed.