Funny question here, but I have heard a lot about the legendary durability of the 3.0 and 3.2 liter engines, and I still have a Grassroots Motorsports buyers guide issue that claims the 3.0 to be good for 300K fairly regularly. It seems like many of the used 911's that I am encountering for sale are advertising rebuilt engines at between 75-120K miles. What gives? Is it just that many have spent significant time at the track over the years?

Thanks in Advance...

Dan

 

Dan,

My 85 3.2 has 188k+ miles and the motor is in great condition. Compression and leakdown are fine as well as smog comes back "cleaner than some new cars" according to my mechanic. As for the low mileage rebuilts - I think it maybe due to the fact that, in general, quality tolerances were not that high back 20 years ago and owners neglect proper maintenance. So you get some cherries and you get some lemons.

The 2.7s were notorious for requiring inserts in the case at around 70k. If you are looking for a 911 get a Carrera with a G50, if not 3.0 or 3.2 are fine. When I found my current 911 some 7-8 years ago, I had mechanics do PPI's on several car. It took me nearly 2 years on and off to find a car with no prior accident history and with a driveline in great condition. Milage should not be the only consideration in your purchasing decision. My mechanic tested many low miles cars but told me not to buy them.

Hope that helped.
Blu and Au

 

I think Bruce Anderson is responsible for the 'bulletproof' legend of the 3.0. However, just about every year of 911 motor has some issues. The 2.7s pull head studs and the mag case gets cooked. The 3.0's snap headstuds. The 3.2's have premature valve guide wear. The 3.6's sometimes have valve guide wear problems, and have dubious connecting rod bolts.

And that's just the tip of the iceberg.

There's nothing magic about the 911 powerplant, but they're pretty amazing, too.

 

The connecting rod bolts were reduced in size from the 3.2 engine on. That's why it's especially important, if the heads come for any reason, and the 911 sees any track time, that the rod bolts be replaced with the stronger ARP or Raceware bolts.

 

The true problem with all the rebuilds is that the low mileage cars aren't being driven enough to keep them in shape. The 3.0s break down into two camps - high mileage cars that have been daily drivers since day one, and low mileage cars that have had intermittent periods of sitting for too long. I think a high-mileage SC with good maintenance records is a better bet than a low miler with none.

Emanuel

 

I am with epbrown on this... I am always wary ol 20yr old cars with low mileage. If u end up doing a rebuild on a 60k mile car it would raise more questions than one done on a 120k mile car.
By the same token I am always suspicious when u see cars that had their clutch replaced at 50-60k miles. My car has 125k miles and has seen the track often but still has the original clutch... Makes u wonder on how those low miles cars were driven.

 

My brother had his motor removed on his '83 Euro SC for the tensioner upgrade and other routine maintenance two years ago. The shop (a very reputable one with two top notch mechanics) that did the work examined components in the top end of the motor to check for wear and to assess the conditon of that part of the motor after 19 years of use and 125,000 miles. They found no significant wear present anywhere on the motor.

We know the full history of this car and regular and preventative maintenance has always been performed on time on this car. The car has been driven regularily, tracked a few times over it's life, and has been driven hard (but not abused) by all of it's owners (including my brother). Find a good one (SC), and it should last quite a while with proper maintenance.

Jay
90 964

 

Don't dismiss a well-cared-for low-mileage car. I just sold, sadly, an immaculate '81 SC. I bought it 10 years ago with 39K miles, and sold it with 68K. It runs perfectly, and the PPI compression test showed 175 psi in 4 of the cylinders, and 170 in the other two. It uses a quart of oil in approx. 3000 miles. During my ownership, it cost me less than $500 (yes, five-hundred) in non-routine maintenance.

 

Todd, this is why I specified records. A well-maintained low-miler can be as good, but I'd want proof things were being kept up: fluids changed and hoses replaced. Without that assurance, I'd see the car as riskier than a high-mileage car.

Emanuel

 

I agree that it would be riskier than a high-mileage car WITH the same documentation, as a general rule. However, many people who bought these cars new didn't know how important records would become, so they didn't keep them. My SC had some records when I bought it, but not all. Sometimes people walk away from these older cars without complete records for that reason alone, which COULD be a big mistake, IMO. There are often many other ways to tell how a car has been maintained. Of course, virtually all of these cars should have records for the last many years.

 

I had an 1983SC that was a daily driver... 250,000 miles and just starting to smoke a bit.
I dyno'd the car when it had about 200,000 miles on it and got 173hp. It had the upper
rebuild at 111,000 miles and that is it. I totaled the car Christmas day.... yea, I was
depressed till the insurance company gave me $15,000. I thought about another
SC but I went with a 89 Carrera, so we'll see if it does as good as the SC.

 

My '76 C3 was the first year for the 3 liter motor. When it started snapping headstuds at ~110,000 eveything in the motor, except valve guides, was well within specs.

So from my perspectibe it appears that headstuds and valve guides are the weakest areas.

Not surprisingly I see the same weaknesses in the newer 3.6s

When I rebuilt my '97 M64/21 I made sure that headstuds, valveguides and rodbolts were all replaced(as well as a few other little things).

 

The SC engines are bullet-proof.

The issue is that age has taken it's toll on the cylinder head studs. Let's face it... they're 20+ years old.. and they are starting to break.

I just rebuilt my '82 105k mile SC. I did not split the cases. The cylinders were perfect. The valves/guides were perfect. There were however, a couple of cylinder head studs that looked like they were ready to snap.

I ended up installing new factory rings, 24 new cylinder head studs/barrel nuts, new timing chains/guides/tensioners, new valve springs, and had all new valve guides/valve guide seals, and a high quality 5 angle valve grind done, all new gaskets/seals/oil return tubes, etc..., and all new exhaust studs/bolts, new clutch, open up tranny and install new synchros as well as a few other parts... while-you're-in-there :-)

But in the end.. the only thing that was a potential problem were the cylinder head studs.

I think what you find is that a lot of cars have had a broken cylinder head studs... and the "while you're in there" syndrome set in.... which is... rebuilding the top end/timing chain system... and it only makes sense... since... uh.. you're in there :-).

TonyG

 

I have a customer with an 80 SC into the mid 200K area on the original engine, does every service and drives it hard every once in a while. my 3.2 made it 180 before the second owner slacked off on maintaince and it spun #5 rod bearing.

And "while I'm in there" syndrome has hit me too.

 

For what it's worth, I bought an 87 Carrera Targa and had to have the valve guides replaced at 47k miles and had the alternator go out around the same time. Apparently these are the two main weak points of the Carreras so neither fault was unexpected. Other than that, the car has been dead reliable and very enjoyable to own and drive.