When to rebuil engine?

[tpham]

Thinking about having engine rebuilt and was wondering all those who have your engines rebuilt I have following questions:
1. What is your engine size?
2. mileage at rebuild?
3. What prompted you to do so?

In his book Bruce Anderson said 100K to 120K.

84 911.

[mwbaum]

How soon you need to rebuild depends on your driving and maintenance habits, and the type of engine you have. The 3.2 engine is very strong and unless you are unlucky with the valve problems you could get a lot more than 120K before a rebuild is necessary.

[ping1957]

Just had a top end rebuild on my 3.2 @107k miles.
Excessive oil usage was the main reason to go ahead with the rebuild. Worn valve guides were definitly an issue.

[ronin993]

just a test

[Rollins]

How much does a rebuild cost on say an SC ?

[RoninLB]

IMHO, a full rebuild is a consideration if you have top end problems at 100k+ miles. Internal parts will show wear and if you will keep the 911 you might want to keep it bullet proof. True, it may keep running till 250k. Perfection in my 911 became an obsession, be carefull.

[Thomas Owen]

'88 3.2
Needed only valves/valve guides but I did the entire engine since I will keep this car.

[StuttgartDavid]

The serious answer to "When to rebuild your 911 engine?" Is "When it breaks, not before!"

Panic stricken owners (usually new Porsche owners) rebuild their engines out of fear that "something will might go wrong." To try to avoid the cost of a mysterious and sudden engine failure, which is highly unlikely and will probably never happen, they end up spending a guaranteed $5-10k on a fully engine rebuild!
Ironically, this is very near the cost they would spend even if they did suffer from catastrophic engine failure. Even if you put a rod through the case, the additional cost of replacing or machining the damaged parts is simply not very significant compared to the overall cost of most rebuilds.

This raises the question of "when does a 911 engine break?" That answer is (except for the unfortunate later 2.7s in hot climates) "We don't really know, because most idiots rebuild their motors before they need to do so, thus depriving us of the data we need to answer this question." Very few 911 engines die from natural causes if they have had even the most basic of maintenance (valve adjustments and oil changes). The majority of catastrophic engine failures are from operator error - overrevving the engine on a missed downshift, or from simply running the damn thing out of oil. Yes, Bruce Anderson may have a picture of an engine that died from worn valve guides, the most common wear point. However, most worn guides will simply smoke more and more as the years go on, but won't catastrophically snap off unless the valves haven't been kept properly adjusted so they get the proper cooling, dissipating heat to the seats.
Bottom line, spend your money on routine preventive maintenance and driving your car as it was meant to be driven. If yours is the rare 911 engine that suddenly explodes (and the odds are very good that it won't be), the marginal cost of replacing the broken bits will not be material compared to the rest of your mechanic's bill, and will be more than offset by the interest you earned by leaving your money in the bank for all those years. Save the paranoia and needless expenses for other areas of life, like women and relationships, which seem to respond far less efficiently to logical routine maintenance . . .

[Bill Douglas]

Well said David.