Mike_964

My C2 has now done 150.000 km (94K miles) so I am beginning to worry about whether I need to consider a top end rebuild.
The engine still feels strong (can hit the rev limiter in fifth), but when looking at other posts it seems like a lot of people are doing top end rebuilds a lot sooner.
I am doing about 20.000 km (12,5K miles) a year and have had the car for 3,5 year, so I know the last 60.000 km (37,5K miles) has primary been longer trips.
I am doing 3 hours on the track every summer and also some miles on the German Autobahn so it is being maxed out some of the time.
So I thought I would make a small pool, to get some better statistic on when people are doing top end rebuilds.
Feel free to write your thougths.

Henry964

My 1993 C2 has 155.000 kms so I´m in the same zone as you are, my answer would be that you have to do a top end rebuild when ever you have exagerated oil consumption.
There are different school of thought on what means exagerated oil consumption but I leave that to the people that really know this engines

Sire

Go for the whole rebuild, if you have done this and about 50.000 or 100.000 km you need to do the whole rebuild

ilko

An engine rebuild is not part of the maintenance schedule. it's not calculated based on you mileage.

What are your compression and leak-down numbers? Do you have excessive oil usage (more than 1qt per 1000 miles)?

Mike_964

Ilko, I am fully aware that it is not part of a scheduled maintanance. But what I wanted to achieve with this poll, was to get an overview of whether 20% did it before 125K miles or if the ratio was 80%.
We of course tends to hear about all the cases where people do make the rebuild, but it might give the wrong impression.
I have had no compression test made hence no leakdown test.
I must admit that the engine feels strong as written before, so I have not really thought about the necessity of doing a compression test. But when reading about rebuilds, I just suddenly started worrying about whether I was the only one running this kind of mileage without a rebuild.
I actually thinks it sounds a bit strange that a Porsche enginge shouldn´t be able to do at least 125K miles without a rebuild, but when reading other posts it seems like it is about high time.
I guess I need to start with getting a compression test.
Oil consumption varies. If I drive on regular road and don´t run it to the max all the time, then it uses almost nothing. But on vacations driving on the German Autobahn then oil consumption is noticable.
This was exactly the same story with my motorbikes, but I guess all engines uses oils when pushed closed to the max.

ilko

A poll on this board will have no scientific bearing. We are only a small fraction of the owners. Another thing to consider is that in the internet age you hear a lot more about problems because people seek information, look for support, etc. Imagine if everybody started posting how great their car feels and how they didn't get a rebuild this year

Engine rebuilds on Porsche engines with low miles are due to several factors in my opinion.

One of them is that the early cars didn't have cylinder head gaskets and some of those engines developed leaks. Seeing the flag mirrors in you avatar your car may or may not be one of those. The issue was corrected some time during MY1991.

Another reason is that some of the cars have been babied, not warmed up properly, used as Sunday drivers by people who didn't necessarily use them to their full potential, and generally not maintained properly for one reason or another. You may be an enthusiast who drives the car at 9/10ths, but the previous owner only took it out on Saturday nights to get chicks and didn't change the oil once in the last 3 years

On the flip side, if your car is mainly used on the track, wear and tear is greater, so you will need an engine rebuild earlier. Race car motor life is measured by hours instead of miles, so that gives you an idea

If you drive spiritedly, go to the track every once in a while, and maintain your car according to the manual I don't think you should worry about an engine rebuild. Especially if, as you say, the engine feels as strong as ever. Just hope the snow melts soon so you can enjoy it some more .

Rocket Rob

The option of "not yet" wasn't in the poll so I chose the highest option. I agree. Don't rebuilt because you have reached some magic mileage number. Do it for a specific reason, like loss of compression or excessive oil leak. Meanwhile, keep driving and have fun.

Bearclaw

You see this come up in "Should I buy this car?" threads, and many responses always include, "...and since it's above "X" miles, you'll be looking at a top end rebuild soon". That blanket statement just can't be made. As well-stated by Ilko, there are so many factors influencing this, it really has to be viewed case-by-case.

Geoffrey

My street car has 122k miles on it, has not been opened, is used as a daily driver, and used spiritedly. A leakdown test will be your best guide to determine if you need a top end rebuild. If you have leakage past the valves, you need a valve job (top end rebuild). If you have excess oil consumption it may be valve guides wearing out which will then wear out your valve job and you will need the guides replaced (top end rebuild). The "while you're in there" is the valve spring retainers because they are known to break when abused, and valve springs because they are minimal for this engine (or change the installed height of the stock springs).

If your engine is smooth at idle, then you are most likely fine. If the engine intermittantly drops a cylinder or vibrates, or shakes at idle then you probably have some leakage past the valve seats and probably could use a top end rebuild.

Bull

There are so many other variables that mileage, independent of other information, has no bearing on the answer to this question.

Tom W

My first "rebuild" came at about 80k miles when a rod bolt came off and I ended up with a fist sized hole in my engine case. After just over 100 race hours, I'm having the top end removed and work done.

On my street car with 83k miles I plan to do it when it has issues and not before. Issues are as Geoffrey described or significant oil consumption (over 1 liter per 1000 miles).

Mike_964

Thanks for all the input. Judging from my oil consumption and the last 3 valve adjustments (with almost no actual adjustment) I am not that worried. I will do a compression test in the spring and get an oil smaple analysed. If that looks good, then I will stop worry.
I actually first started thinking about it, as I read a bit in a Porsche book by Bruce Anderson, and it left me with the feeling that I was driving a time bomb. But again the book wrote about a lot of different Porsche engines and nothing specific about the 3.6 liters.

boxsey911

My top end was done because of the pre-91 cylinder head gasket issue.

Well done for hitting the rev limiter in 5th!

Mike_964

I need a friend with steadier hands or a camera with a better stabiliser :-)
And remember don´t try this at home... Unless you live near the German Autobahn

964Black

I think rebiuld or not has nothing to do with the mileage.
Does the engine burns/ leak loads of oil? Lack of performance? etc
It the condition the engine is in and not the mileage it has done. There are good engines around with more than 200.000miles without a rebuild.