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How often does a 993 typically need a top end rebuild?

 
Old 01-29-2012, 09:52 PM
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producerjohn
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Default How often does a 993 typically need a top end rebuild?

So, I'm looking to purchase my first 993 (I've owned a 996 C4S and TT), and having read many threads and classified ads, it seems the top end needs to be rebuilt or resealed at around 70k miles on average. Is it really that common a problem?

I've got my eye on a pre OBDII 95, so maybe not as much?

Also, whats the cost of a top end rebuild and/or re seal these days?

I wish there was a sticky buying guide. My eyes are getting tired from searching a million threads that contradict one another.

Thanks
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Old 01-29-2012, 09:57 PM
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Falcondrivr
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From what I can tell from years of reading, oil consumption is the only real indicator of wheather or not a top end is need on a '95. Mine has no rebuild, and the oil consumption is minor. I'll pass 160,000 miles next month. It's my daily driver and does track duty several weekends a year.
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Old 01-29-2012, 10:03 PM
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race911
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As I've said many times, if valve guides were as easy to change (even if not as inexpensive) as brake pads, they'd get changed not much more often than oil.

That said, really the only reason they get changed at that magic "70K" is because of failed smog checks concerning illuminated check engine lights from secondary air issues. In the "olden days" the crappy factory guides wouldn't make it past 30-45k because the engines would have come apart to fix the bent valves caused from a puked chain tensioner. (Some 3.2L era cars, equipped with the pressure fed tensioners, got ~70K valve guide replacements from high oil consumption.)

In any case, it's nothing anyone worries about on a car that isn't in a smog check jurisdiction, OBD2 or not, until you have an oil consumption problem. I'll leave others to debate at what point consumption becomes a problem........

When the heads come apart, and proper non-factory guides are installed, sky's the limit on mileage. Love to hear from Steve Weiner, etc. on what they've seen/heard of on customer engines going the distance after they've done heads. My personal "best" from my customer engines with the original Lukes & Shorman phosphorus bronze guides on a 2.7RS spec engine was 220K after I did it from a factory virgin 2.4T MFI unit that was right at 100K original. I pulled it halfway apart again after about 5 years/100K (200K total) for general oil leaks and I think I changed it back to Solex cams from S. The owner still has the car, and he tracked me down maybe 5-6 years ago to report mileage and that it was still humming along.
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Old 01-29-2012, 10:19 PM
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Ed Burdell
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I have but one data point to offer - my own experience. I bought my car when it had 57k on the odometer. Now it is closing in on 104k, and while my car uses some oil (mostly due to timing chain and valve cover leaks), it's still around half a quart every 3000 miles - still well within spec. It's thrown an occasional CEL, too, but it always resets itself and goes off after awhile. It's never come close to failing an emissions inspection, either. All this with no top end rebuild...now it's possible the previous owners had it done and I'm reaping the benefits of that work, but to have it done befor 57k miles seems unlikely.

The car gets some short, in town driving as well as some longer commutes and the occasional 'keep it near redline' blasts up in the mountains. So far, so good.
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Old 01-29-2012, 10:25 PM
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IXLR8
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Originally Posted by race911 View Post
When the heads come apart, and proper non-factory guides are installed, sky's the limit on mileage.
Ken, who all makes valve guides for the 993, besides the ones from Porsche.

Also, I've Googled, but haven't found a single link to any DIY top end rebuilds or valve guide technical threads. With all the expertise on this and other forums, I'm surprised a detailed step by step how-to with pics hasn't been posted.
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Old 01-29-2012, 11:03 PM
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Steve Weiner-Rennsport Systems
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Others may as well, but we make our own. Properly installed and fitted, these last FAR longer than any OEM ones.
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Old 01-29-2012, 11:58 PM
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Just bought a 993 with 60k on the ODO and the guides were shot.
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Old 01-30-2012, 12:00 AM
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race911
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Originally Posted by IXLR8 View Post
Ken, who all makes valve guides for the 993, besides the ones from Porsche.

Also, I've Googled, but haven't found a single link to any DIY top end rebuilds or valve guide technical threads. With all the expertise on this and other forums, I'm surprised a detailed step by step how-to with pics hasn't been posted.
Originally Posted by Steve Weiner-Rennsport Systems View Post
Others may as well, but we make our own. Properly installed and fitted, these last FAR longer than any OEM ones.
I'd rely on the expertise of Steve's product. As I mentioned above, there was a local 356 expert shop, Lukes & Shorman, that pretty much provided the original phosphorus bronze guide to the world. Garretson (where Bruce Anderson was the shop manager, and Jerry Woods was the engine builder) sold some under their own label, but honestly I don't remember if they were repackaged L&S units.

As far as DIY on replacing, not like it's rocket science. More that it's just one of those things that's easier to rely on the 100% bulletproof expertise of a Steve to get the heads back ready to bolt on. Most of the ones I've done were based on pure stubbornness of me doing things 100%. Even with my cousin doing an engine now for his 907, he just had them done even though the machine tools are there (if a bit inelegantly) to do himself.
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Old 01-30-2012, 12:35 AM
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producerjohn
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Originally Posted by 1stgear View Post
Just bought a 993 with 60k on the ODO and the guides were shot.
Is this something that can be checked in a PPI?
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Old 01-30-2012, 02:05 AM
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Steve Weiner-Rennsport Systems
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Originally Posted by producerjohn View Post
Is this something that can be checked in a PPI?
Yes it can, however it requires removal of the valve covers and an accurate measurement of side play in the valve assembly. This takes an experienced tech to do this to get reliable results.
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Old 01-30-2012, 06:05 AM
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Toto111
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Originally Posted by Steve Weiner-Rennsport Systems View Post
Yes it can, however it requires removal of the valve covers and an accurate measurement of side play in the valve assembly. This takes an experienced tech to do this to get reliable results.
How do we correctly assess the abilities of the tech doing the PPI? Are there any specific lines of questions that should be asked to the tech to "check" if he is capable?
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Old 01-30-2012, 08:52 AM
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Originally Posted by Steve Weiner-Rennsport Systems View Post
Yes it can, however it requires removal of the valve covers and an accurate measurement of side play in the valve assembly. This takes an experienced tech to do this to get reliable results.
Layman's translation; your PPI just went from $300 to $900, as you will be paying for a valve cover gasket replacement on a car you may not be buying.
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Old 01-30-2012, 09:34 AM
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I had mine done at 60k miles due to the SAI. The shop said the exhaust guides were pretty shot at that point. I've been told by more than one experienced engine builder that the OEM exhaust guides wear very quickly, but the car will run great and just use some oil for a very long time without having any problems ... except for the cursed SAI system.

I've had four or five 1995 993s, none of which had top end work done on them, and they all used some oil but ran great.

Since my 97 had its guides replaced with the phosphorous bronze guides in Jan. of 07, the car doesn't use any oil at all -- 88k miles now.

If I were in the market, I would not be very concerned about it on a 95 car as long as it runs well and has good compression and leakdown. I'd be a little more apt to try to budget some money for it on a 96-98 car that had not been addressed, but as long as the SAI is not throwing codes, you can probably enjoy the car for a while before doing it, or just deal with cleaning out the passages and putting in a quart of oil every once in a while.
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Old 01-30-2012, 11:47 AM
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Originally Posted by race911 View Post
Most of the ones I've done were based on pure stubbornness of me doing things 100%.
I like the idea of having control of the quality; one of the reasons for DIY plus I get to enjoy myself in the process.

In my case, I have years till I have to worry about guides. I'll see what Google comes up with as sources for guides. Thanks, Ken!
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Old 01-30-2012, 12:04 PM
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Originally Posted by IXLR8 View Post
I like the idea of having control of the quality; one of the reasons for DIY plus I get to enjoy myself in the process.

In my case, I have years till I have to worry about guides. I'll see what Google comes up with as sources for guides. Thanks, Ken!
Sounds like you may be able to get some from Steve.
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