Which years are the worst for valve guides

[umfan866]

I've posted before about the valve guide issue, asking how certain it is in the 3.2s. Responses have been mixed.

That being said, which are the WORST years for the valve guide issue ?

I have a mechanic who says that he doesn't see the issue much in 84-86 Carreras, and that Porsche may have "unofficially" changed the material in 87-89, with 87 being *particularly* problematic since it was the first year of that change. I just had an 87 fail a PPI (plugs were wet with oil indicating excess oil in the cylinders).. so am I going to have a better chance on an 88-89 and/or 84-86 (assuming no valve job has been done)?

Also I understand that the issue didn't stop in 1989 but went all the way into the 993's (so up to 98). I am looking at 1995 993's and while they don't have the SAI issue they may still have valve guide problems that require a top end as well.

Does anybody have any real data on this, either from experience, or reference to published documents by the Porsche factory?

I had been looking for a car that already has a valve job, but lately I switched to looking at cars that have not had it, and so I want to know which years in particular to avoid (and I'm thinking avoid all of the 87's for know.)

[Steve@Rennsport]

All 911's have issues with guide materials; '74 to the present.

The main variable is how they were fitted at the factory and some were set tighter than others.

Make sure that any valve job used NON-factory guides and were set up correctly. Further, make sure they used Viton guide seals, not the teflon ones.

[sig_a]

Excessive 87/89 911 valve guide wear is an unauthenticated urban legend. Abnormal wear stems from operator abuse and maintenance neglect. Your mechanic is delusional.

[der Mond]

My '87 has 150K miles and seems OK.

[Rot 911]

Originally Posted by sig_a

Excessive 87/89 911 valve guide wear is an unauthenticated urban legend. Abnormal wear stems from operator abuse and maintenance neglect. Your mechanic is delusional.

I disagree. I think there has been substantial evidence that the material used for the 3.2 valve guides led to some premature valve guide wear issues. There were a disproportionate number of 3.2 engines showing valve guide wear in the 60K mile range. A small number, but enough to be an issue. At 130K miles my valve guides were shot. That aside, I think the 3.2 engines are fairly bullet proof.

[john walker's workshop]

got at least 125K, then they're worn. maybe not using much oil yet, but if you had the heads disassembled, you could generally detect some extra slop. the intake stems wear also, noticeable with a micrometer. i've done valve guides on 3.2s with 60K that were fouling a plug due to oil use down the guide, but that doesn't happen too much. the old 2.7s had copper based guides and the valve could wobble about 1/2" sometimes, so that's my vote for the worst.

[sig_a]

How would substantial evidence distinguish between operator abuse vs. material failure? Has Porsche AG ever indicated problem with valve guide material? So far, no problem with my 3.2.

[charleskieffner]

87 cab with 118k with the last 8000 miles having the SNOT run out of it.

1589 miles phx-fontana-(5)-time trials-and then fontana,ca. back to phx. used 1/4(.25) of a quart of oil. FIFTH (5th) GEAR PINNED WIDE ******* OPEN at calif. motor speedway


i'll just wait this horrible situation out for the time being and build the hell out of my tranny. then when i start eating oil like porsche says is normal(one quart every 600-800 miles) i might worry a little .........not much.

when it looks like a mo-skeeter fogger....we'll pull it.

after the tranny done and then the engine........the entire car will be new again!

to be real technical..............my build date was 11/86

[john walker's workshop]

the problem with worn guides, other that oil use, is that the valve wobble beats the hell out of the seats. they get ovalled. round valve, ovalled seat....extra leakdown %. i've seen it particularly on 3.2s, when cutting the seats. often they don't clean all around until quite a bit of material is removed. so much sometimes, you wonder if the heads can take another grind further on down the road.

[RWebb]

heat is transferred away from the valve via the valve guide (and then into the head, a giant heat sink for the valve)

if there is gap, then the risk of breaking off the stem increases ---> so, the risk of wiping out the entire motor increases....

[umfan866]

Update - the car I had PPI'd did have exactly 125k on it, so it may be the miles as much as the fact that it is an 87.

[slodave]

My valve guides have 227,000+ miles on them. I have no smoke on startup. It sat for about two months and started without problem and has sat for shorter periods without problem as well. I am very curious to see my valve guides and everything else as well and see the wear. The engine is strong, but likes to mark its territory - very well! In other words, the internals seem OK, but I have replaced almost, if not every externally accessible gasket/O-ring/seal...

Anyway, the cars are built to last! Get a PPI, look at all of the service records if you can.

Dave

[KFC911]

Originally Posted by sig_a

How would substantial evidence distinguish between operator abuse vs. material failure?...

Where did you get the idea that "operator abuse" enters into the equation? This is the very first time I've ever heard anyone mention that...

ps: Avoiding '87s will only limit your "selection pool", and will not decrease that "slight" chance imo.

[Bill Verburg]

They are all bad oem

[KFC911]

What do you mean Bill? I've always been under the impression that it's a relatively small (?) percentage that are "bad". Not questioning, just curious...thanks!

[Zef]

Originally Posted by Bill Verburg

They are all bad oem

I am curious also...thinking that happen only at 40 to 60 K...

[Bill Verburg]

Valve guides have been a constant source of trouble since I bought my first 911 in the early '70s. Every year and every model has had issues.

The one constant in all that time was to rplace w/ US made phosphor-bronze guides. There may be other more modern materials but the p/b guides have proven themselves.

[sig_a]

[QUOTE=KC911;3455263]Where did you get the idea that "operator abuse" enters into the equation? This is the very first time I've ever heard anyone mention that...

Did they let their engine overheat? Did they run without proper oil fill? Did they over rev the engine continuously for long periods of time etc.? Unsubstantiated rumors are numerous on this BB. With enough repetition myth becomes reality.

Here's what I want to know. What has Porsche AG have to say on the subject. They made the machine; they are the experts.

[KFC911]

Originally Posted by sig_a

Did they let their engine overheat? Did they run without proper oil fill? Did they over rev the engine continuously for long periods of time etc.? Unsubstantiated rumors are numerous on this BB. With enough repetition myth becomes reality.....

I'm not trying to perpetuate any myths, if that's what you're implying, simply trying to learn more about these cars. Of course, the three items you mention are obvious abuse, but do they contribute to "worn valve guides"? I'm not arguing at all, but in all of the discussions, I've never heard any mention of "operator abuse" being a contributing factor. If I'm being dense here, someone please tell me, and I'll shut up

[charleskieffner]

the biggest operator error is letting these cars sit! just like planes/motorcycles and boats.

IT AINT GOOD!

hell most owners on here, own museum pieces!

ask anyone who makes a living working on them what is their biggest complaint...........people dont drive them as intended.

it is writtian in granite that daily drivers suffer less problems than those of us who do let them sit. and im guilty of it as well. its a toy, thats all. if i drive mine 2 times a month during the summer im lucky and thats pushing it. the last 8000 miles over 2 years was really working it alot! like an obsession!

im blessed to live in a state with alot of rural roads, and on occassion can blip the hell out of the throttle or take it to (2) tracks PIR and FIREBIRD raceways.

im all for going to the track for a host of reasons..........first being testing. lets see if what we did, works as intended. second run some good race fuel. car loves it. third........in 1 hours time at WFO any problem will surface and rear its ugly head real damn fast and its back to the drawing board.

the P.O. on mine put about 4000 miles a year on it up until he died. not a hell of alot of mileage in the big picture. my daily driver gmc truck sees an easy 25K miles a year in comparison.

soooooooooo my suggestion to all................DRIVE THE SNOT OUT OF THEM!