Valve guide...UUUHHHGGGG!!!

[needlevalve]

Hello all, it's my turn to share a bit of a misfortune on the board. I have a 1975 911S (2.7). I pulled my lower valve covers off yesterday to investigate a ticking noise that has been present for some time now. Up until this point, I had speculated that a rocker arm was worn as the noise was coming from the middle of the lower driver's side valve cover and I don't burn oil etc. Well as it turns out one of the valve guides is worn (I was able to shift the valve stem).

Is it odd for only one guide to wear? (they others seemed tight when lifted off the seat)

How concerned should I be about using the car?

Like I say, it does't use oil (no smoke) but I can definately hear the extra noise (ticking or tapping) from the worn guide.

Also, does anyone have any experience with cost/manhours of having this kind of work done?

Thanks for the input!

BTW- I am uncertain whether the origional guides have been upgraded from the copper type (guess I'll find out when I get in there).

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Matt Macpherson
1975 911 S
nvalve@yahoo.com

[john walker's workshop]

you will probably find the rest of them worn upon disassembly. at least all the exhaust guides. ticky valves after a good valve adjustment are a sign of worn guides. basically it's a valve grind to fix. about a 30 hour job if a pro does it, and should include replacing all ex valves, maybe the intakes too if they don't mic out well, all the guides with phosphorus bronze units, and total top end gasket set. then the question is should you do the whole teardown/overhaul while you're at it.

[needlevalve]

John, thanks for the info. Well we know not for whom the bell tolls until a ticking emerges from the rocker assemblies .

John, in your experience should I be concerned about using the car this season? I would prefer to wait until winter to do a tear down. On the other hand, I don't want to pop the head of the valve off so my engine can chew it up.

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Matt Macpherson
1975 911 S
nvalve@yahoo.com

[john walker's workshop]

that's a hard one to forsee. the old copper guides got so sloppy that you could move the valve side to side 10mm sometimes. didn't do a lot for heat transfer out of the valve. but for sure there's still lots of them out on the road in that condition. so it's your call.

[Clark Griswald]

Is that the potential risk of worn guides, a valve head snapping off? I have never heard of this.

I have suspect guides on my '86 and am wondering what potential damage could happen if I don't replace them.

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Chuck Moreland - '86 Cab, '77 Targa, Family Truckster

[Early_S_Man]

Chuck, (and Matt, too)

I take it you don't have Bruce Anderson's Porsche 911 Performance Handbook! The details of the end result of worn valve guides ... driven a bit too far are well illustrated in the rebuild section.

Yes, all air, oil & valve guide cooled VW & Porsche engines suffer under the threat of a dropped exhaust valve head, after valve guides are worn too much ... bouncing around, holing a piston and other assoted havoc that can happen in less time than you can read this post!

Of course, a calibrated oil temp. gauge update, lower-temp thermal switch and manual switch for your front oil cooler fan would help minimize the risk ... if you can keep your oil temps ALWAYS BELOW 210 degrees F, but the threat is still there. Do you feel lucky?

All it would take to put you over the edge would be a broken fan belt, and a couple of miles of driving before you noticed the alternator warning lamp ... whump, screech ... then silent coast down, after disengaging clutch, after hearing/feeling the back tires lockup!!!

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Warren Hall
1973 911S Targa

[john walker's workshop]

warren tells it like it is.

[Evans, Marv]

Oh scarry!!
I had the same scenario Warren describes happen to me a long time ago with a VW bus. I was going 60+ MPH, heard some screeching noise, looked down to see the generator & oil lights on, put in the clutch & coasted to the side of the road. Engine was seized & the only evidence was a small chunk of aluminum (engine case) sitting in the engine compartment. Later I learned an exhaust valve had broken off, went through the piston which disintegrated & went into the sump. The chunk of aluminum was punched out of the case by the rod flying around & that's what finally siezed the engine. Never heard a thing, it happened so fast.

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Marv Evans
'72 911E

[Jdub]

1971 SuperBeetle. Loud snap from rear of car. Opened hood and noticed nothing... Drove car. Semi honks horn. Look in rearview, and a plume of smoke is following my car!

Coasted right into the VW dealership off of I-95, car smoking, potential new car buyers running away from the scene!

True story. I cannot believe I didn't notice that the fan belt had snapped.

Jw

[movin]

What is the best valve guide material? and where can I get it?

[Doug Zielke]

First this:



Then this:



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Doug
'81 SC Coupe (aka: "Blue Bomber")
Canada West Region PCA
members.home.net/zielke/911SC.htm

[Clark Griswald]

That is scary.

Is it the exhaust valves that typically have the problem? I found it impossible to reach in and test the intakes. The exhaust are hard enough to reach.

My Carrera is coming up on 100k with original guides. I notice a click even after my last valve adjust, but I am not sure I adjusted them just right. I will go in again, and test for wear at the same time.

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Chuck Moreland - '86 Cab, '77 Targa, Family Truckster

[needlevalve]

Yes Griswald, I believe it is most commonly the exhaust valve guides that take the beating.

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Matt Macpherson
1975 911 S
nvalve@yahoo.com

[john walker's workshop]

nice work doug. phosphorus bronze is the guide of choice. it's more orange colored than a brass guide. that's why exhaust valves should not be reused. they're already stressed enough.

[rstoll]

Here's one for you. Had a 1966 microbus when I was a kid. Aftermarket aircleaner nut came loose, went down the carb, locked her up. Coasted into the driveway, tore it down the next morning. The nut was imbedded in the head. I pryed the nut out, reassembled and it ran fine. Tough little motor.

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Robert Stoll
83 SC
83 944

[makaio]

Whenever there is talk of major repairs I start to get nervous, and the talk of valve guides scares me. I don't think mine are bad but I don't know.

Here are the facts:

1.170,000 miles
2.burns 1 quart of oil every 500 miles or so
3.no smoke on deceleration, or start up
4.just a hint of valve noise
5.I don't know if the motor has ever been apart. I believe it has, because the timing chains apear to be new, and they are not the master link stytle.
6. the temp gauge runs between 8 and 9 o'clock when 90 + degrees outside.

so what do you think?


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Matt Chamblin
78 911 SC

[needlevalve]

Hey Makaio, it's pretty easy to check for worn guides. Warren describes the process of doing this in great detail in a previous post (if only Haynes was as descriptive as Warren (lol). Try searching "valve guides" or "valves". In essence it involves pulling your valve covers and checking each valve stem for movement once it is lifted off it's seat. The ticking sound on mine is quite evident, and I could definatly notice too much movement on one of the valve stems. Word around the campfire is if one is gone, chances are the others are too. The indicaters seem to be ticking valves (even after valve adjustment) and/or smoking.

I wouldn't get too paranoid about it after reading all the worst case scenarios. Defenatly worth pulling the covers though if you suspect something...BIG peace of mind for a couple hours underneath the car.

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Matt Macpherson
1975 911 S
nvalve@yahoo.com

[Superman]

Here's an observation I'd like someone to talk knowdegeably about. My valves are just about whisper quiet when cold, and somewhat noisy when at operating temp. What's up with that?

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'83 SC

[movin]

A few high performance suppliers are recommending Beryllium Copper valve guides for longevity. They are very expensive but to me worth the cost if they can last as long as the rest of the engine, 200,000mi+. Anyone else have experience with this type of valve guide?