Mechanical Over-rev...Ouch!

Fellas,

Well the saga continues... I mentioned in a thread last week about a mishap at Driver's Ed where a mechanical over-rev snuck its way into my engine via a missed shift at high speeds... pesky 901, long-throw transmissions!!

I mentioned in my post that the car dropped a cylinder and was running on 5 as I limped into the pits. Some preliminary checking validate that there was spark at the cylinders, so I packed it in until I could get further diagnosis.

I dropped it off at the mechanic's (who was also at the Driver's Ed event), and he did a compression check. The test revealed that cylinder number two is sitting at 40 psi, while the other five are in the 140 psi range. His recommendation was to "operate" on the left bank, focusing on number two and the two around it. He mentioned that there is a slight chance that a valve lash gap closed up causing the leak, but highly unlikely. He believes a piston kissed the valve and we have a bent valve causing the leak.

Warren suggested possibly a broken rocker, which I was(am still) hoping for. At the initial dianosis, the valve covers were still on, so he had not gotten that far just yet.

He estimates $2,500 to fix this problem, and I was wondering if someone could list the high level steps necessary to complete this job. I have some reasonbly solid mechanical knowledge, but have never been into my 911 yet. I really wanted to assess what was involved and what could be driving that kind of estimate. I know parts must be minimal, so the removal of the engine and disassembly of the top end must be fairly extensive.

Any thoughts, insights?


Thanks a lot,

JA

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John
73 911S

I think I'm somewhat of a Neanderthal Kamikaze mechanic when I think of situations like yours. Financial constraints have at times been quite limiting.

So, I'm listening to threads like these because I wonder "why can't you just get the head off, maybe even all three cylinders, replace the valve and grind the seat, new gaskets and you're back on the road?" I guess it's because we can't stop at that.

Of course, I waited too long to get a Porsche. With other engines you can practically use coins for feeler gauges. Neanderthal, you know.

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'83 SC

You can do it very easily. Just take your time and read up, and ask questions here. Heck I think it was 200$ to do all six heads with a 3 angle valve job relacing guides and seals. If you did hit the piston a valve may cost 100$ the piston I don't know about buying individual ones and if the valve banged around scoring the cylinder. i'd guess may be 500$ to do it your self, maybe less. Plus the experience.

Supe,

You know how you feel when somebody tells you something that you know is right, but for one reason or another, you just don't want to listen? Your logic is right-on, and I know you are right. I even feel fairly confident in my mechanical knowledge and abilities overall. I guess for me the fear is two-fold:

1) The fear of getting it apart and because of other priorities or time or whatever, it taking two, three or more months to complete.

2) The biggest fear, is what if something obscure bites me, like getting the cam out of time and hurting other pistons, valves, etc.. or bending or breaking something in the trans/clutch during the R&R?

I know, I know... I can do it. Maybe this time, once and for all, I will get tired of writing $2,500 checks and make this my last trip to the mechanic for reasonably straight-forward tasks.

I have been reading this board for six months or so, and have certainly felt other folks pain... Leland, etc... You all have been great company, and I'm sure I will eventually take the plunge as a result of the confidence instilled in me from you all.

Thanks,

JA

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John
73 911S

John,

It sounds to me like your mechanic is trying to take advantage of your wallet in a BIG way!!! A $2500 estimate to repair one side of an engine with a valvetrain problem seems rediculous to the EXTREME!

My stong suggestion is that you get a set of factory service manuals (less than $400) and take your time investigating this problem ... and ditch that mechanic!!!

It would not have taken more than FIVE MINUTES to pull off the valve cover and find out if you have a broken rocker!!! To intentionally NOT do that demonstrates duplicity and greed ... nothing else!!!

I am sure some people are tired of me telling almost everyone to start working on their own car, but I happen to honestly believe there are a bunch of regulars here that are being taken advantage of!!! The only way to stop that is to educate yourself, step-by-step, and I realize taking that first tiny step is hard! But, you will thank yourself if you do so!

Realize this, less than $2500 will get you all the manuals and tools, parts to fix your problem, and leave you more confident and proud than any check I can ever imagine you handing over to a mechanic would!!!

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Warren Hall
1973 911S Targa

Hmmmm....

Dang it! I knew Warren was going to say that, and I have been wanting to send my mechanic on his way, so-to-speak.

How bad is he gouging me? Is this a $300 job? A $500 job, $1,000, $2,000 or what, for a qualified, competent, fair mechanic... assuming you could find one.

I am thinking I should go over there tomorrow and get my car back.....

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John
73 911S

Warren is absolutely right in that a brief exploration is indicted before somethign as drastic as engine removal and some things can be researched quickly, like rocker arms. In all fairness, if a valve and piston have made contact, then the engine must be removed. Engine R&R takes time and you pay. Still, $2,500 is out of line, IMHO.

It is scarry. It just is. Even for me. Something might break, I might get in 'over my head,' etc. Here's my response (and this time no carnival analogies):

1. The same things would scare your mechanic if it was HIS car. The reason he's not scared is that if these bad things happen, earnings increase.

2. Getting through the scarry parts is MOST of the fun.

3. If problems arise, you will deal appropriately with them. You will not do stuff that does not need doing, and you will no ignore stuff you see that needs attention. Believe me, mechanics do not universally take an attitude of responsibility when your car is on the operating table. They're in a hurry and their work frequently reflects this.

4. Oh, by the way, you save a lot of money, too.

Get someone to help with the engine R&R, as this can be scarry. Finally, please just assume that it will take two or three months. I GUARANTEE it will take longer than you think. Unless you plan on 2-3 months, in which case you might get it done ahead of schedule.

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'83 SC

$2,500?? I just did a full rebuild on my 3.2 motor for about this much. If you have even a bit of experience, my advice would be to take on the work your self. I did just that after some shop quoted me nearly 4 grand for the top end alone. This is my first 911 and I only had it a few months so I can relate to the anxiety you may be feeling on taking on a major job like this. Working on 911 engines is not the black art people may want you to believe it is. Do your reasearch and avoid the common pitfalls, ask questions (this BB is great for that). There is more experience on this board than you can point a stick at, certainly helped me out a lot. My car took me only 3 weeks from start to finish. The biggest kick is the satisfaction the job was done right and the fact that you have learnt more than a lot of people ever will about these great engines.

I also like it when fellow car nuts at work say 'hey, nice car', and you can reply 'thanks, I just rebuilt the motor the other week'. They kind of look at you with newfound respect...or maybe I'm getting it confused with the 'this guy needs to get a life' look....anyway, I guess this is a great time to plug my site....
http://users.ev1.net/~davmanku/porsche/carrera.html

[This message has been edited by beetos (edited 09-28-2000).]

I very much agree. doing your own maintenance makes you taller. And better looking. Food tastes better too.

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'83 SC

I too am setting in that boat.

I broke a rocker a little over a week ago and ended up bending the #3 intake valve. The valve is stuck and will not move. I have decided to do the job myself.

Question if I need to get a new head is it possible or do I need to buy all six. A valve keeper is missing (I haven't searched for it yet) Assuming the worst, that I took out a piston/cylinder set is it possible to replace one or will I have to do all. If I have to do all what will it take to use 3.2 cylinders.

Car Info
78 Euro 911sc Targa
~85,000 miles (only spent 3 months in Europe so believe mileage is close)

Omar

[This message has been edited by osidak (edited 09-28-2000).]

Omar,

If all that happened is a bent valve, the head isn't likelyto be hurt at all! I would advise getting all of the valve guides replaced, and a good three-angle valve job on all of the heads ... a set of new rings would be advisable, too. I doubt if the cylinder and piston were hurt, either. Read Bruce Anderson's book on top-end refresh/rebuild ... yours is a perfect candidate!

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Warren Hall
1973 911S Targa

[This message has been edited by Early_S_Man (edited 09-28-2000).]

Warren,
You have been a big help, I haven't gotten into the engine yet, I had ordered all the parts to replace the rocker and that is when I found the valve stuck. I am basically asssuming the worst so I won't go into shock if it turns ugly on me.

The two shops that I spoke said worst case ~$3,000 to $4,000. I had one of those shops replace my head studs last year. Cost ~$2,800. At that time I asked about the doing a top end rebuild and he said all looked good so I didn't do it. I will get that book and read it over. I want to do what is needed to get the car back to where it was and maybe more depending on the damage to my bank account. I am planning on doing the tensioner upgrade as of now. Oh I did have my heads machine last year as one of them was a bit chewed up due to the broken studs would they do a 3 angle valve grind at that point or no?
Omar