What did I do to my car

I have a Euro 78 911sc just had the head studs replaced ~8,000 miles ago and other than that all has been great with my car.

I pulled out onto a busy street before I saw this big transfer truck bearing down on me at warp 7 so I gunned it and took off before i realized it I had pegged redline in 3rd gear. I upshifted to 5th and noticed my car kinda coughed for a second. When pulling back into work my car had a difinite miss and was running rough. worried that I broke something i checked for any smoke behind me oil pressure and level all appeared fine. I parked the car and checked uderneath for oil leaks didn't see any. Looked in the engine compartment nothing. Nothing smelled like oil. I started the engine and didn't hear anything unusal other than a pronounced miss ie the exhaust note would drop as well as rpms (rpms at idle would go from 500 to 1500rpm) I drove it home (kept it under 3000rpms) and jacked it up. Still no oil leaks (this car doesn't leak) I didn't notice any smoke on the way home and oil pressure was normal. The engine is still to hot to dig but I was wondering if you guys have any suggestions where to look in the morning?

osidak

It might be something as simple as an ignition wire. Alot of times they will arc through the insulation, or at the boots at high revs, and from then on, once a carbon path is established the car will miss, and that wire is shot. You might want to do a compression check though.

Leon 78SC

[This message has been edited by leon (edited 09-08-2000).]

My SWAG is you bent something in the valve train. This would not create any kind of a leak except from your wallet.

Randy Jones
1971 911

osidak,

When the studs were replaced, was a top-end rebuild done? If so, what parts were replaced and which were reused?

I have serious doubts that slight over-revving in the correct gear, and upshifting into the correct gear could have caused anything to hit, such as piston and valve ... if they did, a rocker arm would be the first thing to break.

A few years ago, there were quite a few instances of broken valve springs in the SC engines. If such a thing has happened to you now, it might explain your sudden problem.

I would recommend a compression check, followed by a check of valve clearances, with careful checks for a broken rocker and broken valve spring in any suspicious cylinders.

Broken valve springs can be changed with the heads in place.

Be sure to check the condition of your sparkplugs, and ignition components ... wires end-to-end resistance, etc.

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Warren Hall
1973 911S Targa

[This message has been edited by Early_S_Man (edited 09-08-2000).]

pretty sure all SCs have a rev limiter, so unless you downshift into too low a gear and mechanically overrev the engine that way, you can't overrev the engine. Doesn't sound like you downshifted, so I doubt you "overreved" the engine.
But, you still may have revved it higher than you usually do, and something can break/fail at pretty much any time or rpm.

The stalling out was the fuel pump cut off relay even though you were in the redline the max is 7000 so I doubt you hit that

You probably have fouled plug or something ignition related causing the miss

The stalling out was the fuel pump cut off relay even though you were in the redline the max is 7000 so I doubt you hit that

You probably have fouled plug or something ignition related causing the miss

all that was done to my top end was machine the heads, the mechanic stated that all looked good except where those rings sit where a little chewed up. Being my car is a Euro i do not think it has a rev limiter and i think I hit 7000 rpm before i up shifted (the one time i do this) if I broke a rocker how much labor is involved? Please don't tell me it is another tear down.

osidak

If it is a broken rocker or valve spring, you don't have to do another tear-down. If a valve is bent or stuck that is another matter!

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Warren Hall
1973 911S Targa

Oh no. Rockers can be changed with the engine in the car. Might be just time to do a valve adjust and look for broken springs or arms. Then look at ignition if there's still a problem.

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'83 SC

FYI, Euro's have rev limiters. I've got one.
It's on the distributor rotor.

Well I pulled the driver side valve cover and found a broken rocker on cylinder number 3 intake side. I have never done this before so let me describe it. found two pieces laying loose. A screw with a ball end and a slotted top which a presume is the valve adjuster. the casting that it screws into is what broke. and a round metal piece that has a larger flared hole on one side and tapers in 3 steps on the opposite side. This piece has a slight bend on lip of it. Some one had mentioned that this can be done in the car and I must confess I am unable to find my haynes manual. will it cover this or no. if i take it to a shop how much labor would you say is involved.

osidak

I've never done it before, but I'm guessing it's one of the easier procedures you might attempt. You might need to buy a hand tool or two, but you'll still be money, and pride, ahead.

You see, the fulcrum that the rocker sits on is a shaft taht is screwed into the cam carrier I think. Separate shafts for each rocker I believe. The tool fits into the ends of the shafts. Really it's got to be pretty easy so I would suggest doing it yourself.

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'83 SC

Ok i just finished removing all the other valve covers and I found a few other peices of the pie. Appears that the intake rocker on numer three is the only one to break. I found three more peices on the lower right valve cover. if you look at the following link these are the peices i have removed from the car. http://www.pelicanparts.com/911/911_Parts/1978-83/1-3.JPG

numbers
14
18
1 half of 15
the valve adjuster screw and remants of the rocker
and a small circular spring kinda like what you find on a key ring.

using a mirror i can see the valve stem and it looks ok just maybe a little scuffed. The larger of the two valve springs does not appear broken. Who out there has done this before. I would love some tips.

osidak

Pelican has the tool: Valve Spring Compressor, Intake,at:

http://www.pelicanparts.com/catalog/shopcart/ptoo/por_ptoo_miscel_main.htm

That tool, a 5 mm Allen drive, and 8 mm Allen wrench is all you need to pull out the rocker arm shaft and put a new rocker on!

Was there any sign of a broken valve spring ... it might be hard to see, but, the spring might be a little 'off' in appearance?

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Warren Hall
1973 911S Targa

The spring looks ok from what i can tell. Should I replace them just for the hell of it. The small circular metal peice that I mentioned before (like a key ring) apppears to be from a valve stem seal, i was flipping through a catalog and saw one on a seal. I see where the 5mm bolt is but where is the 8mm.
Just looking it appears that all you need to do to remove the rocker is to unscrew the two 5mm from the sides and remove the rocker and shaft at the same time. I am making a list of parts that I will need to order is there anything else I need to add.

Parts Needed:
1 rocker arm
1 rocker arm shaft
1 valve adjusting screw
1 rocker arm shaft washer
1 valve stem seal
1 or 2 valve keepers
1 valve cover gasket set

Tools needed:
rocker shaft hex head socket 1/4"
Intake spring remover

osidak

OK, I thought you must have made a typo on the diagram, since that diagram doesn't have the rocker in it, but now I see ... you found the remains of a valve spring retainer, one keeper, and the remains of the valve spring seal ...

This may be worse than I thought, initially!

I don't think you need to replace the rocker shaft.

You need to replace the valve spring retainer, if I read you correctly, earlier, that it had three steps and was slightly bent on one side. You will need two new keepers, one set of valve springs, and the jam nut for the valve adjuster.

Bruce Anderson has said that only the one defective valve spring need be replaced, as it was fairly random in occurrences among the SC engines, and that there were never multiple failures in one engine.

I am just hoping that valve isn't bent!

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Warren Hall
1973 911S Targa

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

what is an easy way to check the valve to see if it is bent. I was unable to find a diagram with a rocker in it. I really hope the valve didn't bend but knowing my luck it is bent.

if i may ask you to update my parts list. when i say the stepped peice is bent the outer edge is of it is dinged looks like the rocker may have hit it.


Omar

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

After you have made these installations, you'll be able to see if the valve is bent. By driving the car or by compression and leakdown test. But I'm not sure there is another way to check. It sounds like you'll be able to replace the broken pieces with the engine in the car. I recommend doing this, and see what happens.

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'83 SC

Make sure you have all the parts that came loose ie. keepers,washers etc. before you start this motor back up. If you don't you could cause some really serious damage. A loose keeper can destroy a piston, cylinder and head in one fail swoop. Bobby