Living the nightmare

[911freek]

Hi all,

Saturday morning, nice and shine, cool weather.
I coast on the highway when the car makes a strange noise, and the engine stops.
In the rear view mirror there is a small cloud of white smoke. The air is full with the smell of burnt oil.

This morning, I pull the engine down: the middle valve on the left has snapped, with the stem breaking the rock and sending the valve's heavy base into the cylinder, where it shattered the piston and created contemporary art of the cylinder head.

Bits and pieces are found in the other 2 cylinders, though they seem to be fine.

This is a 3L engine, with 95mm bore.

Below are some pics.

Now to the questions:
1. Can I replace just one cylinder/piston/head or should I do all 3 or all 6?
2. should I convert to cast pistons (ie. JE) or stay with Mahle?
3. In this rare occasion that the engine is down and in pieces, is there any other upgrade worth doing?

Thank you all, Me.

[Cairo94507]

Ouch! Sorry to see that. Full rebuild in order for sure. I am sure some of the engine builders on here will chime in as to "while you are in there" mods worth doing.

[Flat6pac]

You can do one piston and cylinder. Piston weight is critical, you probably bent the rod too. Deck height inside the triangle on the edge of the cylinder base in triangle
Bruce

[911freek]

Thanks folks!

I assume that the new piston will weigh more..... Even if replaced by the same Mahle type?

Also, I shall replace the rod as well. Not worth the doubt!

[jkh2cpu]

Pull it apart and clean it up. I would guess that
there is small debris inside the case and in the oil
circulation system.

John.

[Flat6pac]

Like the rods, the pistons have weight groups
Weigh the piston with rings, pin and clips. Match the casting number inside piston 93,letter, 2 numbers for 8.5/8.7 compression
The cylinders have a deck height and size size 0 through 3, deck height in triangle 5 or 6
Weigh the rod with no big bearings but with rod bolts and nuts.
The heads have a letter and number combination on the corner casting, 3.0 heads US 78/79 or Euro through 83 with big ports.
Inside the case the pieces will be mainly behind the oil pump and on the screen. Anything that got through the screen will be through the oil cooler system to the front cooler then back to be filtered.
You do need a build but this tells you how to know what you need and how to tell the supplier what you need.
Bruce

[arbita1]

What caused that??

[RedCoupe]

I would replace all six exhaust valves. Whether it was lean running or detonation that caused the failure of the one valve, another failure might not be far behind.

[porschetub]

Originally Posted by RedCoupe

I would replace all six exhaust valves. Whether it was lean running or detonation that caused the failure of the one valve, another failure might not be far behind.

And valve guide wear,OMG thats messy....sorry to see

[911freek]

Thank you all.

I am not really sure what caused it - I do not even know if it started with the valve, then broke the rock and internal damage - or the other way around.

The way the valve was cut at the stem leads me to think that it was hit hard by the piston. Its either the result of a lean mix, or failure of the guide that got it stuck at the first place.

The stem is still stuck in the block. I am sending this to be professionally rebuilt - and they claim they can fix the head (!). We shall now see.


Here is what it looked like:

[billybek]

I wouldn't be able to fix that head or have it fixed and trust it.
As a matter of fact I don't think I could trust a shop that said they could repair that head.

I would shop around for a rebuilder if you are not going to do it yourself.
Sorry to see the carnage and good luck with your overhaul.

[Henry Schmidt]

911 Vintage Parts will have everything you need to get this project back together.
If you decide to just replace only the broken parts, they will have one of each or sets of good used no matter what parts you need.
One rod, one piston, one head or sets of good used or reconditioned, well checked parts.

Ken @ 760-731-4911

info@911vintageparts.com

[Flat6pac]

You mentioned chips of piston in the other cylinders. They lol be in the other side too. As the piston discinigrated, there was no more vacuum in the cylinder so pressure was blowing back up the intake with metal as the other cylinders were still sucking. You'll find metal in every cylinder.
Bruce

[Josh D]

Broken valve spring maybe?

I've read about exhaust valves breaking off at the stem due to an overheat caused by worn valve guides, but this is an intake valve.

[JohnJL]

I am interested in the answer to Bruces question too...just how far and where did the bits all go....

[Lapkritis]

Depends on the intake system. If only a bank shares a plenum/carb hat then only that bank will have potential for FOB reversion. If there's a central plenum for all 6 cylinders then all 6 will have the potential.

[911freek]

Washing the crank case today, chips in there as well.... So they indeed traveled far.

I decided to replace all valves and springs. Found a cylinder head and piston of the exact same type. The head shall be rebuilt by a professional engine rebuilding plant that also does airplane engines - they have neat technology for fixing that....

I will however get a replacement head (found one on Ebay for $280) just in case, but then of course its state is unknown.

Now my key issue is my wife..... Somehow she thinks that sending the kids to college is more important. I do not see it this way as they will not learn how to fix the engine there, and even if they do - it will take 4 darn years before the car is running again.

Women.... Any technical advise on that?

:-)

[spyerx]

Originally Posted by 911freek

Now my key issue is my wife..... Somehow she thinks that sending the kids to college is more important. I do not see it this way as they will not learn how to fix the engine there, and even if they do - it will take 4 darn years before the car is running again.
Women.... Any technical advise on that?
:-)

I operate on a firm "don't ask don't tell" policy with my wife. I don't question her new shoes, bags, clothes, on and on and she doesn't question cars, wheels, stacks of tires, constant UPS delivery of parts showing up in the garage. We are very happy like this.

The key will be to convince her without your Porsche, your one release from the realities of day to day life, you will lose the will to push on and support the family and kids as you do today. The Porsche IS the college ticket. It IS the family meal ticket. The Porsche is the key to a happy life. Think she'll buy it?

[Lapkritis]

We have "allowances" from the cash pool every month... If I want a big ticket item, then I have to wait until I have saved within the pool. The Porsche takes months of limited fun for some jobs. . At the end of the day, it's a toy and this system keeps me from getting carried away.

[DSPTurtle]

Are you in Florida 911freek?