FredR

The hydro-locked concept makes more sense than seizure - all it takes is a leaky injector- if this is what happened and you tried bumping it down a hill you just have to hope the conrod is still straight.

Was the motor "seized" one day and later free? If so the fuel would have drained drop by drop into the crankcase leaving the motor free later on. But hang on- you said you were cranking the motor and it would not fire and eventually it "seized"- unburnt fuel in the cylinders- could this have accumulated until hydrolock occurred? I would think not given the valves were opening and closing but having never tried it...? Liquid pumped into the exhaust port would drop into the exhaust but on the inlet side, bigger valve, bigger opening..hmmm. Thoughts anyone?

Tmm20

It took months and months before it broke free. I tried using a breaker bar and four foot cheater pipe to break it free and the breaker bar shattered and blasted me in the head so hard it cut my scalp literally to the bone. I could see my own skull. That's how hard it was seized. No way a rod is bent, I'd know that by now, I've driven it several times just smoking like an Indian chief.

FredR

Did you take the plugs out at all and then try to crank it? If it was hydrolocked I have no idea how long it would take to bleed down- not that long I suspect.

With any problem of this nature always important to understand the root cause of the problem. At the moment to me there does not seem to be a credible string of events here [cause/effect] so do not give up hope on this one just yet.

FYI- the folks on this list like to help owners in distress recover but generally, we like to see 928's be what they are warts and all. Most are not the least little bit interested in hybrids and if and when you abandon the 928 motor most will probably abandon your case- nothing personal- just how it is so let's try to sort this sucker out!

Compression test time!

James Bailey

If you are getting plumes of blue smoke when you get back on the gas after you let off the gas and coast....that is a classic sign of poor ring seal. Coasting with the throttle closed creates a big vacuum in the intake which does pull oil up past the rings against gravity really, really well.

Tmm20

Yes all plugs were pulled and I tried to turn over by hand and with starter, nothing. It was definitely mechanically seized somehow. Weird part is that it would turn backwards freely but it would seize when it hit one specific spot and would go no further. I did not turn it more than a few degrees backwards knowing the issues with spinning the belts backwards and cams getting out of time.

Also, I will never be selling this car. If I go to a Chevy/ls swap I absolutely would not expect further help. I understand the "purists" but that doesn't mean I will keep an older engine with parts that are already NLA just to please someone who is never going to drive my car - no offense! If the rings turn out to be shot that is the end of the engine for me and a swap will be easier than doing the rings and everything else that needs done "while you're in there" on the way in and out just to get to the rings. The cost outweighs the value of the car. I just don't have that much interest in staying "$5,000 away from a $10,000 car" just to keep the purists pleased. I know that's like insulting someone's mother here but you have to consider cost vs benefit if the engine is basically shot for all intents and purposes and parts like I mentioned are already going NLA. Its just a losing battle unless you've got a really good engine to start with and a car with a complete and good condition interior (I do not).

I'm hoping that mentioning my intent doesn't keep others with knowledge from chiming in just because they're upset that I would consider an engine swap to preserve the utility and feasibility of the car just because they might be upset with what someone does with their own car... MY car that they don't own, will never own, and will never drive because I'm not selling, ever...

If it is at all possible I fully intent to repair and retain the original engine - let me be clear on that.

FredR

I have seen a seized thrust bearing broken free with brute force but not seized pistons. That you broke a 4 ft cheater bar, presumably a 3/4 inch sq drive job, tells you something. I can visualise excessive heating and cooling helping to break such seizure but not ambient type heating/cooling - root cause analysis definitely needed on this one!

Tmm20

Yep, big boy 3/4 inch breaker bar shattered like glass under the force of my 125lb frame putting everything I had into it. I punch above my weight. That hurt, bad. I thought I lost an eye when it happened because it hit me so hard I couldn't see for several minutes.

I am extremely thankful for the input so far, and yes root cause analysis is extremely welcomed. None of this makes sense, and I've been doing all my own work since I was 16. I've never taken a single car I've owned to the shop for anything but tires since I dont own a tire machine.

Edit; I had even pulled the valve covers to check for a broken cam or cam chain and then tried to break it loose, no plugs and no valve covers. I would sit and watch the chains and cams spin and then lock SOLID when it hit that one spot and would move no further beyond it.

FredR

Well you have just stated that the pistons were not seized for starters! The engine would not go backwards if it was seized would it?

FredR

Have you had the cam covers off and had a look in there?

A problem in there is more in line with the info you have just opened up.

Tmm20

That's what I thought but I had wondered if they were twisted somehow and just got jammed up on the up/down stroke but not vice versa?

I truly can't make sense of any of this. I am amazed it runs as smooth as it does - its idling better than it did when I bought the damn thing! If I could track down where this oil is coming from I'd be good to go!

Tmm20

Both valve covers have been removed and replaced during the diagnosis and I see nothing wrong in there, chains are good, chain guides are in place, etc.

FredR

Any chance there was a problem with the starter motor solenoid jammed in there?

Could that explain movement in one direction and not the other at the time? Cannot get my head around that one at the moment.

Tmm20

I had originally assumed the starter was fried and swapped it out for a brand new unit as when I would try to crank it after the seize it just made a loud SLAM as the starter engaged the flywheel but would not spin.

When I swapped in the brand new unit and it did the same thing I knew the problem was worse than I thought, and that's when I realised the engine itself was seized and would not turn.


Edit; and you're just the last in a LONG list of folks who can't wrap their heads around why the hell it would turn backwards but not forwards. Don't feel bad.

Also, when it seized up there was a LOUD CRACK! sound that came from the engine bay and the cranking of the starter instantly stopped dead.

The sound was analogous to if you took a five pound sledge and smacked the block HARD. A metal on metal CRACK sound. Hard to explain better than that.

Tmm20

And I just got off the phone with the fourth local Porsche expert today ive spoken to who has no clue what the hell could have happened. Guy said he's been working on them 30 years and has never heard anything even remotely like this. When they seize, according to him, they're done and that's the end - they never turn backwards freely and absolutely never break loose ever again. It just does not make logical sense.

FredR

In root cause analysis always remember that info that eliminates problems is just as important as info that incriminates! We now know quite a lot more relevant info than we did from your original mail - a positive!

Sounds as though you possibly goosed the starter motor from excessive/repeated use- remember these are not designed to work continuously.

Your latest info tells me that something suddenly got in the way of the rotating assembly so what possibilities could we be talking about here?
Could any of the following have relevance?
-A friend of mine could not rotate his motor because the valve seat fell out of the head and jammed the valve open and locked the piston when rotated forwards- but the motor was not seized.
-Something fell into the inlet tract and jammed the piston
-Did you do anything to the car just before the problem occurred?
- could something have dropped off the clutch and jammed forward progression of the motor
- is it possible one of the accessories was jammed? I doubt a belt driven accessory could lock the motor completely but...?
- when did you come to understand the pistons were not seized and that you could move the motor backwards [slightly]?