924Board.org

mrgtturbo · Joined: 06 Jan 2003 Posts: 526 Location: Skowhegan, ME

In one of the 924's I had hauled in the motor is unturnable from the crank.

I guess this means it needs to be torn down, but does it also mean it needs a true rebuild?

Thanks
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81' 931

Paul · Posted: Sun Mar 14, 2004 11:26 am Post subject:

You can pour some oil in the spark plug holes and let it soak a couple of days, but you're probably looking at new piston rings at the very least.

Pull the valve cover and see what the cam and lifters look like.

mrgtturbo · Joined: 06 Jan 2003 Posts: 526 Location: Skowhegan, ME

So when an engine freezes, it freezes at the rings... that's the point where it binds?

Is this normal of an engine that has sat for years, or most commonly one that has other issues?
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81' 931

Paul · Posted: Sun Mar 14, 2004 12:01 pm Post subject:

No the rings are usually broken as you try to pound the corroded piston out of the rusty cylinder.

mrgtturbo · Joined: 06 Jan 2003 Posts: 526 Location: Skowhegan, ME

Oh..... so it's not that big of a deal then.

Is it worth screwing with?
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81' 931

Paul · Posted: Sun Mar 14, 2004 12:22 pm Post subject:

I'd pull the valve cover and see what condition the cam and lifters are in.

If they are rusty and corroded, the price goes up quickly.

The block can almost always be saved by boring it out to the next oversize. Of course that means new pistons and rings.

Most of the time the crank is ok unless the oil pan is full of water.

mrgtturbo · Joined: 06 Jan 2003 Posts: 526 Location: Skowhegan, ME

The oil looked very good in it.

So I guess the biggest concern is the head area.
If all is well there, how much of a cost is to be expected doing my own work, (minus the boring)?
Rough guess.
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81' 931

Paul · Posted: Sun Mar 14, 2004 12:56 pm Post subject:

Pistons are not cheap.

Roger · Joined: 06 Jan 2003 Posts: 1235 Location: Cordova, TN

All depends on the work necessary, and you wont know untill you start tearing the engine down. Problem is when you start talking about overborring and a complete head rebuild the parts will cost more than the car is worth. Depending on what you find I would consider just finding a used motor that is in beter condition.
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1981 924 NA

Some people are like Slinkies. Not really good for anything, but you
still can't help but smile when you see one tumble down the stairs.

Joes924Racer · Posted: Sun Mar 14, 2004 3:18 pm Post subject:

Dont jump to fast get a pistons out Ive had them wedged in
there I had to pound it out. The piston in one cyl. started to
self destruct.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

mrgtturbo · Joined: 06 Jan 2003 Posts: 526 Location: Skowhegan, ME

This is not a "huge" concern anyway... I mean not at the moment.
My car money is pretty much prioritized at getting the 931 back up an going. Unless it looks like one of these 924's would be alot cheaper to get road worthy between the 2. In that case I'll fix up one of them first, sell my Probe GT and have the money to finish of the 931.

However it goes, I'm not dicouraged with the 924's yet. One motor turns over pretty good.... but not firing yet.

I'm more asking to know if the other one, (the froze one), is worth my while to keep, or just take what I can from it. But that depends on the money it will cost me to repair, money I can't and wouldn't part with right now anyway.
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81' 931

Paul · Posted: Mon Mar 15, 2004 1:53 am Post subject:

It may be ok, but even if you are not going to spend anytime on it now, fill the cylinders with oil. (Do not reinstall the spark plugs) Also remove the valve cover and oil the hell out of the cam and lifters.

mrgtturbo · Joined: 06 Jan 2003 Posts: 526 Location: Skowhegan, ME

Thanks for the advice.

Time for me to get out there and get something done.

Later guys.
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81' 931

Sleykin · Posted: Mon Mar 15, 2004 4:50 am Post subject:

One thing I have had some success with is filling the cylinders with oil through the plug holes and then fitting an air fitting to one of the holes that has closed valves. Leave it sit with 125PSI of air on it which will force about 800 pounds of force on the crank. Only down side is when it finally goes it will gush oil out some of the other holes.
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Glenn Neff
Medford, OR
87' 924S

Paul · Posted: Mon Mar 15, 2004 6:29 am Post subject:

Sleykin, your math is a little off.

Based on 125 psi and a bore of 3.41 inches, I get 1141 pounds of force!!!