Froze engine

[lgoodson@pacbell.net]

Here's one for all of the ace mechanics.. I have a 72 240Z that was running just fine untill parked in 1980.It has been garaged ever since. But now the engine will not turn over even by hand. A drop of the oil pan revealed nothing. No water or other contaminants. This car has only 56,000 miles and looks original. It currently has a light oil in it and has had oil introduced into the cylinders. The only clue is that I noticed a water leak that hade been leaking out at the rear of the head on the pasenger side but once again there was no water in the oil.

So what could be causing the engine to be locked up??

 

Thanks for the help

Larry

[SHO-Z]

Rings are rusted to the cylinder is my guess. If you have the pan off start unbolting the rod one at a time and you will find which cylinder is froze.

[hoov100]

Put a few ounces of PB blaster down it and let it sit for about 5 minutes, then pour MMO in after, let it sit for a few hours, then take a big breaker bar on the crank bolt and yank to break it free. It's most likely going to seriously shorten the life of the motor, but it beets pulling it out and going through it to get it running.

[lgoodson@pacbell.net]

Yea it could be one or two of the rear cylinders causing the problem. The pan is currently back on the car so I'll have to wait on that but no matter which cylinder I will still have to pull the head and then I will know for sure what is going on. Actually I don't own the car, still in negotiations. I was planning on another LT1 conversion but then again I might want to keep it stock. Sold my last 240Z LT1 for 12000 and the buyer wants 3 more. Mine is now in Japan living life. If I had known that that is where it was going to end up, I wouldnt have sold it. I had a lot of myself in that car.

Larry

Edited December 25, 2010 by lgoodson@pacbell.net

[lgoodson@pacbell.net]

UPDATE, Well I did the PB Baster thing but it didn't work. With the head off I could not see any serious problem so I pulled the pan. Saw nothing there so I decided to pull a piston or two. The pistons didn't want to come out. So I drove the out with a 4 lb mallet and at first a piece of hardwood. Still didn't budge so I used a steel rod and this time the piston moved but at the same time I noticed that the connecting rods were not moving. I couldn't move them from side to side so I started to think that they were also frozen up. The problem with removing the pistons is that you need to be able to rotate the crank but with stuck pistons and frozen rist pins, that crank was not going to move. But with a lot of persistance and a pin stuck into the counter balane balancing holes with a long pipe attached and the use of the starter I was able to move the crank a 1/4" at a time untill I was able to pry the rods over into alignment and pound out the pistons, #5 and #6.

Now I will have a shop remove the rist pins and rings, clean and reassemble them and I should be good to go..... to the next step. The head after sitting for 31 years looks kind of sad, The are 4 or 6 valves that have sat open so I am going to have it rebuilt

 

What next???

 

The carbs are seized also but with a little PB Blaster and WD I was able to get the butterflies working again but they probably need to be rebuilt. I have been told that the SU's are easy ro rebuild. Does anyone know what is involved?

 

Next time you see an engine that has been sitting for a long time, you'll know what to expect and this was stored in side too.

 

The good news is that with a little rubbing compoud, the original paint should clean up nice. It did so on some test spots but I have to find a remover to remove some side molding that was put on with adhesive without removing the paint.

Any ideas?