Hello everyone. I recently purchased a 2009 Mustang GT with a 4.6 3V engine. It is showing 147K miles and is equipped with a 5-speed trans. Based on the previous owner, the car began turning over slowly and at times too slow to start. Eventually, they were driving it and it died and had not started since. I think the car ended up sitting for a while, maybe a few weeks. They said it only set a crank sensor code during this time. The price was discounted considerably and with a near flawless exterior, I bought the car. I got a new Motorcraft battery from the local dealer, cleaned the terminal ends and checked all the grounds I could access from the topside. Here is the strange thing that I don't understand. I have tried to rotate the engine by hand (breaker bar and 18 mm socket) and it won't budge in inch. I mean I felt the engine was solidly locked up tight. However, when I sit inside the car and crank it with the key, it turns over, not very well or very fast, but it turns. I have even used a grease pencil to make a mark on the harmonic balancer and then cranked it with the key to see if the engine is actually turning over or just the starter whining and not actually turning the engine. Well, everytime I crank it with the key, the pencil mark is in a different location indicating the engine has turned and is not seized up. But if I try to turn it manually with the breaker bar, there is absolutely no movement at all. I have removed all spark plugs to inspect the cylinders and it still does not crank by hand. How can this be? I guess I may have a burnt up starter or current draw issues as far as the slow cranking. The oil looks fresh and there is no indication of water in the cylinders, or crankcase. Thoughts?

 

5 spd auto or 5 spd manual?

If the car is manual, is it in neutral when you try to turn the engine by hand? If not, it will not budge because your trying to turn the trans as well since the clutch is not pushed in.

 

It is a 5 spd manual trans.

In all my years, I've never had an engine that absolutely would not budge with a breaker bar, yet the starter would crank the engine somewhat. I'm wondering about three different possibilities. The first one can be determined quickly and definitively I'm sure, could it be that an overhead cam engine with dual timing chains provides too much resistance to turn over with a breaker bar/socket setup?

Could there be some kind of resistance in the clutch assembly since when I sit in the car and depress the clutch, the engine will turn? I have not tried to turn it with a breaker bar while someone sits inside and depresses the clutch. That would seem to rule that possibility in or out, I would suppose.

Finally, and I'm afraid most likely, perhaps the engine is like about 80% seized up, enough that a breaker bar won't turn it, but a fully charged battery and starter will spin it, albeit very slowly.

 

What Derf00 said. Put the car in neutral. If a starter will turn it over, a breaker bar will.

 

Yes, I'm sorry, I forgot to clearly state that, I had the car in neutral for all these tests. This what is so perplexing to me, the starter will indeed turn the engine over, but a breaker bar absolutely will not. I had a 3-foot cheater pipe over the breaker bar and pulled right up to that point when you can just sense that if you push it any further you will snap the crank bolt off in the crankshaft...it absolutely would not budge a fraction of an inch. There is something else in play here but likely isn't worth my time to worry about it. Something is wrong with this engine or the starter or perhaps both. With all the plugs out and it won't turn by hand, I've never seen that before unless the engine is solidly locked up. So how is the starter turning it? I'm out of state right now until this weekend, I just thought I would pick everyone's brains to see what I'm missing here. Any ideas would be greatly appreciated!

 

What you are describing is impossible. I understand your frustration. Have you tried to do a compression test?

 

Yeah, that was the same thing a friend told me, and he is also an ASE mechanic. It has him scratching his head to when he couldn't turn the engine manually either. That is why I posted about this, it's a strange one indeed. My friend is telling me to start looking for another engine because anytime an engine won't turn over manually, something is wrong internally no matter what the starter does or doesn't do. He's probably right, I think.

I cannot do a compression check because when the starter does turn the engine, it is nowhere near fast enough to measure compression.

 

I wonder if the timing chain is broken in some way that prevents this. Crazy.

 

Agreed. Easiest way to check the chains is to remove the valve covers. If the chains are busted, it's cheaper and faster to buy a used engine to swap out.

 

Agree