How hard to turn cam shaft?

wmburns · Dec 10, 2009

I have a 2000 SOHC Windsor with a broken timing set. The motor did run for a few seconds with low oil pressure. I am breaking the motor down to see what is salvageable.

The timing set is toast (broken tensioners and guides) and have been removed. The roller followers have been removed so the cam can be moved without damaging anything.

Note, the motor was still in time when it died.

The cam shaft can not be rotated by hand. I can rotate by using a tool against the cam gear. How much effort should it take to rotate the cam shaft without the valves?

I suspect I already know the answer that the cam shaft has been galled from not having enough oil.

Signed
Wishful thinking.

Gearbanger 101 · Dec 10, 2009

I'd say its toast. The fact that the tensioner and guides bit the bullet when the cam ceased up contradicts your belief that the engine was still "in time" when it ceased up. When the tensioners and guides go, it throws everything out of whack. Even if it was only for a second or two, that’s enough time to bend valves, break followers and crack pistons.

Just for perspective.....before I rebuilt the engine in my ’96 Cougar, the previous owner had also run it low on oil, ceasing up the cams and wiping out the valve train. Valves smashed into pistons, feelers were bent, or broken and the cam journals in the heads were scorn beyond repair. Pistons had visual contact marks from the valves, but since I was rebuilding the engine with forged rods and pistons anyway, I didn’t really car. I replaced the heads with a set of low mileage PI castings and never looked back.....but it wasn’t cheap!

You can tear it down and inspect it visually if you wish, but a vent valve or cam feeler may not make themselves apparent until the engine is back together. Chances are, the top end of the engine is toast and probably beyond repair.....at least at a reasonable cost anyway.

This might just be a good time for you to look into a used low mileage Windsor engine out of a truck, swap over your Mustang intake components and sensors and just cut your losses.

sneaky98gt · Dec 10, 2009

I don't really know how much it should take, but FWIW, when I did my PI cam swap, it took a pair of channel lock pliers to turn my camshaft. Although it was a smooth rotation and wasn't all that difficult to do.

Gearbanger 101 · Dec 10, 2009

If the engine is locked up, you probably shouldn't be able to turn it at all with the cam feelers still in place. Remove them and then try turning it over by hand....but I warn you...modular engines run low on oil starve the cam shafts first, so expect scoring on both the cams and cam journals in the heads as well.

Pull the cams themselves and visually inspect them. Its the only way you're going to know for sure if the cams/head were damaged.

patman0911 · Dec 10, 2009

I'm pretty sure when i did my cam swap I was able to grab the gear with two hands and turn the cam even with the rockers still in. It takes some effort to over come the spring pressure but they turn smoothly. I'd think they'd turn pretty easy without the rockers in.

If you've already got the chains off then you're only about 5 minutes from having the cams out - you coulda had 'em out and been checking out those journals in the time it took to post this

wmburns · Dec 10, 2009

Allow me to add details. The motor was at idle at the time. The oil pressure went to zero while stopped at a light. The loss of oil pressure was noticed quickly but the motor stopped before it could be shut off.

I know the motor was still in time because upon initial tear down, the chains were still intact. The plastic guides broke and a piece wedged between the timing chain and the crank shaft gear stopping the motor cold.

The roller followers have been removed. Therefore, there is nothing pressing against the cam to resist turning other than the cam bearings.

I have never torn a modular down to this level before (replace the entire engine). I would have expected to be able to rotate the cam with moderate hand pressure.

What I was hoping to learn if it is "normal" for the cam to be so difficult to turn. Or it for certain the cam bearings are galled/siezed.

For the record, my Mustang already has a new salvage motor. This tear down is to see if there is anything at all that can be done with the remains (perhaps another project).

There was this little optimist hoping that all this motor needed was a new timing set.

Rickyll7 · Dec 11, 2009

If it's hard to turn with the chain off and the followers out, then your heads and cams are toast.

wmburns · Dec 12, 2009

can damaged cam bearings be repaired?

As predicted (and somewhat expected), several of the cam bearings are galled. Several look fine. Several have light scratches. One has deep scratches with metal transfer from the bearing surface to the cam shaft.

The cam shaft itself does not appear heavily scratched. But the softer aluminum has taken the worst of it.

Question? Is it cost effective to repair/polish the head cam towers? What about the cam shaft itself? Are these heads good for anything at all (150k miles)?

Thanks for your help and input.

Gearbanger 101 · Dec 12, 2009

You could shop around to various machine shops and see what they would charge you to repair the damage on both the cams and the cam journals (as well as the caps i'm assumeing?) Just keep in mind, brand spanking new PI heads, assembled with cams, valves and springs can be had for about $400 each through Summit. IMO, its not worth the price to have them repaired when you still don't know 100% if the rest of the head didn't take a beating as well.

How hard to turn cam shaft?

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