On a 240Z, I have removed all 14 head bolts, the 2 timing cover bolts, and the intake and exhaust manifolds, the fuel pump and the air conditioning bracket. Everything I can see bolted on to the head has been removed. The problem is the head won't come off of the block. I have tried to pry it off, but it still seems like it is bolted on. Can anyone help?

Thanks!

Assuming the valvetrain has already been removed, that's all I can think of.

Yah, the valve train is removed. 3 of the head bolts are snapped off (they broke while removing them), but I that should not keep it from coming off - what do you think?

It sounds like the head may be stuck to the head gasket. That's not unusual. I have been able to get stuck heads off by hitting the sides of the head with a heavy rubber mallet, but you may need to use a thin putty knife to help break it loose. I had a stuck differential cover recently and used this putty knife set from Harbor Freight and they worked great http://www.harborfreight.com/4-piece-stainless-steel-putty-knife-set-94325.html.

-Mike

Edited November 21, 201014 yr by Mike B

Yep. I used a 5 lb dead-blow hammer to loosen mine.

Thanks for the comments, guys! I think I'll try using a putty knife tomorrow. Funny, that's what my father-in-law suggested, too!

I'd sooner try the hammer method, maybe put a chunk of a 2x4 up against the head to keep from marring the surface and give it a few hits with a 5lb sledge. With a putty knife, I'd be afraid of pushing chunks of gasket material and other debris into the oil/coolant passages...

If you had a blown head gasket, the carbon can force it's way up one or two studs and make it almost impossible to remove the head, but if the studs broke

at the base, then that won't be the problem.

I have had this on an old Toyota, and took hours to get the head off.

Also on a tractor engine. I had the weight of the front of the tractor hanging on a chain block by the head lifting brackets, with all the head nuts removed,

and a five foot crowbar between the head and block. Took all day with penetrating oil and swearing to get that head off. Couldn't screw the studs out.

It was like they were welded in the holes.:

Yes.....I've had head bolts stuck so bad from carbon build-up they had to be sent to a machine shop to be removed from the head. If the head bolts broke off up in the head, you won't be able to drive it off with the block of wood as Andrew mentioned (and I agree with), but you may be able to break it loose. Then pick it straight up if the bolts are up in the head. I'd be careful with a putty knife on an aluminum head (IMO).

Try draining the oil and coolent, then using a leakdown test fitting put some compressed air in the cylinders (60 to 80 psi) then tap the head with a dead blow. I've used this method with success on several motors in the past. Start on #2 then go to #4. If you have broken studs on a common cylinder, hit that one with pressure first. Lock the crank in position to keep the pressure from driving the piston down. Don't get desperate and jam a steel blade against your aluminum head or you WILL be going to the machine shop to resurface the head. That is the last resort.

Yes last resort. The five foot crowbar was my last resort.

Don't get desperate and jam a steel blade against your aluminum head or you WILL be going to the machine shop to resurface the head. That is the last resort.

I agree it is the last resort, which is why I mentioned the mallet method first. I think it is safe to say that with three broken head bolts he is going to be headed to the machine shop anyway at this point. I guess the other option is just to leave the head on and take the whole engine to them and let them deal with it. I was worried about using a putty knife to get my aluminum diff cover off too, but it worked out fine, so I think it can be done as long as you are careful.

-Mike

Thanks for the posts, guys. I'm just about to go back out to work on it again. There are 3 head bolts broken off, but one of them is broken off in the threads, so I'm sure that one is not one of the ones holding it down. The other 2 that broke off are in the 2 back holes (#6 cylinder, closest to the driver). One of those broke off about 3" down, so the end of it is inside the head. The other one is one of the cam shaft bolts, and it broke off at the very top. After taking the cam shaft spacer out, there is still about 1/4" sticking out above the head, and I can see some black stuff (carbon?) around the edge of the bolt.

I just wanted to make sure there are no more bolts other than the 14 head bolts and the 2 timing cover bolts - that's all of them, right?

Edited November 21, 201014 yr by Denny