Sign in to follow this  
Denny

How to remove 240Z head

    Recommended Posts

    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!

    Share this post


    Link to post
    Share on other sites

    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?

    Share this post


    Link to post
    Share on other sites

    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 by Mike B

    Share this post


    Link to post
    Share on other sites

    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!

    Share this post


    Link to post
    Share on other sites

    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...

    Share this post


    Link to post
    Share on other sites

    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.:

    Share this post


    Link to post
    Share on other sites

    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).

    Share this post


    Link to post
    Share on other sites

    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.

    Share this post


    Link to post
    Share on other sites
    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

    Share this post


    Link to post
    Share on other sites

    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 by Denny

    Share this post


    Link to post
    Share on other sites

    Hi

    Before you try to remove the head there are 2 things you need to make sure you do. First DO NOT remove the Cam tower bolts. The cam is Line bored and you will never get it back inline unless you have a machine shop do it. Second is to make sure you install a small piece of wood between the cam chain and guide. If you do not you will have to remove the oil pan when the chain Tension pops out. Like stated before a rubber mallet should break it loose. Good luck hope this helps a little. Any other things you want to ask drop me a line at mikej707@comcast.net. I bought mine new in 1971 and have rebuilt several over the years. They are a great cars.

    Mike

    Share this post


    Link to post
    Share on other sites

    First, the cam tower bolts do not hold the head down, and do not remove them, as Mike said.If you have already done so, it is a fiddly job to realine them, but is possible. Use the search function on this forum.

    If one stud broke half way down, you could have the scenario I referred to in my first post, in which

    case as the head is alluminum you may have a job to remove it. Some advice from a machine shop would be my suggestion,

    unless there is some majic product that will dissolve the carbon around that stud.

    Did this engine have a blown head gasket, and a bad miss?

    Are you planning to remove the entire motor. If so perhaps a machine shop could drill the stud out. This could probably work, but it is a deep drill job.

    Another idea which I have never tried is if you managed to work the head loose enough to get a hacksaw blade in there you may be able to cut the stud off.

    You would certainly damage the alloy head, doing this and it would be a long job. Find another motor!!!

    Good luck. Let us know the outcome.

    Edited by olzed

    Share this post


    Link to post
    Share on other sites

    Oh Man ! I am getting ready to do this. My sons 260 is leaking coolant right at the rear of the head/driver side. Just a dribble part of the time but using sealant does not inspire much confidence for me. Any tips to not breaking head bolts. I know soaking would probably be a waste of time. Would penetrating oil even get to where it was needed?DSCF6127.jpg

    Edited by torker

    Share this post


    Link to post
    Share on other sites

    Put some radiator product in. It may stop the leak if it hasn't got a blown gasket from the cylinder area. If the head gasket has blown from the cylinder area, which will show up with a miss and low compression, don't run the engine for too long as this is when the trouble with carbon jamming up the studs will occur.

    On the tractor I owned I ran it all day with a blown head gasket, and then ran into big trouble to remove the head.

    Hope this rambling from an old guy makes sense.:ermm:

    Very much doubt if penetrating oil would get down to the threads, but no harm to try.

    Don't try to remove the studs while the engine is hot as the threads can gall up.

    The same applys for spark plugs in an alloy head, or bolts any where for that matter.

    I have a weeping head on my 240 and have kept it at bay with rad. sealant for 11 years.

    So- touch wood, it will last as long as I do.

    Edited by olzed

    Share this post


    Link to post
    Share on other sites

    It has a blown head gasket, that's why the head needs to come off. Around the edge of the bolt still sticking up about 1/4 inch, I can see something black. This is probably carbon, I am guessing from some of the posts I've seen here. Thanks, everyone! I've put lots of Blaster PB around the broken head bolts to try dissolving the carbon, but I don't know if that's doing any good. If anyone has more ideas about how to dissolve the carbon, I'd appreciate hearing these.

    I broke the head loose with a rubber mallet. I can separate the front part of the head from the block now. The back part, where the broken head bolts are, is still stuck. Yesterday, I built a scaffold above that part of the head and am using a come-along like a hoist to try to lift it. Unfortunately, that is not working.

    My father-in-law came up with an idea we are going to try today - that is, to use a puller, grappling around parts of the head and pressing down on the bolt that is still sticking up above the head. I think this may work - I've got my fingers crossed!

    Edited by Denny

    Share this post


    Link to post
    Share on other sites

    If you have a welder, try this. take a nut and center it on the broken stud, then weld them together by filling the hole in the nut with the weld pool. Hit that sucker with an impact while it's still hot. If it breakes again, it will be above the deck and you will get a second shot at it when the head is finally removed. On the bright side, it will incinerate the carbon. If you don't have a welder, try using a B tank with a turbo tip on the studs you can reach. This wont burn the carbon off, but it will break it up some.

    Share this post


    Link to post
    Share on other sites

    Well, I finally got the head off. We used a puller on the bolt that was still sticking out about a 1/4 inch. That alone didn't work until we put a spacer between the head and the block and then retightened the head bolts on the opposite side to force the stuck side up. After doing this several times, it finally came loose enough to pull the head off. It was the toughest head I've ever pulled, granted, I haven't pulled that many of them! Thanks for all your help!

    Now the machine shop guy says the water holes are too corroded. He suggests getting another head. I was wondering about the possibility of putting a 280ZX turbo head on it - has anyone out there done this (on a 240Z)? What else would need to be changed in order to do the turbo? Or would you recommend just staying with a stock head?

    Edited by Denny

    Share this post


    Link to post
    Share on other sites
    Well, I finally got the head off. We used a puller on the bolt that was still sticking out about a 1/4 inch. That alone didn't work until we put a spacer between the head and the block and then retightened the head bolts on the opposite side to force the stuck side up. After doing this several times, it finally came loose enough to pull the head off. It was the toughest head I've ever pulled, granted, I haven't pulled that many of them! Thanks for all your help!

    Now the machine shop guy says the water holes are too corroded. He suggests getting another head. I was wondering about the possibility of putting a 280ZX turbo head on it - has anyone out there done this (on a 240Z)? What else would need to be changed in order to do the turbo? Or would you recommend just staying with a stock head?

    I think the biggest thing to worry about there is if your compression ratio will be really low as a result? Maybe I'm remembering it wrong and they lowered the CR just by using dished pistons, but the head geometry may be different... Searching the forums for the casting number would probably tell you

    Share this post


    Link to post
    Share on other sites

    Well Denny, pleased you got the head off. That method you describe I must remember. Just a shame the head is corroded. Other heads will fit, but you may be better to get the same type if possible. There should be heaps available,

    with all the engine swaps that have been done.

    As INF says Compression Ratio is the problem with a 280zx head.

    Was the stud frozen with carbon or rust.

    Share this post


    Link to post
    Share on other sites

    Mike, you're wrong about the cam towers. Olzed, it really isn't a fiddly job to put them back on. You just put them back on and when you install the cam spin it in the towers by hand just to be sure you have them aligned. I've done it a couple times. I installed a cam and changed the towers to run internal oiling then pulled the towers again to change to a bigger cam later. Even when I put the internal oil towers on my E31 head, it was no problem at all. Just bolt them up and spin the cam to make sure they're all aligned and that's it.

    Denny, run the same head if you don't want to screw with anything else on an L24 block. If you run a later head with bigger valves I think you need to eyebrow or notch the block. Not a big deal, but it is more work that you don't have to do if you stick with a stock head. Heads are pretty easy to come by and should run you somewhere between $50-$200 for a good take off head, more if you find one that has a valve job and is all ready to bolt on.

    Share this post


    Link to post
    Share on other sites

    Ditto what Jon says.......and don't over-torque the cam tower bolts....... 10 to12 foot pounds max if my memory serves me correctly.

    Edited by Diseazd

    Share this post


    Link to post
    Share on other sites

    Not too fiddly granted. Make sure to get them back in the same place from which they came.

    Share this post


    Link to post
    Share on other sites

    Create an account or sign in to comment

    You need to be a member in order to leave a comment

    Create an account

    Sign up for a new account in our community. It's easy!

    Register a new account

    Sign in

    Already have an account? Sign in here.

    Sign In Now
    Sign in to follow this