How to remove 240Z head

[Denny]

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, 2010 by Denny

[mikej707]

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

[olzed]

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 November 22, 2010 by olzed

[torker]

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?

Edited November 23, 2010 by torker

[olzed]

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.

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 November 23, 2010 by olzed

[Denny]

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 November 23, 2010 by Denny

[5thhorsemann]

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.

[Denny]

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 November 24, 2010 by Denny

[Inf]

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

[olzed]

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.

[jmortensen]

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.

[Diseazd]

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 November 24, 2010 by Diseazd