Cylinder head install, one more question

[Ron Hyslop]

I have everything removed and all the head bolts out except the last one on drivers side but it's taped in the almost out position, now how do I break the head free from the block without damaging the block surface?

[5-90]

If you have that one fully unscrewed from the hole, I've found it easier to just leave it in there and pull it out with the head. Make sure it's in that hole when you put the head back, and yer alright.

5-90

[Ron Hyslop]

I've got that that bolt unscrewed and some tape around the bolt so it won't fall back. My problem is I can't budge the cylinder head loose from the block. What's the prescribed method for breaking the head loose from the block?

[Toph]

I've never swapped a head on a 4.0, but on other motors I've found that a swift blow on the side at one of the ends with hard rubber mallet will shake things loose a bit. Either that, or a piece of 2x4 and a small sledge can accomplish the same thing. Just enough of a tap to loosen things up a bit.

[5-90]

Yeah - hard rubber mallet, chunk of wood, rawhide mallet, one of your kids - anything that isn't metal that you can get a good swing in with should serve. I've been known to give it a good poke with a broomstick or wooden shovel handle when needed - you learn to improvise after a while.

Of course, I've learned to pull I6 heads with the manifolds in place - which makes for a nice place to lift and break the gasket loose...

5-90

[AZ Jeff]

As animalistic as it sounds, a big crowbar or similar, jammed into an intake or an exhaust port (NOT against the valve stem) and levering up works fine for removing heads

Just don't mangle the valve, or trash the edge of the port by letting the prybar slip out of the hole.

I have done lots of heads this way over the last 30+ years.

[5-90]

Which is why I suggested a broomstick or a shovel handle.

I'm pretty damn confident with tools, but I've got to be desperate to shove something metal down a port. I'd actually bolt the intake back on and lift that, if it came down to it.

5-90

[old_man]

I use a sharpened chisel at the parting line where the gasket is. In a pinch a large screwdriver. You need to be real carefull prying with something in the ports. There are places where the metal is not that thick and it is easy to break. I have a flat bar with a hole in it that I screw down using a intake/exhaust bolt. I then hook it to my slide hammer and give it a good wham.

[AZ Jeff]

Hey guys, I am not suggesting random careless yanking any 'ol place on the ports.

My tool of choice is actually a Craftsman 18" long breaker bar shoved in the port handle-end first. Its got a benign, round end, and won't go deep enough to mess up a valve stem.

I guess what I am saying is experience tells me when and where I can do this, and when it's not wise. BTW, I do NOT recommend this method be used on cast aluminum heads.

[Ron Hyslop]

Used a wood block and one sound rap with a hammer and it came loose. Turns out the valves are all OK in the original head and that there is some scoring and cylinder wall erosion at the top of #3 cylinder bore(motor is toast). This 87 xj was manufactured in the fall of 86 and came out of the factory with the distributor intstalled one tooth off. I bought the car when it was 8 years old and had 60000mi on it. Every third of fourth start it would shake like crazy and act like the starter cut out in the middle of the start cycle. It took me a year or so to figure out what was wrong with it and since I installed the distributor correctly it has run great. It is my opinion that on those rough starts, the spark jumped ahead to the next cylinder, ignited the mixture way to soon before TDC, causing huge pressure in the cylinder and eventually cylinder wall erosion as the hot gases leaked past the piston rings. I am hopefull that the dealer where I bought the head will allow me to return it and I'll buy a Mopar remanufactured engine. If not I guess I'll by a short block and install my new head on it. Thanks for all your collective help, this is my first foray into tearing engines apart.

[gptrilik]

Any pics of the toasted cylinder? I would love to have a look.

Thanks,

George Trilikis
00XJ

Originally Posted by Ron Hyslop

Used a wood block and one sound rap with a hammer and it came loose. Turns out the valves are all OK in the original head and that there is some scoring and cylinder wall erosion at the top of #3 cylinder bore(motor is toast). This 87 xj was manufactured in the fall of 86 and came out of the factory with the distributor intstalled one tooth off. I bought the car when it was 8 years old and had 60000mi on it. Every third of fourth start it would shake like crazy and act like the starter cut out in the middle of the start cycle. It took me a year or so to figure out what was wrong with it and since I installed the distributor correctly it has run great. It is my opinion that on those rough starts, the spark jumped ahead to the next cylinder, ignited the mixture way to soon before TDC, causing huge pressure in the cylinder and eventually cylinder wall erosion as the hot gases leaked past the piston rings. I am hopefull that the dealer where I bought the head will allow me to return it and I'll buy a Mopar remanufactured engine. If not I guess I'll by a short block and install my new head on it. Thanks for all your collective help, this is my first foray into tearing engines apart.

[Ron Hyslop]

My daughter is coming buy this afternoon with her digital camera. I'll see if I can get a couple pics posted this evening.