overheating

[Ross Clover]

having an overheating problem cracked head is suspected. I have a 95 head totally redbuilt ported etc. willit bolt on to the 90 block, both are multi port both apear the same externally is there any valve clearance issues , does high out put version change anything please need to fix before summer cripples me

[Mudderoy]

having an overheating problem cracked head is suspected. I have a 95 head totally redbuilt ported etc. willit bolt on to the 90 block, both are multi port both apear the same externally is there any valve clearance issues , does high out put version change anything please need to fix before summer cripples me

Well unless you are certain you have a head leak, maybe you can tell us more about the problem. It may not be a head leak.

[ice_cold]

If you pull the rad cap off and start the engine and get a geyser...heads blown.
Are you sure the system is air free?
All the fans working correctly?
Thermostat working properly?
Take my word for it, check the easy/little things before busting the head off.

Mike

[xj4life2]

heres the long and the short of for ya, kept this in my records for swaps we were doing :

There are four of them and you really cannot swap them around, so you had better know what you have and what fits where.

All years of 4.0L production used cast iron cylinder heads. In 1987-1990 the cylinder head casting number is 2686. The fastest VIP (Visual Identification Point) on this head is the mostly rectangular shaped intake ports that have an abnormal looking relief at the top for injector clearance. Note also that the intake ports are facing each other on the front two and rear two cylinders but the exhaust do it on the center two. The exhaust ports are a rounded "D" shape.

The 1991-1995 head castings (c/n 7120 and 33007119) appear identical to the 2686 until you get to the port side of the cylinder head. There, you'll discover the VIP to be the intake port which now has much smaller relief for the fuel injector and the exhaust ports now look like a squared off circle or a rounded off square depending on your perception .

From 1996-1999, the Jeep 4.0L used head casting 0630. This cylinder head has two receiver holes for two dowel pins that were added to the block for cylinder head alignment . The intake ports were changed once again, and there was a newly designed rocker cover and gasket on the scene, that will not retro back. Also, the move was made to lighter pressure beehive-shaped valve springs and a different profile cam.

the center exhaust ports on this head run off a common port without a divider at the gasket surface. This is the quickest VIP of this head.

The 1999-2005 cylinder head has casting number 0331, and includes the same two head dowel receiver holes. Surprise, surprise: the intake ports have changed once again. they have gone back to that small relief at the top type port again, and the exhaust ports are the smallest that they have ever been. The interior of these ports are very rough "as cast" and are very easy to recognize. However the VIP on this head is the spark plug side of the cylinder head where there are four new bosses to mount the coil packs

Hope this helps

[Ross Clover]

1990 had pressure tank with warped plastic lid that allowed system to overheat and boil over (big bloody mess everywere) swapped rad and overflow tank plus rest of hoses shutoff etc. from 1995 also swapped clutch fan from same (other was free spinning) temp much better but sill too hot 3/4 on gauge water pump replaced from old owner last year do different models run in opposite direction or all run same? system was flushed when rad swapped electric fan from 95 installed with switch helps a little heater on helps a little but with rising outside temps i don't want kill motor (not finished replacement yet) should i remove thermostat or will that not let it cool enough

[xj4life2]

First of all yes different years run different directional water pumps and you should always check. There are two ways to do this , first note the direction of the impellers is it the same as the one you took off ? nest if you look at the shaft the impeller is pressed onto it will have either a R (right) or L (left) stamped on it so you will know the direction it will spin. Next on the 1990 you must run at least a 180* t stat or the ECM will never trigger, beside if you have no T-stat the water will never be held in the radiator so it will never have a chance to cool. Finally here's what I had to do on my 1990. First of all I knew I had a 192* t-stat so I fired it up and watched the temp guage, It went to the red and then cooled back to the 210 mark , So now I know that at the red I'm actually at 192* . I have tried several different senders and none of them work correct at all so I have marked the guage as it is. Yes the guage itself could be bad but I know how it works so I'm good with it. I did verify the temp with our thermal senceing gun. So it could be that the guage / sender is not correct. I would also recomend that you run a bypass on the electrical fan so you can control when it comes on.Good Luck hope this helps !!

[Ross Clover]

thanks i will check direction on pump replace tstat again and check on off cycles with temp gun to check gauge and sending unit