see title of thread…
My first tip is to confirm that there is a need to change the gasket. Head gasket failures on the 4.0 Jeep I6 are somewhat rare.
If you confirm that the gasket has failed it is somewhat easier to remove the head with the exhaust and intake manifolds attached if a ‘cherry picker’ engine lift is available.
well I need to change those gaskets too, I think so that s a plan. I can build some kind of lifting device.
pretty sure its the head gasket, losing water from radiator, getting water in oil, and smelling antifreeze in exhaust
Don’t re use the head bolts.
Together those are somewhat compelling indicators of a breach somewhere.
A 2x4 laying across from fender to fender attached to the head with a well positioned chain will enable 2 people to lift and remove the head safely. To reinstall the head installing 2 pieces of threaded rod into the block that are long enough to protrude out the top of the head will make reassembly much easier and prevent damaging the new gasket.
I recall a note regarding the frontmost manifold bolt requiring a sealer on the threads to prevent coolant leaking.
Make sure the mating surfaces of both head and block are flat. A couple or three thousandths is acceptable. Anything over that and it really needs to be surfaced.
If the engine is high miles my preference is to always have a valve job performed while the head is off.
If the valve job is not done then at a minimum the valve seals should be replaced. Seals come with the head gasket set so use them and eliminate that as a source of oil consumption.
Inspect the head and block very carefully with a good light looking for cracks, as OK said check flatness, and good luck. At least the job is mostly labor.
Since you already have coolant in your oil there is no harm in breaking the head free my stepfather’s way.
Don’t remove anything but the valve covers and loosten but don’t remove the head bolts and START THE ENGINE.
thanks guys, good tips and i have a book. its been getting slowly worse over the past few months, but hasn t blown or gotten hot yet.
Buy a valve spring compressor and remove valves and scrape the crud buildup off them. You can do it with a pocket knife. Removing valves is easy and obvious and fun. Also if the exhaust valves are too ugly, you can change them.
Guys, please correct me if I’m wrong . . .
But I seem to remember reading that some of the Jeep 4.0 heads were prone to cracking
I don’t recall what model years were affected, though
I’ve never removed a head from an engine, but I was wondering if I had to do it, that it might be easier in the long run to remove the engine from the car first and do the head work with the aid of an engine stand or the engine just sitting on the garage floor. What are other’s experience with this? Would you ever remove the engine first when doing a head gasket job?
The rear head on V6 engines in FWD automobiles can be a real pain but removing the engine was never worthwhile on any. And luckily I never had to remove the heads from an Aerostar van but I imagine it would be necessary due to the cramped positioning. But the engine and transmission were somewhat easily removed by lowering them as a unit on their subframe. I have replaced those engines and it is much easier to work on the power train on a work bench.
I've never removed a head from an engine, but I was wondering if I had to do it, that it might be easier in the long run to remove the engine from the car first and do the head work with the aid of an engine stand or the engine just sitting on the garage floor.
In general, no. It’s usually easier to remove the head then remove the engine.
Generally easier to yank a head with the manifolds attached unless you’re dealing with something like a Subaru Boxer engine.
The heads on a Subaru can be removed with the block in place but it’s generally easier to pull the motor rather than wrestle them in place.
Would you ever remove the engine first when doing a head gasket job?Certainly not easier on the good old 4.0 I-6.
I also would discourage starting the engine with the head bolts loosened.
The 4.0L I-6 is a direct descendant of Nash’s seven main bearing OHV six of the 1930s. It is/was one of the best engines Nash/AMC/Jeep/Diamler-Chrysler ever made. Untouched examples with over 300K miles abound.
Speaking of “starting” the engine with things loosened
Years ago, the guy I worked next to had pulled the head on a straight 6, because he was going to replace the head gasket
Because he was a pretty smart guy, he put a large brightly colored towel over the block and left the hood open, so that anybody walking by could see plain as day that major engine work was being performed. Not only that, but the head was sitting on the bench, just a few feet from the car.
One more thing, the key was not in the ignition. It was sitting on the seat
Well, his antagonist happened to stop by while the guy was out getting lunch. He saw the head on the bench, saw the hood open, and saw the towel over t engine. He stuck the key in the ignition and cranked over the engine, just to see what would happen . . . ! Then he left
A little birdie told the guy what had happened. He spent some time examining the engine for any obvious damage, then put #1 piston on TDC, cleaned everything up and put the head back, with new bolts, headgasket, seals, coolant, oil, etc.
It started right up, he burped the coolant, and went on a test drive. After coming back, he noticed a few drops of oil on the floor. He racked the car, saw the oil was near the balancer, cleaned it off, and drove the car again. When he came back, same thing.
He knew something was wrong, so he cleaned it, and left it running, while it was on the rack. He looked again, and saw it was definitely coming from near the balancer. He lowered the car, shut off the engine, and removed the balancer. He saw a small hole in the aluminum timing case cover, which was almost certainly caused by the timing chain whipping around, while his antagonist tried to “start” the engine. He had to pay for the part himself, since he couldn’t prove conclusively that his antagonist was responsible
The shop foreman told the guy he also believed the antagonist was responsible, but he can’t do anything without conclusive proof. He told the guy next time he’s doing engine work, to disconnect the negative battery cable, to make it harder for anybody to create mischief
Later on, the 2 mechanics were observed wrestling in the shop. One had the other in a choke hold . . .
On a Jeep with a straight six, there is no reason to pull the engine in order to remove the head…
I would remove the engine first on an air cooled VW, but not on a cast ion inline 6.
That’s a flash from the past @oldtimer. For sure an old Beetle engine would get dropped out to remove a head. But 2 men can have a VW engine on the bench in 15 minutes.
One man could do it if he was my size, I used that example because that was the only common car that I can think of the i wouldn’t change head in place, unless I was doing other repairs that would be easier with the engine out.