Fuel injector cleaning or replace.

So the HB was bad. Actually was starting to come apart. I wasn’t able to check compression because the 8 piece kit I got from HF will not screw into a Jeep 4.0 head. The threaded adapters aren’t long enough.

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Jody Treadway said:
He's right. There's no way I wouldn't pop the timing cover off and VERIFY cam timing if I was that close. You're like 10 minutes from knowing
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I'm a glutton for punishment I guess. I should have checked that timing.
 
On a cam in block motor you can be 180 out and replace the chain, it’s just 2 dots to line up and some rtv on the cover.

Those chains are known to stretch and the little rubber dampers get worn through
 
So I ended up swapping the 8 piece for the 10 piece compression tester from HF. It works! Bad news 1 - 4 40 psi. 5 - 6 120. So I decided to do a wet test with Marvel Mystery Oil. Put 30 ml or so in 1-4. All came up to about 60 psi. Am I right in thinking a head gasket and head job should make it run?
 
ghost said:
So I ended up swapping the 8 piece for the 10 piece compression tester from HF. It works! Bad news 1 - 4 40 psi. 5 - 6 120. So I decided to do a wet test with Marvel Mystery Oil. Put 30 ml or so in 1-4. All came up to about 60 psi. Am I right in thinking a head gasket and head job should make it run?
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Is it too late to check cam timing? Did you replace the balancer and button it up already?
 
Could be rings stuck in the piston grooves or poor valve seats as well. If you take the head off you should pull pistons and clean then take the head apart and lap the valves. Both would be mostly time little money. Aldo check for the typical head cracks known for some 4.0 heads. I’ve seen plenty of people rebuild 4.0 in the car
 
ghost said:
Yea I put the balancer back on. With 4 of 6 low on compression isn’t that a moot point?
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Worth a shot if low compression due to cam/crank timing.
I'd about get it running and see if the rings free up a bit. It's not going to hurt anything that isn't already messed up
 
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Shreddinlettuce said:
Could be rings stuck in the piston grooves or poor valve seats as well. If you take the head off you should pull pistons and clean then take the head apart and lap the valves. Both would be mostly time little money. Aldo check for the typical head cracks known for some 4.0 heads. I’ve seen plenty of people rebuild 4.0 in the car
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I pull this head it’s going to a shop for testing and rebuilding.
Jody Treadway said:
Worth a shot if low compression due to cam/crank timing.
I'd about get it running and see if the rings free up a bit. It's not going to hurt anything that I want already messed up
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I’m probably gonna take it to the shop to do that. Been working on it in the back yard on my trailer with the step son.

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Took it back to my shop in Hartsville today. I have a 92 2wd I checked on and it’s got no spark. Did a compression test and she’s low on 1 and 2. So to me no point in swapping that motor in. No real surprise there though. I did hook up the leak down tester to number 1 and 2 and can feel air coming out the intake. So clearly the intake valves are leaking.
 
ghost said:
Took it back to my shop in Hartsville today. I have a 92 2wd I checked on and it’s got no spark. Did a compression test and she’s low on 1 and 2. So to me no point in swapping that motor in. No real surprise there though. I did hook up the leak down tester to number 1 and 2 and can feel air coming out the intake. So clearly the intake valves are leaking.
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Were the valves closed when you tested it?
 
If the injectors are original and the Jeep’s been sitting for years, cleaning might help a little, but they’re usually too gummed up inside to be reliable. A pro ultrasonic clean is the only way to really bring them back, but honestly it’s often better to just get a new matched set. Go with quality ones like Bosch EV6/EV14 style they flow better and make the 4.0 run smoother
 
Jody Treadway said:
Were the valves closed when you tested it?
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Turning it over by hand I watched the exhaust valve open and close then the intake. Looked down the spark plug hole to see the top of the piston. I feel like it was as closed as it could be.
 
hannahjo790 said:
If the injectors are original and the Jeep’s been sitting for years, cleaning might help a little, but they’re usually too gummed up inside to be reliable. A pro ultrasonic clean is the only way to really bring them back, but honestly it’s often better to just get a new matched set. Go with quality ones like Bosch EV6/EV14 style they flow better and make the 4.0 run smoother
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With that kit I posted I was able to fire the injectors with cleaning fluid.
 
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