Kale

Hello all,

I'm new to the forum and i recently picked up a 1996 Jeep Cherokee sport 4.0l from a friend. The jeep was running, but not in great condition. It needed multiple things done, in which i completed. It needed a head gasket, so i removed the head and reinstalled everything (Fel-Pro gasket). I kept the pushrods and rocker arms in the correct order.

When i torqued down the rocker arm bolts initially, the engine had no compression. i was very confused and stumped for a few days. I eventually loosened the rocker arm bolts a little and the engine fired up instantly. This is really confusing to me because the rockers on this car are non-adjustable. The loose rocker bolts eventually kept loosening and the chatter grew stronger and stronger. I can't fully tighten them because they cause the valves to not seal. What could cause this? i've searched and searched but everything with rocker arms and jeeps has to do with them being too LOOSE, not TIGHT.

~Could the lifters be stuck open? (i've only read that they collapse)
~Could the push rods be up-side down? (i read somewhere that the stock pushrods are reversible)
~Maybe the rods are not seating correctly in the lifters? (i did take them out and place them in the lifters again just to make sure they are in the correct spot)

I'm new with jeeps, but not with cars and engines. I feel like i missed somthing obvious because of the lack of search results on my issue. If there is anyone that can shed any knowlege on this subject please chime in! I also posted a similar thread on a different jeep forum to get more input on my problem.

cruiser54

This is a new one on me.

dans98xj

do you know if he had the head off before you bought it? i would get a new push rod from the dealer or part store and compare it to the ones that are in the jeep. It sounds like they are too long. Also check to see that the lifters were not changed over to solid lifters. Was there a new cam installed? if there had been a new cam with a higher lift and duration then stock lifters and push rods would have to be changed as well.

CCKen

More reading on the subject:


http://www.jeepforum.com/forum/f11/r...ssion-3481450/

Bugout4x4

Been reading your great stuff over there the last week. A link to the preload protocol appears to be missing on this one? I am interested also if you happen to have one?

Kale

Thanx for all the input guys, and thank you CCken for the input on both forums lol.

I got the jeep from my neighbor and it had been sitting for a couple years. it fired right up, but the head gasket was very bad, the oil was chocolate milk. Could it be possible that the lifters were rusted open to cause this condition?

The jeep has around 110k miles on it, so im sure the head was removed at one point to replace the head gasket. the pushrods could have been replaced? but the thing is that he jeep was running before i removed the head (it wasn't running great though, coming to think of it, but it still had compression)

CCKen

Still waiting for the results of a compression check on all six cylinders.


A compression loss check would be good. You can determine which valve may be stuck open.


With around 80 psi applied to a cylinder when it is at its TDC compression stroke, listen...


Air escaping from the throttle body indicates the intake valve is stuck open, air escaping from the exhaust tail pipe indicates the exhaust valve is stuck open. Air escaping from the oil filler hole in the rocker cover indicates bad rings or a blown piston.

CCKen

It is missing because I don't have prepared instructions to link to. I don't want to waste key strokes explaining the process unless someone really needs it.

CCKen

OP,


You could try a trick I learned from working on aircraft recip engines.


Torque the rockers down to 21 ft/lbs with the applicable cylinder at TDC of its compression stroke.


Apply around 80 psi air to the cylinder. Using a rawhide mallet, give the valve stem end of the rocker a rap to see if any air escaping shuts off. Sometimes a valve can get stuck open from crap under the valve seat. This process can dislodge that crap on occasion.

Kale

I need to borrow a tester from a buddy of mine because the threads on my tester aren't narrow and long enough to catch the threads on the cherokee. I will post the results as soon as i get my hands on one.

On a further post down you mentioned something could be stuck, causing the valve to not seal properly. I'm not sure if that could be the case here because wouldnt that result in there being too much play when the rocker was torqued? I can literally watch the rocker hit the valve and push it down when i torque it.

freegdr

You had to loosen all b4 it started.....Something sounds strange . This what yours look like ?



When i torqued down the rocker arm bolts initially, the engine had no compression. i was very confused and stumped for a few days. I eventually loosened the rocker arm bolts a little and the engine fired up instantly.

Kale

Doesn't look that pretty and clean, but it sure does look like that

freegdr

No parts missing ?

Kale

no sir, absolutely not.
Maybe i can try using a different torque wrench? i will be able to do a compression test tomorrow and figure out the hard numbers.

freegdr

All torque is how tight bolt is . If you loosen bolt and it runs its a issue valves being held opens.