PDA

View Full Version : So the 5.2 is dead....



zjeepin
01-12-2006, 12:40 PM
i guess some of you remember my thread from a few weeks ago about my heater, then last week with the CPS... Well after the CPS didn't fix it, i bought a computer, installed it, and still no go...(luckily the local parts store let me return it) So i had it towed over to a local mechanic where they found the valves werent moving. We are assuming the timing chain/gears have failed hopefully not the cam gear or camshaft. Then the mech noticed slack in several of the rocker arms. is it possible to have bent the valves trying to start it or just after the timing went out?

norton
01-12-2006, 06:58 PM
thats wierd that a timing CHAIN would fawk up. generally when your timing messes up (going down the high-way or something), your going to have fucked up your valves right then and there. i havent read your other threads, but it sounds like you where never able to actually start it after something went bad. i dont think trying to start it once your timing was already off could have done much damage. if your timings off your shit shouldnt turn over at all, at least thats how it went on my brothers teg when his timing BELT broke. we replaced the timing belt but had it off just like 2 teeth and it would not turn over untill we got all the teeth lined up exactly.

luckily Honda makes a back up system to protect the valves from getting smacked and bent when the weak ass design of a BELT snaps. i think that Honda has now been using timing CHAINS since like 2001 on all their motors.

CurtP
01-12-2006, 08:31 PM
is it possible to have bent the valves trying to start it or just after the timing went out?

It depends - is the 5.2 an interference or non-interference engine? More than likely it's an interference motor and you've done some damage to the heads and pistons. You'll know once you get the motor torn down.

Are you going to drop in another 5.2 or rebuild your original? Stock or built?

OverkillZJ
01-12-2006, 08:53 PM
Damn...

nate
01-12-2006, 08:56 PM
I don't believe the 5.2 is an interference motor, though I'm not positive.

Rubber Chuck
01-12-2006, 10:15 PM
Generally timing chains don't break.......more often the stretch and will cause the issues you have. Is there alot of miles on your 5.2?

If the 5.2 has lots of miles.....it is possible the rockers are worn and that is the slack you have.

Not that this is Grand Cherokee tech......just wanna clear up some misinformation......Honda does use Timing Belts......just had to look up a t-belt for a 03' civic today and it is listed in the Gates catalog as an interference motor......meaning the valves will crash the piston if the belt breaks while driving.

zjeepin
01-13-2006, 11:58 AM
Generally timing chains don't break.......more often the stretch and will cause the issues you have. Is there alot of miles on your 5.2?

If the 5.2 has lots of miles.....it is possible the rockers are worn and that is the slack you have.

Not that this is Grand Cherokee tech......just wanna clear up some misinformation......Honda does use Timing Belts......just had to look up a t-belt for a 03' civic today and it is listed in the Gates catalog as an interference motor......meaning the valves will crash the piston if the belt breaks while driving.


its got 161k miles, so yeh its got some miles. the short version of its story is i replaced a water pump, and it never started back up. eventually i found the valves weren't moving as i tried to start it and there is a ton of slack in just a couple of the rockers, it appears one valve is stuck all the way open. im trying to find a used motor to go in it because i don't have alot of money to dump into this jeep and i'd like to get rid of it once its running again.

grnd93
01-13-2006, 01:27 PM
I think you can get away with a new chain. If the motor turns over (cranks, but doesn't start) it's unlikely there is, or has been any valve to piston contact. The reason you have loose rockers may be because those valves are closed and the lifters have bled down from sitting. I'd spend the $50, or whatever a chain costs and see if it will run. I've also seen timing gears with plastic teeth that shear off. The only 2 engines I've seen this happen on didn't use a chain, or belt, but the gears were in direct contact with each other. Pull your timing cover and see what ya got.

zjeepin
01-13-2006, 03:20 PM
I think you can get away with a new chain. If the motor turns over (cranks, but doesn't start) it's unlikely there is, or has been any valve to piston contact. The reason you have loose rockers may be because those valves are closed and the lifters have bled down from sitting. I'd spend the $50, or whatever a chain costs and see if it will run. I've also seen timing gears with plastic teeth that shear off. The only 2 engines I've seen this happen on didn't use a chain, or belt, but the gears were in direct contact with each other. Pull your timing cover and see what ya got.


you can tell that the valve spring is compressed tho

grnd93
01-13-2006, 04:14 PM
The valve spring is compressed but the rocker arm is loose?

ATL ZJ
01-13-2006, 05:10 PM
im trying to find a used motor to go in it because i don't have alot of money to dump into this jeep and i'd like to get rid of it once its running again.

Man, everybody's selling out.. :( Thinking of building something else maybe?

zjeepin
01-13-2006, 06:07 PM
Man, everybody's selling out.. :( Thinking of building something else maybe?

Dont worry cam, its not my rig, its my stock DD ZJ. I'll be keeping the black one till the unibody falls apart. I got two zj's right now. i'd like to get rid of the stocker in favor of a tow rig.


The valve spring is compressed but the rocker arm is loose?

HAVE YOU READ THE THREAD??? YES THE ROCKER IS LOOSE

grnd93
01-13-2006, 09:52 PM
Just making sure it was clear in my head.

Yeah, sounds like you may have smacked a valve then. Sucks!

ATL ZJ
01-14-2006, 03:51 PM
Dont worry cam, its not my rig, its my stock DD ZJ. I'll be keeping the black one till the unibody falls apart. I got two zj's right now. i'd like to get rid of the stocker in favor of a tow rig.



HAVE YOU READ THE THREAD??? YES THE ROCKER IS LOOSE

Ohhh good.. All this time I was wondering if you were as dumb as I was daily driving a grand cherokee on 37s.. Yeah a towrig's on my list too.

zjeepin
01-16-2006, 01:49 PM
Ohhh good.. All this time I was wondering if you were as dumb as I was daily driving a grand cherokee on 37s.. Yeah a towrig's on my list too.


as it stands now I am DD a ZJ on 37's, having alot of trouble finding an engine to replace the blown up POS. None of the salvage places around here have one with less than 110k