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well i think im screwed

xDUMPTRUCKx

NAXJA Forum User
Location
highway to hell
bent push rod, rocker arm, cracked spring retainer, bent valve and who knows what else.

my valve doesnt even like to move right now, i can get it to move 1/8 inch and its very difficult. so what do i do now? pull the head and take it in for a valve job? or for $150 i can get a used head from a jeep place or for $65 i can pul one myself, what do you guys think, whats my next move here?
 
xXJx said:
bent push rod, rocker arm, cracked spring retainer, bent valve and who knows what else.

my valve doesnt even like to move right now, i can get it to move 1/8 inch and its very difficult. so what do i do now? pull the head and take it in for a valve job? or for $150 i can get a used head from a jeep place or for $65 i can pul one myself, what do you guys think, whats my next move here?
I have no idea what the answer to your question is, but I'm curious as to what happened to cause all that damage.
 
xXJx said:
bent push rod, rocker arm, cracked spring retainer, bent valve and who knows what else.

my valve doesnt even like to move right now, i can get it to move 1/8 inch and its very difficult. so what do i do now? pull the head and take it in for a valve job? or for $150 i can get a used head from a jeep place or for $65 i can pul one myself, what do you guys think, whats my next move here?

Pull the head and take it to a local cylinder head exchange shop. I'm not sure if you ever make it over to Orange County much, but 'same day cylinder head' does -okay- work at a an okay price. I wouldnt take their heads to the track, nor are they the cheapest out there, but its an affordable long term repair.

Same Day Cylinder Head Service
(714) 680-3006
1169 E Elm Ave
Fullerton, CA 92831
 
Kejtar said:
I have no idea what the answer to your question is, but I'm curious as to what happened to cause all that damage.


there was a mud hole on the trail, and i was i 4lo, and i was tryin to keep the rpms up theres and i guess i got em waaaaay too high. came out of the mud running like crap.
 
xXJx said:
bent push rod, rocker arm, cracked spring retainer, bent valve and who knows what else.

my valve doesnt even like to move right now, i can get it to move 1/8 inch and its very difficult. so what do i do now? pull the head and take it in for a valve job? or for $150 i can get a used head from a jeep place or for $65 i can pul one myself, what do you guys think, whats my next move here?

If yours is buildable / repairable...use it. If you have high miles only do what you need to fix it, like valve seals, if you had it out anyhow.

Lots of the time if you completey rebuild the upper end, and have a high milage lower end....you'll be doing the lower end NEXT.

Just something I've seen on a lotta junk.

Good luck.
 
The basic question is how many miles are on the engine, what condition is it in otherwise, and what condition is the vehicle itself in. In other words, does it make good economic sense to do the job "right," or if it's an old and tired engine in an old and tired vehicle, maybe it makes more sense to do a shade tree repair.

I once, long ago in another life, had a sailboat with a 4-cylinder engine (Atomic 4). When I sold the boat, the buyer's inspector picked up low compression on one cylinder. The boat was 12 years old at that point and the buyer admitted that he would probably replace the engine within a couple of years, so he didn't want to hang me out to dry -- but he was planning to take the boat from Connecticut down to the Chesapeake Bay, going through New York's Hell's Gate and then offshore. So he wanted to be sure the engine would be reliable.

I agreed to do a valve job. Got the head off and found one exhaust valve badly burned. Local shop happened to have an Atomic 4 valve in stock, so I bought one valve, slapped it in, gave it a quick lapping-in, and buttoned up the head.

I was in contact with the owner a couple of years later and he said the engine was still running smooth and strong.

I think if it were mine I would seek out someone with a beater 4-cyl engine who could sell me a used valve, I'd throw it in and lap it to the head, put everything back together, and drive it.

And in the future keep the revs below 5,000 RPM.
 
Eagle said:
The basic question is how many miles are on the engine, what condition is it in otherwise, and what condition is the vehicle itself in. In other words, does it make good economic sense to do the job "right," or if it's an old and tired engine in an old and tired vehicle, maybe it makes more sense to do a shade tree repair.

I once, long ago in another life, had a sailboat with a 4-cylinder engine (Atomic 4). When I sold the boat, the buyer's inspector picked up low compression on one cylinder. The boat was 12 years old at that point and the buyer admitted that he would probably replace the engine within a couple of years, so he didn't want to hang me out to dry -- but he was planning to take the boat from Connecticut down to the Chesapeake Bay, going through New York's Hell's Gate and then offshore. So he wanted to be sure the engine would be reliable.

I agreed to do a valve job. Got the head off and found one exhaust valve badly burned. Local shop happened to have an Atomic 4 valve in stock, so I bought one valve, slapped it in, gave it a quick lapping-in, and buttoned up the head.

I was in contact with the owner a couple of years later and he said the engine was still running smooth and strong.

I think if it were mine I would seek out someone with a beater 4-cyl engine who could sell me a used valve, I'd throw it in and lap it to the head, put everything back together, and drive it.

And in the future keep the revs below 5,000 RPM.

Ditto
 
Eagle said:
The basic question is how many miles are on the engine, what condition is it in otherwise, and what condition is the vehicle itself in. In other words, does it make good economic sense to do the job "right," or if it's an old and tired engine in an old and tired vehicle, maybe it makes more sense to do a shade tree repair.


I think if it were mine I would seek out someone with a beater 4-cyl engine who could sell me a used valve, I'd throw it in and lap it to the head, put everything back together, and drive it.

And in the future keep the revs below 5,000 RPM.


well it only has 114k on it. the top end was recently rebuilt and the bottom was said to be bulletproof. ive got 2 donor vechiles at the local pick a part, i think as you said i will just go and pull valves from those. this is the only problem valve, all the others seem to be up to spec. can somebody give me a run down on what is involvoed on replacing just one valve?
 
slap it and lap it :)
 
A new valve doesn´t cost very much. Or a good used one. Inspect the valve seat, to see if it looks burnt, melted or has a serious ding in it. Put your new valve in there and push the top to the side, should be very little side play. Work it up and down by hand, should slide pretty easy. Might want to have a look in the guide with a flashlight and see if there is any serious scuff marks or spalling. You can clean it up some with a brass rifle bore brush, if it´s too dirty to see well.
Buy the two cans of lapping compound coarse and fine and a lapping tool which looks like a little toilet plunger (I make my own with jewelers wax and a wood dowel). Put a little coarse compound on the seat and turn the valve, while gently pushing it into the seat (with the little toilet plunger), as soon as the seat is shinny all the way around, use the fine compound. The object is to get a good seal, the less you polish the better. If I have trouble seeing where the polishing compound is working, I´ll use an ink marker on the seat and take a couple of turns with the compound.
Borrow a new spring from the auto parts place and measure the hieght with a good ruler, check it against your spring. The installed hieght of the spring is close to 1.8 inches. My manual doesn´t show the uninstalled hieght.
If you don´t have a dial gauge, you can screw a piece of welding rod (or coat hanger) someplace on the head and bend it till it just touches the side of the valve rod very near the guide, with the valve about 1/16" out of the seat ( a little wad of paper towel stuck between the valve and the seat). Push the valve all the way towords the coat hanger pointer and adjust the coat hanger till it just touches the side of the valve rod, push the rod as far away from the coat hanger pointer as possible and see how much play you have with a feeler gauge. Think the the outside tolerance is .003, much over .004 and I wouldn´t trust it for very long (it´s probably gonna rattle).
The 4 banger has some pretty stiff springs (much stiffer than most other motors) that leads me to believe they may get old, tired, short and soft.
IMO I wouldn´t change anything unless it was bad, why change all the valves? If I was gonna change anything, on a hunch, it would be the seals and springs. I learned this stuff in Dodge truck school, about fifty years ago. There theory was, only change whats broke, old tested parts are often better than new untested parts. Or new isn´t necessarily better. Maybe it´s just a Dodge thing, but it stuck with me all these years.
Some other guys may have some more tips, Really not very hard. Watch the "O" rings don´t slip when your installing the keepers.
 
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thanks 8mud! thats what i needed. now say my valve guide is damaged, then should i take it to the shop? also if my piston got scratched or dented or damaged and i replace the valve is it still going to run okay?
 
Any time I work on an older head, I have the valve guides reamed and sleeved. Never have them knurled. Knurling will last about 15k miles and then you will have a real oil burner on your hands.
 
Takes a special tool, to deal with even mildly damaged seats, takes a shop if they are really bad. If they are damaged, lapping probably isn´t gonna get it done, you will probably just round out the seat and valve if you try. lapping is just to clean it up some and make sure the seal is good.
If the piston is just dinged and not cracked through, probably isn´t gonna hurt anything. I´ve had bad luck with pistons that are damaged at the edge, Don´t know why, for sure, but they seem to heat damage easier if they have a chip at the edge. If any material came off of the piston, make sure you dig it out from on top of the ring with a very small screwdriver and a vacuum cleaner. Or blow it out with air or it´s gonna scratch the cylinder wall eventually.
Get a good book with the specs, as long as you have the head off, spend a couple of hours checking the piston to cylinder wall clearnace and if your feeling really curious, all of the valve stem to guide clearances. You can tell a lot, just by feeling the ridge at the top of the cylinder, I can usually tell with my finger tips, when it´s time for piston work. It´s worth the effort, just to know, what shape your motor is in and how much wear it has. When I´m cleaning up a head, I often just scrape everything I can get to with a small screw driver, don´t even try to get it perfectly clean. Try to keep in mind anything you loosen and don´t remove, will eventually find it´s way into your oil pump screen.
 
You are better off getting a bone yard head and throwing some new seals in it. Cheap easy and will be fine.
 
:UPADTE:

well seeing how there is a half off sale at the pick aprt a few miles from my house this weekend, i believe i might just pull the whole head off this commanche and pull all the valves, seals, springs, and whatever else i feel like off another 2.5 cherokee thats there. im in the process of removing the throttle body right now and its a major P.I.T.A! Ithe bolts that hold it onto the intake manifold are all in wierd places that are difficult to get to. I cant find my snap on crowsfoot set so thats making things very difficult.....

also i cant seem to find the coolant drain thats supposed to be under the exaust manifold, should i be worred about this when i pull the head? does it really matter all that much?
 
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