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budget 258 rebuild

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TheBirdman View Drop Down
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    Posted: Oct/25/2017 at 10:34am
Hey Guys, Ive got a question to run past you.

I bought a 1983 eagle 4 door a few days ago, got it idling,but there was a lot of smoky blowby coming out the valve cover. I then did a compression test, and found that cylinder 4 only made 35 psi. I stuck a borescope in the spark plug hole and found a bunch of pitting in the piston. I pulled the head yesterday, and it looks like it overheated, closed up the ring gap, and popped a good chunk out of the top of the piston. Now I got this car for $350, and while I want to get it driving, the budget is tight on this one. I dragged it off a farm where is had been sitting outside for around 20 years, so it is never going to win any beauty awards or go racing or conquer moab or anything.
In the next week or so Ill be borrowing my buddys engine hoist and stand, and at the very least I am going to put one new piston, rings, and new main and rod bearings in, and dingleball hone the cylinders. It is very likely Ill get new pistons and rings for all 6, since they seem to be pretty cheap in complete packs. The question is, once I have the engine out and apart, is there anything else in there I should replace that is known to go bad after 90k miles? (it might actually be 190k but from the amount of wear I doubt it)
This certainly isnt going to be a full rebuild, just the basics to get this 258 up and chugging along happily again. Again, tight budget, but if there is another cheap thing or two I can do to postpone this things inevitable death for a few more years, let me know.

Thanks
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amcfool1 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/25/2017 at 1:02pm
hi, I just did a full restification on an 84 eagle 4dr sedan. good luck! for sure change the rear main (and front) seals, timing chain is a good idea. There is an upgraded one piece Felpro oil pan gasket that is a must #OS34308R, and if you can, a better cam is always a good idea. gz
george z
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Pdok Quote  Post ReplyReply Direct Link To This Post Posted: Oct/25/2017 at 1:20pm
Maybe redo the oil pump, and purge all oil passages.

x2 on the cam/lifters.  It's another expense, but what a great opportunity to get a big boost in overall performance while you've got the motor out.  Never going to be an easier time for a cam swap.  Sounds like the head is fine, but if you can get to the guides and seals, those aren't too bad, plus check for flatness.  I'd pull the valves at least to check the seat wear.  A light head recondition without replacing valves and springs should be quick and fairly cheap.
76 Grem X 258/904,4.0 head/MPFI, Comp X250H cam, Hughes springs, Clifford header, serpentine swap.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DaemonForce Quote  Post ReplyReply Direct Link To This Post Posted: Oct/25/2017 at 3:07pm
Originally posted by TheBirdman TheBirdman wrote:

Now I got this car for $350, and while I want to get it driving, the budget is tight on this one.

Don't bother. That was dumb. If you're not ready to splurge on a ton of things that are going to surprise you, just move on. If you believe ANY part of this is going to be fast or easy, you're already way in over your head. You are not ready for a project of this level and the fact that this car sat around for 20 years is the first big red flag. Every time we have a new AMC owner on here, this is the case. Maybe you have a shot at this with the right tools, equipment, fair amount of aggression and possibly a friend that can provide help and a LOT of beer but the reality is that cars of this make and especially this model(and some CJ/DJ trucks) are extremely prone to bad ownership and neglect.

This particular incarnation of the L6 was pushed out during the worst part of the emissions era with smog pumps, miles of now rotting vacuum lines, poor atomizers, mystery electrical doohickies that caused more life threatening situations than anything else I've ever encountered and it suffered poor engineering as you may have already discovered from a leaky plastic valve cover, failing intake heater, poor flowing head design along with those siamesed #3-#4 exhaust ports that are so badly designed they cause further trauma making the upper engine half prone to warps and cracking...Oh and garbage tier mechanics that have a tendency to tune these engines by ear, which may be one reason for steady lean out and detonation of an OEM cast piston. Couple this with one of the worst 3spd automatics paired with gears that I should only see at Bonneville and you've got a winner.
Originally posted by TheBirdman TheBirdman wrote:

I dragged it off a farm where is had been sitting outside for around 20 years, so it is never going to win any beauty awards or go racing or conquer moab or anything.

Yet you're on a budget and ready to go to town on a bad engine that needs a LOT of aftermarket support that is deprecated by a superior engine that already litters every junk yard across the states...Except the one major yard in Garretson. I get it. You want something to do or you want to breathe new life into old iron. Before you spend any amount of money on this, you need a solid goal that is not just within sight but within reach. You're not going to get very far with this at the moment and here's why:
Originally posted by TheBirdman TheBirdman wrote:

In the next week or so Ill be borrowing my buddys engine hoist and stand, and at the very least I am going to put one new piston, rings, and new main and rod bearings in, and dingleball hone the cylinders. It is very likely Ill get new pistons and rings for all 6, since they seem to be pretty cheap in complete packs.

They're also cheap because nobody wants to produce them at a competitive price anymore. Back in 2014 a few months after starting my last job I was in a constant back and forth game over the phone every other day with Summit trying to get a set of pistons from Keith Black and Sealed Power. SP would either drop orders or push me onto KB which also had serious supply problems. It took a grand total of 3 months before I could get a piston and ring kit ready for this engine and then another 6 months before I could get specs on some last minute parts that should have been the very first parts going back into the block. In other words, I'm not expecting that you're going to take a lot of time on this but there's a ton of variables waiting for you to play that game with them.
Originally posted by TheBirdman TheBirdman wrote:

The question is, once I have the engine out and apart, is there anything else in there I should replace that is known to go bad after 90k miles?

Only the whole timing assembly and whatever caused this car to be left to rot. The rest I'm sure you'll discover as you pull it apart. I know all of this sounds really horrific but when all of this works right, it's fun. When it fails and is put out to pasture, it's becomes even more of a catastrophic nightmare. Beware of contact corrosion(often bluish green bleeding out of molex connectors), bad ECMs, too much timing, bad fuel, a rusted or cracked fuel tank, a failing water pump, rotted belts, rotted harmonic balancer, bad/frayed wires in the harness, "empty" connections(you'll understand when you find it), oil pan sludge that doesn't budge, oh and any attempts to replace that reprehensible plastic valve cover with an aftermarket aluminum dress up. Beyond all that, maybe a leaking rear main seal.
Originally posted by TheBirdman TheBirdman wrote:

This certainly isnt going to be a full rebuild, just the basics to get this 258 up and chugging along happily again. Again, tight budget, but if there is another cheap thing or two I can do to postpone this things inevitable death for a few more years, let me know.

A few years? Assuming it's not seeing very many miles until then just get a quality head gasket. Beyond all of that I want to say give up and pull a complete 4.0L from a 87-95 Cherokee, swap the oil pump and pan and give that wagon a new 4.0L exhaust. Makes the stroker update less nightmarish at that point. The 258, especially the ones that were outfitted to the Eagles are a waste of time to upgrade, though they ARE home to the main core components that make an update possible. If this was a mid-70's Hornet, this would be a different tune. I'm sure you'll figure it out soon. Sleepy
1971 Javelin SST
1970 American 304 2v | 1967 FMX | AM20-3.31
1983 Eagle Limited
1990 Jeep 4(.7)L | 1982 T-5M | Dana30/35-2.72
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Post Options Post Options   Thanks (1) Thanks(1)   Quote TheBirdman Quote  Post ReplyReply Direct Link To This Post Posted: Oct/25/2017 at 3:31pm
I appreciate the tips, but please dont assume that Im not up to the task just because Im new to your forum. That kind of condescending smugness is what drives people away from cars as a hobby.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote purple72Gremlin Quote  Post ReplyReply Direct Link To This Post Posted: Oct/25/2017 at 6:24pm
Originally posted by TheBirdman TheBirdman wrote:

I appreciate the tips, but please dont assume that Im not up to the task just because Im new to your forum. That kind of condescending smugness is what drives people away from cars as a hobby.
Don't pay attention to DamionForce. He doesn't know as much as he thinks he does.
As for your car, parts aren't too bad to get for the 258. If you are on a strict budget, possibly find a good used 258. I've sold running 258s for 75 bucks. Don't have any now. Other wise I'd get one new STD piston. Take a look at the bearings...if they look ok..maybe reuse them. But I would definitely put a rear seal and timing chain and gears in. But it's alot of work to remove the engine out of an Eagle. So on that thought, I'd put all new bearings in. Elbow grease is cheap.

Edited by purple72Gremlin - Oct/25/2017 at 6:31pm
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AMXRWB View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AMXRWB Quote  Post ReplyReply Direct Link To This Post Posted: Oct/25/2017 at 7:03pm
We have an Eagle that we fixed the worn out items on.Today it is the go to car for our family year round.We have owned it about 20 years and has outlasted many new cars our other family members have had. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amcenthusiast Quote  Post ReplyReply Direct Link To This Post Posted: Oct/25/2017 at 8:35pm
You might get lucky if you try contacting your nearest AMC Club...

http://www.amonational.com/chapter/dakota-amc

but you can't get lucky if you don't try: http://richardwiseman.com/Luck.shtml

'defeatism' is the basically the opposite: https://www.alleydog.com/glossary/definition.php?term=Defeatism

Juxtaposed to 'Rooting for the Underdog' (a positive mental condition) is what is called 'Underdog Complex' (a negative mental condition) which is similar to Defeatism but the lacks anti-social feature, whereas the person with Underdog Complex will actively seek like minded fellows with which to share their typically exaggerated annoyances with the 'underdog entity' (aka 'AMC Underdog Complex', as opposed to 'Rooting for Underdog -AMC'.

Actually I thing DF was attempting to make friends through socialization and commiseration... where I don't think he was 'down talking' to you in particular (take no personal offense anybody)

As a long term AMCer I've seen this happen a lot; a certain type of new person gets full of inspiration and seeks to defend the reputation of AMC products but in the passage of time they 'acclimate' (negatively) and acquire a taste for the negative aspects of the products and seek others to commiserate with...

...how to say it right but one might catch the gist of the concept...

Good luck & more AM power to you;  you can do this and complete your goal if you muster up the willpower and determination.
Link to XRV8 Race Parts website: http://amcramblermarlin.1colony.com/favorite_links.html
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Pdok Quote  Post ReplyReply Direct Link To This Post Posted: Oct/25/2017 at 9:23pm
To the OP.  You'll be fine.  Do what you want, and just roll with the punches.  You had it running enough to see smoke, right?  That's good.  If you don't want to fully rebuild, then don't! Millions of car owners in every country on earth just fix what's wrong...sure, lots of them chase down other problems with keeping old cars running.  It's what comes with a 40 year old car.  heck, in Mexico they wrapped a Chevy 350  piston in burlap when the rings gave out, and it had enough compression to get another 1000 miles home. 
So I'm betting the motor is fine, even with fixing a blown piston, it will be fine.  Your cylinder walls may be scored, maybe need that healed up, but you'll get thousands of good miles out of the mechanicals if you put it back together right.

The stuff on the outside of the engine will eat you up a little, that's no lie.  But, it's an adventure, and you can do the internet fix on a lot of the ignition/smog stuff from the 80's, if you can dodge the emissions regs.  Don't let the negativity get you, but you've got to be willing to take a few hits when the unexpected stuff pops up.  I love these old cars, and the Eagles (just like the CJ's of that vintage) have a lot of value just because the motor itself stubbornly keeps alive.  It's a great motor.

Once you reach the end of your 258, a drivetrain swap might be cheaper than a full rebuild (doubtful...), but I'm always wondering how many of the "good" 4.0's are still going to be around waiting to get snapped up at the Junkyards in 10 years.
76 Grem X 258/904,4.0 head/MPFI, Comp X250H cam, Hughes springs, Clifford header, serpentine swap.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote TheBirdman Quote  Post ReplyReply Direct Link To This Post Posted: Oct/25/2017 at 10:39pm
Thanks for the encouragement guys. It actually idled surprisingly well, for having a busted piston and half the vacuum lines disconnected. After a little research, I was surprised how cheap entire rebuild kits are for these. 400 bucks for pistons, rings, main/rod bearings, gasket set, timing gears/chain, oil pump, freeze plugs,  cam, and lifters, plus 40 or so for a main seal, front seal, and valve stem seals? heck, thats cheaper than vw beetle rebuild kits. If its such a PITA to get the motor out, I might as well drop another $200 on a bunch of extra parts and some piece of mind. The cylinder walls all have a decent ridge on them, but I dont see any scoring, even on the cylinder that ate some cast iron chunks.
Ill take a good look at the finances, I guess worst case I wait till next payday. Thatll give me time to get the engine out and the head cleaned up. Ill probably have the head inspected and leak checked too. Im in so rush, aside from wanting to get her running in time for some blasting around in the snow.

Heres a picture to explain why I dont want to spend the money or time finding a 4.0 for it
https://i.imgur.com/txXiqW2.jpg - https://i.imgur.com/txXiqW2.jpg
I dont really care if it has 200 horsepower or 80, as long as its got enough torque to pull itself up a hill and the 4wd works.
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