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258 Engine Replacement |
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Fahques
AMC Apprentice Joined: Jan/06/2016 Location: philadelphia Status: Offline Points: 49 |
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Posted: Jan/23/2018 at 10:09am |
I have an 1982 Concord D/L Wagon and was told by my mechanic, after a compression test, that one of my cylinders is dead. He's assuming it's a dropped valve. I noticed at one point it shot white smoke for about 20 seconds and hasn't happened again.
I'm not enough of a mechanic to replace an engine myself, so my questions are along the lines of How difficult is it to find a replacement 258 motor that runs? About how much am I looking at as far as cost goes to get a motor and have someone install it? The body and interior of the car is is GREAT shape, but is it still worth the trouble? I'm trying to get some information for experienced AMC folks since there's not too many in my area. I do have it up for sale now locally but I'm not sure I want to get rid of it. I love the car. Any info would be a big help and much appreciated. Thanks |
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Lyle
AMC Addicted Joined: Jul/17/2014 Location: None Status: Offline Points: 772 |
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There are plenty of engine re-builders doing 258's or 4.2l Jeep engines (long block) with warranty in your area for $1500 or less. It's the same engine and drop in.
Your mechanic should be able to look it up and give you a quote for engine + swapping it out for you. If your not mechanically inclined I'd go this route over getting one from a wrecker as your going to have to put a lot of faith in the wrecker selling you a decent engine. If someone on the forum is willing to sell you a good one that would be good also. Hate to see a good AMC go to waste and for $2500 you will likely get many more years of enjoyment for really little cost.
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amcfool1
AMC Addicted Joined: Jun/18/2011 Location: roanoke va Status: Offline Points: 1069 |
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you could also just have the head rebuilt, should cost around $500-600 no need to pull whole motor. how many miles on it? good luck, gz
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george z
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Fahques
AMC Apprentice Joined: Jan/06/2016 Location: philadelphia Status: Offline Points: 49 |
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2500 seems reasonable to me. I've done a few things to it, replace the gas tank, fuel/brake lines, fuel/water pumps, basic stuff. Motor rebuilds are out of my league. I don't have the space or the knowledge.
It has 75xxx miles and again is in good shape otherwise. I'll check around then for rebuilders and see what I can come up with. Thanks |
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billd
Moderator Group Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894 |
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If you were closer I'd say "bring it over" as I have the equipment/shop/parts (even good used blocks, heads and more) to build a NICE 258 - but distance is an issue.
Dropping a valve in these isn't common but is bloody simple to diagnose - pull the valve cover off. Since the valves and springs will be sticking up in your face after you remove the valve cover, you'll know if he's right or wrong........ |
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Lyle
AMC Addicted Joined: Jul/17/2014 Location: None Status: Offline Points: 772 |
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Just my experience, but if you loose a valve you likely lost the piston, rod or both also unless it's just keepers and caught right away.
Also a rebuilt head on an older bottom end will shorten the life of the bottom end. You get new springs, valves, lifters on an old tired cam, worn bottom bearings on higher compression seating valves, lots of new gaskets and things to go south. By the time your done putting in new bearings, gaskets, timing set, cam, possibly need to hone or bore, new pistons ... you have bought the rebuilt engine already. Rebuilding is for those that like to, have the tools/time, or in the business. Not saying it's a bad thing but not for everyone.
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19592 |
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I've rebuilt heads on high mileage engines before. 75K isn't that bad. Even if it does shorten the life of the bottom end some due to the higher compression, it shouldn't be a significant amount... maybe 10% shorter? Assuming you would want to rebuild at around 110K if everything was the same, you might have to rebuild at 95-100K with the new head at 75K. Worth it for 20-25K miles/3-4 years of driving? I'd say so. If nothing else gives you 3-4 years to save for a bottom end rebuild, and you won't have to do anything to the head again. Wouldn't hurt to check the valve seals and seats, but should be fine to use as is with only 20K or so on it.
The last engine I planned on rebuilding I didn't. Machine shop volunteered that for $150 they would assemble the bottom end and guarantee it for a year -- no mileage limit. Sold!! All I had to do was put my head (which had been rebuilt a year before -- changed to a 99 4.0L head), oil pan, water pump, etc. on. The head change wasn't the reason for the rebuild. The head change probably made the piston wear show up more, but I rebuilt due to oil use. It was using a bit of oil before I changed the head (changed instead of rebuilding because I got a deal on a 99 head and intake -- complete 4.0L with thrown rod), found out the valve guides and seals weren't the problem real quick! I can't say whether the new head increased oil consumption or not, just that it didn't decrease it. Had plenty of power, so I didn't think the bores were worn, but they were... |
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Frank Swygert
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tomj
AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7519 |
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faques -- you may not be a mechanic but you can do the diagnostics, at least go/no-go on the extent of damage...
see if you can pull the valve cover off to look. even wthout expertise you can probably puzzle out things wildly out of place. ID the 12 valves -- actually the valve springs, and their keepers; all you can really see of the valves is the stem inside the spring and the 1/4" or so round tip under the rocker. the rockers will be strung on a shaft, or individually bolted to the head (probably the latter). google images of your year head valve cover off. certainly, no pieces should be loose or floating around! the rockers ... rock/pivot. the tip touches each valve stem, the other end has a push rod poking up from the bowels of the motor. wiggle each one -- they ought not wiggle. if one has fallen out, there you go -- stuck valve, needs head rebuild, not that big a deal mechanically some rockers will be at rest, and various of them in operating positions (where ever the engine stopped when turned off). poke aroudn for broken springs, or thigns waaay different from the others. spend a good half hour or more staring and poking. most mechanical diagnosis is done like this -- carefully, methodically poke and prod. there's no harm to be done under there short of a hammer or pry bar. worse would be dropping screws etc down into the guys -- don't do that ;-) you might not get anywhere, but you got nothin to lose. |
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1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
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Fahques
AMC Apprentice Joined: Jan/06/2016 Location: philadelphia Status: Offline Points: 49 |
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Farna , Billd and Tomj--Thanks for all the info, looks like I'm pulling a valve cover at least to see what I can see.
If I was in Iowa, I would bring it over. My mechanic said similar things to what Lyle said...once you plan to do the head, you don't know what else is wrong and you most likely will have more problems in the future with the rest of the motor, then it's lots of time and money I'll take a peek and be hoping for the best I guess |
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Urquiola
AMC Fan Joined: Feb/05/2018 Location: Spain Status: Offline Points: 3 |
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Hi!: this is not about 258 rebuild, but installing a Jeep Cherokee 4.0 HO head, manifolds, ECU, and adding Bosch Fuel Injectors, to improve power and economy. Experiences? Regards, Salut +
http://www.jeepstrokers.com/forum/viewtopic.php?f=6&t=24 - http://www.jeepstrokers.com/forum/viewtopic.php?f=6&t=24 |
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