AMC Eagle Den Forum

The Mighty 258 => The Engine => Topic started by: papacarn on March 06, 2012, 12:45:38 AM

Title: new exhaust and intake gastkets
Post by: papacarn on March 06, 2012, 12:45:38 AM
Well the old SX4 may never run again. Started tearing her down tonight to get ready for new gaskets tomorrow. If I were to get rid of all the hoses and wires that go to that carb and intake the car would be 100 lbs lighter. I wonder what engineer was laughing when he decided to make a half an overhaul to change an exhaust gasket? Even the power steering brackets have more bolts then the one on my 10 yard dump truck. I guess the didn't want it to fall off. I'm letting the exhaust manifold to head pipe bolts soak in liquid wrench overnight. I don't think she's had any exhaust work for quite a few years. Things are a little tight underneath; I may be wishing I had gone with an Eagle wagon before this little project is complete
Title: Re: new exhaust and intake gastkets
Post by: vangremlin on March 06, 2012, 09:58:57 PM
Good luck with this "simple" project lol
Title: Re: new exhaust and intake gastkets
Post by: BenM on March 07, 2012, 12:39:26 AM
I've been in there a few times. If the exhaust pipe nuts aren't rusted badly I can comfortably do the whole thing in an afternoon. Good luck.
Title: Re: new exhaust and intake gastkets
Post by: papacarn on March 07, 2012, 01:21:13 AM
  I'm going to be into it more then one afternoon. I've got the manifolds back in place and tight. The exhaust is hooked up, but I gotta tell you, I couldn't figure out how to torque the bottom row of manifold bolts. I used a 1/4" drive to get them back in, but my torque wrench's are 1/2" and I have an inch scale in 3/8". Neither would fit. Can't get a good reading with a swivel. The ones in the back were a real bugger. I may have even said things I can't post (ha ha). Valve cover is leaking, and cross at front differential needs to be replaced. Tomorrow will be busy if local parts store doesn't have to order. They don't keep many AMC parts in stock.

(http://i1242.photobucket.com/albums/gg521/papacarn/engine2.jpg)
(http://i1242.photobucket.com/albums/gg521/papacarn/Rons_engine.jpg)
Title: Re: new exhaust and intake gastkets
Post by: Prafeston on March 07, 2012, 08:43:54 AM
What is written on the inside of the engine bay on the shock mount thing?
Title: Re: new exhaust and intake gastkets
Post by: doc65 on March 07, 2012, 09:02:46 AM
Looks like New Eng & mileage...
Title: Re: new exhaust and intake gastkets
Post by: GRONK on March 07, 2012, 09:57:31 AM
Just replace the exhaust manifold on a friends 258 and YES, it's a bugger.  Getting off was simple.  Getting back on was a challenge.  Had to enlarge a few of the mounting holes on the exhaust because it was slightly warped.  After a few hours of fighting, I asked my wife for help and her hands were small enough that she sat on the valve cover and got ALL of the friggin' lower bolts in by hand.  Once they were in it was simple to tighten everything back up.  I felt stupid for working on them so long before asking for help.....
Title: Re: new exhaust and intake gastkets
Post by: doc65 on March 07, 2012, 11:02:30 AM
Sounds like the beginning of one of those commercials:  Eagle, $400, New Gasket, $35, Time $$$, Having a wife that isn't afraid to break a nail OR get a little grease under one... PRICELESS!!!  :)
Title: Re: new exhaust and intake gastkets
Post by: papacarn on March 07, 2012, 03:30:37 PM
  The writing on the firewall is indeed the last time the engine got rings, bearings, and valve job. It was done 12-24-94, and had 100,948 miles. I bought the car in 2005, and it only had 118,404. Now has 143,176.
  Napa had my u joint, but had to order the valve cover gasket. No big deal, it will be here in the morning. Should have her back on the road this weekend for sure.
  If the engineers had made provisions to cast indentations in the bottom of the intake where each of those 4 bottom bolts are located, to allow for a socket on a 6" extension to contact the bolt straight, this would be an easy project. Of course if I hadn't dropped one of those bolts, that didn't hit the shop floor, and had to crawl under the car looking for it, I wouldn't have noticed the bad u-joint. Things have a way of working out.
Title: Re: new exhaust and intake gastkets
Post by: papacarn on March 09, 2012, 09:41:43 PM
  Well, I just thought I would be done this weekend. That is not going to happen. When I replaced the leaking valve cover gasket, I found my real problem. Seems my leaking exhaust gasket was in fact the head gasket right behind it. The front head bolt on the exhaust side is broken. I'm going to use a piece of 3/8 tubing as shin stock to center a 1/4 inch bit while I try to drill out the broken piece deep enough to get a easy out in. If I can get the broken piece out of the block, I will put in a new head bolt and try it. As of now it is not leaking water yet, just making a weird sound under compression. If that doesn't stop the compression leak, I will have to pull the head.

(http://i1242.photobucket.com/albums/gg521/papacarn/enginehead1.jpg)
(http://i1242.photobucket.com/albums/gg521/papacarn/enginebolt1.jpg)
(http://i1242.photobucket.com/albums/gg521/papacarn/engineheadbolt.jpg)
Title: Re: new exhaust and intake gastkets
Post by: carnuck on March 09, 2012, 10:25:26 PM
My Spirit has the same problem. I cleaned the hole out with brake clean and rag pieces on a drill bit then put the broken bolt back in with "The Right Stuff" on it. Hasn't lost a drop since (3 years ago) I figure I'll fix it when I pull the head to put a 4.0L head on.
Title: Re: new exhaust and intake gastkets
Post by: mudkicker715 on March 09, 2012, 10:31:19 PM
I just pulled the head off of a 258 that bolt came out with a bunch of rust dust. none of the others were rusted
Title: Re: new exhaust and intake gastkets
Post by: doc65 on March 09, 2012, 11:43:31 PM
at least on all the 4.0s I've rebuilt that, was I believe the only bolt that actually went thru into the water jacket, I always put that,one in with sealant(RiteStuff)
Title: Re: new exhaust and intake gastkets
Post by: papacarn on March 10, 2012, 02:59:28 PM
    Need some advice from you veteran Eagle mechanics. What is the latest version of the 258 that will have the same double decker head bolt as my 81. The parts house in my small town says it's no longer listed for the 81 eagle SX/4, but I know that engine was used long after that. I would rather not go searching in wrecking yards just yet. We still have snow on the ground. Thanks in advance...Papa!
Title: Re: new exhaust and intake gastkets
Post by: papacarn on March 10, 2012, 06:08:40 PM
  So far, I've been able to determine that the head bolts in my 258 are 7/16 long and short flange on the manifold side, and 7/16 no flange on the passenger side. I have located a complete set on eBay for 15.00. I will probably go that way, even though I only need one short flange bolt. The way my luck has been running, it can't hurt to have a few extras laying around.
Title: Re: new exhaust and intake gastkets
Post by: GRONK on March 11, 2012, 10:07:38 AM
Look for a local FASTENAL near you.  I bought a set of 50 bolts w/ everything else needed for $12.  I now have enough for many more projects.
Title: Re: new exhaust and intake gastkets
Post by: papacarn on March 11, 2012, 02:51:14 PM
  Thank you GRONK, that is some good information. I googled store locator for Fastenal, and the closest one is in Sandpoint, Idaho. That is about 45 minutes from me. I will definitely check them out next time we are there.
Title: Re: new exhaust and intake gastkets
Post by: papacarn on March 27, 2012, 01:28:56 PM
Well, the old Eagle is back on the road to recovery. Replaced the head gasket and head bolt. Had to come up with a plan to put head back in place without moving gasket. Can't believe there are no dowels to hold it in place. I drilled holes in a piece of 2 inch pvc pipe and inserted a piece of nylon rope which I attached to the head at #5 valves with wire. I controled the front of the head and moved it into place while my wife held it above the block with the makeshift hoist. When it was centered, she rotated the pipe slowly and lowered it into place.
(http://i1242.photobucket.com/albums/gg521/papacarn/100_2776-1.jpg)
(http://i1242.photobucket.com/albums/gg521/papacarn/100_2777-1.jpg)
(http://i1242.photobucket.com/albums/gg521/papacarn/100_2779.jpg)
(http://i1242.photobucket.com/albums/gg521/papacarn/100_2778.jpg)
Title: Re: new exhaust and intake gastkets
Post by: captspillane on March 27, 2012, 03:01:10 PM
I make studs using old driver side head bolts. A few minutes on a grinding wheel takes the hex head off and leaves a smooth shank. Twist two into the block at opposing corners and lower the head gasket down the shank, then the head. You can drop it perfectly into place yourself that way. Snug up all the other head bolts and then twist out the corner studs for use in your next rebuild.

This is also the way I install 4.0 heads on 4.2 blocks. An old 4.0 head bolt will have 7/16 threads at the top for accessories and 1/2 threads and shank at the bottom. Flip them upside down with the hex head ground off and you have a perfect adaptor that works alot better than the spacers that are sold.
Title: Re: new exhaust and intake gastkets
Post by: papacarn on March 27, 2012, 07:42:05 PM
More good information, I've been a Chevy man most of my life, but I'm learning. Anyway she is back on the road. I took her for a 40 mile test run this afternoon. No obvious leaks, and nice and quite. Also has a little more punch; that compression leak robbed some of her power, besides sounding terrible. I'm going to replace the front u-joint tomorrow, and call it a done deal. Thank you to all who offered advice. Happy Motoring!