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post #1 of (permalink) Old 12-08-2002, 07:11 PM
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Rebuilding 258 CID I6, 87 Wrangler; looking for lessons learned:

Rebuilding my 258; 1987 engine has 160,000 miles on it, never rebuilt, and mine since it was new: I have the traditional Haynes manual, and a limited experience rebuilding e.g., done one engine, 289 Ford in a 66 Mustang. I am wondering if any of you can provide any valuable lessons learned about the stuff not in the Haynes.

I am starting with a top end (Head), and also probably the timing chain, timing chain sprockets and a front oil seal, and stopping there for the winter. This engine is really a leaker.

This spring I will pull the engine and take care of the block. I just got done replacing the oil pump. I still have to do the normal compression checks, but a top-end is looking inevitable due to a temperature problem.

I have a hot engine problem I am chasing. I have replaced the radiator (looked really bad inside), thermostat, and now the oil pump trying to cool it down (oil pressure was very low, about 10 - 20 psi at idle and I wanted to be sure at minimum I was getting oil to the crankcase and to pick up the oil pressure a bit); I figured the low oil pressure was from a bad pump. I put in a 185 degree F thermostat. Engine runs at about 210 - 220 degrees F. Seems too warm to me. When I pulled the oil pan, there was the infamous white film in the pan. I know that indacates, water in the oil from probably a head gasket, or worst case a cracked cylinder wall, or a cracked or warped head. I was hoping the white film was just from condensation, but since the new oil pump did not improve the tempreature significantly I am moving on to the head. I am pulling the cylinder head to inspect, and while I am there doing the top-end.

Also, I have completely and properly rerouted all the ancillary vacuum and air lines that through the years were anything but routed properly.

V/R
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post #2 of (permalink) Old 12-08-2002, 08:28 PM
 
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Re: Rebuilding 258 CID I6, 87 Wrangler; looking for lessons learned:

Don't waste your time and money on your old head.
Find and re-work a 4.0 head for it instead.
See Tim Weaver's article on my site (below).
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post #3 of (permalink) Old 12-09-2002, 05:20 AM
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Re: Rebuilding 258 CID I6, 87 Wrangler; looking for lessons learned:

Good paper. I will give this serious consideration. Thanks alot. If nothing else, it answers alot of what does the head and manifold do for performance.

It is really a good site.

Thanks [img]images/graemlins/laugh.gif[/img]
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post #4 of (permalink) Old 12-09-2002, 08:15 AM
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Re: Rebuilding 258 CID I6, 87 Wrangler; looking for lessons learned:

have the head plained down some to help keep the compression up. i didn't, but wish i would have.

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post #5 of (permalink) Old 12-09-2002, 10:48 AM
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Re: Rebuilding 258 CID I6, 87 Wrangler; looking for lessons learned:

Thanks. Will do. Guess I'll have a machine shop look at it while they have it for cracks etc.

Can anyone describe what I should look for when I take the head off the block. I know to look for cracks, but are they always visible? and where will the cracks be usually? How do I tell if the head gasket is "blown", other than the water in the oil? Can you tell that it is blown, or do you just assume it?

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post #6 of (permalink) Old 12-09-2002, 11:04 AM
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Re: Rebuilding 258 CID I6, 87 Wrangler; looking for lessons learned:

1. Be careful with shaving the head, it can lead to chronic piging.
2. By the time you've go the head off lots of the evidence is gone.
3. Lots of cracks can't be seen with the naked eye.
4. Have the head:
a. Boiled, this is simple hot chemical or steam cleaning.
b. Magnafluxed, chemicals are applied to the head and it's subject to UV light which shows up cracks.
c. Pressure checked, This proves the valve job and head surfacing holds compression.
5. I use Seafoam and Carb Spray to remove carbon build up on the pistion.
6. Then blow out the carbon with compressed air and dry the cylinder.
7. Coat the cylinder with oil and examine it for scratches.
8. Keep oil on the cylinder walls till reassembly to keep down rust.
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post #7 of (permalink) Old 12-09-2002, 05:10 PM
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Re: Rebuilding 258 CID I6, 87 Wrangler; looking for lessons learned:

If you have the head and front of the engine off, it would be simple to crawl under, drop the pan, and yank out the pistons for a ring job and fresh bearings. If you dont need the block bored, a simple hone will make that old girl runlike new! Just my $.02
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post #8 of (permalink) Old 12-09-2002, 05:20 PM
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Re: Rebuilding 258 CID I6, 87 Wrangler; looking for lessons learned:

1. I agree with Eddie on the hone job!
2. If you go this route then buy a ridge reamer and remove the ridge.
3. If you do drop the crank...have it gone over by the machinest.
4. Then repalce all the bearings.
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post #9 of (permalink) Old 12-09-2002, 06:25 PM
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Re: Rebuilding 258 CID I6, 87 Wrangler; looking for lessons learned:

Wow! Thanks for all the heads-up. I will take it all under advisement.

I am trying to talk myself in to doing the pistons and cylinders while I'm at it. Don't know how much shiverin' I want to do. It's about 15 degrees at night around here, and warms up to a tropical 45 - 50 on good days. Usually not on the 50 side.

I have read about the hone tool. Is that a good way to go? If it really works adequately, I think I'll give it a try. I keep hearing so much about machine shops, and boreing, balancing, etc. makes me kinda' gun shy to go that deep in the home garage.

When I rebuilt our mustang engine (289), my wife and I pulled the engine and sent it out for the machine work. Had the shop balance it. However this isn't a sports car. I just want it to run strong, and climb up straight walls.

I appreciate the advise; this is like a Jeep mechanics 301 course.

Good stuff.
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post #10 of (permalink) Old 12-09-2002, 06:41 PM
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Re: Rebuilding 258 CID I6, 87 Wrangler; looking for lessons learned:

That cylinder hole should not be out of round or tapered vertically You can check that with an inexpensive dial gauge..

1. Engine Honing by hand has been done for years.
2. It ain't rocket science.
3. All you're doing is knocking down the glaze on the cylinder walls.
a. You can use a hone mounted on a drill, or,
b. You can use emery paper and use circular strokes.
c. Just make a good cross hatch pattern.
4. The rings will smooth out the bore as they seat.
5. Here's a good description of what you'll Be Doing.
6. Make sure you've got your engine specs for refrence.
7. Yep, if you start a borin' and balancin' then take it to a machinist...
8. Just go slow and check/double check your engine measurments to the engine specs to see if you really do need to pull the block and have it rebored.
9. Discuss with your machinest just what you want to do, and have him explain the hand operation. You'll be a lot more comfortable doing it with a little infomation.
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