Can someone point me in the direction of...

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Topic author
Tnsser
Posts: 86
Joined: Tue Nov 30, 2021 11:47 pm
Location: Tennessee

Can someone point me in the direction of...

Post by Tnsser »

A good resource for changing the oil pump and the crank bearings. I've read both were doable from under the engine with the oil pan removed. Thanks.
1984 Jeep J10 258 AMC 4 speed (New project)
1991 Chevrolet S10 283 swapped and slammed
1991 Mazda Miata Turbo. Total rebuild with 230 hp
1979 Honda CB750 Cafe
2006 Ducati Monster S2R
1964 International Scout 80. All original
1984 Chevrolet C10 built 350 slammed
Knoxville Tennessee

Theodore
Posts: 377
Joined: Tue Sep 04, 2018 5:26 pm
Location: East Tennessee

Re: Can someone point me in the direction of...

Post by Theodore »

Hey, Tnsser, see youre in Knoxville; Ive had a good experience with Smoky Mountain Auto & Jeep Repair in Sevierville. Would recommend giving them a yell.
1990 Grand Wagoneer - "Theodore" - AMC 360, fuel-injected, TF727, NP229 - Sand Metallic - restoring to stock - Build Thread

Topic author
Tnsser
Posts: 86
Joined: Tue Nov 30, 2021 11:47 pm
Location: Tennessee

Re: Can someone point me in the direction of...

Post by Tnsser »

Thanks but I'm going to do it myself. Just trying to do as much studying on it before I tackle it.
1984 Jeep J10 258 AMC 4 speed (New project)
1991 Chevrolet S10 283 swapped and slammed
1991 Mazda Miata Turbo. Total rebuild with 230 hp
1979 Honda CB750 Cafe
2006 Ducati Monster S2R
1964 International Scout 80. All original
1984 Chevrolet C10 built 350 slammed
Knoxville Tennessee
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tgreese
Posts: 7118
Joined: Fri Jun 08, 2012 6:31 am
Location: Medford MA USA

Re: Can someone point me in the direction of...

Post by tgreese »

Tnsser wrote: Sun Jan 02, 2022 4:16 pm A good resource for changing the oil pump and the crank bearings. I've read both were doable from under the engine with the oil pan removed. Thanks.
Your TSM is the best resource. There is an '82 TSM here - https://oljeep.com/edge_parts_man.html that will cover these aspects of your engine. Better to get the book that is specific for '85, but it's not cheap https://www.bjsoffroad.com/1984-87-Jeep ... _1056.html You might find it on CD-ROM for less somewhere online. BJ's will give you a modest discount as a member of this forum.

Realize that the 258 changed a lot for 1981, so don't go with any earlier manuals.

Do you have a rod knock now, or are you hoping for better oil pressure?

Replacing the crank bearings is not a job I would consider doing from under the Jeep. Do you mean just the rod bearings? Typically I think of the main bearings when someone says crank bearings. Pretty sure the main bearings won't come out with the crank in the block. IIRC the 258 has a conventional oil pump in the sump, which should be easy to change. If I felt it needed bearings, I'd do an old-fashioned overhaul on the bench - rod bearings (likely a crank kit), rings, valve job.

I'd also mention that the 258 has a cast iron crank, and unlike a forged steel crank, the crank surfaces wear down along with the bearings. The usual service is to install a refurbished crank with fitted bearings - a crank kit. When you exchange your crank, they will give you a replacement that is the next size under, say 0.010" or 0.020".
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.

Topic author
Tnsser
Posts: 86
Joined: Tue Nov 30, 2021 11:47 pm
Location: Tennessee

Re: Can someone point me in the direction of...

Post by Tnsser »

tgreese wrote: Mon Jan 03, 2022 9:32 am
Tnsser wrote: Sun Jan 02, 2022 4:16 pm A good resource for changing the oil pump and the crank bearings. I've read both were doable from under the engine with the oil pan removed. Thanks.
Your TSM is the best resource. There is an '82 TSM here - https://oljeep.com/edge_parts_man.html that will cover these aspects of your engine. Better to get the book that is specific for '85, but it's not cheap https://www.bjsoffroad.com/1984-87-Jeep ... _1056.html You might find it on CD-ROM for less somewhere online. BJ's will give you a modest discount as a member of this forum.

Realize that the 258 changed a lot for 1981, so don't go with any earlier manuals.

Do you have a rod knock now, or are you hoping for better oil pressure?

Replacing the crank bearings is not a job I would consider doing from under the Jeep. Do you mean just the rod bearings? Typically I think of the main bearings when someone says crank bearings. Pretty sure the main bearings won't come out with the crank in the block. IIRC the 258 has a conventional oil pump in the sump, which should be easy to change. If I felt it needed bearings, I'd do an old-fashioned overhaul on the bench - rod bearings (likely a crank kit), rings, valve job.

I'd also mention that the 258 has a cast iron crank, and unlike a forged steel crank, the crank surfaces wear down along with the bearings. The usual service is to install a refurbished crank with fitted bearings - a crank kit. When you exchange your crank, they will give you a replacement that is the next size under, say 0.010" or 0.020".
Yes oil pressure is low. I'm not super worried about it but I want to go ahead and start learning what needs to be done.
1984 Jeep J10 258 AMC 4 speed (New project)
1991 Chevrolet S10 283 swapped and slammed
1991 Mazda Miata Turbo. Total rebuild with 230 hp
1979 Honda CB750 Cafe
2006 Ducati Monster S2R
1964 International Scout 80. All original
1984 Chevrolet C10 built 350 slammed
Knoxville Tennessee
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tgreese
Posts: 7118
Joined: Fri Jun 08, 2012 6:31 am
Location: Medford MA USA

Re: Can someone point me in the direction of...

Post by tgreese »

Sorry if I'm rambling ... you clearly have spent a lot of time around cars and this may be old news.

Thinking about this some - I recall you can sometimes remove the upper half of main bearings using a tool that fit into the oil hole of the crank journal. This sticks out of the hole and as you turn the crank, it pushes the bearing shell out of the block. There has to be something that stops the bearing from rotating while the engine is running, and typically that's a pair of notches in the bearing cap that key into the lower half of the bearing.

Still, I would not try this. Especially with a 258, you have lots of room to work and pulling the engine will make this all much easier and mistake-proof. You will want to measure the bearing clearance with Plastigage if nothing else.

A 258 has a really long stroke, and the rod velocity will get very high if you wind it out. Should be ok as long as you don't punch through the oil film and have metal-to-metal contact. Once you get a noise it'll only get worse as you drive it.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.

Topic author
Tnsser
Posts: 86
Joined: Tue Nov 30, 2021 11:47 pm
Location: Tennessee

Re: Can someone point me in the direction of...

Post by Tnsser »

tgreese wrote: Mon Jan 03, 2022 1:32 pm Sorry if I'm rambling ... you clearly have spent a lot of time around cars and this may be old news.

Thinking about this some - I recall you can sometimes remove the upper half of main bearings using a tool that fit into the oil hole of the crank journal. This sticks out of the hole and as you turn the crank, it pushes the bearing shell out of the block. There has to be something that stops the bearing from rotating while the engine is running, and typically that's a pair of notches in the bearing cap that key into the lower half of the bearing.

Still, I would not try this. Especially with a 258, you have lots of room to work and pulling the engine will make this all much easier and mistake-proof. You will want to measure the bearing clearance with Plastigage if nothing else.

A 258 has a really long stroke, and the rod velocity will get very high if you wind it out. Should be ok as long as you don't punch through the oil film and have metal-to-metal contact. Once you get a noise it'll only get worse as you drive it.
I'm going to check the lifters thus weekend. I'm pretty sure it's just a clogged lifter. But usually if I run some Rotella T6 and Mystery Oil through it for a few 100 miles the lifter clears and starts pumping up. Well not this time. The oil pressure gets up to 65 on cold starts and stays about 10psi on hot idle. It just doesn't get back over 30psi when hot reving to 3k or so. If I pull it I'm going to install an LS in its place. Was just wanting to run this one for another year.
1984 Jeep J10 258 AMC 4 speed (New project)
1991 Chevrolet S10 283 swapped and slammed
1991 Mazda Miata Turbo. Total rebuild with 230 hp
1979 Honda CB750 Cafe
2006 Ducati Monster S2R
1964 International Scout 80. All original
1984 Chevrolet C10 built 350 slammed
Knoxville Tennessee
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