Getting worried about my 258

Getting worried about my 258
C dubya

C dubya

Active Jeeper
Posts
388
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Location
Bartlesville, OK
Vehicle(s)
83 Jeep CJ-7 Renegade,
258 I-6,
T-4(Soon to be a T-19),
Dana 300,
1987 Grand Wagoneer,
360 V8, 2008 Chevy 2500HD Z71 Crewcab, 6.0 V8
Well the motor was overheating on my 1983 CJ7 . It overheated on the PO(boiled over) who is family so I knew the history. Jeep has 126k on it. Well long story short after replacing the radiator, waterpump, thermostat, and thermostat housing. Then having the cooling system professionally flushed she still runs hot. Not to boiling over, but the very edge of operating temp. Wouldn't be surprised if she did boil over on the highway. Talked to my gearhead buddy and I'm beginning to think it could be a head or worn out motor issue. On the chassis forum I talked about my oil pressure guage readings. He mentioned trying 20w-50 oil just to see if the gauge responded. I haven't done a compression or had a leak down done. She runs good and has alot of pep for a potentially tired motor. What do you boys think?

If it turns out she is wore out I'm just going to garage her and start the frame off process. Was hoping I could get at least a year out of her before that. Long post
 
C dubya said:
Well the motor was overheating on my 1983 CJ7 . It overheated on the PO(boiled over) who is family so I knew the history. Jeep has 126k on it. Well long story short after replacing the radiator, waterpump, thermostat, and thermostat housing. Then having the cooling system professionally flushed she still runs hot. Not to boiling over, but the very edge of operating temp. Wouldn't be surprised if she did boil over on the highway. Talked to my gearhead buddy and I'm beginning to think it could be a head or worn out motor issue. On the chassis forum I talked about my oil pressure guage readings. He mentioned trying 20w-50 oil just to see if the gauge responded. I haven't done a compression or had a leak down done. She runs good and has alot of pep for a potentially tired motor. What do you boys think?

If it turns out she is wore out I'm just going to garage her and start the frame off process. Was hoping I could get at least a year out of her before that. Long post
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I had this same problem had done every thing done u have done, check the oil for milkyness, and take the rad cap off start her up, let it get to operating temp and watch for bubbles in coolant, not just what looks like soapy bubbles but some that are being blown up at the cap area. If neither of this is happening then have your rad not just flushed or boiled out, have a process called rodding out done this is where they take the rad apart and run cleaning rods though it. U could have alot of build up in some tubes causing it not to cool all the water causing it to overheat. MIne also would run a little hot not much in town but on the highway it would get hot like you said. This is what I would suggest. It fixed my problem hopefully it will fix yours.:)
 
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1986cj7 said:
I had this same problem had done every thing done u have done, check the oil for milkyness, and take the rad cap off start her up, let it get to operating temp and watch for bubbles in coolant, not just what looks like soapy bubbles but some that are being blown up at the cap area. If neither of this is happening then have your rad not just flushed or boiled out, have a process called rodding out done this is where they take the rad apart and run cleaning rods though it. U could have alot of build up in some tubes causing it not to cool all the water causing it to overheat. MIne also would run a little hot not much in town but on the highway it would get hot like you said. This is what I would suggest. It fixed my problem hopefully it will fix yours.:)
Click to expand...

You really think a brand new radiator would need to be rodded?
 
C dubya said:
You really think a brand new radiator would need to be rodded?
Click to expand...
Sorry missed the new rad part maybe I should read a little closer huh!:dunno: But if you haven't checked the oil for milkyness and coolant for bubbles there good sighs that a cracked head, head gasket, or block. But from the sounds of it you already checked these.
 
I will check the oil over the weekend. I have only checked the dip stick, but the oil looked clean from that end. Cooling system has been completely burped and does not leak. I'm beginning to fear that it is a head issue. If it comes to that I will be moving to the build thread and taking her apart. Wanted to hold off until after the winter to get that going, but I gues now is as good as ever.:rolleyes:
 
What would milky oil imply? Just wondering in case its what I see.
 
Are you still running the stock carb or has that been messed with?
 
Yep, stock everything. No upgrade of any kind has been done.
 
you could try running a comp test. if you have 2 cyls in a row low on compression, then you probably have a head gasket issue.
 
Well I came home to a puddle of coolant under the cj. I will try and get it in for a leak down this week. Everything else is on hold. Not looking good.
 
The two cylinder in a row having low compression could be a cracked block, 0r cracked head. I check compression with all the plugs out to. But since the AMC 258 i6 / 4.2l are all iron head and block and all, I think also most likey a blown head gasket. So it might not be as bad as it seems. I've never tried taking the head off with the motor in, if all the head bolts have enough clearance it may be possible. But I know mine, the valve cover is close to the firewall and is hard enough to take off and on. So can someone with a little more knowelge chime in I'd like to know myself!
 
Didn't get a chance to look at the oil this weekend. Made an appt to have a leak down test done on thursday. If the compression is good and it's just a head gasket or the head I will probably patch her up and continue to enjoy. If the motor is too tired I'm going to tear her down. We will see after thursday.
 
C dubya said:
What would milky oil imply? Just wondering in case its what I see.
Click to expand...
it'll look sorta like chocolate milk. does your jeep still have the factory fan shroud? and is the clutch fan working? could be something simple as that.
 
x2 on the fan shourd, I forgot that I had also put a fan shourd on mine was missing, before rodding the rad out. Mine was missing believe it of not the shourd will help out alot. Expecealy in sitting traffic. Mine didn't have a fan clutch so I didn't think of that.
 
I still have the factory fan shroud installed. I don't think I have a fan clutch. Seems like the fan runs all the time, constantly turned by the the pulleys.
 
Starting to have enough checks on the list that bad stuff is coming up. :eek:
 
I hear that. I planned to rebuild it all along, just figured to get to get past the winter. If the head is cracked I am just going to bring it home and pull it. Get it completely striped and bored 30 over. Throw a comp cams 4x4 energy cam in and do a 4.0 had swap. Want to do fi but probably end up with an mc2100. Refresh the Transmission and Dana 300 and put a true track in the rear. That's the plan anyways.
 
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