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Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go hereXJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.
Okay for starters I have a 94 zj with the 4.0 inline 6. I took the engine apart to replace the head gasket initially. Upon taking the cylinder head in for inspection I learned it was cracked so I of course purchased a new one. I started rubbing away the flash rust on the cylinder walls (it’s had the head off for 6 months) then proceeded to cleaning the surface of the engine block. When doing so, I noticed two cracks in the surface of the engine. Both between the number 7 head bolt (second from the front on the drivers side) and the coolant chamber on each side. Does this mean I’m screwed? I’ve dumped all the money I can afford to into this engine as it is to temporarily be my daily driver. I’m wondering, considering the placement of the cracks, if I could add some thread sealant to the #7 bolt (like the #11 requires) and temporarily get by? I certainly can’t afford a new block and it doesn’t appear to be a super deep crack. Any ideas or suggestions for a cheap quick fix are also welcome in addition to answering my questions. Thank you in advance! Photos below!
Sure note: there was significant amount of buildup around the cracks. I was thinking maybe a sign that they had been there awhile? Or for all I know the gasket just happened to stick a little worse there. Not certain just thought I’d throw that bit of info out there.
Last edited by Jose Schmoe; 01-04-2021 at 04:20 PM.
I can't quite tell but it doesn't look like the crack goes into the threads. I personally would put everything back together and move on. Very closely examine the rest of the block and make sure it is level.
I would put it all back together and move on with life. I don’t think they will cause any serious issues. Likely they were there before and honestly unless you do a complete engine rebuild or replacement you always take a certain risk with head jobs. I think you’ll be OK.
This might be a stupid question, but you did get all of the head gasket off there right? A couple of the pictures look like you still have a layer of head gasket material on there. You'll need to clean that up a little better before you put a new gasket on there anyway.
Okay so I took my cylinder heads to the engine shop to be machined down for head gasket replacement (‘94 4.0L ZJ). While there, they ran (I’m assuming) some kind of compression test and called me back to tell me my heads were shot. They said there were several micro fractures throughout it I understood them correctly. Obviously I’m in need of new heads but with 300k on the engine, what would you guys replace? I was planning to just replace the heads (I recently purchased new lifter rods and rockers) but my dad seems to think it would be in my best interest to buy a long block.
IMO this is just a bad engine and you're throwing good money after bad. You got a new head, push rods, rocker arms-- what else? 300K on a beat engine? What about the rings and all the bearings? Oil pump? You should at least look at them. Pull the pan and start measuring.
You can even get a good used engine for ~200 bucks just slap it in and be much better off than you are now.
I mean, a 94 ZJ head is a strong head. To crack that, blow the head gasket and crack the block that thing took a beating. And 300K. Bail out now while you still got a chance.
I can't quite tell but it doesn't look like the crack goes into the threads. I personally would put everything back together and move on. Very closely examine the rest of the block and make sure it is level.
10-4 thanks man! You’re correct, it doesn’t go into the threads. On one side it goes through the very top thread only but no further.
This might be a stupid question, but you did get all of the head gasket off there right? A couple of the pictures look like you still have a layer of head gasket material on there. You'll need to clean that up a little better before you put a new gasket on there anyway.
yes I did! You’re correct, those spots were where the gasket stuck a bit worse than other spots but I carefully bladed them off and rubbed it a bit more to smooth it out!
I mean, a 94 ZJ head is a strong head. To crack that, blow the head gasket and crack the block that thing took a beating. And 300K. Bail out now while you still got a chance.
Gasket ended up being fine, it actually never overheated more that 220ish and that was around 2 months before it finally went. I just thought due to symptoms that it was a gasket. Turns out it was the head! It just randomly died riding through town! I could wait several hours or a day and it would fire back up temporarily. So I just took a chance and tore into it
Just how super overheated did it get to do all that cracking?
Oddly enough, on me personally, never over 220-230 which was weeks before it actually quit! Judging by the buildup around this crack, I was honestly thinking it must have been there awhile. I’m hoping the main problem was the head because I can’t find where anything compromised the gasket. As in I didn’t find a spot where and oil/ air or fuel mixed or opened with the outside.
...it finally went. ... It just randomly died riding through town! I could wait several hours or a day and it would fire back up temporarily.
That's new and important information. Sounds like seizing. Absolutely calls for complete teardown, but again, with 300K on a cracked block, why bother. Throw that block away.
01-04-2021, 04:16 PM
Cracked block. Helpppp!
