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.

 

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.

 

the worst can probably happen is the head gasket wont last

alternative is a used engine, so I would probably push ahead with what you got, under the circs you outlined, and keep a good eye on the temp gauge

...except if strongly advised otherwise by a consensus of experienced engine guys, such as probably exist on this forum !

 

Put back together and dive it , then start looking for a motor to replace it .

 

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.

 

From your other post:

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.

 

Its been compromised and not worth the risk. Find another block.

 

Just how super overheated did it get to do all that cracking?

 

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.

 

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!

 

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

 

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.

 

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.