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Discussion Starter · #1 ·
Hi guys I have a few questions about the block surface. I am trying to put in my hks 1.2mm metal head gasket. I just took my block to get machined and after they were finished decking it you can see tiny little hairline cracks around a few of the head bolt holes. You can barely catch your finger nail on them and the longest is probably less than a cm long. I am wondering if these will be a problem since I do not really want to buy a new block. Also, the guy told me that there was a low spot right near the front on the little piece extending from the rectangular shape of the block surface. Please let me know if you have tried reusing a block in similar condition or if you think I should not try it. I will be shooting for 400 rwhp so it will have to hold up for that. Appreciate any help and info for my problem. Thanks.
 

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I had these cracks on 4 out of 4 machined 7m blocks. I returned all 3 of my jdm engines because of it, and decided to run my original block (which also had the crack) and hope it sealed. I put a little fipg around the headbolt head and washer -- just in case. Anyway I haven't had any problems since. What was weird was that nobody had ever heard of or seen this problem before, but I have yet to see a machined block that didn't have it.


Here is a picture I took. Unfortunately, the flash created a glare on the block surface and you can't see the crack -- but I used a sharpie and put two black lines around the hairline crack. All of my blocks only had one crack, and all of them were located on the same headbolt hole (dead center of the block)
 

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Discussion Starter · #4 ·
pics

Hmm exactly what I wanted to hear hehe thanks. I will probably reuse it then unless you can see in the pics that mine is worse than what you had. How long has your block lasted you and what kind of hp/boost are you running daily? Oh also what is fipg heh. Still not sure about the low spot on the block though. I had the same problems with the flash on my pictures so trashed most of them but did take a few without the flash. All the pictures are of the same cracks but are from different angles. The low spot you can't see well or even feel but the picture will show the location. How does the machine work look to you guys? First timer here, so I don't know what to expect and still trying to learn. Do you think I will have to lap it also? Thanks again for the info.

low spot
cracks 1
cracks 2
cracks 3
cracks 4
cracks 5
 
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Honestly, I think assembling everything and dropping it in is just asking for trouble. Those cracks are pretty big. Maybe it's just me, but I wouldn't want to get everything done just to have the engine bomb on me in the future.
 

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Yeah, those look a lot worse. The red arrow is the crack I have, but the other ones you have would make me look for a new block since they are more severe, and they go to the cooling jackets. If the red-arrow crack were to leak, it would leak oil into the headbolt hole -- which would just have oil in the head -- so it wouldn't really be a leak. If your cracks leaked -- they would leak coolant into the headbolt hole -- which would bring coolant into the head -- like a bhg. Plus your cracks look like more of a structural failure



Sorry man, and better luck with your next block.
 

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sounds like a bad block to me. better luck with the next one man. I wouldnt risk running it, but your machinist should have found it when he was working the block.
 

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The machinist needs a kick in the plums for not mangafluxing before doing all that work.

I had a similar occurance on a different application, the shop ended up eating a $700+ machine work bill for not doing the proper testing beforehand.
 

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it seems to me that the head would crack before the block if you overtightened the head bolts. bah, maybe Al has less rigid characteristics so it bends/deforms rather than cracks.
 

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Agreed. Those look more like overheating based failures and not overtorque problems (got hot, cast expanded and cracked around the harder bolt). You would get similar effects from a manifold with too little hole to bolt clearance. Take it up with your machinist. The low spot is normally the area you put the FIPG on per the TSRM (so it looks), so that might be a non issue.


Bob
 

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take it back to the shop and reem them out...maybe u can get them to get u a new block due to incompitance (sp) but i wouldnt hold my breath. tough break man
 
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