I recently did the head gaskets on a 98 LS1. Reason was cause coolant was shooting a foot above radiator like a geyser. All is done and ran good for first 30 minutes. Next day turned it on to do some finishing touches when it started heating up again. I suspect that the block could have a crack. My question is, are LS1 blocks suppose to have a 2-3 inch hairline crack running vertical on the outside of block at the bank 1 cylinder 7 spot? I think it is cracked cause last owner hit a side walk and bent the left side of K frame and bent it until left tire was in contact with the fender, which is the same side that the small crack is on. can anybody with an LS1 in their garage answer my question if the crack is suppose to be there. Thanks in advance

 

snap a pic if you can get one.

 

I dont know how to upload pictures

 

I uploaded pictures to my albums. check them out and let me know if that crack is normal. quality is a little bad cause I took pictures while doing the build but not of the crack. just lucky i had an image where i could zoom in and trim it to get image of the crack

 

https://ls1tech.com/forums/picture.p...ictureid=54146

 

 

 

 

Does it spray out of there or weep? Or did you just happen to see it while trying to figure out what could be wrong?

 

I dont see any visible leaks. I noticed the crack before i put the heads but couldnt tell whether it was a crack or not. I'm just thinking maybe its a small crack on the outside and maybe on the cylinder wall too since its starting to shoot water out the radiator cap again. I dont think i made any mistakes on installing the heads. got the heads rebuilt and followed all torque specs on the head bolts. also want to add that the #7 spark plug was wet before i removed the heads which is also where the crack is on the outside. I'm assuming the block deck was warped or the crack caused this all along. what do you think?

 

It could just be some left over in the casting. Did you or have you done a compression test on the 2 cylinders around the crack? Or all of them for that matter just for other peace of mind?

 

Did the shop resurface your heads before they put them back together??

 

yes they resurfaced them with the belt sander type machine. I got a little mad cause I know its not recommended but I was hoping it would still last around 50,000 miles. I am gonna check compression today. have any of you guys ever felt the top coolant hose and it feels like the coolant is just spitting towards the radiator?

 

I bet they did not resurface them I bet they used the belt sander to just remove the old gasket material and just told you they resurfaced them.

Also did you make sure the dowel pins in the block were in place when you put the heads back on? Alot of times the dowel pins will get stuck in the head when the head is removed and the dowel pins will fall out wile moving the heads around or forgotten about when the heads are put back on.

Lastly did you use the GM MLS head gaskets or did you use the Graphite head gaskets?

 

Yea the dowel pins were there and fully seated. I used the regular felpro graphite head gaskets

 

If you want to see if that crack is a problem or not, do these:
- borrow a cooling system pressure tester, pump up the cooling system to 20 psi and see if it holds pressure steady;
- use a block test kit to detect presence of combustion gases in coolant;
- leakdown test;
- compression test;

blow the crack out with compressed air and spray a little brake cleaner on the crack, does the crack absorb it...?

Block Test Kit: http://www.tooltopia.com/lisle-75500.aspx

 

are you sure there isnt just some air still trapped in the coolant system somewhere?

 

ok, I have a compression gauge, block tester but how do I pump 20 psi into cooling system. is it a handheld pump or compressor?

 

AutoZone would have a loaner...



Cooling System Pressure Tester:


You remove the radiator cap and place the end of this on the radiator, lock it down, and pump up while watching the gauge... when you hit 18-20 psi stop pumping and see if pressure stays steady for 30 minutes, look for leaks on the block [and also radiator, hoses, heater, etc] during this time.


[ The shiny adapter piece is for testing the radiator cap to see if it holds pressure. ]

 

generally you will find a cracked head befor a block.. right between the valves besides thats the outside of the block the inside has a sleeve