View Full Version : Leaking coolant into block, please help

12-21-10, 05:33 PM
Hey guys, not really sure what to think of this but I need some help. I got my heads back from TEA so I started prepping the block. On the passenger side, the head bolt hole, second from the firewall leaks coolant. I noticed because I was blowing it out with air and drying it with paper towels but it never emptied. Right after sticking a paper towel down there and drying it out I looked and could kinda see coolant slowly leaking in. It looked like a tiny hole right next where that screwed up motor mount bolt was.

I'm guessing I'm screwed?

12-21-10, 05:37 PM
That is some Christmas present. :helpless:


Take a pic and maybe some one can weld up the hole and retap the threads.

12-21-10, 06:25 PM
I siphoned out enough coolant so it wouldn't leak into the bolt hole. Then I added coolant to the bolt hole to see if I could see it leaking out. Didn't see anything but it does leak really slowly back into the block. I took a picture but it doesn't show much. What happens if I just go ahead with the build as normal? Coolant can't leak into the bolt hole if there is a bolt there right?


12-21-10, 06:49 PM
I do not think there is a problem. The only reason there is any coolant in the hole is because you spilled it there when removing the head. Nornally, the head bolt holes are not supposed to have coolant in them EVER. That is why all of the instructions on head swaps tell us to get all of the coolant out - so the block does not crack from having trapped water turn to steam once assembled.

I think all that has occurred is that the hole drilled in the block for the motor mount has intersected the hole in the block for the head bolt. Although I have not encountered this specific set of facts before there was an instance reported and discussed on the other forum in which a head bolt hole on the cylinder closest to the firewall intersected a perpendicular hole drilled in the back of the block. The consensus was that, while unusual it did not matter as long as both bolts could be torqued down. As in your case, it was only discovered when the owner started using compressed air.

The bottom line is (I think) that there is no problem unless or until you have hole that penetrates the water jacket/cavity of the block.

12-21-10, 08:03 PM
The other reason not to have water in the bolt holes is that it can crack the wall if you tighten the bolt.

I would drain the block and make sure all the holes are dry before assembly.

Check for leaks after and if it leaks, you know what you need to do.

12-21-10, 08:14 PM
I agree with heavy IF you want to be ultra safe about it and darkman makes total sense, too. If that coolant is leaking in, then putting a bolt into it should make the coolant leak back through whatever hole is there and be okay.

I'd ignore it and build the motor back up or at the most follow heavy's recommendation and drain the block before reassembly.

12-21-10, 08:23 PM
I used to use thread sealant on all head bolts to ensure they were all torqued to spec. It sealed the threads and reduced friction. (Not locktite more like a gasket sealer)

12-21-10, 10:05 PM
Sounds good, thanks for the advice. I've drained the block and it's just about is prepped for the heads, no coolant in the holes and I've cleaned out all the threads and removed all the old gasket material. Carbon build up is also completely off of 5 pistons, so 3 more to go. On to the starter, cam, and oil pump tomorrow.

12-21-10, 10:51 PM
I use compressed air and contact cleaner with a 6" cotton swab to make sure the bolt holes are clean and dry.

Gun cleaning brushes and swabs work also.

Brush gets all the old sealant and crap out of the threads.

12-21-10, 11:30 PM
Ah cool, I used compressed air then rolled up shop towels then an old head bolt with gashes cut in on each side to clean out the debris.