I just finished up a cam swap (xe274). I have vortec heads and had them worked for the lift, but they were not milled. Anyways, I had completed the break in procedure and have had the engine running several times since. It hasnt been on the road yet, but the last time I had it running doing some carb tuning I looked underneath the car just rountinely checking for leaks and I see a steady drip of oil falling on the header collector. I shut it off and began tracing the leak, and I found it leaking from the back of the head where it mates to the block. Now Im wondering what could I have possibly done wrong here? I checked the torque on the head bolts which were new ARPs and they were where they should be. I used GM 10105117 head gaskets, and Im wondering if there could be a failure in them. Or maybe perhaps oil was getting passed a bolt somewhere?? I have it torn back down and am about to pull the head to see what I can see. Has this happened to anyone? I might be able to tell more when I get the head off, but Im worried I wont get a definitive answer when I do it.

 

Sounds like a leak from the intake manifold end gasket.

 

I dont think its the intake its perfectly dry all across it. I had to get a mirror to look back there, and I even cleaned it up and ran it again just for a minute to be sure where it was coming from. Its hard to describe. I found a pic of the front of a block, where I circled on the front is where it is coming from in the back of my engine (couldnt find a rear pic of a block).

 

In that area, on the back of the block... if its on the drivers side of the rear of the block, theres sometimes an oil gallery plug there that could possibly be leaking. Otherwise I would say its running down the head from your valve cover. The only thing that could really leak in an area like that is coolant, if it seeped up an improperly sealed head bolt. There is no oil in that area, aside from the possible oil gallery plug I mentioned.

 

Thats what I was kind of leaning towards, being something to do with the oil drain in the head, and it is on the drivers side. Its not coming from the valve cover either, thats why I was just really perplexed about this. Im just hoping all I did was damage the gasket somehow when putting on the head and thats the problem, that way Ill be able to see and remedy it. Because if its not that Ill be real hesitant to put it all back together only for it to happen again. I dont know would maybe some sort of blockage of the drain cause it to seep out?? Im just trying to get ideas of any possibilities on this.

 

If it didn't leak before the cam swap, none of those things make sense that they would leak after.

The things you disturbed, those leaking make sense.

 

Mine leaks in the same spot, but on the pass side. I havent been able to figure out what it is either. Been meaning to get a mirror back there. Drips right on my collector, along with the leaky seperable header tube (2210) its a little smokey over there.

Isnt it great getting a new motor together and having it leak already?

 

Im gonna pull the head tommorow and be real careful about it so hopefully I can see if anything is flawed under there. Im really hoping I can tell if the head gasket has some sort of damage to it, but as it is its undrivealbe which is killing me cause I need to get it to the exhaust shop to get some pipes run.
I was having a hard time pinpointing the leak, but luckily I had a large dentist type mirror on a stick that I poked back there and saw it clear as day.

Five7Kid-- Youre right. I mean it didnt leak a drop before I did this swap. So it has to be something that I disturbed head wise. Im just hoping I can get some answers when I pull the head.

 

Pulling the head will accomplish nothing. You couldn't have "disturbed" anything on the head during a cam swap that would cause it to leak.

 

Its my only option. What do you propose I do? The oil is clearly coming out from where the head mates with the block. The head is not in question, but the head gasket is. I mean there is nothing else there besides the head, head gasket, and block. I did pull the heads to have them modified, and put new gaskets in during the cam swap so something could possibly have been disturbed. Maybe not getting the block surface clean enough? Maybe damaging the gasket when reinstalling the head? Right now I dont know what it could possibly be, but since that is where the leak is coming from I gotta pull the head.

 

i did not read it all

but

I had a problem just like that and it turns out the corner of the head gasket was bent back

if you do not have big guns dont set a head down by yourself

 

The rubber piece at the end of the gasket or a valve cover. If you see oil pooling at the base of the head that doesn't mean it's coming from that location. Really, with a blown head gasket, you'll see coolant before you'll see oil. Be 110% sure.

 

im going to second that pulling the head just isnt the answer and it isnt worth it. If pulling the head would fix it, I'm not sure I'd even bother with it then. I'd just live with the leak, LOL. I've torn these things down more than enough times to get my fill of it and pulling a head while hte motor is in the car is pretty inconvenient...

The way I see it, it's either coming from the intake manifold, the oil gallery plug, or the valvecover. ANY of those 3 options can cause oil to seep down the block down that angle there. There is nothing there but coolant. The only way oil could come out right there is if you're leaking out combusion chamber fumes from it at the same time, and even with that ridiculous scenario, I doubt much oil would make it.

It's coming from somewhere else and making it's way down there.

 

I just got done pulling the head, and its a gasket failure. It wasnt sealing anywhere. Where the initial leak was coming from there was oil under the gasket. Water was leaking in too. Theres trace amounts of liquid in 1 and 3, and it looks like oil was getting in the water. I took a pic but its with my phone so its not great, but theres definitely liquid down around the ring. I really hope it wasnt enough to do any damage; like I said I havent had this car on the road yet. The longest Ive had it running was during the 20min break in, and it wasnt leaking anything during that.

 

that liquid is such a small amount that i would be willing to bet it is what remained in the head after you drained the coolant... and pulled the head
like they said before a blown headgasked that is leaking oil is probably one of the more impossible failure modes....

which one of those cylinders is the cleanest on the drivers side?

 

The pic is of 1 and 3 with 1 having the most water in it. 5 and 7 were bone dry, but like I said before there was oil under the gasket all around the drain where the initial oil leak was coming from at the back of the head. The water jacket had some funk in it like oil was getting in.

 

ok... guess you think you found the problem... nothing left to do now but replace that gasket and pray... i do suggest the pray part as again this is a near IMPOSSIBLE situation

 

Yes, I will be praying lol, but then again I have come to expect the impossible during this project. There have just been several bizarre things that have happened, this being one of them.

 

Are your heads warped? I guess it didnt seal at all on the front half of the engine.... that's pretty odd.

 

carpenter square

a big one