96 850t burning or leaking coolant after head gasket

Post by **rspi** » 31 Oct 2013, 16:33

Maybe the copper spray bite you somehow. Before you put the gasket on the block, did you go over the block surface with acetone? Same with the bottom side of the head? As you seen on my photo's, that head and block were very clean.

I believe the head gasket on our S70 failed due to something not being perfect with the previous head job. Two years after we had the car we started having a little coolant loss. A year later we were loosing 8 oz per week (about 60 miles). When I pulled the head the seal wasn't that bad so I knew it wasn't on there long. I did that head 15 months ago and all seems well for now.

futureboycolin · Post by **futureboycolin** » 31 Oct 2013, 16:37

I made those mating surfaces spotless.

I'm thinking that maybe the head was a bit warped, and the cleaning exposed that? It was pretty gunky.

Another possibility is that I scrubbed too hard with the plastic Brillo pads. The Permatex copper may also be the issue. Any way I turn it, when I get the head off again I guess I'll find out what went wrong. I'll keep you posted.

Post by **rspi** » 31 Oct 2013, 16:44

Plastic should NOT have done any damage.

Did you use ACETONE before putting the gasket on?

futureboycolin · Post by **futureboycolin** » 31 Oct 2013, 16:46

Yeah I scrubbed the head and block down with acetone soaked Green Brillo pads. It was super clean.

futureboycolin · Post by **futureboycolin** » 31 Oct 2013, 17:13

I already ordered the parts for a head gasket job.

I really couldn't find any external leak. I topped up the coolant again, and I have a new lower thermostat housing with new bolts and gasket on the way too. So if that doesn't fix it, I don't know what it could be.

There was no head gasket issues before I started this job.

The thing that gets me is that the exhaust is misty...not opaque white fog, but definitely misty still, and it's been driven a bit since I repaired it. The complicating thing is that it's been cool and humid in N Indiana... It can't take longer than a couple drives for all the residue of the job to burn off the cylinders, can it?

I topped up the coolant again, and if it leaks out by Monday, I guess I'll know it's external. Hopefully if that's the case then FCP will let me return the parts I don't use. I'll post a video of the exhaust on Monday before I start anything.

futureboycolin · Post by **futureboycolin** » 31 Oct 2013, 18:24

http://www.cadillacforums.com/forums/ca ... never.html

Oh S#!t.

Post by **erikv11** » 31 Oct 2013, 18:56

I have only seen one internal head gasket leak of this type, it was similar to what you describe: misty not opaque. The other giveaway is that a lot of moisture would drip out of the exhaust pipe, from it condensing on the pipe walls.

I agree with you, a couple drives should burn off the great majority of residue. From the inside absolutely, even from the outside of the engine though.

Post by **erikv11** » 31 Oct 2013, 19:05

I don't think scratches are in themselves a problem (I think I am referring to your other thread where you mentioned scratches ... sorry about that), but if I see any scratches at all then I stop doing whatever is causing them. If something can scratch the block, then it can in theory scratch it enough to wear a low spot. I've never used green pads, I asked around a lot when I did the first one and since some people advised against it, I stay away from them. A good gasket remover and a razor blade has been the only way that has seemed adequate to me. And a razor blade you have to be very careful with, keep it vertical and scrape with it, do not gouge the block.

Someone with experience can tell you if a block has low spots using a straight edge.

Acetone is great for removing oily residue but will do nothing to dissolve the really crusty gasket bits adhering to the block.

Post by **sdube** » 31 Oct 2013, 20:52

it's possible the thermostat housing is only leaking when the car is running. I had this problem before. I had cracked the thermostat housing while replacing the thermostat, when I put the new one, I didn't tighten the lower bolt enough and it was leaking really bad - only when I drive the car.

Post by **rspi** » 31 Oct 2013, 20:54

I asked about the acetone to make sure the surfaces were dry and oil free after all the other cleaning.

As for the scrub pads... are all of those little green plastic type scrub pads Scotchbrite pads? I think I used one of those a little. I did spend some time cleaning behind it to get all of the little pieces cleaned up. Scary!