Well just when you think somethings gonna last forever............

crap.

So, it consistently keeps fogging a bit out of the port every time you crank it?

You also double checked the manifolds dimensions as it sat down into the valley without gaskets.. so you know gasket crush will at least be decent enough? And you also sealed around your water ports with an extra dab of sealer for good measure?

Probably a dumb question here.. but before you button it back up.. can you get a mirror down next to the exhaust port to see if its weeping inside the exhaust port itself? Or maybe even clean it with solvent the best you can and then dry it out real good to use your finger down inside after you apply pressure? Could also just leave the paper towel stuffed down inside the port and apply pressure for a bit to see if it catches any moisture without having cranked it over?

Main reason that I ask is that the steam from the intake port leak may have overheated and cracked the floor under WOT/longer runs, as we had originally guessed. Funny as that sounds that steam would do more damage than fire in a port.. the extra water vapor running through the exhaust port has been known to cause cracks as it supposedly allows much greater heat soak into the aluminum as the gas passes through the port. Causes the port to remain a bit wet and stays hotter bewteen the power strokes.. causes heat spikes. Cleans everything up real nice.. just not so good for older AL. Never seen it actually happen.. I just hang on some of the smarter guys coattails and parrot what I've heard through the years. Probably stretching it a bit and just a WAG.

Hope everything works out for ya.

 

The puffs clear up after a few revs of the starter. I've got it all buttoned back up, fixing to fire it off this afternoon. You can see the exhaust port without any kind of aids. There's no coolant/water/moisture there at all. That was my first guess as to where the coolant was getting into the exhaust, a leak in the port floor, but that never panned out. The port has just as much soot inside it as the rest.

 

Well all that work was for naught. Cranked it up late this afternoon and right off it had a dead miss that wasn't there before. Killed it and decided to pull the plugs and check em to see if maybe I cracked one removing them. Started with the #4. It looked OK, but I decided to crank the starter again to see if anything came out of the hole. Well something did, namely water. Not as much as did before I started this work, but enough to tell me to stop where I was and tear it down again, this time the heads will come off to see what's happened inside #4. Only bright side is I've yet to spend a dime on it so far. The header and intake gaskets were stuff I'd bought in the past that were left over's.

 

I'm startin' to think now that you popped a gasket.

Did the engine ever overheat before you realized what was going on here?

Did you pull on a couple of head bolts to make sure everything's tight?

 

it's an 11 year old rebuilt engine...time to bebuild again...

 

Maybe resealed but I doubt rebuilt...

 

It's overheated dozens of times in the past 11 years. Never blew a head gasket (Felpro expanded graphite sprayed with Copper Kote) I'm thinking maybe the seat inserts have somehow loosened in the heads, or it's cracked the chamber roof. Going back to work for the next 4-5 days so I won't get a chance to fully tear it down anytime soon. I haven't checked the head bolt torque, I'll get an idea when I get to that stage of unbolting the heads.

 

Well I finally got around to pulling the heads off and am pretty sure the head is OK. The gasket appears to be blown. It's pushed the fire ring slightly out into the (#4) cylinder. Also slightly less so in the case of the #3 fire ring as well. I'll get some pics later today. As for the use of the Felpro 1262R gaskets on the intake, they squish just fine, I used some RTV around the coolant ports, that turned out to be completely unnecessary. There's no intake to head anomalies as far as fit. And these heads were milled .060 for a previous engine build. It still amazes me as to why very little coolant found it's way into the oil pan on this 11 year old engine. But after seeing the cylinder walls, that answered my question. There's ZERO wear in the bores. Very little carbon buildup in the cylinders too, but that I attribute to the fuel I've fed it over the years, 90% of this was Chevron 93 premium. The other 10% was other name brand fuels (Shell, Texaco, Conoco) Gonna clean up the heads and check the deck surfaces with a straight edge before deciding on whether or not to send em to the machineshop for a pressure test. Might do it anyway just to get the valve guides checked out.

 

That's what I thought, Leak down test is your best friend.

 

HUH ???

 

Ok, got some time to work on it today after enduring the IRS's abortion called "Obamacare" . The head gasket after closer inspection was blown between the #3 & 4 cylinders, the coolant found it way into the #4 via the fire ring which was pushed out slightly into cylinder. This is a first for me as all other head gasket failures I've dealt with were of the "catastrophic" type. (all the sudden) . This was what you'd call a "slow motion" event that started with a slight leak and gradually got worse. The head is fine as is the block and rotating assembly, no wear in the bores at all, pistons look much as they did 11 years ago when I bolted the heads on. What little carbon buildup came right off with spray carb cleaner. Ditto for the heads, the thin layer on the heads of the valves was a little harder to remove, had to use the old wire wheel on the drill. Now waiting on my order for gaskets to get here from Summit Racing. I used the 9333PT1's last time, this time going with their graphite racing gaskets. Should be good to go for another 11 years.

 

Glad you finally got it sorted out and figured that had to be it.

Hopefully I don;t start another debate session as that's not my intent.. but also wanted to quickly mention that running your temps that high will easily cause the gasket squirm that seems to be occurring here. Seen lots of intake gaskets like that through the years and composite head gaskets on iron block/al heads don;t really care to move that much over the long term either. MLS will easily handle that extra movement and can also be reused to make them cheaper in the long run. My near 12:1 Cheby will be buttoned back up for the 4th time with used cometics and never an issue. Saves me money every time I tear it down and freshen it up.

I'd try like hell to keep temps lower and not surpass 230'ish if at all possible. And running cooler will allow slightly thinner oil packages along with more aggressive tunes as well.

 

You are already half way there,do the hd gaskets to or you might be kicking yourself.Aluminum expands 5 times faster than cast iron & your hd gaskets are constantly rubbing between those 2 surfaces & over time it takes it`s toll.I did auto machine work for 7 yrs & have seen it many times,I`d hate to see you shoot yourself in the foot.

 

Oh sorry, I had made a post earlier in the thread suggesting you perform a leak down test to make sure it was safe. The leak down test would have quickly shown you had a blown head gasket.

 

Not in this case. The pressure would have been counteracted against the coolant in the system. Only a full draining of the system then leaving it sitting for hours under pressure would yield results, and any leakdown would have been attributed to the pressure getting by the rings. The coolant leak was miniscule from it until that last couple times the car was run. Even then it wasn't enough to cause a misfire till the gasket fully failed. This is why it had me puzzled into believing the heads were somehow the culprit.