Steamy Exhaust - Blown Gasket?

A couple of weeks ago the Falcon burped some coolant. Checked the radiator, found it low, added coolant, temp tested it, all was fine.

A few days ago, temps spiked hotter than common, then came down to typical. Found my coolant low again, added, all was fine again. Suspect a sticking thermostat. :!:

Just yesterday, did it again. Time to replace the thermostat. Temp got high, but never not outside of "normal".

Today, similar spike, similar return to typical. Then temps started running all over between typical and hot, still never above "normal". New development : a lot of steam coming from the exhaust, like on a cold morning, but the weather is dry and mid-60's. Checked the coolant, 1/2 gallon low.

I suspect a blown head gasket (shim) letting coolant into the combustion chamber. I haven't checked which cylinder yet. Oil and coolant are not mixing. Exhaust is not smoky, but steamy, excessively steamy. All runs well otherwise. What's the likelihood of this? Perhaps the head cracked? :arg:

I think I'm going to source up a head gasket and try swapping it first before I commit to replacing the head or engine (I want to swap for a 7-main anyway).

Thoughts or experiences? Advice?

Today, similar spike, similar return to typical. Then temps started running all over between typical and hot, still never above "normal". New development : a lot of steam coming from the exhaust, like on a cold morning, but the weather is dry and mid-60's. Checked the coolant, 1/2 gallon low.

I suspect a blown head gasket (shim) letting coolant into the combustion chamber. I haven't checked which cylinder yet. Oil and coolant are not mixing. Exhaust is not smoky, but steamy, excessively steamy. All runs well otherwise. What's the likelihood of this? Perhaps the head cracked?

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Your are probally right on the head gasket they useally get progrssively worse. Cracked head will show up as pressure in the cooling system also a possability you can check that with a tester. I have used KW Block sealer somtimes as temp fix if needed to keep using the car

Pull the spark plugs. If you do it hot you may see steam coming from the problem hole. Also the plug will be steam cleaned. The bad thing is the whole cylinder is now also steam cleaned including the lubricant so the rings are starting to dig into the bore. The spikes are coming from the compression blowing bubbles into the cooling system. The bubbles build up till they finally move. The water pumps cant move air so when you get air in the pump it makes things really hot really quick.

It'll be a week or so before I can further check this. Thanks for the input.

8) i agree that it does sound like a bad head gasket.

Speaking of head gaskets... does anyone recommend one over another?

The originals were steel shims. CI lists 2 layered gaskets. Summit has a different one. I haven't even checked the local parts places yet.

I have a can of copper based spray adhesive/sealant. I bought it for an exhaust gasket some time back. Supposedly it can be used head gaskets as well to decrease the chance of failure. Ever used the stuff?

I'm hoping to get around to checking out my problem this weekend. Life keeps getting in the way.

You'll find a few adherents of spray sealer to augment a standard gasket. I'm one, liking Hylomar blue spray on both sides.

A couple of the old schoolers here, still like the aluminium paint.

Most important thing with a "BHG" is to determine accurately why it failed. Incorrect torquing (bad threads, human error, fastener problems), corrosion, overheating (warpage) are all common enough contributors. Knowing the cause makes a repeat far less likely.

Regards, Adam.

Pull the spark plug and see if one or more are steamed clean. Besides the gasket it could also be a cracked head or cylinder. I had a Pontiac V-8 develop a crack in the bore of cylinder #8. I was all ready for a failed head gasket and had to go to plan "B". Anyway, I noticed low coolant and no external leaks. It was the clean spark plug that told me what cylinder the problem was. But it wasn't until I pulled the head that I knew for sure.

I replaced the thermostat today, it was giving me a little grief and may have been the primary culprit. The temps did spike a couple of times with this 'stat even when the coolant level was good. So now that end is good.

I checked and cleaned the plugs and none looked suspect to the steaming. However, as #4 was fouling out (happens periodically), I found that #3 (not uncommon) and #6 especially (odd) were fouled.

With a fresh 'stat (180 degree), topped coolant and clean plugs, I fired her up. She idled just fine, stayed cool and no steam for about 45 minutes. Confident, I took her out for a lap around the block, about 3 miles part of which on the highway. All seemed well except for a little stumbling at idle after a long decel with downshifts, which cleared up shortly after getting underway again. This isn't too terribly uncommon as the intake tends to load a little rich around 3 and 4 and lean at 1 and 6. I suppose about everyone has this problem or one similar to it.

Checked the coolant level and the darn thing was low.

I topped it off again, thinking maybe she burped an air pocket(s) at speed that she couldn't at idle. After all, I did drain the radiator to swap the 'stat. Drove for another lap. All seemed well still.

Checked the coolant level and the darn thing was low.

I suspected that the radiator cap was allowing coolant by. There was evidence of this from the overflow tube. 10 months ago, I swapped in an aluminum radiator http://fordsix.com/forum/viewtopic.php?f=10&t=60817. During such I found that the lower seal didn't fit tight to the bottom of the fill neck, so I added a rubber washer to tighten it up. Today, I pulled the rubber out, thinking maybe it was causing the coolant pressure to run too high, and added one against the cap since the top seal has never sealed well, this was evidenced by coolant blowing past the cap during one of her big burps. I put the rubber back, topped of the radiator and drove another lap. The idle stumble got worse and took longer to recover. Got back and guess what!

Checked the coolant level and the darn thing was low.

With no external leaks, still no visible steam, I pulled the plugs. #6 showed the tell-tale steam clean on the exhaust port side of the plug. All of the other plugs looked normal, so the problem is isolated to the #6 cylinder. I suppose the extra neck washer keeps the pressure high enough to force more coolant into the 6th cylinder. Next step is to pull the head and check the gasket. I'm hoping to get to that next weekend.

FIXED!

I pulled the head Friday evening to find the head gasket had deteriorated between the rear passenger side water jacket and the #6 cylinder bore. All else of the gasket appeared fine.

I cleaned the head thoroughly, de-crudded the combustion chambers of the years of carbon build-up, same for the block and pistons, chased all threaded bosses, and checked the deck for stresses and warpage. I coated the gasket surfaces on both the head and the block (masking the combustion chambers, pistons, and jackets) installed a couple of head alignment studs (7/16-14 partially threaded hex bolts with the heads cut off) and reassembled. Total time was about 8 hours, split across Friday evening and Saturday.

Today, I got the chance to run her through a heat cycle to check for leaks. Then test drove her for about a 5 mile loop. All checked fine, the plugs look clean, and she idles smoother now than she did before the whole problem started. The slight low-rpm spark rattle went away as well, thanks to the loss of the carbon build-up.

Tomorrow she'll return to road use.