Opinions anyone? I have an sbc 350 that I pulled from another vehicle for use (hopefully) in my 39 Poncho. I had dreams of a minor refresh (hone, rings, bearings,etc) The engine ran fine when pulled but would steam excessively for about 20-30 minutes at idle, so I was hoping to find a bad head gasket. I finally got around to doing a compression test and pulling the heads and I’m a bit baffled. Compression as follows- first reading/ reading after squirting oil into the cylinder. #1. 165 / didn’t oil it. #2. 165 / didn’t oil it #3. 140 / 150 #4. 90 / 100 Evidence of water intrusion? #5. 140 / 150 #6. 110 / 130 #7. 90 / 130 #8. 120 /160 So much for the el cheapo refresh… The #4 cylinder wall looks “mottled” like it’s been full of water? It’s not pitted, just discolored. I thought I saw evidence of a crack in the wall, so had a buddy perform a dye penetrant inspection and it looks good. There was no evidence of a blown head gasket. The plug looks the same as the others. Cylinder head valve area and piston surface are not “steam cleaned” and look like the others. I’ll call the local machine shop this week I guess and have the heads and block checked out.. I’m just wondering if any of you HAMB’ers out there have seen anything similar?
When you say "steams excessively" do you mean there is vapor coming out of the tailpipe? Sure looks like #4 has had some moisture in it at one time or another. Do you know the history of the motor?
#4 had water in it for sure, most likely was stored uncovered in the past and the intake valve was open on that cylinder.
yeah, condensation from an open valve, during storage, leaves pitting over a large area of a bore. But usually you can feel the pits.
The engine came out of my school bus. It came with the bus and has an unknown past. I drove it all over the southeast US with no issues, except the steaming. When started a LOT of white steam would come out the tailpipe. Kind of like a steam locomotive…big cloud. At idle, it would take 20 minutes or more to clear up, regardless of weather, and then no steam at all. Didn’t seem to use water at an excessive rate either. The bus has a cavernous exhaust, so I figured maybe it’s just condensation boiling out? BUT, after planting a new engine in the bus, no steam, so it has to be something with the engine. hmmmm …
block or head cracked or a rust or casting defect hole through one, or a head gasket leaking, are the likely suspects.
Well…you’re exactly where I’m at, except I find zero evidence of any of them. Hopefully the machine shop can shed some light.
the few engines I've seen with a lot of steam, had a very clean spark plug to point me in the right direction.
Can you post a pic showing the deck. Looks like head gasket is still on there. From the discoloration around that cylinder looks like head gasket issue, could be deck or head related. Better pics of the gasket and deck itself will give more info.
I see possible evidence of water leakage on #4 just above the water passage to the lower left in the picture. I would have it checked for cracks, decked and bored to the next oversize. Overhaul kits are not too expensive to make a good engine.
Asside from the compression numbers, and what the cylinders look like...White smoke out the tailpipe could also be a blown transmission modulator valve...sucking trans fluid into intake
Also smoke propagates and dissipates differently in the air from steam. Depending on the weather conditions, smoke will hang in the air, while steam will cool and disappear.
My experience in this regard was an off topic 70's era Ford product. The smoke was white. No blue tint that I could see...the other telltale that the smoke had something to do with the transmission was how erratically it shifted.
Around here, steam usually disappears very soon after it leaves the tailpipe. And I've seen white from ATF burning, also.
That right there looks like a blown/leaking/seeping head gasket. Also seems to correspond with the clean area of the piston top.
I’m with every one else on the deck issue. Pic of the heads would help. And I would pressure test the heads if it were mine before I spent any money on machine work.
that cylinder looks like it is cracked around the 7 o,clock position just below the blue mark that "badshifter' put two post up,