I've been told that when a head gasket blows, the block is also sometimes cracked. I did a compression test on the side with blown gasket and the numbers all came back high(all ~150). Does this mean my block is just fine? What sort of head work needs to be done in order to make sure everything will be fine again? Is there any other possibility that something else may also have been damaged?

 

basically you dont want your coolant to get in your oil and run on that it will destroy the internals. uhh if block is fine which is should be most cases then just take the heads off send them to a machine shop to have the works on them. they make sure theyre flat, redo valve seats most likely, and can pressure test them.

 

When the head gasket blows the block is sometimes cracked? lol
I think their head on crack. Unless something catastrophic or unusual happened the block is fine. Just check it for flatness.

 

Warped, maybe, but not necessarily cracked.

 

Its really depends on why the head gasket blew. If it got way too hot, then its possible the block is warped or cracked (or the heads too actually). If it was a flawed gasket (unlikely, a flawed one won't last very long) then the block is probably fine. Its really luck of the draw though. How much does Jeebus like you right now??

A pressure test of the cooling system is the only good way to find out. If theres an external leak, it will probably be visible during the test. If its internal, it will show by losing pressure fairly quick. If it doesn't lose any significant amount of pressure, you're ok.

If you get water in the oil, it will look very milky, similar to a chocolate milkshake. Water is not a very good lubricant.

 

Air_Adam: That's a great question, about why it blew--I have no idea. Relatively low miles(1200 or so) on the engine, temps have always been great as well. I'd hate to just replace it without knowing why it blew to begin with.

 

If it went that soon then it was probably an installation error.

 

Did you use sealant on the head bolt threads ? If not The threads will leak coolant into the cylinder's And will be just like a blown head gasket . Years ago a friend of mine messed up a real nice 1972 350 4 bolt . He put no sealant on the head bolts on the build . The coolant / water rusted 2 cylinders from sitting in them .

 

Why do you think you've got a blown head gasket?

 

Then it doesn't have a blown head gasket.

What's REALLY going on here? Any history to this?

Often, when a head gasket blows (especially the usual, between cylinders) and people keep driving it anyway, the hot combustion gases blasting through the gap, scour a rut in the casting. A new gasket can't possibly seal to that; it requires decking the block and/or head to restore it to flatness. That's about the only form of damage to the castings that a blown gasket causes. It won't create a crack.

On the other hand, depending on why the gasket blew in the first place, the same thing that caused the castings to warp bad enough for the gasket to slip out, might also have caused them to crack. This would be a possibility in SEVERE overheating, like total coolant loss and the driver kept on driving it until it absolutely wouldn't drive any more. You didn't do that, did you???

But it doesn't sound like you have a blown gasket in the first place, so I don't see any need to get all worked up over any of that, at this point. Even if it is, sounds like it's just a 6-cyl, so don't waste any money on fixing it; that's just crazy talk. Throw it in the trash and get another one at the junkyard, it'd be FAR cheaper and easier.

 

I've definitely got a puddle of oil/coolant, which is the usual indicator for a blown head gasket.

The history is that I was driving to work when I notice a cloud of smoke behind me. When I stopped, there was a cloud of smoke coming from the engine bay. The driver side exhaust manifold has a huge burnmark where oil was hitting it and burning off right at the point it turns down to the y-pipe. There's oil all over the driver side firewall.

As to junking it... I'm going to pick up a 3.4 from the junkyard today, if they have any left, but if I could fix this one cheaply, I can replace my worn-out low-power 2.8 in my '83.

 

Ummmm..... no.

It's the usual indicator of an intake gasket leak, or a water pump leak and a valve cover gasket leak at the same time, or a freeze plug and an oil pressure sending unit, or a thousand other combinations of common failures. To bypass all of that and jump straight to "head gasket" is madness. There's almost NO POSSIBLE WAY for a head gasket to leak both of those fluids externally.

While I've never worked on one of those 6-cyls, never even really seen one in one of these cars except to notice one there and quickly avert my eyes in shame, I hear from my little bro who has one in his S truck, that the distributor O-ring is a constant source of oil leaks; and that he replaces his every few months because of it. And of course, the oil pressure sending unit (which I don't know where it is on those) is a known source of leaks in just about EVERY kind of motor; if that happens to be above your exhaust soakment, then it could also be the source of the oil.

Rather than jumping hastily to erroneous and unfounded conclusions about head gaskets and engine replacements, a smarter thing to do would be to get a couple of cans of engine degreaser, go to the quarter car wash, soak the whole motor - top, bottom, front, rear, and sides - in it for a while, and blast it off until it's sterile. That way, you can take the direct path to a repair, by actually SEEING where the leaks are coming from instead of guessing or assuming, and fix them. And then, even if it turns out that you DO need a new motor or a head gasket or whatever, at least you won't be forced to wallow around in a sea of slime and funk for days on end, because instead, your engine room will be clean and schmutz-free.

 

Pressure test your cooling system, like I suggested before. It will tell you where the leak is coming from, and how sevre the leak actually is.

 

I ended up pulling the engine since I need to replace the main bearings and got a better look. There was a ton of coolant still in the engine, perfectly green. All the oil that came out looked great. The valve cover on that side was a major pain to get off, due to so much sealant I used last time I installed. No evidence of a leak at all.

I did notice a small puddle of oil inside the open hole on the oil filter housing. I wonder if that has somehow gone bad and was responsible for shooting oil everywhere? Intake manifold looks to be perfectly seated with no evidence of an oil leak at all. What I'm still trying to figure out is how exactly the oil would leave a burn mark on the top of the exhaust manifold... there's nothing there that could shoot out in enough force and in that area.

How do I do a pressure test of the cooling system?

I'm considering fabbing up an engine cradle and starting the engine on that, to get a better look at where the oil is coming from.

 

When you took it to the quarter car wash and cleaned it up as described and easily observed the FRESH leak on your CLEAN engine, where did you see the oil?

 

No where, because I didn't take it. It blows oil out too quickly to be driven(all of it in about a mile). So at this point, I'm still guessing, but observing, and making notes about things to look at. Once I get the main bearings replaced, I'll drop it back in and find the leak-- with bad main bearings, it won't keep the idle steady and oil pressure drops as a result.

 

If it blows oil out that quickly, it shouldn't take you more than a minute or two of looking to figure out where it's coming from.

 

If this is a gen 1 small block... did you remove the AIR pump and its bracket from this engine?

 

Back in October, I unhooked and plugged everything for the AIR system, but left the pump there.

When it first blew, I looked but couldn't tell. I was afraid to start it back up due to concerns that it may have been a head gasket and starting it was going to damage it further.