Ok, here's the short story: I picked up a 1996 Ranger XLT for $500. After some repairs, I started driving it to work. The engine is quiet other than the timing belt tensioner. The power isn't great, but it runs ok. I have 235/75/15 (29 inch tall) tires and 3.45 rear gears, so I'm sure that doesn't help. I changed the oil and filter along with the fuel filter. I've driven it around 100 miles. I checked the oil and I'm about a quart low. I found the oil, it's in the air intake tube. Needless to say, if you remove the oil dipstick tube, oil fill cap or the hose connecting the valve cover to the air intake tube, you see smoke! Like a train! I haven't done a compression test yet. I found what looks like water in the oil (white-ish creamy) on the dipstick. Here's my question: How can you tell the difference between a blown head gasket and a bad cylinder?

 

Water in the oil is most likely a blown head gasket, that is the number 1 cause or a water jacket wall that has a hole in it. Since you said smoke is pouring out, that is what makes me think that. I would definitely get it fixed as soon as you can afford to and hopefully it is just the head gasket.

 

If you find oil in the intake, Check your PCV valve (or positive crankcase ventilation valve) it gets stuck from oil residue and stays open so not only gas escapes. Oil comes with it.

 

muddy, whiteish colored oil is a sure sign of a blown head gasket, probably blown into the exhaust as well if it smoking, probably steam more than smoke, good luck getting back up and running

 

don't run it anymore than absolutely necessary, anti freeze will tear the hell out of the bearings

 

Update/more info: I just changed the PCV. It looked like the original PCV, but the smoke didn't stop. I only drove it about 100 miles and about a quart of oil ended up in the air intake tube. Is that a lot of blow-by for a blown head gasket? Or is that a piston that the rings are shot? The truck sat for about 1-2 years, so the radiator was clogged. I had been trying to flush all of the rust and deposits out, so it only has water in the cooling system. I ended up replacing the radiator and all the hoses. The smoke that was coming out of the dipstick tube was white but didn't have a burnt oil smell. There is no blue smoke coming out of the tailpipe either. That being said, should I look more at the head gasket vs. piston rings?

 

Could be both. Do a comp test, that will narrow it down.

 

Hey Morris, How could a compression test tell if it's a blown head gasket vs. a bad cylinder? If the head gasket is blown, wouldn't the compressed gases just leak out the dipstick tube? Of course, if it's a bad cylinder the compression would be low. If it were the rings causing the problem, wouldn't there be blue smoke coming out the tailpipe?

 

I'm not sure if it would tell you if you have a blown head gasket. I'm just going on the fact that if compression is low, it would tell you if the rings are bad. I had a bronco that had bad blowby. It blew smoke out the exhaust and I got a ticket and had to pull it off the road.
Oil in the intake is that pcv vent for sure. You said you changed it and still had oil. Idk then, I'm not sure how else oil would get into the intake.

Like others have said, water/coolant in the oil is a sign there is a blown gasket. I also don't know much about how a comp test works. I've never done one. I just know that it can tell you which cylinder has low compression.

 

a compression test can tell you if you have a blown head gasket, or it can deceive. I've been told that if you have a blown head gasket between two cylinders, you may not read low compression, because they're piggybacking off of each other. I did a compression test on my jeep with a extremely low compression in cylinder 1, and I tore it down only to find a good looking head gasket that was perfectly fine. put a new head gasket in it, but haven't checked compression, and it runs fine, although it has a bit of a skip at idle. here is some stuff on blown head gaskets.. heres the link if you want to read them all, if not, here is a few.. http://wiki.answers.com/Q/What_are_t...wn_head_gasket

Low compression does not necessarily mean a blown head gasket, but it is a good indicator if there is a sharp drop in compression on one or two cylinders, with no drop in the others. Sometimes a blown head gasket will cause a whistling or wheezing sound, but not always. It will not always cause water to enter the oil - or oil to enter the water - but they are signs to look for. Overheating will almost always occur, due to the exhaust entering the coolant. Check your overflow bottle for exhaust smells. Watch for bubbles or overflow of coolant from the radiator while running the engine. Check for muddy gray-looking oil or bubbles on the dipstick.

Often (but not always), a blown head gasket will also cause deposit of water on a piece of cardboard held an inch from the tailpipe output while the engine is running (when this is happening, it is likely that the catalytic converter has been ruined and the muffler will corrode in short order as well). Sometimes drops of water will be seen dropping from the end of the tailpipe.

One of the most common tell-tale signs is a milky-gray ring around your oil cap. When coolant enters the engine oil through a crack in the head or through a blown gasket, it evaporates and leaves a milky ring around the oil cap. Another easy way to tell is to check your oil dipstick. Change your oil and pull out the dipstick. Make sure that you take note of how far up the dipstick the oil is. Top off your cooling system and fill your cooling reservoir to the top. Screw radiator cap back on and start engine. Run engine for about 20-30 minutes or until it reaches normal operating temperature. Allow engine to cool (engine must cool completely to get accurate oil reading). Check oil dipstick again. If the oil has a watery appearance and has risen noticeably up the dipstick, then you probably have a blown head gasket or a warped head. Also, look for a sweet-smelling liquid coming out of your tailpipe. Any of the above symptoms could be the result of a blown head gasket.

 

oh, and another thing, you can tell if its a valve leaking by blowing air into the cylinder and listening for it to escape around and into the valve cover. and if you squirt a bit of oil into the spark plug hole onto the piston, and run the compression test again, if the compression is back up to normal, its the ring.. I can't remember how much oil it is exactly, but its really not much. start out with a very small dose of oil, test it, add maybe double that much oil, test, and so on.

 

Let it run with the radiator cap off and watch in the radiator for bubbles. The combustion gases will come back through the cooling system.